scrub.c 93.2 KB
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/*
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 * Copyright (C) 2011, 2012 STRATO.  All rights reserved.
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 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/blkdev.h>
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#include <linux/ratelimit.h>
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#include "ctree.h"
#include "volumes.h"
#include "disk-io.h"
#include "ordered-data.h"
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#include "transaction.h"
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#include "backref.h"
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#include "extent_io.h"
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#include "dev-replace.h"
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#include "check-integrity.h"
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#include "rcu-string.h"
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#include "raid56.h"
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/*
 * This is only the first step towards a full-features scrub. It reads all
 * extent and super block and verifies the checksums. In case a bad checksum
 * is found or the extent cannot be read, good data will be written back if
 * any can be found.
 *
 * Future enhancements:
 *  - In case an unrepairable extent is encountered, track which files are
 *    affected and report them
 *  - track and record media errors, throw out bad devices
 *  - add a mode to also read unallocated space
 */

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struct scrub_block;
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struct scrub_ctx;
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/*
 * the following three values only influence the performance.
 * The last one configures the number of parallel and outstanding I/O
 * operations. The first two values configure an upper limit for the number
 * of (dynamically allocated) pages that are added to a bio.
 */
#define SCRUB_PAGES_PER_RD_BIO	32	/* 128k per bio */
#define SCRUB_PAGES_PER_WR_BIO	32	/* 128k per bio */
#define SCRUB_BIOS_PER_SCTX	64	/* 8MB per device in flight */
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/*
 * the following value times PAGE_SIZE needs to be large enough to match the
 * largest node/leaf/sector size that shall be supported.
 * Values larger than BTRFS_STRIPE_LEN are not supported.
 */
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#define SCRUB_MAX_PAGES_PER_BLOCK	16	/* 64k per node/leaf/sector */
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struct scrub_page {
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	struct scrub_block	*sblock;
	struct page		*page;
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	struct btrfs_device	*dev;
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	u64			flags;  /* extent flags */
	u64			generation;
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	u64			logical;
	u64			physical;
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	u64			physical_for_dev_replace;
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	atomic_t		ref_count;
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	struct {
		unsigned int	mirror_num:8;
		unsigned int	have_csum:1;
		unsigned int	io_error:1;
	};
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	u8			csum[BTRFS_CSUM_SIZE];
};

struct scrub_bio {
	int			index;
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	struct scrub_ctx	*sctx;
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	struct btrfs_device	*dev;
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	struct bio		*bio;
	int			err;
	u64			logical;
	u64			physical;
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#if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
	struct scrub_page	*pagev[SCRUB_PAGES_PER_WR_BIO];
#else
	struct scrub_page	*pagev[SCRUB_PAGES_PER_RD_BIO];
#endif
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	int			page_count;
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	int			next_free;
	struct btrfs_work	work;
};

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struct scrub_block {
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	struct scrub_page	*pagev[SCRUB_MAX_PAGES_PER_BLOCK];
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	int			page_count;
	atomic_t		outstanding_pages;
	atomic_t		ref_count; /* free mem on transition to zero */
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	struct scrub_ctx	*sctx;
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	struct {
		unsigned int	header_error:1;
		unsigned int	checksum_error:1;
		unsigned int	no_io_error_seen:1;
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		unsigned int	generation_error:1; /* also sets header_error */
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	};
};

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struct scrub_wr_ctx {
	struct scrub_bio *wr_curr_bio;
	struct btrfs_device *tgtdev;
	int pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
	atomic_t flush_all_writes;
	struct mutex wr_lock;
};

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struct scrub_ctx {
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	struct scrub_bio	*bios[SCRUB_BIOS_PER_SCTX];
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	struct btrfs_root	*dev_root;
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	int			first_free;
	int			curr;
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	atomic_t		bios_in_flight;
	atomic_t		workers_pending;
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	spinlock_t		list_lock;
	wait_queue_head_t	list_wait;
	u16			csum_size;
	struct list_head	csum_list;
	atomic_t		cancel_req;
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	int			readonly;
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	int			pages_per_rd_bio;
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	u32			sectorsize;
	u32			nodesize;
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	int			is_dev_replace;
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	struct scrub_wr_ctx	wr_ctx;
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	/*
	 * statistics
	 */
	struct btrfs_scrub_progress stat;
	spinlock_t		stat_lock;
};

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struct scrub_fixup_nodatasum {
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	struct scrub_ctx	*sctx;
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	struct btrfs_device	*dev;
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	u64			logical;
	struct btrfs_root	*root;
	struct btrfs_work	work;
	int			mirror_num;
};

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struct scrub_nocow_inode {
	u64			inum;
	u64			offset;
	u64			root;
	struct list_head	list;
};

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struct scrub_copy_nocow_ctx {
	struct scrub_ctx	*sctx;
	u64			logical;
	u64			len;
	int			mirror_num;
	u64			physical_for_dev_replace;
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	struct list_head	inodes;
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	struct btrfs_work	work;
};

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struct scrub_warning {
	struct btrfs_path	*path;
	u64			extent_item_size;
	char			*scratch_buf;
	char			*msg_buf;
	const char		*errstr;
	sector_t		sector;
	u64			logical;
	struct btrfs_device	*dev;
	int			msg_bufsize;
	int			scratch_bufsize;
};

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static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx);
static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx);
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static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
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static int scrub_setup_recheck_block(struct scrub_ctx *sctx,
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				     struct btrfs_fs_info *fs_info,
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				     struct scrub_block *original_sblock,
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				     u64 length, u64 logical,
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				     struct scrub_block *sblocks_for_recheck);
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static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
				struct scrub_block *sblock, int is_metadata,
				int have_csum, u8 *csum, u64 generation,
				u16 csum_size);
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static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
					 struct scrub_block *sblock,
					 int is_metadata, int have_csum,
					 const u8 *csum, u64 generation,
					 u16 csum_size);
static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
					     struct scrub_block *sblock_good,
					     int force_write);
static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
					    struct scrub_block *sblock_good,
					    int page_num, int force_write);
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static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
					   int page_num);
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static int scrub_checksum_data(struct scrub_block *sblock);
static int scrub_checksum_tree_block(struct scrub_block *sblock);
static int scrub_checksum_super(struct scrub_block *sblock);
static void scrub_block_get(struct scrub_block *sblock);
static void scrub_block_put(struct scrub_block *sblock);
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static void scrub_page_get(struct scrub_page *spage);
static void scrub_page_put(struct scrub_page *spage);
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static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
				    struct scrub_page *spage);
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static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
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		       u64 physical, struct btrfs_device *dev, u64 flags,
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		       u64 gen, int mirror_num, u8 *csum, int force,
		       u64 physical_for_dev_replace);
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static void scrub_bio_end_io(struct bio *bio, int err);
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static void scrub_bio_end_io_worker(struct btrfs_work *work);
static void scrub_block_complete(struct scrub_block *sblock);
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static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
			       u64 extent_logical, u64 extent_len,
			       u64 *extent_physical,
			       struct btrfs_device **extent_dev,
			       int *extent_mirror_num);
static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
			      struct scrub_wr_ctx *wr_ctx,
			      struct btrfs_fs_info *fs_info,
			      struct btrfs_device *dev,
			      int is_dev_replace);
static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx);
static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
				    struct scrub_page *spage);
static void scrub_wr_submit(struct scrub_ctx *sctx);
static void scrub_wr_bio_end_io(struct bio *bio, int err);
static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
static int write_page_nocow(struct scrub_ctx *sctx,
			    u64 physical_for_dev_replace, struct page *page);
static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
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				      struct scrub_copy_nocow_ctx *ctx);
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static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
			    int mirror_num, u64 physical_for_dev_replace);
static void copy_nocow_pages_worker(struct btrfs_work *work);
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static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
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static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
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static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
{
	atomic_inc(&sctx->bios_in_flight);
}

static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
{
	atomic_dec(&sctx->bios_in_flight);
	wake_up(&sctx->list_wait);
}

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static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
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{
	while (atomic_read(&fs_info->scrub_pause_req)) {
		mutex_unlock(&fs_info->scrub_lock);
		wait_event(fs_info->scrub_pause_wait,
		   atomic_read(&fs_info->scrub_pause_req) == 0);
		mutex_lock(&fs_info->scrub_lock);
	}
}

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static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
{
	atomic_inc(&fs_info->scrubs_paused);
	wake_up(&fs_info->scrub_pause_wait);

	mutex_lock(&fs_info->scrub_lock);
	__scrub_blocked_if_needed(fs_info);
	atomic_dec(&fs_info->scrubs_paused);
	mutex_unlock(&fs_info->scrub_lock);

	wake_up(&fs_info->scrub_pause_wait);
}

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/*
 * used for workers that require transaction commits (i.e., for the
 * NOCOW case)
 */
static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
{
	struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;

	/*
	 * increment scrubs_running to prevent cancel requests from
	 * completing as long as a worker is running. we must also
	 * increment scrubs_paused to prevent deadlocking on pause
	 * requests used for transactions commits (as the worker uses a
	 * transaction context). it is safe to regard the worker
	 * as paused for all matters practical. effectively, we only
	 * avoid cancellation requests from completing.
	 */
	mutex_lock(&fs_info->scrub_lock);
	atomic_inc(&fs_info->scrubs_running);
	atomic_inc(&fs_info->scrubs_paused);
	mutex_unlock(&fs_info->scrub_lock);
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	/*
	 * check if @scrubs_running=@scrubs_paused condition
	 * inside wait_event() is not an atomic operation.
	 * which means we may inc/dec @scrub_running/paused
	 * at any time. Let's wake up @scrub_pause_wait as
	 * much as we can to let commit transaction blocked less.
	 */
	wake_up(&fs_info->scrub_pause_wait);

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	atomic_inc(&sctx->workers_pending);
}

/* used for workers that require transaction commits */
static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx)
{
	struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;

	/*
	 * see scrub_pending_trans_workers_inc() why we're pretending
	 * to be paused in the scrub counters
	 */
	mutex_lock(&fs_info->scrub_lock);
	atomic_dec(&fs_info->scrubs_running);
	atomic_dec(&fs_info->scrubs_paused);
	mutex_unlock(&fs_info->scrub_lock);
	atomic_dec(&sctx->workers_pending);
	wake_up(&fs_info->scrub_pause_wait);
	wake_up(&sctx->list_wait);
}

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static void scrub_free_csums(struct scrub_ctx *sctx)
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{
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	while (!list_empty(&sctx->csum_list)) {
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		struct btrfs_ordered_sum *sum;
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		sum = list_first_entry(&sctx->csum_list,
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				       struct btrfs_ordered_sum, list);
		list_del(&sum->list);
		kfree(sum);
	}
}

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static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
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{
	int i;

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	if (!sctx)
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		return;

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	scrub_free_wr_ctx(&sctx->wr_ctx);

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	/* this can happen when scrub is cancelled */
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	if (sctx->curr != -1) {
		struct scrub_bio *sbio = sctx->bios[sctx->curr];
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		for (i = 0; i < sbio->page_count; i++) {
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			WARN_ON(!sbio->pagev[i]->page);
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			scrub_block_put(sbio->pagev[i]->sblock);
		}
		bio_put(sbio->bio);
	}

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	for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
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		struct scrub_bio *sbio = sctx->bios[i];
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		if (!sbio)
			break;
		kfree(sbio);
	}

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	scrub_free_csums(sctx);
	kfree(sctx);
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}

static noinline_for_stack
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struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
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{
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	struct scrub_ctx *sctx;
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	int		i;
	struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
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	int pages_per_rd_bio;
	int ret;
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	/*
	 * the setting of pages_per_rd_bio is correct for scrub but might
	 * be wrong for the dev_replace code where we might read from
	 * different devices in the initial huge bios. However, that
	 * code is able to correctly handle the case when adding a page
	 * to a bio fails.
	 */
	if (dev->bdev)
		pages_per_rd_bio = min_t(int, SCRUB_PAGES_PER_RD_BIO,
					 bio_get_nr_vecs(dev->bdev));
	else
		pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
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	sctx = kzalloc(sizeof(*sctx), GFP_NOFS);
	if (!sctx)
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		goto nomem;
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	sctx->is_dev_replace = is_dev_replace;
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	sctx->pages_per_rd_bio = pages_per_rd_bio;
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	sctx->curr = -1;
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	sctx->dev_root = dev->dev_root;
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	for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
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		struct scrub_bio *sbio;

		sbio = kzalloc(sizeof(*sbio), GFP_NOFS);
		if (!sbio)
			goto nomem;
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		sctx->bios[i] = sbio;
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		sbio->index = i;
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		sbio->sctx = sctx;
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		sbio->page_count = 0;
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		btrfs_init_work(&sbio->work, btrfs_scrub_helper,
				scrub_bio_end_io_worker, NULL, NULL);
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		if (i != SCRUB_BIOS_PER_SCTX - 1)
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			sctx->bios[i]->next_free = i + 1;
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		else
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			sctx->bios[i]->next_free = -1;
	}
	sctx->first_free = 0;
	sctx->nodesize = dev->dev_root->nodesize;
	sctx->sectorsize = dev->dev_root->sectorsize;
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	atomic_set(&sctx->bios_in_flight, 0);
	atomic_set(&sctx->workers_pending, 0);
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	atomic_set(&sctx->cancel_req, 0);
	sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
	INIT_LIST_HEAD(&sctx->csum_list);

	spin_lock_init(&sctx->list_lock);
	spin_lock_init(&sctx->stat_lock);
	init_waitqueue_head(&sctx->list_wait);
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	ret = scrub_setup_wr_ctx(sctx, &sctx->wr_ctx, fs_info,
				 fs_info->dev_replace.tgtdev, is_dev_replace);
	if (ret) {
		scrub_free_ctx(sctx);
		return ERR_PTR(ret);
	}
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	return sctx;
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nomem:
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	scrub_free_ctx(sctx);
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	return ERR_PTR(-ENOMEM);
}

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static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
				     void *warn_ctx)
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{
	u64 isize;
	u32 nlink;
	int ret;
	int i;
	struct extent_buffer *eb;
	struct btrfs_inode_item *inode_item;
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	struct scrub_warning *swarn = warn_ctx;
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	struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
	struct inode_fs_paths *ipath = NULL;
	struct btrfs_root *local_root;
	struct btrfs_key root_key;

	root_key.objectid = root;
	root_key.type = BTRFS_ROOT_ITEM_KEY;
	root_key.offset = (u64)-1;
	local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
	if (IS_ERR(local_root)) {
		ret = PTR_ERR(local_root);
		goto err;
	}

	ret = inode_item_info(inum, 0, local_root, swarn->path);
	if (ret) {
		btrfs_release_path(swarn->path);
		goto err;
	}

	eb = swarn->path->nodes[0];
	inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
					struct btrfs_inode_item);
	isize = btrfs_inode_size(eb, inode_item);
	nlink = btrfs_inode_nlink(eb, inode_item);
	btrfs_release_path(swarn->path);

	ipath = init_ipath(4096, local_root, swarn->path);
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	if (IS_ERR(ipath)) {
		ret = PTR_ERR(ipath);
		ipath = NULL;
		goto err;
	}
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	ret = paths_from_inode(inum, ipath);

	if (ret < 0)
		goto err;

	/*
	 * we deliberately ignore the bit ipath might have been too small to
	 * hold all of the paths here
	 */
	for (i = 0; i < ipath->fspath->elem_cnt; ++i)
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		printk_in_rcu(KERN_WARNING "BTRFS: %s at logical %llu on dev "
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			"%s, sector %llu, root %llu, inode %llu, offset %llu, "
			"length %llu, links %u (path: %s)\n", swarn->errstr,
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			swarn->logical, rcu_str_deref(swarn->dev->name),
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			(unsigned long long)swarn->sector, root, inum, offset,
			min(isize - offset, (u64)PAGE_SIZE), nlink,
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			(char *)(unsigned long)ipath->fspath->val[i]);
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	free_ipath(ipath);
	return 0;

err:
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	printk_in_rcu(KERN_WARNING "BTRFS: %s at logical %llu on dev "
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		"%s, sector %llu, root %llu, inode %llu, offset %llu: path "
		"resolving failed with ret=%d\n", swarn->errstr,
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		swarn->logical, rcu_str_deref(swarn->dev->name),
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		(unsigned long long)swarn->sector, root, inum, offset, ret);

	free_ipath(ipath);
	return 0;
}

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static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
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{
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	struct btrfs_device *dev;
	struct btrfs_fs_info *fs_info;
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	struct btrfs_path *path;
	struct btrfs_key found_key;
	struct extent_buffer *eb;
	struct btrfs_extent_item *ei;
	struct scrub_warning swarn;
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	unsigned long ptr = 0;
	u64 extent_item_pos;
	u64 flags = 0;
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	u64 ref_root;
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	u32 item_size;
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	u8 ref_level;
	const int bufsize = 4096;
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	int ret;
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	WARN_ON(sblock->page_count < 1);
558
	dev = sblock->pagev[0]->dev;
559 560
	fs_info = sblock->sctx->dev_root->fs_info;

561 562 563 564
	path = btrfs_alloc_path();

	swarn.scratch_buf = kmalloc(bufsize, GFP_NOFS);
	swarn.msg_buf = kmalloc(bufsize, GFP_NOFS);
565 566
	swarn.sector = (sblock->pagev[0]->physical) >> 9;
	swarn.logical = sblock->pagev[0]->logical;
567
	swarn.errstr = errstr;
568
	swarn.dev = NULL;
569 570 571 572 573 574
	swarn.msg_bufsize = bufsize;
	swarn.scratch_bufsize = bufsize;

	if (!path || !swarn.scratch_buf || !swarn.msg_buf)
		goto out;

575 576
	ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
				  &flags);
577 578 579
	if (ret < 0)
		goto out;

J
Jan Schmidt 已提交
580
	extent_item_pos = swarn.logical - found_key.objectid;
581 582 583 584 585 586
	swarn.extent_item_size = found_key.offset;

	eb = path->nodes[0];
	ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
	item_size = btrfs_item_size_nr(eb, path->slots[0]);

587
	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
588
		do {
589 590 591
			ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
						      item_size, &ref_root,
						      &ref_level);
592
			printk_in_rcu(KERN_WARNING
593
				"BTRFS: %s at logical %llu on dev %s, "
594
				"sector %llu: metadata %s (level %d) in tree "
595 596
				"%llu\n", errstr, swarn.logical,
				rcu_str_deref(dev->name),
597 598 599 600 601
				(unsigned long long)swarn.sector,
				ref_level ? "node" : "leaf",
				ret < 0 ? -1 : ref_level,
				ret < 0 ? -1 : ref_root);
		} while (ret != 1);
602
		btrfs_release_path(path);
603
	} else {
604
		btrfs_release_path(path);
605
		swarn.path = path;
606
		swarn.dev = dev;
607 608
		iterate_extent_inodes(fs_info, found_key.objectid,
					extent_item_pos, 1,
609 610 611 612 613 614 615 616 617
					scrub_print_warning_inode, &swarn);
	}

out:
	btrfs_free_path(path);
	kfree(swarn.scratch_buf);
	kfree(swarn.msg_buf);
}

618
static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *fixup_ctx)
619
{
620
	struct page *page = NULL;
621
	unsigned long index;
622
	struct scrub_fixup_nodatasum *fixup = fixup_ctx;
623
	int ret;
624
	int corrected = 0;
625
	struct btrfs_key key;
626
	struct inode *inode = NULL;
627
	struct btrfs_fs_info *fs_info;
628 629
	u64 end = offset + PAGE_SIZE - 1;
	struct btrfs_root *local_root;
630
	int srcu_index;
631 632 633 634

	key.objectid = root;
	key.type = BTRFS_ROOT_ITEM_KEY;
	key.offset = (u64)-1;
635 636 637 638 639 640 641

	fs_info = fixup->root->fs_info;
	srcu_index = srcu_read_lock(&fs_info->subvol_srcu);

	local_root = btrfs_read_fs_root_no_name(fs_info, &key);
	if (IS_ERR(local_root)) {
		srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
642
		return PTR_ERR(local_root);
643
	}
644 645 646 647

	key.type = BTRFS_INODE_ITEM_KEY;
	key.objectid = inum;
	key.offset = 0;
648 649
	inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
	srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
650 651 652 653 654 655
	if (IS_ERR(inode))
		return PTR_ERR(inode);

	index = offset >> PAGE_CACHE_SHIFT;

	page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681
	if (!page) {
		ret = -ENOMEM;
		goto out;
	}

	if (PageUptodate(page)) {
		if (PageDirty(page)) {
			/*
			 * we need to write the data to the defect sector. the
			 * data that was in that sector is not in memory,
			 * because the page was modified. we must not write the
			 * modified page to that sector.
			 *
			 * TODO: what could be done here: wait for the delalloc
			 *       runner to write out that page (might involve
			 *       COW) and see whether the sector is still
			 *       referenced afterwards.
			 *
			 * For the meantime, we'll treat this error
			 * incorrectable, although there is a chance that a
			 * later scrub will find the bad sector again and that
			 * there's no dirty page in memory, then.
			 */
			ret = -EIO;
			goto out;
		}
682 683
		fs_info = BTRFS_I(inode)->root->fs_info;
		ret = repair_io_failure(fs_info, offset, PAGE_SIZE,
684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718
					fixup->logical, page,
					fixup->mirror_num);
		unlock_page(page);
		corrected = !ret;
	} else {
		/*
		 * we need to get good data first. the general readpage path
		 * will call repair_io_failure for us, we just have to make
		 * sure we read the bad mirror.
		 */
		ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
					EXTENT_DAMAGED, GFP_NOFS);
		if (ret) {
			/* set_extent_bits should give proper error */
			WARN_ON(ret > 0);
			if (ret > 0)
				ret = -EFAULT;
			goto out;
		}

		ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
						btrfs_get_extent,
						fixup->mirror_num);
		wait_on_page_locked(page);

		corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
						end, EXTENT_DAMAGED, 0, NULL);
		if (!corrected)
			clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
						EXTENT_DAMAGED, GFP_NOFS);
	}

out:
	if (page)
		put_page(page);
719 720

	iput(inode);
721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739

	if (ret < 0)
		return ret;

	if (ret == 0 && corrected) {
		/*
		 * we only need to call readpage for one of the inodes belonging
		 * to this extent. so make iterate_extent_inodes stop
		 */
		return 1;
	}

	return -EIO;
}

static void scrub_fixup_nodatasum(struct btrfs_work *work)
{
	int ret;
	struct scrub_fixup_nodatasum *fixup;
740
	struct scrub_ctx *sctx;
741 742 743 744 745
	struct btrfs_trans_handle *trans = NULL;
	struct btrfs_path *path;
	int uncorrectable = 0;

	fixup = container_of(work, struct scrub_fixup_nodatasum, work);
746
	sctx = fixup->sctx;
747 748 749

	path = btrfs_alloc_path();
	if (!path) {
750 751 752
		spin_lock(&sctx->stat_lock);
		++sctx->stat.malloc_errors;
		spin_unlock(&sctx->stat_lock);
753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780
		uncorrectable = 1;
		goto out;
	}

	trans = btrfs_join_transaction(fixup->root);
	if (IS_ERR(trans)) {
		uncorrectable = 1;
		goto out;
	}

	/*
	 * the idea is to trigger a regular read through the standard path. we
	 * read a page from the (failed) logical address by specifying the
	 * corresponding copynum of the failed sector. thus, that readpage is
	 * expected to fail.
	 * that is the point where on-the-fly error correction will kick in
	 * (once it's finished) and rewrite the failed sector if a good copy
	 * can be found.
	 */
	ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
						path, scrub_fixup_readpage,
						fixup);
	if (ret < 0) {
		uncorrectable = 1;
		goto out;
	}
	WARN_ON(ret != 1);

781 782 783
	spin_lock(&sctx->stat_lock);
	++sctx->stat.corrected_errors;
	spin_unlock(&sctx->stat_lock);
784 785 786 787 788

out:
	if (trans && !IS_ERR(trans))
		btrfs_end_transaction(trans, fixup->root);
	if (uncorrectable) {
789 790 791
		spin_lock(&sctx->stat_lock);
		++sctx->stat.uncorrectable_errors;
		spin_unlock(&sctx->stat_lock);
792 793 794
		btrfs_dev_replace_stats_inc(
			&sctx->dev_root->fs_info->dev_replace.
			num_uncorrectable_read_errors);
795 796
		printk_ratelimited_in_rcu(KERN_ERR "BTRFS: "
		    "unable to fixup (nodatasum) error at logical %llu on dev %s\n",
797
			fixup->logical, rcu_str_deref(fixup->dev->name));
798 799 800 801 802
	}

	btrfs_free_path(path);
	kfree(fixup);

803
	scrub_pending_trans_workers_dec(sctx);
804 805
}

A
Arne Jansen 已提交
806
/*
807 808 809 810 811 812
 * scrub_handle_errored_block gets called when either verification of the
 * pages failed or the bio failed to read, e.g. with EIO. In the latter
 * case, this function handles all pages in the bio, even though only one
 * may be bad.
 * The goal of this function is to repair the errored block by using the
 * contents of one of the mirrors.
A
Arne Jansen 已提交
813
 */
814
static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
A
Arne Jansen 已提交
815
{
816
	struct scrub_ctx *sctx = sblock_to_check->sctx;
817
	struct btrfs_device *dev;
818 819 820 821 822 823 824 825 826 827 828 829 830 831
	struct btrfs_fs_info *fs_info;
	u64 length;
	u64 logical;
	u64 generation;
	unsigned int failed_mirror_index;
	unsigned int is_metadata;
	unsigned int have_csum;
	u8 *csum;
	struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
	struct scrub_block *sblock_bad;
	int ret;
	int mirror_index;
	int page_num;
	int success;
832
	static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
833 834 835
				      DEFAULT_RATELIMIT_BURST);

	BUG_ON(sblock_to_check->page_count < 1);
836
	fs_info = sctx->dev_root->fs_info;
837 838 839 840 841 842 843 844 845 846 847
	if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
		/*
		 * if we find an error in a super block, we just report it.
		 * They will get written with the next transaction commit
		 * anyway
		 */
		spin_lock(&sctx->stat_lock);
		++sctx->stat.super_errors;
		spin_unlock(&sctx->stat_lock);
		return 0;
	}
848
	length = sblock_to_check->page_count * PAGE_SIZE;
849 850 851 852 853
	logical = sblock_to_check->pagev[0]->logical;
	generation = sblock_to_check->pagev[0]->generation;
	BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
	failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
	is_metadata = !(sblock_to_check->pagev[0]->flags &
854
			BTRFS_EXTENT_FLAG_DATA);
855 856 857
	have_csum = sblock_to_check->pagev[0]->have_csum;
	csum = sblock_to_check->pagev[0]->csum;
	dev = sblock_to_check->pagev[0]->dev;
858

859 860 861 862 863
	if (sctx->is_dev_replace && !is_metadata && !have_csum) {
		sblocks_for_recheck = NULL;
		goto nodatasum_case;
	}

864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896
	/*
	 * read all mirrors one after the other. This includes to
	 * re-read the extent or metadata block that failed (that was
	 * the cause that this fixup code is called) another time,
	 * page by page this time in order to know which pages
	 * caused I/O errors and which ones are good (for all mirrors).
	 * It is the goal to handle the situation when more than one
	 * mirror contains I/O errors, but the errors do not
	 * overlap, i.e. the data can be repaired by selecting the
	 * pages from those mirrors without I/O error on the
	 * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
	 * would be that mirror #1 has an I/O error on the first page,
	 * the second page is good, and mirror #2 has an I/O error on
	 * the second page, but the first page is good.
	 * Then the first page of the first mirror can be repaired by
	 * taking the first page of the second mirror, and the
	 * second page of the second mirror can be repaired by
	 * copying the contents of the 2nd page of the 1st mirror.
	 * One more note: if the pages of one mirror contain I/O
	 * errors, the checksum cannot be verified. In order to get
	 * the best data for repairing, the first attempt is to find
	 * a mirror without I/O errors and with a validated checksum.
	 * Only if this is not possible, the pages are picked from
	 * mirrors with I/O errors without considering the checksum.
	 * If the latter is the case, at the end, the checksum of the
	 * repaired area is verified in order to correctly maintain
	 * the statistics.
	 */

	sblocks_for_recheck = kzalloc(BTRFS_MAX_MIRRORS *
				     sizeof(*sblocks_for_recheck),
				     GFP_NOFS);
	if (!sblocks_for_recheck) {
897 898 899 900 901
		spin_lock(&sctx->stat_lock);
		sctx->stat.malloc_errors++;
		sctx->stat.read_errors++;
		sctx->stat.uncorrectable_errors++;
		spin_unlock(&sctx->stat_lock);
902
		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
903
		goto out;
A
Arne Jansen 已提交
904 905
	}

906
	/* setup the context, map the logical blocks and alloc the pages */
907
	ret = scrub_setup_recheck_block(sctx, fs_info, sblock_to_check, length,
908 909
					logical, sblocks_for_recheck);
	if (ret) {
910 911 912 913
		spin_lock(&sctx->stat_lock);
		sctx->stat.read_errors++;
		sctx->stat.uncorrectable_errors++;
		spin_unlock(&sctx->stat_lock);
914
		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
915 916 917 918
		goto out;
	}
	BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
	sblock_bad = sblocks_for_recheck + failed_mirror_index;
919

920
	/* build and submit the bios for the failed mirror, check checksums */
921 922
	scrub_recheck_block(fs_info, sblock_bad, is_metadata, have_csum,
			    csum, generation, sctx->csum_size);
A
Arne Jansen 已提交
923

924 925 926 927 928 929 930 931 932 933
	if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
	    sblock_bad->no_io_error_seen) {
		/*
		 * the error disappeared after reading page by page, or
		 * the area was part of a huge bio and other parts of the
		 * bio caused I/O errors, or the block layer merged several
		 * read requests into one and the error is caused by a
		 * different bio (usually one of the two latter cases is
		 * the cause)
		 */
934 935 936
		spin_lock(&sctx->stat_lock);
		sctx->stat.unverified_errors++;
		spin_unlock(&sctx->stat_lock);
A
Arne Jansen 已提交
937

938 939
		if (sctx->is_dev_replace)
			scrub_write_block_to_dev_replace(sblock_bad);
940
		goto out;
A
Arne Jansen 已提交
941 942
	}

943
	if (!sblock_bad->no_io_error_seen) {
944 945 946
		spin_lock(&sctx->stat_lock);
		sctx->stat.read_errors++;
		spin_unlock(&sctx->stat_lock);
947 948
		if (__ratelimit(&_rs))
			scrub_print_warning("i/o error", sblock_to_check);
949
		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
950
	} else if (sblock_bad->checksum_error) {
951 952 953
		spin_lock(&sctx->stat_lock);
		sctx->stat.csum_errors++;
		spin_unlock(&sctx->stat_lock);
954 955
		if (__ratelimit(&_rs))
			scrub_print_warning("checksum error", sblock_to_check);
956
		btrfs_dev_stat_inc_and_print(dev,
957
					     BTRFS_DEV_STAT_CORRUPTION_ERRS);
958
	} else if (sblock_bad->header_error) {
959 960 961
		spin_lock(&sctx->stat_lock);
		sctx->stat.verify_errors++;
		spin_unlock(&sctx->stat_lock);
962 963 964
		if (__ratelimit(&_rs))
			scrub_print_warning("checksum/header error",
					    sblock_to_check);
965
		if (sblock_bad->generation_error)
966
			btrfs_dev_stat_inc_and_print(dev,
967 968
				BTRFS_DEV_STAT_GENERATION_ERRS);
		else
969
			btrfs_dev_stat_inc_and_print(dev,
970
				BTRFS_DEV_STAT_CORRUPTION_ERRS);
971
	}
A
Arne Jansen 已提交
972

973 974 975 976
	if (sctx->readonly) {
		ASSERT(!sctx->is_dev_replace);
		goto out;
	}
A
Arne Jansen 已提交
977

978 979
	if (!is_metadata && !have_csum) {
		struct scrub_fixup_nodatasum *fixup_nodatasum;
A
Arne Jansen 已提交
980

981 982 983
nodatasum_case:
		WARN_ON(sctx->is_dev_replace);

984 985 986 987 988 989 990 991 992 993
		/*
		 * !is_metadata and !have_csum, this means that the data
		 * might not be COW'ed, that it might be modified
		 * concurrently. The general strategy to work on the
		 * commit root does not help in the case when COW is not
		 * used.
		 */
		fixup_nodatasum = kzalloc(sizeof(*fixup_nodatasum), GFP_NOFS);
		if (!fixup_nodatasum)
			goto did_not_correct_error;
994
		fixup_nodatasum->sctx = sctx;
995
		fixup_nodatasum->dev = dev;
996 997 998
		fixup_nodatasum->logical = logical;
		fixup_nodatasum->root = fs_info->extent_root;
		fixup_nodatasum->mirror_num = failed_mirror_index + 1;
999
		scrub_pending_trans_workers_inc(sctx);
1000 1001
		btrfs_init_work(&fixup_nodatasum->work, btrfs_scrub_helper,
				scrub_fixup_nodatasum, NULL, NULL);
1002 1003
		btrfs_queue_work(fs_info->scrub_workers,
				 &fixup_nodatasum->work);
1004
		goto out;
A
Arne Jansen 已提交
1005 1006
	}

1007 1008
	/*
	 * now build and submit the bios for the other mirrors, check
1009 1010
	 * checksums.
	 * First try to pick the mirror which is completely without I/O
1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025
	 * errors and also does not have a checksum error.
	 * If one is found, and if a checksum is present, the full block
	 * that is known to contain an error is rewritten. Afterwards
	 * the block is known to be corrected.
	 * If a mirror is found which is completely correct, and no
	 * checksum is present, only those pages are rewritten that had
	 * an I/O error in the block to be repaired, since it cannot be
	 * determined, which copy of the other pages is better (and it
	 * could happen otherwise that a correct page would be
	 * overwritten by a bad one).
	 */
	for (mirror_index = 0;
	     mirror_index < BTRFS_MAX_MIRRORS &&
	     sblocks_for_recheck[mirror_index].page_count > 0;
	     mirror_index++) {
1026
		struct scrub_block *sblock_other;
1027

1028 1029 1030 1031 1032
		if (mirror_index == failed_mirror_index)
			continue;
		sblock_other = sblocks_for_recheck + mirror_index;

		/* build and submit the bios, check checksums */
1033 1034 1035 1036 1037
		scrub_recheck_block(fs_info, sblock_other, is_metadata,
				    have_csum, csum, generation,
				    sctx->csum_size);

		if (!sblock_other->header_error &&
1038 1039
		    !sblock_other->checksum_error &&
		    sblock_other->no_io_error_seen) {
1040 1041 1042 1043 1044 1045 1046 1047 1048
			if (sctx->is_dev_replace) {
				scrub_write_block_to_dev_replace(sblock_other);
			} else {
				int force_write = is_metadata || have_csum;

				ret = scrub_repair_block_from_good_copy(
						sblock_bad, sblock_other,
						force_write);
			}
1049 1050 1051 1052
			if (0 == ret)
				goto corrected_error;
		}
	}
A
Arne Jansen 已提交
1053 1054

	/*
1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112
	 * for dev_replace, pick good pages and write to the target device.
	 */
	if (sctx->is_dev_replace) {
		success = 1;
		for (page_num = 0; page_num < sblock_bad->page_count;
		     page_num++) {
			int sub_success;

			sub_success = 0;
			for (mirror_index = 0;
			     mirror_index < BTRFS_MAX_MIRRORS &&
			     sblocks_for_recheck[mirror_index].page_count > 0;
			     mirror_index++) {
				struct scrub_block *sblock_other =
					sblocks_for_recheck + mirror_index;
				struct scrub_page *page_other =
					sblock_other->pagev[page_num];

				if (!page_other->io_error) {
					ret = scrub_write_page_to_dev_replace(
							sblock_other, page_num);
					if (ret == 0) {
						/* succeeded for this page */
						sub_success = 1;
						break;
					} else {
						btrfs_dev_replace_stats_inc(
							&sctx->dev_root->
							fs_info->dev_replace.
							num_write_errors);
					}
				}
			}

			if (!sub_success) {
				/*
				 * did not find a mirror to fetch the page
				 * from. scrub_write_page_to_dev_replace()
				 * handles this case (page->io_error), by
				 * filling the block with zeros before
				 * submitting the write request
				 */
				success = 0;
				ret = scrub_write_page_to_dev_replace(
						sblock_bad, page_num);
				if (ret)
					btrfs_dev_replace_stats_inc(
						&sctx->dev_root->fs_info->
						dev_replace.num_write_errors);
			}
		}

		goto out;
	}

	/*
	 * for regular scrub, repair those pages that are errored.
	 * In case of I/O errors in the area that is supposed to be
1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133
	 * repaired, continue by picking good copies of those pages.
	 * Select the good pages from mirrors to rewrite bad pages from
	 * the area to fix. Afterwards verify the checksum of the block
	 * that is supposed to be repaired. This verification step is
	 * only done for the purpose of statistic counting and for the
	 * final scrub report, whether errors remain.
	 * A perfect algorithm could make use of the checksum and try
	 * all possible combinations of pages from the different mirrors
	 * until the checksum verification succeeds. For example, when
	 * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
	 * of mirror #2 is readable but the final checksum test fails,
	 * then the 2nd page of mirror #3 could be tried, whether now
	 * the final checksum succeedes. But this would be a rare
	 * exception and is therefore not implemented. At least it is
	 * avoided that the good copy is overwritten.
	 * A more useful improvement would be to pick the sectors
	 * without I/O error based on sector sizes (512 bytes on legacy
	 * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
	 * mirror could be repaired by taking 512 byte of a different
	 * mirror, even if other 512 byte sectors in the same PAGE_SIZE
	 * area are unreadable.
A
Arne Jansen 已提交
1134 1135
	 */

1136 1137 1138 1139 1140 1141
	/* can only fix I/O errors from here on */
	if (sblock_bad->no_io_error_seen)
		goto did_not_correct_error;

	success = 1;
	for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1142
		struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1143 1144

		if (!page_bad->io_error)
A
Arne Jansen 已提交
1145
			continue;
1146 1147 1148 1149 1150 1151 1152

		for (mirror_index = 0;
		     mirror_index < BTRFS_MAX_MIRRORS &&
		     sblocks_for_recheck[mirror_index].page_count > 0;
		     mirror_index++) {
			struct scrub_block *sblock_other = sblocks_for_recheck +
							   mirror_index;
1153 1154
			struct scrub_page *page_other = sblock_other->pagev[
							page_num];
1155 1156 1157 1158 1159 1160 1161 1162 1163

			if (!page_other->io_error) {
				ret = scrub_repair_page_from_good_copy(
					sblock_bad, sblock_other, page_num, 0);
				if (0 == ret) {
					page_bad->io_error = 0;
					break; /* succeeded for this page */
				}
			}
I
Ilya Dryomov 已提交
1164
		}
A
Arne Jansen 已提交
1165

1166 1167 1168 1169
		if (page_bad->io_error) {
			/* did not find a mirror to copy the page from */
			success = 0;
		}
A
Arne Jansen 已提交
1170 1171
	}

1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182
	if (success) {
		if (is_metadata || have_csum) {
			/*
			 * need to verify the checksum now that all
			 * sectors on disk are repaired (the write
			 * request for data to be repaired is on its way).
			 * Just be lazy and use scrub_recheck_block()
			 * which re-reads the data before the checksum
			 * is verified, but most likely the data comes out
			 * of the page cache.
			 */
1183 1184 1185 1186
			scrub_recheck_block(fs_info, sblock_bad,
					    is_metadata, have_csum, csum,
					    generation, sctx->csum_size);
			if (!sblock_bad->header_error &&
1187 1188 1189 1190 1191 1192 1193
			    !sblock_bad->checksum_error &&
			    sblock_bad->no_io_error_seen)
				goto corrected_error;
			else
				goto did_not_correct_error;
		} else {
corrected_error:
1194 1195 1196
			spin_lock(&sctx->stat_lock);
			sctx->stat.corrected_errors++;
			spin_unlock(&sctx->stat_lock);
1197
			printk_ratelimited_in_rcu(KERN_ERR
1198
				"BTRFS: fixed up error at logical %llu on dev %s\n",
1199
				logical, rcu_str_deref(dev->name));
A
Arne Jansen 已提交
1200
		}
1201 1202
	} else {
did_not_correct_error:
1203 1204 1205
		spin_lock(&sctx->stat_lock);
		sctx->stat.uncorrectable_errors++;
		spin_unlock(&sctx->stat_lock);
1206
		printk_ratelimited_in_rcu(KERN_ERR
1207
			"BTRFS: unable to fixup (regular) error at logical %llu on dev %s\n",
1208
			logical, rcu_str_deref(dev->name));
I
Ilya Dryomov 已提交
1209
	}
A
Arne Jansen 已提交
1210

1211 1212 1213 1214 1215 1216 1217 1218
out:
	if (sblocks_for_recheck) {
		for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
		     mirror_index++) {
			struct scrub_block *sblock = sblocks_for_recheck +
						     mirror_index;
			int page_index;

1219 1220 1221 1222 1223
			for (page_index = 0; page_index < sblock->page_count;
			     page_index++) {
				sblock->pagev[page_index]->sblock = NULL;
				scrub_page_put(sblock->pagev[page_index]);
			}
1224 1225 1226
		}
		kfree(sblocks_for_recheck);
	}
A
Arne Jansen 已提交
1227

1228 1229
	return 0;
}
A
Arne Jansen 已提交
1230

1231
static int scrub_setup_recheck_block(struct scrub_ctx *sctx,
1232
				     struct btrfs_fs_info *fs_info,
1233
				     struct scrub_block *original_sblock,
1234 1235 1236 1237 1238 1239 1240 1241
				     u64 length, u64 logical,
				     struct scrub_block *sblocks_for_recheck)
{
	int page_index;
	int mirror_index;
	int ret;

	/*
1242
	 * note: the two members ref_count and outstanding_pages
1243 1244 1245 1246 1247 1248 1249 1250 1251
	 * are not used (and not set) in the blocks that are used for
	 * the recheck procedure
	 */

	page_index = 0;
	while (length > 0) {
		u64 sublen = min_t(u64, length, PAGE_SIZE);
		u64 mapped_length = sublen;
		struct btrfs_bio *bbio = NULL;
A
Arne Jansen 已提交
1252

1253 1254 1255 1256
		/*
		 * with a length of PAGE_SIZE, each returned stripe
		 * represents one mirror
		 */
1257 1258
		ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical,
				      &mapped_length, &bbio, 0);
1259 1260 1261 1262
		if (ret || !bbio || mapped_length < sublen) {
			kfree(bbio);
			return -EIO;
		}
A
Arne Jansen 已提交
1263

1264
		BUG_ON(page_index >= SCRUB_PAGES_PER_RD_BIO);
1265 1266 1267 1268 1269 1270 1271 1272 1273
		for (mirror_index = 0; mirror_index < (int)bbio->num_stripes;
		     mirror_index++) {
			struct scrub_block *sblock;
			struct scrub_page *page;

			if (mirror_index >= BTRFS_MAX_MIRRORS)
				continue;

			sblock = sblocks_for_recheck + mirror_index;
1274 1275 1276 1277
			sblock->sctx = sctx;
			page = kzalloc(sizeof(*page), GFP_NOFS);
			if (!page) {
leave_nomem:
1278 1279 1280
				spin_lock(&sctx->stat_lock);
				sctx->stat.malloc_errors++;
				spin_unlock(&sctx->stat_lock);
1281
				kfree(bbio);
1282 1283
				return -ENOMEM;
			}
1284 1285 1286 1287
			scrub_page_get(page);
			sblock->pagev[page_index] = page;
			page->logical = logical;
			page->physical = bbio->stripes[mirror_index].physical;
1288 1289 1290 1291
			BUG_ON(page_index >= original_sblock->page_count);
			page->physical_for_dev_replace =
				original_sblock->pagev[page_index]->
				physical_for_dev_replace;
1292 1293 1294
			/* for missing devices, dev->bdev is NULL */
			page->dev = bbio->stripes[mirror_index].dev;
			page->mirror_num = mirror_index + 1;
1295
			sblock->page_count++;
1296 1297 1298
			page->page = alloc_page(GFP_NOFS);
			if (!page->page)
				goto leave_nomem;
1299 1300 1301 1302 1303 1304 1305 1306
		}
		kfree(bbio);
		length -= sublen;
		logical += sublen;
		page_index++;
	}

	return 0;
I
Ilya Dryomov 已提交
1307 1308
}

1309 1310 1311 1312 1313 1314 1315
/*
 * this function will check the on disk data for checksum errors, header
 * errors and read I/O errors. If any I/O errors happen, the exact pages
 * which are errored are marked as being bad. The goal is to enable scrub
 * to take those pages that are not errored from all the mirrors so that
 * the pages that are errored in the just handled mirror can be repaired.
 */
1316 1317 1318 1319
static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
				struct scrub_block *sblock, int is_metadata,
				int have_csum, u8 *csum, u64 generation,
				u16 csum_size)
I
Ilya Dryomov 已提交
1320
{
1321
	int page_num;
I
Ilya Dryomov 已提交
1322

1323 1324 1325
	sblock->no_io_error_seen = 1;
	sblock->header_error = 0;
	sblock->checksum_error = 0;
I
Ilya Dryomov 已提交
1326

1327 1328
	for (page_num = 0; page_num < sblock->page_count; page_num++) {
		struct bio *bio;
1329
		struct scrub_page *page = sblock->pagev[page_num];
1330

1331
		if (page->dev->bdev == NULL) {
1332 1333 1334 1335 1336
			page->io_error = 1;
			sblock->no_io_error_seen = 0;
			continue;
		}

1337
		WARN_ON(!page->page);
1338
		bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
1339 1340 1341 1342 1343
		if (!bio) {
			page->io_error = 1;
			sblock->no_io_error_seen = 0;
			continue;
		}
1344
		bio->bi_bdev = page->dev->bdev;
1345
		bio->bi_iter.bi_sector = page->physical >> 9;
1346

1347
		bio_add_page(bio, page->page, PAGE_SIZE, 0);
1348
		if (btrfsic_submit_bio_wait(READ, bio))
1349
			sblock->no_io_error_seen = 0;
1350

1351 1352
		bio_put(bio);
	}
I
Ilya Dryomov 已提交
1353

1354 1355 1356 1357 1358
	if (sblock->no_io_error_seen)
		scrub_recheck_block_checksum(fs_info, sblock, is_metadata,
					     have_csum, csum, generation,
					     csum_size);

1359
	return;
A
Arne Jansen 已提交
1360 1361
}

M
Miao Xie 已提交
1362 1363 1364 1365 1366 1367 1368 1369 1370 1371
static inline int scrub_check_fsid(u8 fsid[],
				   struct scrub_page *spage)
{
	struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
	int ret;

	ret = memcmp(fsid, fs_devices->fsid, BTRFS_UUID_SIZE);
	return !ret;
}

1372 1373 1374 1375 1376
static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
					 struct scrub_block *sblock,
					 int is_metadata, int have_csum,
					 const u8 *csum, u64 generation,
					 u16 csum_size)
A
Arne Jansen 已提交
1377
{
1378 1379 1380 1381 1382
	int page_num;
	u8 calculated_csum[BTRFS_CSUM_SIZE];
	u32 crc = ~(u32)0;
	void *mapped_buffer;

1383
	WARN_ON(!sblock->pagev[0]->page);
1384 1385 1386
	if (is_metadata) {
		struct btrfs_header *h;

1387
		mapped_buffer = kmap_atomic(sblock->pagev[0]->page);
1388 1389
		h = (struct btrfs_header *)mapped_buffer;

1390
		if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h) ||
M
Miao Xie 已提交
1391
		    !scrub_check_fsid(h->fsid, sblock->pagev[0]) ||
1392
		    memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1393
			   BTRFS_UUID_SIZE)) {
1394
			sblock->header_error = 1;
1395
		} else if (generation != btrfs_stack_header_generation(h)) {
1396 1397 1398
			sblock->header_error = 1;
			sblock->generation_error = 1;
		}
1399 1400 1401 1402
		csum = h->csum;
	} else {
		if (!have_csum)
			return;
A
Arne Jansen 已提交
1403

1404
		mapped_buffer = kmap_atomic(sblock->pagev[0]->page);
1405
	}
A
Arne Jansen 已提交
1406

1407 1408
	for (page_num = 0;;) {
		if (page_num == 0 && is_metadata)
1409
			crc = btrfs_csum_data(
1410 1411 1412
				((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE,
				crc, PAGE_SIZE - BTRFS_CSUM_SIZE);
		else
1413
			crc = btrfs_csum_data(mapped_buffer, crc, PAGE_SIZE);
1414

1415
		kunmap_atomic(mapped_buffer);
1416 1417 1418
		page_num++;
		if (page_num >= sblock->page_count)
			break;
1419
		WARN_ON(!sblock->pagev[page_num]->page);
1420

1421
		mapped_buffer = kmap_atomic(sblock->pagev[page_num]->page);
1422 1423 1424 1425 1426
	}

	btrfs_csum_final(crc, calculated_csum);
	if (memcmp(calculated_csum, csum, csum_size))
		sblock->checksum_error = 1;
A
Arne Jansen 已提交
1427 1428
}

1429 1430 1431 1432 1433 1434
static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
					     struct scrub_block *sblock_good,
					     int force_write)
{
	int page_num;
	int ret = 0;
I
Ilya Dryomov 已提交
1435

1436 1437
	for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
		int ret_sub;
I
Ilya Dryomov 已提交
1438

1439 1440 1441 1442 1443 1444
		ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
							   sblock_good,
							   page_num,
							   force_write);
		if (ret_sub)
			ret = ret_sub;
A
Arne Jansen 已提交
1445
	}
1446 1447 1448 1449 1450 1451 1452 1453

	return ret;
}

static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
					    struct scrub_block *sblock_good,
					    int page_num, int force_write)
{
1454 1455
	struct scrub_page *page_bad = sblock_bad->pagev[page_num];
	struct scrub_page *page_good = sblock_good->pagev[page_num];
1456

1457 1458
	BUG_ON(page_bad->page == NULL);
	BUG_ON(page_good->page == NULL);
1459 1460 1461 1462 1463
	if (force_write || sblock_bad->header_error ||
	    sblock_bad->checksum_error || page_bad->io_error) {
		struct bio *bio;
		int ret;

1464
		if (!page_bad->dev->bdev) {
1465 1466 1467
			printk_ratelimited(KERN_WARNING "BTRFS: "
				"scrub_repair_page_from_good_copy(bdev == NULL) "
				"is unexpected!\n");
1468 1469 1470
			return -EIO;
		}

1471
		bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
1472 1473
		if (!bio)
			return -EIO;
1474
		bio->bi_bdev = page_bad->dev->bdev;
1475
		bio->bi_iter.bi_sector = page_bad->physical >> 9;
1476 1477 1478 1479 1480

		ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
		if (PAGE_SIZE != ret) {
			bio_put(bio);
			return -EIO;
1481
		}
1482

1483
		if (btrfsic_submit_bio_wait(WRITE, bio)) {
1484 1485
			btrfs_dev_stat_inc_and_print(page_bad->dev,
				BTRFS_DEV_STAT_WRITE_ERRS);
1486 1487 1488
			btrfs_dev_replace_stats_inc(
				&sblock_bad->sctx->dev_root->fs_info->
				dev_replace.num_write_errors);
1489 1490 1491
			bio_put(bio);
			return -EIO;
		}
1492
		bio_put(bio);
A
Arne Jansen 已提交
1493 1494
	}

1495 1496 1497
	return 0;
}

1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556
static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
{
	int page_num;

	for (page_num = 0; page_num < sblock->page_count; page_num++) {
		int ret;

		ret = scrub_write_page_to_dev_replace(sblock, page_num);
		if (ret)
			btrfs_dev_replace_stats_inc(
				&sblock->sctx->dev_root->fs_info->dev_replace.
				num_write_errors);
	}
}

static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
					   int page_num)
{
	struct scrub_page *spage = sblock->pagev[page_num];

	BUG_ON(spage->page == NULL);
	if (spage->io_error) {
		void *mapped_buffer = kmap_atomic(spage->page);

		memset(mapped_buffer, 0, PAGE_CACHE_SIZE);
		flush_dcache_page(spage->page);
		kunmap_atomic(mapped_buffer);
	}
	return scrub_add_page_to_wr_bio(sblock->sctx, spage);
}

static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
				    struct scrub_page *spage)
{
	struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
	struct scrub_bio *sbio;
	int ret;

	mutex_lock(&wr_ctx->wr_lock);
again:
	if (!wr_ctx->wr_curr_bio) {
		wr_ctx->wr_curr_bio = kzalloc(sizeof(*wr_ctx->wr_curr_bio),
					      GFP_NOFS);
		if (!wr_ctx->wr_curr_bio) {
			mutex_unlock(&wr_ctx->wr_lock);
			return -ENOMEM;
		}
		wr_ctx->wr_curr_bio->sctx = sctx;
		wr_ctx->wr_curr_bio->page_count = 0;
	}
	sbio = wr_ctx->wr_curr_bio;
	if (sbio->page_count == 0) {
		struct bio *bio;

		sbio->physical = spage->physical_for_dev_replace;
		sbio->logical = spage->logical;
		sbio->dev = wr_ctx->tgtdev;
		bio = sbio->bio;
		if (!bio) {
1557
			bio = btrfs_io_bio_alloc(GFP_NOFS, wr_ctx->pages_per_wr_bio);
1558 1559 1560 1561 1562 1563 1564 1565 1566 1567
			if (!bio) {
				mutex_unlock(&wr_ctx->wr_lock);
				return -ENOMEM;
			}
			sbio->bio = bio;
		}

		bio->bi_private = sbio;
		bio->bi_end_io = scrub_wr_bio_end_io;
		bio->bi_bdev = sbio->dev->bdev;
1568
		bio->bi_iter.bi_sector = sbio->physical >> 9;
1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626
		sbio->err = 0;
	} else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
		   spage->physical_for_dev_replace ||
		   sbio->logical + sbio->page_count * PAGE_SIZE !=
		   spage->logical) {
		scrub_wr_submit(sctx);
		goto again;
	}

	ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
	if (ret != PAGE_SIZE) {
		if (sbio->page_count < 1) {
			bio_put(sbio->bio);
			sbio->bio = NULL;
			mutex_unlock(&wr_ctx->wr_lock);
			return -EIO;
		}
		scrub_wr_submit(sctx);
		goto again;
	}

	sbio->pagev[sbio->page_count] = spage;
	scrub_page_get(spage);
	sbio->page_count++;
	if (sbio->page_count == wr_ctx->pages_per_wr_bio)
		scrub_wr_submit(sctx);
	mutex_unlock(&wr_ctx->wr_lock);

	return 0;
}

static void scrub_wr_submit(struct scrub_ctx *sctx)
{
	struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
	struct scrub_bio *sbio;

	if (!wr_ctx->wr_curr_bio)
		return;

	sbio = wr_ctx->wr_curr_bio;
	wr_ctx->wr_curr_bio = NULL;
	WARN_ON(!sbio->bio->bi_bdev);
	scrub_pending_bio_inc(sctx);
	/* process all writes in a single worker thread. Then the block layer
	 * orders the requests before sending them to the driver which
	 * doubled the write performance on spinning disks when measured
	 * with Linux 3.5 */
	btrfsic_submit_bio(WRITE, sbio->bio);
}

static void scrub_wr_bio_end_io(struct bio *bio, int err)
{
	struct scrub_bio *sbio = bio->bi_private;
	struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;

	sbio->err = err;
	sbio->bio = bio;

1627 1628
	btrfs_init_work(&sbio->work, btrfs_scrubwrc_helper,
			 scrub_wr_bio_end_io_worker, NULL, NULL);
1629
	btrfs_queue_work(fs_info->scrub_wr_completion_workers, &sbio->work);
1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660
}

static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
{
	struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
	struct scrub_ctx *sctx = sbio->sctx;
	int i;

	WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
	if (sbio->err) {
		struct btrfs_dev_replace *dev_replace =
			&sbio->sctx->dev_root->fs_info->dev_replace;

		for (i = 0; i < sbio->page_count; i++) {
			struct scrub_page *spage = sbio->pagev[i];

			spage->io_error = 1;
			btrfs_dev_replace_stats_inc(&dev_replace->
						    num_write_errors);
		}
	}

	for (i = 0; i < sbio->page_count; i++)
		scrub_page_put(sbio->pagev[i]);

	bio_put(sbio->bio);
	kfree(sbio);
	scrub_pending_bio_dec(sctx);
}

static int scrub_checksum(struct scrub_block *sblock)
1661 1662 1663 1664
{
	u64 flags;
	int ret;

1665 1666
	WARN_ON(sblock->page_count < 1);
	flags = sblock->pagev[0]->flags;
1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677
	ret = 0;
	if (flags & BTRFS_EXTENT_FLAG_DATA)
		ret = scrub_checksum_data(sblock);
	else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
		ret = scrub_checksum_tree_block(sblock);
	else if (flags & BTRFS_EXTENT_FLAG_SUPER)
		(void)scrub_checksum_super(sblock);
	else
		WARN_ON(1);
	if (ret)
		scrub_handle_errored_block(sblock);
1678 1679

	return ret;
A
Arne Jansen 已提交
1680 1681
}

1682
static int scrub_checksum_data(struct scrub_block *sblock)
A
Arne Jansen 已提交
1683
{
1684
	struct scrub_ctx *sctx = sblock->sctx;
A
Arne Jansen 已提交
1685
	u8 csum[BTRFS_CSUM_SIZE];
1686 1687 1688
	u8 *on_disk_csum;
	struct page *page;
	void *buffer;
A
Arne Jansen 已提交
1689 1690
	u32 crc = ~(u32)0;
	int fail = 0;
1691 1692
	u64 len;
	int index;
A
Arne Jansen 已提交
1693

1694
	BUG_ON(sblock->page_count < 1);
1695
	if (!sblock->pagev[0]->have_csum)
A
Arne Jansen 已提交
1696 1697
		return 0;

1698 1699
	on_disk_csum = sblock->pagev[0]->csum;
	page = sblock->pagev[0]->page;
1700
	buffer = kmap_atomic(page);
1701

1702
	len = sctx->sectorsize;
1703 1704 1705 1706
	index = 0;
	for (;;) {
		u64 l = min_t(u64, len, PAGE_SIZE);

1707
		crc = btrfs_csum_data(buffer, crc, l);
1708
		kunmap_atomic(buffer);
1709 1710 1711 1712 1713
		len -= l;
		if (len == 0)
			break;
		index++;
		BUG_ON(index >= sblock->page_count);
1714 1715
		BUG_ON(!sblock->pagev[index]->page);
		page = sblock->pagev[index]->page;
1716
		buffer = kmap_atomic(page);
1717 1718
	}

A
Arne Jansen 已提交
1719
	btrfs_csum_final(crc, csum);
1720
	if (memcmp(csum, on_disk_csum, sctx->csum_size))
A
Arne Jansen 已提交
1721 1722 1723 1724 1725
		fail = 1;

	return fail;
}

1726
static int scrub_checksum_tree_block(struct scrub_block *sblock)
A
Arne Jansen 已提交
1727
{
1728
	struct scrub_ctx *sctx = sblock->sctx;
A
Arne Jansen 已提交
1729
	struct btrfs_header *h;
1730
	struct btrfs_root *root = sctx->dev_root;
A
Arne Jansen 已提交
1731
	struct btrfs_fs_info *fs_info = root->fs_info;
1732 1733 1734 1735 1736 1737
	u8 calculated_csum[BTRFS_CSUM_SIZE];
	u8 on_disk_csum[BTRFS_CSUM_SIZE];
	struct page *page;
	void *mapped_buffer;
	u64 mapped_size;
	void *p;
A
Arne Jansen 已提交
1738 1739 1740
	u32 crc = ~(u32)0;
	int fail = 0;
	int crc_fail = 0;
1741 1742 1743 1744
	u64 len;
	int index;

	BUG_ON(sblock->page_count < 1);
1745
	page = sblock->pagev[0]->page;
1746
	mapped_buffer = kmap_atomic(page);
1747
	h = (struct btrfs_header *)mapped_buffer;
1748
	memcpy(on_disk_csum, h->csum, sctx->csum_size);
A
Arne Jansen 已提交
1749 1750 1751 1752 1753 1754 1755

	/*
	 * we don't use the getter functions here, as we
	 * a) don't have an extent buffer and
	 * b) the page is already kmapped
	 */

1756
	if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
A
Arne Jansen 已提交
1757 1758
		++fail;

1759
	if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h))
A
Arne Jansen 已提交
1760 1761
		++fail;

M
Miao Xie 已提交
1762
	if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
A
Arne Jansen 已提交
1763 1764 1765 1766 1767 1768
		++fail;

	if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
		   BTRFS_UUID_SIZE))
		++fail;

1769
	len = sctx->nodesize - BTRFS_CSUM_SIZE;
1770 1771 1772 1773 1774 1775
	mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
	p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
	index = 0;
	for (;;) {
		u64 l = min_t(u64, len, mapped_size);

1776
		crc = btrfs_csum_data(p, crc, l);
1777
		kunmap_atomic(mapped_buffer);
1778 1779 1780 1781 1782
		len -= l;
		if (len == 0)
			break;
		index++;
		BUG_ON(index >= sblock->page_count);
1783 1784
		BUG_ON(!sblock->pagev[index]->page);
		page = sblock->pagev[index]->page;
1785
		mapped_buffer = kmap_atomic(page);
1786 1787 1788 1789 1790
		mapped_size = PAGE_SIZE;
		p = mapped_buffer;
	}

	btrfs_csum_final(crc, calculated_csum);
1791
	if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
A
Arne Jansen 已提交
1792 1793 1794 1795 1796
		++crc_fail;

	return fail || crc_fail;
}

1797
static int scrub_checksum_super(struct scrub_block *sblock)
A
Arne Jansen 已提交
1798 1799
{
	struct btrfs_super_block *s;
1800
	struct scrub_ctx *sctx = sblock->sctx;
1801 1802 1803 1804 1805 1806
	u8 calculated_csum[BTRFS_CSUM_SIZE];
	u8 on_disk_csum[BTRFS_CSUM_SIZE];
	struct page *page;
	void *mapped_buffer;
	u64 mapped_size;
	void *p;
A
Arne Jansen 已提交
1807
	u32 crc = ~(u32)0;
1808 1809
	int fail_gen = 0;
	int fail_cor = 0;
1810 1811
	u64 len;
	int index;
A
Arne Jansen 已提交
1812

1813
	BUG_ON(sblock->page_count < 1);
1814
	page = sblock->pagev[0]->page;
1815
	mapped_buffer = kmap_atomic(page);
1816
	s = (struct btrfs_super_block *)mapped_buffer;
1817
	memcpy(on_disk_csum, s->csum, sctx->csum_size);
A
Arne Jansen 已提交
1818

1819
	if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
1820
		++fail_cor;
A
Arne Jansen 已提交
1821

1822
	if (sblock->pagev[0]->generation != btrfs_super_generation(s))
1823
		++fail_gen;
A
Arne Jansen 已提交
1824

M
Miao Xie 已提交
1825
	if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
1826
		++fail_cor;
A
Arne Jansen 已提交
1827

1828 1829 1830 1831 1832 1833 1834
	len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
	mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
	p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
	index = 0;
	for (;;) {
		u64 l = min_t(u64, len, mapped_size);

1835
		crc = btrfs_csum_data(p, crc, l);
1836
		kunmap_atomic(mapped_buffer);
1837 1838 1839 1840 1841
		len -= l;
		if (len == 0)
			break;
		index++;
		BUG_ON(index >= sblock->page_count);
1842 1843
		BUG_ON(!sblock->pagev[index]->page);
		page = sblock->pagev[index]->page;
1844
		mapped_buffer = kmap_atomic(page);
1845 1846 1847 1848 1849
		mapped_size = PAGE_SIZE;
		p = mapped_buffer;
	}

	btrfs_csum_final(crc, calculated_csum);
1850
	if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1851
		++fail_cor;
A
Arne Jansen 已提交
1852

1853
	if (fail_cor + fail_gen) {
A
Arne Jansen 已提交
1854 1855 1856 1857 1858
		/*
		 * if we find an error in a super block, we just report it.
		 * They will get written with the next transaction commit
		 * anyway
		 */
1859 1860 1861
		spin_lock(&sctx->stat_lock);
		++sctx->stat.super_errors;
		spin_unlock(&sctx->stat_lock);
1862
		if (fail_cor)
1863
			btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1864 1865
				BTRFS_DEV_STAT_CORRUPTION_ERRS);
		else
1866
			btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1867
				BTRFS_DEV_STAT_GENERATION_ERRS);
A
Arne Jansen 已提交
1868 1869
	}

1870
	return fail_cor + fail_gen;
A
Arne Jansen 已提交
1871 1872
}

1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883
static void scrub_block_get(struct scrub_block *sblock)
{
	atomic_inc(&sblock->ref_count);
}

static void scrub_block_put(struct scrub_block *sblock)
{
	if (atomic_dec_and_test(&sblock->ref_count)) {
		int i;

		for (i = 0; i < sblock->page_count; i++)
1884
			scrub_page_put(sblock->pagev[i]);
1885 1886 1887 1888
		kfree(sblock);
	}
}

1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902
static void scrub_page_get(struct scrub_page *spage)
{
	atomic_inc(&spage->ref_count);
}

static void scrub_page_put(struct scrub_page *spage)
{
	if (atomic_dec_and_test(&spage->ref_count)) {
		if (spage->page)
			__free_page(spage->page);
		kfree(spage);
	}
}

1903
static void scrub_submit(struct scrub_ctx *sctx)
A
Arne Jansen 已提交
1904 1905 1906
{
	struct scrub_bio *sbio;

1907
	if (sctx->curr == -1)
S
Stefan Behrens 已提交
1908
		return;
A
Arne Jansen 已提交
1909

1910 1911
	sbio = sctx->bios[sctx->curr];
	sctx->curr = -1;
1912
	scrub_pending_bio_inc(sctx);
A
Arne Jansen 已提交
1913

1914 1915 1916 1917 1918 1919 1920 1921 1922
	if (!sbio->bio->bi_bdev) {
		/*
		 * this case should not happen. If btrfs_map_block() is
		 * wrong, it could happen for dev-replace operations on
		 * missing devices when no mirrors are available, but in
		 * this case it should already fail the mount.
		 * This case is handled correctly (but _very_ slowly).
		 */
		printk_ratelimited(KERN_WARNING
1923
			"BTRFS: scrub_submit(bio bdev == NULL) is unexpected!\n");
1924 1925 1926 1927
		bio_endio(sbio->bio, -EIO);
	} else {
		btrfsic_submit_bio(READ, sbio->bio);
	}
A
Arne Jansen 已提交
1928 1929
}

1930 1931
static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
				    struct scrub_page *spage)
A
Arne Jansen 已提交
1932
{
1933
	struct scrub_block *sblock = spage->sblock;
A
Arne Jansen 已提交
1934
	struct scrub_bio *sbio;
1935
	int ret;
A
Arne Jansen 已提交
1936 1937 1938 1939 1940

again:
	/*
	 * grab a fresh bio or wait for one to become available
	 */
1941 1942 1943 1944 1945 1946 1947 1948
	while (sctx->curr == -1) {
		spin_lock(&sctx->list_lock);
		sctx->curr = sctx->first_free;
		if (sctx->curr != -1) {
			sctx->first_free = sctx->bios[sctx->curr]->next_free;
			sctx->bios[sctx->curr]->next_free = -1;
			sctx->bios[sctx->curr]->page_count = 0;
			spin_unlock(&sctx->list_lock);
A
Arne Jansen 已提交
1949
		} else {
1950 1951
			spin_unlock(&sctx->list_lock);
			wait_event(sctx->list_wait, sctx->first_free != -1);
A
Arne Jansen 已提交
1952 1953
		}
	}
1954
	sbio = sctx->bios[sctx->curr];
1955
	if (sbio->page_count == 0) {
1956 1957
		struct bio *bio;

1958 1959
		sbio->physical = spage->physical;
		sbio->logical = spage->logical;
1960
		sbio->dev = spage->dev;
1961 1962
		bio = sbio->bio;
		if (!bio) {
1963
			bio = btrfs_io_bio_alloc(GFP_NOFS, sctx->pages_per_rd_bio);
1964 1965 1966 1967
			if (!bio)
				return -ENOMEM;
			sbio->bio = bio;
		}
1968 1969 1970

		bio->bi_private = sbio;
		bio->bi_end_io = scrub_bio_end_io;
1971
		bio->bi_bdev = sbio->dev->bdev;
1972
		bio->bi_iter.bi_sector = sbio->physical >> 9;
1973
		sbio->err = 0;
1974 1975 1976
	} else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
		   spage->physical ||
		   sbio->logical + sbio->page_count * PAGE_SIZE !=
1977 1978
		   spage->logical ||
		   sbio->dev != spage->dev) {
1979
		scrub_submit(sctx);
A
Arne Jansen 已提交
1980 1981
		goto again;
	}
1982

1983 1984 1985 1986 1987 1988 1989 1990
	sbio->pagev[sbio->page_count] = spage;
	ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
	if (ret != PAGE_SIZE) {
		if (sbio->page_count < 1) {
			bio_put(sbio->bio);
			sbio->bio = NULL;
			return -EIO;
		}
1991
		scrub_submit(sctx);
1992 1993 1994
		goto again;
	}

1995
	scrub_block_get(sblock); /* one for the page added to the bio */
1996 1997
	atomic_inc(&sblock->outstanding_pages);
	sbio->page_count++;
1998
	if (sbio->page_count == sctx->pages_per_rd_bio)
1999
		scrub_submit(sctx);
2000 2001 2002 2003

	return 0;
}

2004
static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
2005
		       u64 physical, struct btrfs_device *dev, u64 flags,
2006 2007
		       u64 gen, int mirror_num, u8 *csum, int force,
		       u64 physical_for_dev_replace)
2008 2009 2010 2011 2012 2013
{
	struct scrub_block *sblock;
	int index;

	sblock = kzalloc(sizeof(*sblock), GFP_NOFS);
	if (!sblock) {
2014 2015 2016
		spin_lock(&sctx->stat_lock);
		sctx->stat.malloc_errors++;
		spin_unlock(&sctx->stat_lock);
2017
		return -ENOMEM;
A
Arne Jansen 已提交
2018
	}
2019

2020 2021
	/* one ref inside this function, plus one for each page added to
	 * a bio later on */
2022
	atomic_set(&sblock->ref_count, 1);
2023
	sblock->sctx = sctx;
2024 2025 2026
	sblock->no_io_error_seen = 1;

	for (index = 0; len > 0; index++) {
2027
		struct scrub_page *spage;
2028 2029
		u64 l = min_t(u64, len, PAGE_SIZE);

2030 2031 2032
		spage = kzalloc(sizeof(*spage), GFP_NOFS);
		if (!spage) {
leave_nomem:
2033 2034 2035
			spin_lock(&sctx->stat_lock);
			sctx->stat.malloc_errors++;
			spin_unlock(&sctx->stat_lock);
2036
			scrub_block_put(sblock);
2037 2038
			return -ENOMEM;
		}
2039 2040 2041
		BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
		scrub_page_get(spage);
		sblock->pagev[index] = spage;
2042
		spage->sblock = sblock;
2043
		spage->dev = dev;
2044 2045 2046 2047
		spage->flags = flags;
		spage->generation = gen;
		spage->logical = logical;
		spage->physical = physical;
2048
		spage->physical_for_dev_replace = physical_for_dev_replace;
2049 2050 2051
		spage->mirror_num = mirror_num;
		if (csum) {
			spage->have_csum = 1;
2052
			memcpy(spage->csum, csum, sctx->csum_size);
2053 2054 2055 2056
		} else {
			spage->have_csum = 0;
		}
		sblock->page_count++;
2057 2058 2059
		spage->page = alloc_page(GFP_NOFS);
		if (!spage->page)
			goto leave_nomem;
2060 2061 2062
		len -= l;
		logical += l;
		physical += l;
2063
		physical_for_dev_replace += l;
2064 2065
	}

2066
	WARN_ON(sblock->page_count == 0);
2067
	for (index = 0; index < sblock->page_count; index++) {
2068
		struct scrub_page *spage = sblock->pagev[index];
2069 2070
		int ret;

2071
		ret = scrub_add_page_to_rd_bio(sctx, spage);
2072 2073
		if (ret) {
			scrub_block_put(sblock);
2074
			return ret;
2075
		}
2076
	}
A
Arne Jansen 已提交
2077

2078
	if (force)
2079
		scrub_submit(sctx);
A
Arne Jansen 已提交
2080

2081 2082
	/* last one frees, either here or in bio completion for last page */
	scrub_block_put(sblock);
A
Arne Jansen 已提交
2083 2084 2085
	return 0;
}

2086 2087 2088
static void scrub_bio_end_io(struct bio *bio, int err)
{
	struct scrub_bio *sbio = bio->bi_private;
2089
	struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
2090 2091 2092 2093

	sbio->err = err;
	sbio->bio = bio;

2094
	btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
2095 2096 2097 2098 2099
}

static void scrub_bio_end_io_worker(struct btrfs_work *work)
{
	struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2100
	struct scrub_ctx *sctx = sbio->sctx;
2101 2102
	int i;

2103
	BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124
	if (sbio->err) {
		for (i = 0; i < sbio->page_count; i++) {
			struct scrub_page *spage = sbio->pagev[i];

			spage->io_error = 1;
			spage->sblock->no_io_error_seen = 0;
		}
	}

	/* now complete the scrub_block items that have all pages completed */
	for (i = 0; i < sbio->page_count; i++) {
		struct scrub_page *spage = sbio->pagev[i];
		struct scrub_block *sblock = spage->sblock;

		if (atomic_dec_and_test(&sblock->outstanding_pages))
			scrub_block_complete(sblock);
		scrub_block_put(sblock);
	}

	bio_put(sbio->bio);
	sbio->bio = NULL;
2125 2126 2127 2128
	spin_lock(&sctx->list_lock);
	sbio->next_free = sctx->first_free;
	sctx->first_free = sbio->index;
	spin_unlock(&sctx->list_lock);
2129 2130 2131 2132 2133 2134 2135 2136

	if (sctx->is_dev_replace &&
	    atomic_read(&sctx->wr_ctx.flush_all_writes)) {
		mutex_lock(&sctx->wr_ctx.wr_lock);
		scrub_wr_submit(sctx);
		mutex_unlock(&sctx->wr_ctx.wr_lock);
	}

2137
	scrub_pending_bio_dec(sctx);
2138 2139 2140 2141
}

static void scrub_block_complete(struct scrub_block *sblock)
{
2142
	if (!sblock->no_io_error_seen) {
2143
		scrub_handle_errored_block(sblock);
2144 2145 2146 2147 2148 2149 2150 2151 2152
	} else {
		/*
		 * if has checksum error, write via repair mechanism in
		 * dev replace case, otherwise write here in dev replace
		 * case.
		 */
		if (!scrub_checksum(sblock) && sblock->sctx->is_dev_replace)
			scrub_write_block_to_dev_replace(sblock);
	}
2153 2154
}

2155
static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u64 len,
A
Arne Jansen 已提交
2156 2157 2158
			   u8 *csum)
{
	struct btrfs_ordered_sum *sum = NULL;
2159
	unsigned long index;
A
Arne Jansen 已提交
2160 2161
	unsigned long num_sectors;

2162 2163
	while (!list_empty(&sctx->csum_list)) {
		sum = list_first_entry(&sctx->csum_list,
A
Arne Jansen 已提交
2164 2165 2166 2167 2168 2169
				       struct btrfs_ordered_sum, list);
		if (sum->bytenr > logical)
			return 0;
		if (sum->bytenr + sum->len > logical)
			break;

2170
		++sctx->stat.csum_discards;
A
Arne Jansen 已提交
2171 2172 2173 2174 2175 2176 2177
		list_del(&sum->list);
		kfree(sum);
		sum = NULL;
	}
	if (!sum)
		return 0;

2178
	index = ((u32)(logical - sum->bytenr)) / sctx->sectorsize;
2179
	num_sectors = sum->len / sctx->sectorsize;
2180 2181
	memcpy(csum, sum->sums + index, sctx->csum_size);
	if (index == num_sectors - 1) {
A
Arne Jansen 已提交
2182 2183 2184
		list_del(&sum->list);
		kfree(sum);
	}
2185
	return 1;
A
Arne Jansen 已提交
2186 2187 2188
}

/* scrub extent tries to collect up to 64 kB for each bio */
2189
static int scrub_extent(struct scrub_ctx *sctx, u64 logical, u64 len,
2190
			u64 physical, struct btrfs_device *dev, u64 flags,
2191
			u64 gen, int mirror_num, u64 physical_for_dev_replace)
A
Arne Jansen 已提交
2192 2193 2194
{
	int ret;
	u8 csum[BTRFS_CSUM_SIZE];
2195 2196 2197
	u32 blocksize;

	if (flags & BTRFS_EXTENT_FLAG_DATA) {
2198 2199 2200 2201 2202
		blocksize = sctx->sectorsize;
		spin_lock(&sctx->stat_lock);
		sctx->stat.data_extents_scrubbed++;
		sctx->stat.data_bytes_scrubbed += len;
		spin_unlock(&sctx->stat_lock);
2203
	} else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2204 2205 2206 2207 2208
		blocksize = sctx->nodesize;
		spin_lock(&sctx->stat_lock);
		sctx->stat.tree_extents_scrubbed++;
		sctx->stat.tree_bytes_scrubbed += len;
		spin_unlock(&sctx->stat_lock);
2209
	} else {
2210
		blocksize = sctx->sectorsize;
2211
		WARN_ON(1);
2212
	}
A
Arne Jansen 已提交
2213 2214

	while (len) {
2215
		u64 l = min_t(u64, len, blocksize);
A
Arne Jansen 已提交
2216 2217 2218 2219
		int have_csum = 0;

		if (flags & BTRFS_EXTENT_FLAG_DATA) {
			/* push csums to sbio */
2220
			have_csum = scrub_find_csum(sctx, logical, l, csum);
A
Arne Jansen 已提交
2221
			if (have_csum == 0)
2222
				++sctx->stat.no_csum;
2223 2224 2225 2226 2227 2228
			if (sctx->is_dev_replace && !have_csum) {
				ret = copy_nocow_pages(sctx, logical, l,
						       mirror_num,
						      physical_for_dev_replace);
				goto behind_scrub_pages;
			}
A
Arne Jansen 已提交
2229
		}
2230
		ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2231 2232 2233
				  mirror_num, have_csum ? csum : NULL, 0,
				  physical_for_dev_replace);
behind_scrub_pages:
A
Arne Jansen 已提交
2234 2235 2236 2237 2238
		if (ret)
			return ret;
		len -= l;
		logical += l;
		physical += l;
2239
		physical_for_dev_replace += l;
A
Arne Jansen 已提交
2240 2241 2242 2243
	}
	return 0;
}

2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274
/*
 * Given a physical address, this will calculate it's
 * logical offset. if this is a parity stripe, it will return
 * the most left data stripe's logical offset.
 *
 * return 0 if it is a data stripe, 1 means parity stripe.
 */
static int get_raid56_logic_offset(u64 physical, int num,
				   struct map_lookup *map, u64 *offset)
{
	int i;
	int j = 0;
	u64 stripe_nr;
	u64 last_offset;
	int stripe_index;
	int rot;

	last_offset = (physical - map->stripes[num].physical) *
		      nr_data_stripes(map);
	*offset = last_offset;
	for (i = 0; i < nr_data_stripes(map); i++) {
		*offset = last_offset + i * map->stripe_len;

		stripe_nr = *offset;
		do_div(stripe_nr, map->stripe_len);
		do_div(stripe_nr, nr_data_stripes(map));

		/* Work out the disk rotation on this stripe-set */
		rot = do_div(stripe_nr, map->num_stripes);
		/* calculate which stripe this data locates */
		rot += i;
2275
		stripe_index = rot % map->num_stripes;
2276 2277 2278 2279 2280 2281 2282 2283 2284
		if (stripe_index == num)
			return 0;
		if (stripe_index < num)
			j++;
	}
	*offset = last_offset + j * map->stripe_len;
	return 1;
}

2285
static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
2286 2287
					   struct map_lookup *map,
					   struct btrfs_device *scrub_dev,
2288 2289
					   int num, u64 base, u64 length,
					   int is_dev_replace)
A
Arne Jansen 已提交
2290 2291
{
	struct btrfs_path *path;
2292
	struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
A
Arne Jansen 已提交
2293 2294 2295
	struct btrfs_root *root = fs_info->extent_root;
	struct btrfs_root *csum_root = fs_info->csum_root;
	struct btrfs_extent_item *extent;
2296
	struct blk_plug plug;
A
Arne Jansen 已提交
2297 2298 2299 2300 2301 2302 2303 2304
	u64 flags;
	int ret;
	int slot;
	u64 nstripes;
	struct extent_buffer *l;
	struct btrfs_key key;
	u64 physical;
	u64 logical;
L
Liu Bo 已提交
2305
	u64 logic_end;
2306
	u64 physical_end;
A
Arne Jansen 已提交
2307
	u64 generation;
2308
	int mirror_num;
A
Arne Jansen 已提交
2309 2310 2311 2312
	struct reada_control *reada1;
	struct reada_control *reada2;
	struct btrfs_key key_start;
	struct btrfs_key key_end;
A
Arne Jansen 已提交
2313 2314
	u64 increment = map->stripe_len;
	u64 offset;
2315 2316 2317 2318 2319
	u64 extent_logical;
	u64 extent_physical;
	u64 extent_len;
	struct btrfs_device *extent_dev;
	int extent_mirror_num;
2320
	int stop_loop = 0;
D
David Woodhouse 已提交
2321

A
Arne Jansen 已提交
2322
	nstripes = length;
2323
	physical = map->stripes[num].physical;
A
Arne Jansen 已提交
2324 2325 2326 2327 2328
	offset = 0;
	do_div(nstripes, map->stripe_len);
	if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
		offset = map->stripe_len * num;
		increment = map->stripe_len * map->num_stripes;
2329
		mirror_num = 1;
A
Arne Jansen 已提交
2330 2331 2332 2333
	} else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
		int factor = map->num_stripes / map->sub_stripes;
		offset = map->stripe_len * (num / map->sub_stripes);
		increment = map->stripe_len * factor;
2334
		mirror_num = num % map->sub_stripes + 1;
A
Arne Jansen 已提交
2335 2336
	} else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
		increment = map->stripe_len;
2337
		mirror_num = num % map->num_stripes + 1;
A
Arne Jansen 已提交
2338 2339
	} else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
		increment = map->stripe_len;
2340
		mirror_num = num % map->num_stripes + 1;
2341 2342 2343 2344 2345
	} else if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
				BTRFS_BLOCK_GROUP_RAID6)) {
		get_raid56_logic_offset(physical, num, map, &offset);
		increment = map->stripe_len * nr_data_stripes(map);
		mirror_num = 1;
A
Arne Jansen 已提交
2346 2347
	} else {
		increment = map->stripe_len;
2348
		mirror_num = 1;
A
Arne Jansen 已提交
2349 2350 2351 2352 2353 2354
	}

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

2355 2356 2357 2358 2359
	/*
	 * work on commit root. The related disk blocks are static as
	 * long as COW is applied. This means, it is save to rewrite
	 * them to repair disk errors without any race conditions
	 */
A
Arne Jansen 已提交
2360 2361 2362 2363
	path->search_commit_root = 1;
	path->skip_locking = 1;

	/*
A
Arne Jansen 已提交
2364 2365 2366
	 * trigger the readahead for extent tree csum tree and wait for
	 * completion. During readahead, the scrub is officially paused
	 * to not hold off transaction commits
A
Arne Jansen 已提交
2367 2368
	 */
	logical = base + offset;
2369 2370 2371 2372 2373 2374 2375 2376 2377
	physical_end = physical + nstripes * map->stripe_len;
	if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
			 BTRFS_BLOCK_GROUP_RAID6)) {
		get_raid56_logic_offset(physical_end, num,
					map, &logic_end);
		logic_end += base;
	} else {
		logic_end = logical + increment * nstripes;
	}
2378
	wait_event(sctx->list_wait,
2379
		   atomic_read(&sctx->bios_in_flight) == 0);
2380
	scrub_blocked_if_needed(fs_info);
A
Arne Jansen 已提交
2381 2382 2383 2384 2385

	/* FIXME it might be better to start readahead at commit root */
	key_start.objectid = logical;
	key_start.type = BTRFS_EXTENT_ITEM_KEY;
	key_start.offset = (u64)0;
2386
	key_end.objectid = logic_end;
2387 2388
	key_end.type = BTRFS_METADATA_ITEM_KEY;
	key_end.offset = (u64)-1;
A
Arne Jansen 已提交
2389 2390 2391 2392 2393 2394 2395
	reada1 = btrfs_reada_add(root, &key_start, &key_end);

	key_start.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
	key_start.type = BTRFS_EXTENT_CSUM_KEY;
	key_start.offset = logical;
	key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
	key_end.type = BTRFS_EXTENT_CSUM_KEY;
2396
	key_end.offset = logic_end;
A
Arne Jansen 已提交
2397 2398 2399 2400 2401 2402 2403
	reada2 = btrfs_reada_add(csum_root, &key_start, &key_end);

	if (!IS_ERR(reada1))
		btrfs_reada_wait(reada1);
	if (!IS_ERR(reada2))
		btrfs_reada_wait(reada2);

A
Arne Jansen 已提交
2404 2405 2406 2407 2408

	/*
	 * collect all data csums for the stripe to avoid seeking during
	 * the scrub. This might currently (crc32) end up to be about 1MB
	 */
2409
	blk_start_plug(&plug);
A
Arne Jansen 已提交
2410 2411 2412 2413 2414

	/*
	 * now find all extents for each stripe and scrub them
	 */
	ret = 0;
2415 2416 2417 2418 2419 2420 2421 2422 2423 2424
	while (physical < physical_end) {
		/* for raid56, we skip parity stripe */
		if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
				BTRFS_BLOCK_GROUP_RAID6)) {
			ret = get_raid56_logic_offset(physical, num,
					map, &logical);
			logical += base;
			if (ret)
				goto skip;
		}
A
Arne Jansen 已提交
2425 2426 2427 2428
		/*
		 * canceled?
		 */
		if (atomic_read(&fs_info->scrub_cancel_req) ||
2429
		    atomic_read(&sctx->cancel_req)) {
A
Arne Jansen 已提交
2430 2431 2432 2433 2434 2435 2436 2437
			ret = -ECANCELED;
			goto out;
		}
		/*
		 * check to see if we have to pause
		 */
		if (atomic_read(&fs_info->scrub_pause_req)) {
			/* push queued extents */
2438
			atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
2439
			scrub_submit(sctx);
2440 2441 2442
			mutex_lock(&sctx->wr_ctx.wr_lock);
			scrub_wr_submit(sctx);
			mutex_unlock(&sctx->wr_ctx.wr_lock);
2443
			wait_event(sctx->list_wait,
2444
				   atomic_read(&sctx->bios_in_flight) == 0);
2445
			atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
2446
			scrub_blocked_if_needed(fs_info);
A
Arne Jansen 已提交
2447 2448
		}

2449 2450 2451 2452
		if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
			key.type = BTRFS_METADATA_ITEM_KEY;
		else
			key.type = BTRFS_EXTENT_ITEM_KEY;
A
Arne Jansen 已提交
2453
		key.objectid = logical;
L
Liu Bo 已提交
2454
		key.offset = (u64)-1;
A
Arne Jansen 已提交
2455 2456 2457 2458

		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
		if (ret < 0)
			goto out;
2459

2460
		if (ret > 0) {
2461
			ret = btrfs_previous_extent_item(root, path, 0);
A
Arne Jansen 已提交
2462 2463
			if (ret < 0)
				goto out;
2464 2465 2466 2467 2468 2469 2470 2471 2472
			if (ret > 0) {
				/* there's no smaller item, so stick with the
				 * larger one */
				btrfs_release_path(path);
				ret = btrfs_search_slot(NULL, root, &key,
							path, 0, 0);
				if (ret < 0)
					goto out;
			}
A
Arne Jansen 已提交
2473 2474
		}

L
Liu Bo 已提交
2475
		stop_loop = 0;
A
Arne Jansen 已提交
2476
		while (1) {
2477 2478
			u64 bytes;

A
Arne Jansen 已提交
2479 2480 2481 2482 2483 2484 2485 2486 2487
			l = path->nodes[0];
			slot = path->slots[0];
			if (slot >= btrfs_header_nritems(l)) {
				ret = btrfs_next_leaf(root, path);
				if (ret == 0)
					continue;
				if (ret < 0)
					goto out;

L
Liu Bo 已提交
2488
				stop_loop = 1;
A
Arne Jansen 已提交
2489 2490 2491 2492
				break;
			}
			btrfs_item_key_to_cpu(l, &key, slot);

2493
			if (key.type == BTRFS_METADATA_ITEM_KEY)
2494
				bytes = root->nodesize;
2495 2496 2497 2498
			else
				bytes = key.offset;

			if (key.objectid + bytes <= logical)
A
Arne Jansen 已提交
2499 2500
				goto next;

L
Liu Bo 已提交
2501 2502 2503
			if (key.type != BTRFS_EXTENT_ITEM_KEY &&
			    key.type != BTRFS_METADATA_ITEM_KEY)
				goto next;
A
Arne Jansen 已提交
2504

L
Liu Bo 已提交
2505 2506 2507 2508 2509 2510
			if (key.objectid >= logical + map->stripe_len) {
				/* out of this device extent */
				if (key.objectid >= logic_end)
					stop_loop = 1;
				break;
			}
A
Arne Jansen 已提交
2511 2512 2513 2514 2515 2516 2517 2518

			extent = btrfs_item_ptr(l, slot,
						struct btrfs_extent_item);
			flags = btrfs_extent_flags(l, extent);
			generation = btrfs_extent_generation(l, extent);

			if (key.objectid < logical &&
			    (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
2519 2520 2521
				btrfs_err(fs_info,
					   "scrub: tree block %llu spanning "
					   "stripes, ignored. logical=%llu",
2522
				       key.objectid, logical);
A
Arne Jansen 已提交
2523 2524 2525
				goto next;
			}

L
Liu Bo 已提交
2526 2527 2528 2529
again:
			extent_logical = key.objectid;
			extent_len = bytes;

A
Arne Jansen 已提交
2530 2531 2532
			/*
			 * trim extent to this stripe
			 */
L
Liu Bo 已提交
2533 2534 2535
			if (extent_logical < logical) {
				extent_len -= logical - extent_logical;
				extent_logical = logical;
A
Arne Jansen 已提交
2536
			}
L
Liu Bo 已提交
2537
			if (extent_logical + extent_len >
A
Arne Jansen 已提交
2538
			    logical + map->stripe_len) {
L
Liu Bo 已提交
2539 2540
				extent_len = logical + map->stripe_len -
					     extent_logical;
A
Arne Jansen 已提交
2541 2542
			}

L
Liu Bo 已提交
2543
			extent_physical = extent_logical - logical + physical;
2544 2545 2546 2547 2548 2549 2550
			extent_dev = scrub_dev;
			extent_mirror_num = mirror_num;
			if (is_dev_replace)
				scrub_remap_extent(fs_info, extent_logical,
						   extent_len, &extent_physical,
						   &extent_dev,
						   &extent_mirror_num);
L
Liu Bo 已提交
2551 2552 2553 2554 2555 2556 2557

			ret = btrfs_lookup_csums_range(csum_root, logical,
						logical + map->stripe_len - 1,
						&sctx->csum_list, 1);
			if (ret)
				goto out;

2558 2559 2560
			ret = scrub_extent(sctx, extent_logical, extent_len,
					   extent_physical, extent_dev, flags,
					   generation, extent_mirror_num,
2561
					   extent_logical - logical + physical);
A
Arne Jansen 已提交
2562 2563 2564
			if (ret)
				goto out;

2565
			scrub_free_csums(sctx);
L
Liu Bo 已提交
2566 2567
			if (extent_logical + extent_len <
			    key.objectid + bytes) {
2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584
				if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
					BTRFS_BLOCK_GROUP_RAID6)) {
					/*
					 * loop until we find next data stripe
					 * or we have finished all stripes.
					 */
					do {
						physical += map->stripe_len;
						ret = get_raid56_logic_offset(
								physical, num,
								map, &logical);
						logical += base;
					} while (physical < physical_end && ret);
				} else {
					physical += map->stripe_len;
					logical += increment;
				}
L
Liu Bo 已提交
2585 2586 2587 2588 2589
				if (logical < key.objectid + bytes) {
					cond_resched();
					goto again;
				}

2590
				if (physical >= physical_end) {
L
Liu Bo 已提交
2591 2592 2593 2594
					stop_loop = 1;
					break;
				}
			}
A
Arne Jansen 已提交
2595 2596 2597
next:
			path->slots[0]++;
		}
C
Chris Mason 已提交
2598
		btrfs_release_path(path);
2599
skip:
A
Arne Jansen 已提交
2600 2601
		logical += increment;
		physical += map->stripe_len;
2602
		spin_lock(&sctx->stat_lock);
L
Liu Bo 已提交
2603 2604 2605 2606 2607
		if (stop_loop)
			sctx->stat.last_physical = map->stripes[num].physical +
						   length;
		else
			sctx->stat.last_physical = physical;
2608
		spin_unlock(&sctx->stat_lock);
L
Liu Bo 已提交
2609 2610
		if (stop_loop)
			break;
A
Arne Jansen 已提交
2611
	}
2612
out:
A
Arne Jansen 已提交
2613
	/* push queued extents */
2614
	scrub_submit(sctx);
2615 2616 2617
	mutex_lock(&sctx->wr_ctx.wr_lock);
	scrub_wr_submit(sctx);
	mutex_unlock(&sctx->wr_ctx.wr_lock);
A
Arne Jansen 已提交
2618

2619
	blk_finish_plug(&plug);
A
Arne Jansen 已提交
2620 2621 2622 2623
	btrfs_free_path(path);
	return ret < 0 ? ret : 0;
}

2624
static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
2625 2626 2627
					  struct btrfs_device *scrub_dev,
					  u64 chunk_tree, u64 chunk_objectid,
					  u64 chunk_offset, u64 length,
2628
					  u64 dev_offset, int is_dev_replace)
A
Arne Jansen 已提交
2629 2630
{
	struct btrfs_mapping_tree *map_tree =
2631
		&sctx->dev_root->fs_info->mapping_tree;
A
Arne Jansen 已提交
2632 2633 2634
	struct map_lookup *map;
	struct extent_map *em;
	int i;
2635
	int ret = 0;
A
Arne Jansen 已提交
2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651

	read_lock(&map_tree->map_tree.lock);
	em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
	read_unlock(&map_tree->map_tree.lock);

	if (!em)
		return -EINVAL;

	map = (struct map_lookup *)em->bdev;
	if (em->start != chunk_offset)
		goto out;

	if (em->len < length)
		goto out;

	for (i = 0; i < map->num_stripes; ++i) {
2652
		if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
2653
		    map->stripes[i].physical == dev_offset) {
2654
			ret = scrub_stripe(sctx, map, scrub_dev, i,
2655 2656
					   chunk_offset, length,
					   is_dev_replace);
A
Arne Jansen 已提交
2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667
			if (ret)
				goto out;
		}
	}
out:
	free_extent_map(em);

	return ret;
}

static noinline_for_stack
2668
int scrub_enumerate_chunks(struct scrub_ctx *sctx,
2669 2670
			   struct btrfs_device *scrub_dev, u64 start, u64 end,
			   int is_dev_replace)
A
Arne Jansen 已提交
2671 2672 2673
{
	struct btrfs_dev_extent *dev_extent = NULL;
	struct btrfs_path *path;
2674
	struct btrfs_root *root = sctx->dev_root;
A
Arne Jansen 已提交
2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685
	struct btrfs_fs_info *fs_info = root->fs_info;
	u64 length;
	u64 chunk_tree;
	u64 chunk_objectid;
	u64 chunk_offset;
	int ret;
	int slot;
	struct extent_buffer *l;
	struct btrfs_key key;
	struct btrfs_key found_key;
	struct btrfs_block_group_cache *cache;
2686
	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
A
Arne Jansen 已提交
2687 2688 2689 2690 2691 2692 2693 2694 2695

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	path->reada = 2;
	path->search_commit_root = 1;
	path->skip_locking = 1;

2696
	key.objectid = scrub_dev->devid;
A
Arne Jansen 已提交
2697 2698 2699 2700 2701 2702
	key.offset = 0ull;
	key.type = BTRFS_DEV_EXTENT_KEY;

	while (1) {
		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
		if (ret < 0)
2703 2704 2705 2706 2707 2708 2709 2710 2711
			break;
		if (ret > 0) {
			if (path->slots[0] >=
			    btrfs_header_nritems(path->nodes[0])) {
				ret = btrfs_next_leaf(root, path);
				if (ret)
					break;
			}
		}
A
Arne Jansen 已提交
2712 2713 2714 2715 2716 2717

		l = path->nodes[0];
		slot = path->slots[0];

		btrfs_item_key_to_cpu(l, &found_key, slot);

2718
		if (found_key.objectid != scrub_dev->devid)
A
Arne Jansen 已提交
2719 2720
			break;

2721
		if (found_key.type != BTRFS_DEV_EXTENT_KEY)
A
Arne Jansen 已提交
2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732
			break;

		if (found_key.offset >= end)
			break;

		if (found_key.offset < key.offset)
			break;

		dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
		length = btrfs_dev_extent_length(l, dev_extent);

2733 2734
		if (found_key.offset + length <= start)
			goto skip;
A
Arne Jansen 已提交
2735 2736 2737 2738 2739 2740 2741 2742 2743 2744

		chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
		chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
		chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);

		/*
		 * get a reference on the corresponding block group to prevent
		 * the chunk from going away while we scrub it
		 */
		cache = btrfs_lookup_block_group(fs_info, chunk_offset);
2745 2746 2747 2748 2749 2750

		/* some chunks are removed but not committed to disk yet,
		 * continue scrubbing */
		if (!cache)
			goto skip;

2751 2752 2753
		dev_replace->cursor_right = found_key.offset + length;
		dev_replace->cursor_left = found_key.offset;
		dev_replace->item_needs_writeback = 1;
2754
		ret = scrub_chunk(sctx, scrub_dev, chunk_tree, chunk_objectid,
2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775
				  chunk_offset, length, found_key.offset,
				  is_dev_replace);

		/*
		 * flush, submit all pending read and write bios, afterwards
		 * wait for them.
		 * Note that in the dev replace case, a read request causes
		 * write requests that are submitted in the read completion
		 * worker. Therefore in the current situation, it is required
		 * that all write requests are flushed, so that all read and
		 * write requests are really completed when bios_in_flight
		 * changes to 0.
		 */
		atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
		scrub_submit(sctx);
		mutex_lock(&sctx->wr_ctx.wr_lock);
		scrub_wr_submit(sctx);
		mutex_unlock(&sctx->wr_ctx.wr_lock);

		wait_event(sctx->list_wait,
			   atomic_read(&sctx->bios_in_flight) == 0);
2776 2777 2778 2779 2780 2781 2782 2783
		atomic_inc(&fs_info->scrubs_paused);
		wake_up(&fs_info->scrub_pause_wait);

		/*
		 * must be called before we decrease @scrub_paused.
		 * make sure we don't block transaction commit while
		 * we are waiting pending workers finished.
		 */
2784 2785
		wait_event(sctx->list_wait,
			   atomic_read(&sctx->workers_pending) == 0);
2786 2787 2788 2789 2790 2791 2792
		atomic_set(&sctx->wr_ctx.flush_all_writes, 0);

		mutex_lock(&fs_info->scrub_lock);
		__scrub_blocked_if_needed(fs_info);
		atomic_dec(&fs_info->scrubs_paused);
		mutex_unlock(&fs_info->scrub_lock);
		wake_up(&fs_info->scrub_pause_wait);
2793

A
Arne Jansen 已提交
2794 2795 2796
		btrfs_put_block_group(cache);
		if (ret)
			break;
2797 2798
		if (is_dev_replace &&
		    atomic64_read(&dev_replace->num_write_errors) > 0) {
2799 2800 2801 2802 2803 2804 2805
			ret = -EIO;
			break;
		}
		if (sctx->stat.malloc_errors > 0) {
			ret = -ENOMEM;
			break;
		}
A
Arne Jansen 已提交
2806

2807 2808
		dev_replace->cursor_left = dev_replace->cursor_right;
		dev_replace->item_needs_writeback = 1;
2809
skip:
A
Arne Jansen 已提交
2810
		key.offset = found_key.offset + length;
C
Chris Mason 已提交
2811
		btrfs_release_path(path);
A
Arne Jansen 已提交
2812 2813 2814
	}

	btrfs_free_path(path);
2815 2816 2817 2818 2819 2820

	/*
	 * ret can still be 1 from search_slot or next_leaf,
	 * that's not an error
	 */
	return ret < 0 ? ret : 0;
A
Arne Jansen 已提交
2821 2822
}

2823 2824
static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
					   struct btrfs_device *scrub_dev)
A
Arne Jansen 已提交
2825 2826 2827 2828 2829
{
	int	i;
	u64	bytenr;
	u64	gen;
	int	ret;
2830
	struct btrfs_root *root = sctx->dev_root;
A
Arne Jansen 已提交
2831

2832
	if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
2833 2834
		return -EIO;

2835 2836 2837 2838 2839
	/* Seed devices of a new filesystem has their own generation. */
	if (scrub_dev->fs_devices != root->fs_info->fs_devices)
		gen = scrub_dev->generation;
	else
		gen = root->fs_info->last_trans_committed;
A
Arne Jansen 已提交
2840 2841 2842

	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
		bytenr = btrfs_sb_offset(i);
2843 2844
		if (bytenr + BTRFS_SUPER_INFO_SIZE >
		    scrub_dev->commit_total_bytes)
A
Arne Jansen 已提交
2845 2846
			break;

2847
		ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
2848
				  scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
2849
				  NULL, 1, bytenr);
A
Arne Jansen 已提交
2850 2851 2852
		if (ret)
			return ret;
	}
2853
	wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
A
Arne Jansen 已提交
2854 2855 2856 2857 2858 2859 2860

	return 0;
}

/*
 * get a reference count on fs_info->scrub_workers. start worker if necessary
 */
2861 2862
static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
						int is_dev_replace)
A
Arne Jansen 已提交
2863
{
2864
	int ret = 0;
2865 2866
	int flags = WQ_FREEZABLE | WQ_UNBOUND;
	int max_active = fs_info->thread_pool_size;
A
Arne Jansen 已提交
2867

A
Arne Jansen 已提交
2868
	if (fs_info->scrub_workers_refcnt == 0) {
2869
		if (is_dev_replace)
2870 2871 2872
			fs_info->scrub_workers =
				btrfs_alloc_workqueue("btrfs-scrub", flags,
						      1, 4);
2873
		else
2874 2875 2876 2877 2878
			fs_info->scrub_workers =
				btrfs_alloc_workqueue("btrfs-scrub", flags,
						      max_active, 4);
		if (!fs_info->scrub_workers) {
			ret = -ENOMEM;
2879
			goto out;
2880 2881 2882 2883 2884 2885
		}
		fs_info->scrub_wr_completion_workers =
			btrfs_alloc_workqueue("btrfs-scrubwrc", flags,
					      max_active, 2);
		if (!fs_info->scrub_wr_completion_workers) {
			ret = -ENOMEM;
2886
			goto out;
2887 2888 2889 2890 2891
		}
		fs_info->scrub_nocow_workers =
			btrfs_alloc_workqueue("btrfs-scrubnc", flags, 1, 0);
		if (!fs_info->scrub_nocow_workers) {
			ret = -ENOMEM;
2892
			goto out;
2893
		}
A
Arne Jansen 已提交
2894
	}
A
Arne Jansen 已提交
2895
	++fs_info->scrub_workers_refcnt;
2896 2897
out:
	return ret;
A
Arne Jansen 已提交
2898 2899
}

2900
static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info)
A
Arne Jansen 已提交
2901
{
2902
	if (--fs_info->scrub_workers_refcnt == 0) {
2903 2904 2905
		btrfs_destroy_workqueue(fs_info->scrub_workers);
		btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
		btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
2906
	}
A
Arne Jansen 已提交
2907 2908 2909
	WARN_ON(fs_info->scrub_workers_refcnt < 0);
}

2910 2911
int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
		    u64 end, struct btrfs_scrub_progress *progress,
2912
		    int readonly, int is_dev_replace)
A
Arne Jansen 已提交
2913
{
2914
	struct scrub_ctx *sctx;
A
Arne Jansen 已提交
2915 2916
	int ret;
	struct btrfs_device *dev;
2917
	struct rcu_string *name;
A
Arne Jansen 已提交
2918

2919
	if (btrfs_fs_closing(fs_info))
A
Arne Jansen 已提交
2920 2921
		return -EINVAL;

2922
	if (fs_info->chunk_root->nodesize > BTRFS_STRIPE_LEN) {
2923 2924 2925 2926 2927
		/*
		 * in this case scrub is unable to calculate the checksum
		 * the way scrub is implemented. Do not handle this
		 * situation at all because it won't ever happen.
		 */
2928 2929
		btrfs_err(fs_info,
			   "scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails",
2930
		       fs_info->chunk_root->nodesize, BTRFS_STRIPE_LEN);
2931 2932 2933
		return -EINVAL;
	}

2934
	if (fs_info->chunk_root->sectorsize != PAGE_SIZE) {
2935
		/* not supported for data w/o checksums */
2936 2937 2938
		btrfs_err(fs_info,
			   "scrub: size assumption sectorsize != PAGE_SIZE "
			   "(%d != %lu) fails",
2939
		       fs_info->chunk_root->sectorsize, PAGE_SIZE);
A
Arne Jansen 已提交
2940 2941 2942
		return -EINVAL;
	}

2943 2944 2945 2946 2947 2948 2949 2950
	if (fs_info->chunk_root->nodesize >
	    PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
	    fs_info->chunk_root->sectorsize >
	    PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
		/*
		 * would exhaust the array bounds of pagev member in
		 * struct scrub_block
		 */
2951 2952
		btrfs_err(fs_info, "scrub: size assumption nodesize and sectorsize "
			   "<= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails",
2953 2954 2955 2956 2957 2958 2959
		       fs_info->chunk_root->nodesize,
		       SCRUB_MAX_PAGES_PER_BLOCK,
		       fs_info->chunk_root->sectorsize,
		       SCRUB_MAX_PAGES_PER_BLOCK);
		return -EINVAL;
	}

A
Arne Jansen 已提交
2960

2961 2962
	mutex_lock(&fs_info->fs_devices->device_list_mutex);
	dev = btrfs_find_device(fs_info, devid, NULL, NULL);
2963
	if (!dev || (dev->missing && !is_dev_replace)) {
2964
		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
A
Arne Jansen 已提交
2965 2966 2967
		return -ENODEV;
	}

2968 2969 2970 2971 2972 2973 2974 2975 2976 2977
	if (!is_dev_replace && !readonly && !dev->writeable) {
		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
		rcu_read_lock();
		name = rcu_dereference(dev->name);
		btrfs_err(fs_info, "scrub: device %s is not writable",
			  name->str);
		rcu_read_unlock();
		return -EROFS;
	}

2978
	mutex_lock(&fs_info->scrub_lock);
2979
	if (!dev->in_fs_metadata || dev->is_tgtdev_for_dev_replace) {
A
Arne Jansen 已提交
2980
		mutex_unlock(&fs_info->scrub_lock);
2981 2982
		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
		return -EIO;
A
Arne Jansen 已提交
2983 2984
	}

2985 2986 2987 2988 2989
	btrfs_dev_replace_lock(&fs_info->dev_replace);
	if (dev->scrub_device ||
	    (!is_dev_replace &&
	     btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
		btrfs_dev_replace_unlock(&fs_info->dev_replace);
A
Arne Jansen 已提交
2990
		mutex_unlock(&fs_info->scrub_lock);
2991
		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
A
Arne Jansen 已提交
2992 2993
		return -EINPROGRESS;
	}
2994
	btrfs_dev_replace_unlock(&fs_info->dev_replace);
2995 2996 2997 2998 2999 3000 3001 3002

	ret = scrub_workers_get(fs_info, is_dev_replace);
	if (ret) {
		mutex_unlock(&fs_info->scrub_lock);
		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
		return ret;
	}

3003
	sctx = scrub_setup_ctx(dev, is_dev_replace);
3004
	if (IS_ERR(sctx)) {
A
Arne Jansen 已提交
3005
		mutex_unlock(&fs_info->scrub_lock);
3006 3007
		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
		scrub_workers_put(fs_info);
3008
		return PTR_ERR(sctx);
A
Arne Jansen 已提交
3009
	}
3010 3011
	sctx->readonly = readonly;
	dev->scrub_device = sctx;
3012
	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
A
Arne Jansen 已提交
3013

3014 3015 3016 3017
	/*
	 * checking @scrub_pause_req here, we can avoid
	 * race between committing transaction and scrubbing.
	 */
3018
	__scrub_blocked_if_needed(fs_info);
A
Arne Jansen 已提交
3019 3020 3021
	atomic_inc(&fs_info->scrubs_running);
	mutex_unlock(&fs_info->scrub_lock);

3022
	if (!is_dev_replace) {
3023 3024 3025 3026
		/*
		 * by holding device list mutex, we can
		 * kick off writing super in log tree sync.
		 */
3027
		mutex_lock(&fs_info->fs_devices->device_list_mutex);
3028
		ret = scrub_supers(sctx, dev);
3029
		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3030
	}
A
Arne Jansen 已提交
3031 3032

	if (!ret)
3033 3034
		ret = scrub_enumerate_chunks(sctx, dev, start, end,
					     is_dev_replace);
A
Arne Jansen 已提交
3035

3036
	wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
A
Arne Jansen 已提交
3037 3038 3039
	atomic_dec(&fs_info->scrubs_running);
	wake_up(&fs_info->scrub_pause_wait);

3040
	wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
3041

A
Arne Jansen 已提交
3042
	if (progress)
3043
		memcpy(progress, &sctx->stat, sizeof(*progress));
A
Arne Jansen 已提交
3044 3045 3046

	mutex_lock(&fs_info->scrub_lock);
	dev->scrub_device = NULL;
3047
	scrub_workers_put(fs_info);
A
Arne Jansen 已提交
3048 3049
	mutex_unlock(&fs_info->scrub_lock);

3050
	scrub_free_ctx(sctx);
A
Arne Jansen 已提交
3051 3052 3053 3054

	return ret;
}

3055
void btrfs_scrub_pause(struct btrfs_root *root)
A
Arne Jansen 已提交
3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071
{
	struct btrfs_fs_info *fs_info = root->fs_info;

	mutex_lock(&fs_info->scrub_lock);
	atomic_inc(&fs_info->scrub_pause_req);
	while (atomic_read(&fs_info->scrubs_paused) !=
	       atomic_read(&fs_info->scrubs_running)) {
		mutex_unlock(&fs_info->scrub_lock);
		wait_event(fs_info->scrub_pause_wait,
			   atomic_read(&fs_info->scrubs_paused) ==
			   atomic_read(&fs_info->scrubs_running));
		mutex_lock(&fs_info->scrub_lock);
	}
	mutex_unlock(&fs_info->scrub_lock);
}

3072
void btrfs_scrub_continue(struct btrfs_root *root)
A
Arne Jansen 已提交
3073 3074 3075 3076 3077 3078 3079
{
	struct btrfs_fs_info *fs_info = root->fs_info;

	atomic_dec(&fs_info->scrub_pause_req);
	wake_up(&fs_info->scrub_pause_wait);
}

3080
int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
A
Arne Jansen 已提交
3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100
{
	mutex_lock(&fs_info->scrub_lock);
	if (!atomic_read(&fs_info->scrubs_running)) {
		mutex_unlock(&fs_info->scrub_lock);
		return -ENOTCONN;
	}

	atomic_inc(&fs_info->scrub_cancel_req);
	while (atomic_read(&fs_info->scrubs_running)) {
		mutex_unlock(&fs_info->scrub_lock);
		wait_event(fs_info->scrub_pause_wait,
			   atomic_read(&fs_info->scrubs_running) == 0);
		mutex_lock(&fs_info->scrub_lock);
	}
	atomic_dec(&fs_info->scrub_cancel_req);
	mutex_unlock(&fs_info->scrub_lock);

	return 0;
}

3101 3102
int btrfs_scrub_cancel_dev(struct btrfs_fs_info *fs_info,
			   struct btrfs_device *dev)
3103
{
3104
	struct scrub_ctx *sctx;
A
Arne Jansen 已提交
3105 3106

	mutex_lock(&fs_info->scrub_lock);
3107 3108
	sctx = dev->scrub_device;
	if (!sctx) {
A
Arne Jansen 已提交
3109 3110 3111
		mutex_unlock(&fs_info->scrub_lock);
		return -ENOTCONN;
	}
3112
	atomic_inc(&sctx->cancel_req);
A
Arne Jansen 已提交
3113 3114 3115 3116 3117 3118 3119 3120 3121 3122
	while (dev->scrub_device) {
		mutex_unlock(&fs_info->scrub_lock);
		wait_event(fs_info->scrub_pause_wait,
			   dev->scrub_device == NULL);
		mutex_lock(&fs_info->scrub_lock);
	}
	mutex_unlock(&fs_info->scrub_lock);

	return 0;
}
S
Stefan Behrens 已提交
3123

A
Arne Jansen 已提交
3124 3125 3126 3127
int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
			 struct btrfs_scrub_progress *progress)
{
	struct btrfs_device *dev;
3128
	struct scrub_ctx *sctx = NULL;
A
Arne Jansen 已提交
3129 3130

	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
3131
	dev = btrfs_find_device(root->fs_info, devid, NULL, NULL);
A
Arne Jansen 已提交
3132
	if (dev)
3133 3134 3135
		sctx = dev->scrub_device;
	if (sctx)
		memcpy(progress, &sctx->stat, sizeof(*progress));
A
Arne Jansen 已提交
3136 3137
	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);

3138
	return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
A
Arne Jansen 已提交
3139
}
3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215

static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
			       u64 extent_logical, u64 extent_len,
			       u64 *extent_physical,
			       struct btrfs_device **extent_dev,
			       int *extent_mirror_num)
{
	u64 mapped_length;
	struct btrfs_bio *bbio = NULL;
	int ret;

	mapped_length = extent_len;
	ret = btrfs_map_block(fs_info, READ, extent_logical,
			      &mapped_length, &bbio, 0);
	if (ret || !bbio || mapped_length < extent_len ||
	    !bbio->stripes[0].dev->bdev) {
		kfree(bbio);
		return;
	}

	*extent_physical = bbio->stripes[0].physical;
	*extent_mirror_num = bbio->mirror_num;
	*extent_dev = bbio->stripes[0].dev;
	kfree(bbio);
}

static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
			      struct scrub_wr_ctx *wr_ctx,
			      struct btrfs_fs_info *fs_info,
			      struct btrfs_device *dev,
			      int is_dev_replace)
{
	WARN_ON(wr_ctx->wr_curr_bio != NULL);

	mutex_init(&wr_ctx->wr_lock);
	wr_ctx->wr_curr_bio = NULL;
	if (!is_dev_replace)
		return 0;

	WARN_ON(!dev->bdev);
	wr_ctx->pages_per_wr_bio = min_t(int, SCRUB_PAGES_PER_WR_BIO,
					 bio_get_nr_vecs(dev->bdev));
	wr_ctx->tgtdev = dev;
	atomic_set(&wr_ctx->flush_all_writes, 0);
	return 0;
}

static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx)
{
	mutex_lock(&wr_ctx->wr_lock);
	kfree(wr_ctx->wr_curr_bio);
	wr_ctx->wr_curr_bio = NULL;
	mutex_unlock(&wr_ctx->wr_lock);
}

static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
			    int mirror_num, u64 physical_for_dev_replace)
{
	struct scrub_copy_nocow_ctx *nocow_ctx;
	struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;

	nocow_ctx = kzalloc(sizeof(*nocow_ctx), GFP_NOFS);
	if (!nocow_ctx) {
		spin_lock(&sctx->stat_lock);
		sctx->stat.malloc_errors++;
		spin_unlock(&sctx->stat_lock);
		return -ENOMEM;
	}

	scrub_pending_trans_workers_inc(sctx);

	nocow_ctx->sctx = sctx;
	nocow_ctx->logical = logical;
	nocow_ctx->len = len;
	nocow_ctx->mirror_num = mirror_num;
	nocow_ctx->physical_for_dev_replace = physical_for_dev_replace;
3216 3217
	btrfs_init_work(&nocow_ctx->work, btrfs_scrubnc_helper,
			copy_nocow_pages_worker, NULL, NULL);
3218
	INIT_LIST_HEAD(&nocow_ctx->inodes);
3219 3220
	btrfs_queue_work(fs_info->scrub_nocow_workers,
			 &nocow_ctx->work);
3221 3222 3223 3224

	return 0;
}

3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241
static int record_inode_for_nocow(u64 inum, u64 offset, u64 root, void *ctx)
{
	struct scrub_copy_nocow_ctx *nocow_ctx = ctx;
	struct scrub_nocow_inode *nocow_inode;

	nocow_inode = kzalloc(sizeof(*nocow_inode), GFP_NOFS);
	if (!nocow_inode)
		return -ENOMEM;
	nocow_inode->inum = inum;
	nocow_inode->offset = offset;
	nocow_inode->root = root;
	list_add_tail(&nocow_inode->list, &nocow_ctx->inodes);
	return 0;
}

#define COPY_COMPLETE 1

3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276
static void copy_nocow_pages_worker(struct btrfs_work *work)
{
	struct scrub_copy_nocow_ctx *nocow_ctx =
		container_of(work, struct scrub_copy_nocow_ctx, work);
	struct scrub_ctx *sctx = nocow_ctx->sctx;
	u64 logical = nocow_ctx->logical;
	u64 len = nocow_ctx->len;
	int mirror_num = nocow_ctx->mirror_num;
	u64 physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
	int ret;
	struct btrfs_trans_handle *trans = NULL;
	struct btrfs_fs_info *fs_info;
	struct btrfs_path *path;
	struct btrfs_root *root;
	int not_written = 0;

	fs_info = sctx->dev_root->fs_info;
	root = fs_info->extent_root;

	path = btrfs_alloc_path();
	if (!path) {
		spin_lock(&sctx->stat_lock);
		sctx->stat.malloc_errors++;
		spin_unlock(&sctx->stat_lock);
		not_written = 1;
		goto out;
	}

	trans = btrfs_join_transaction(root);
	if (IS_ERR(trans)) {
		not_written = 1;
		goto out;
	}

	ret = iterate_inodes_from_logical(logical, fs_info, path,
3277
					  record_inode_for_nocow, nocow_ctx);
3278
	if (ret != 0 && ret != -ENOENT) {
3279 3280
		btrfs_warn(fs_info, "iterate_inodes_from_logical() failed: log %llu, "
			"phys %llu, len %llu, mir %u, ret %d",
3281 3282
			logical, physical_for_dev_replace, len, mirror_num,
			ret);
3283 3284 3285 3286
		not_written = 1;
		goto out;
	}

3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304
	btrfs_end_transaction(trans, root);
	trans = NULL;
	while (!list_empty(&nocow_ctx->inodes)) {
		struct scrub_nocow_inode *entry;
		entry = list_first_entry(&nocow_ctx->inodes,
					 struct scrub_nocow_inode,
					 list);
		list_del_init(&entry->list);
		ret = copy_nocow_pages_for_inode(entry->inum, entry->offset,
						 entry->root, nocow_ctx);
		kfree(entry);
		if (ret == COPY_COMPLETE) {
			ret = 0;
			break;
		} else if (ret) {
			break;
		}
	}
3305
out:
3306 3307 3308 3309 3310 3311 3312 3313
	while (!list_empty(&nocow_ctx->inodes)) {
		struct scrub_nocow_inode *entry;
		entry = list_first_entry(&nocow_ctx->inodes,
					 struct scrub_nocow_inode,
					 list);
		list_del_init(&entry->list);
		kfree(entry);
	}
3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325
	if (trans && !IS_ERR(trans))
		btrfs_end_transaction(trans, root);
	if (not_written)
		btrfs_dev_replace_stats_inc(&fs_info->dev_replace.
					    num_uncorrectable_read_errors);

	btrfs_free_path(path);
	kfree(nocow_ctx);

	scrub_pending_trans_workers_dec(sctx);
}

3326 3327
static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
				      struct scrub_copy_nocow_ctx *nocow_ctx)
3328
{
3329
	struct btrfs_fs_info *fs_info = nocow_ctx->sctx->dev_root->fs_info;
3330
	struct btrfs_key key;
3331 3332
	struct inode *inode;
	struct page *page;
3333
	struct btrfs_root *local_root;
3334 3335 3336 3337
	struct btrfs_ordered_extent *ordered;
	struct extent_map *em;
	struct extent_state *cached_state = NULL;
	struct extent_io_tree *io_tree;
3338
	u64 physical_for_dev_replace;
3339 3340
	u64 len = nocow_ctx->len;
	u64 lockstart = offset, lockend = offset + len - 1;
3341
	unsigned long index;
3342
	int srcu_index;
3343 3344
	int ret = 0;
	int err = 0;
3345 3346 3347 3348

	key.objectid = root;
	key.type = BTRFS_ROOT_ITEM_KEY;
	key.offset = (u64)-1;
3349 3350 3351

	srcu_index = srcu_read_lock(&fs_info->subvol_srcu);

3352
	local_root = btrfs_read_fs_root_no_name(fs_info, &key);
3353 3354
	if (IS_ERR(local_root)) {
		srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
3355
		return PTR_ERR(local_root);
3356
	}
3357 3358 3359 3360 3361

	key.type = BTRFS_INODE_ITEM_KEY;
	key.objectid = inum;
	key.offset = 0;
	inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
3362
	srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
3363 3364 3365
	if (IS_ERR(inode))
		return PTR_ERR(inode);

3366 3367 3368 3369
	/* Avoid truncate/dio/punch hole.. */
	mutex_lock(&inode->i_mutex);
	inode_dio_wait(inode);

3370
	physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396
	io_tree = &BTRFS_I(inode)->io_tree;

	lock_extent_bits(io_tree, lockstart, lockend, 0, &cached_state);
	ordered = btrfs_lookup_ordered_range(inode, lockstart, len);
	if (ordered) {
		btrfs_put_ordered_extent(ordered);
		goto out_unlock;
	}

	em = btrfs_get_extent(inode, NULL, 0, lockstart, len, 0);
	if (IS_ERR(em)) {
		ret = PTR_ERR(em);
		goto out_unlock;
	}

	/*
	 * This extent does not actually cover the logical extent anymore,
	 * move on to the next inode.
	 */
	if (em->block_start > nocow_ctx->logical ||
	    em->block_start + em->block_len < nocow_ctx->logical + len) {
		free_extent_map(em);
		goto out_unlock;
	}
	free_extent_map(em);

3397 3398
	while (len >= PAGE_CACHE_SIZE) {
		index = offset >> PAGE_CACHE_SHIFT;
3399
again:
3400 3401
		page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
		if (!page) {
3402
			btrfs_err(fs_info, "find_or_create_page() failed");
3403
			ret = -ENOMEM;
3404
			goto out;
3405 3406 3407 3408 3409 3410 3411
		}

		if (PageUptodate(page)) {
			if (PageDirty(page))
				goto next_page;
		} else {
			ClearPageError(page);
3412 3413 3414
			err = extent_read_full_page_nolock(io_tree, page,
							   btrfs_get_extent,
							   nocow_ctx->mirror_num);
3415 3416
			if (err) {
				ret = err;
3417 3418
				goto next_page;
			}
3419

3420
			lock_page(page);
3421 3422 3423 3424 3425 3426 3427
			/*
			 * If the page has been remove from the page cache,
			 * the data on it is meaningless, because it may be
			 * old one, the new data may be written into the new
			 * page in the page cache.
			 */
			if (page->mapping != inode->i_mapping) {
3428
				unlock_page(page);
3429 3430 3431
				page_cache_release(page);
				goto again;
			}
3432 3433 3434 3435 3436
			if (!PageUptodate(page)) {
				ret = -EIO;
				goto next_page;
			}
		}
3437 3438 3439 3440
		err = write_page_nocow(nocow_ctx->sctx,
				       physical_for_dev_replace, page);
		if (err)
			ret = err;
3441
next_page:
3442 3443 3444 3445 3446 3447
		unlock_page(page);
		page_cache_release(page);

		if (ret)
			break;

3448 3449 3450 3451
		offset += PAGE_CACHE_SIZE;
		physical_for_dev_replace += PAGE_CACHE_SIZE;
		len -= PAGE_CACHE_SIZE;
	}
3452 3453 3454 3455
	ret = COPY_COMPLETE;
out_unlock:
	unlock_extent_cached(io_tree, lockstart, lockend, &cached_state,
			     GFP_NOFS);
3456
out:
3457
	mutex_unlock(&inode->i_mutex);
3458
	iput(inode);
3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473
	return ret;
}

static int write_page_nocow(struct scrub_ctx *sctx,
			    u64 physical_for_dev_replace, struct page *page)
{
	struct bio *bio;
	struct btrfs_device *dev;
	int ret;

	dev = sctx->wr_ctx.tgtdev;
	if (!dev)
		return -EIO;
	if (!dev->bdev) {
		printk_ratelimited(KERN_WARNING
3474
			"BTRFS: scrub write_page_nocow(bdev == NULL) is unexpected!\n");
3475 3476
		return -EIO;
	}
3477
	bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
3478 3479 3480 3481 3482 3483
	if (!bio) {
		spin_lock(&sctx->stat_lock);
		sctx->stat.malloc_errors++;
		spin_unlock(&sctx->stat_lock);
		return -ENOMEM;
	}
3484 3485
	bio->bi_iter.bi_size = 0;
	bio->bi_iter.bi_sector = physical_for_dev_replace >> 9;
3486 3487 3488 3489 3490 3491 3492 3493 3494
	bio->bi_bdev = dev->bdev;
	ret = bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
	if (ret != PAGE_CACHE_SIZE) {
leave_with_eio:
		bio_put(bio);
		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
		return -EIO;
	}

3495
	if (btrfsic_submit_bio_wait(WRITE_SYNC, bio))
3496 3497 3498 3499 3500
		goto leave_with_eio;

	bio_put(bio);
	return 0;
}