xfs_aops.c 35.2 KB
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/*
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 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
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 *
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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 as
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 * published by the Free Software Foundation.
 *
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 * This program is distributed in the hope that it would 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.
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 *
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 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
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 */
#include "xfs.h"
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#include "xfs_bit.h"
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#include "xfs_log.h"
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#include "xfs_inum.h"
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#include "xfs_sb.h"
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#include "xfs_ag.h"
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#include "xfs_dir.h"
#include "xfs_dir2.h"
#include "xfs_trans.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir_sf.h"
#include "xfs_dir2_sf.h"
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#include "xfs_attr_sf.h"
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#include "xfs_dinode.h"
#include "xfs_inode.h"
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#include "xfs_alloc.h"
#include "xfs_btree.h"
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#include "xfs_error.h"
#include "xfs_rw.h"
#include "xfs_iomap.h"
#include <linux/mpage.h>
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#include <linux/pagevec.h>
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#include <linux/writeback.h>

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STATIC void
xfs_count_page_state(
	struct page		*page,
	int			*delalloc,
	int			*unmapped,
	int			*unwritten)
{
	struct buffer_head	*bh, *head;

	*delalloc = *unmapped = *unwritten = 0;

	bh = head = page_buffers(page);
	do {
		if (buffer_uptodate(bh) && !buffer_mapped(bh))
			(*unmapped) = 1;
		else if (buffer_unwritten(bh) && !buffer_delay(bh))
			clear_buffer_unwritten(bh);
		else if (buffer_unwritten(bh))
			(*unwritten) = 1;
		else if (buffer_delay(bh))
			(*delalloc) = 1;
	} while ((bh = bh->b_this_page) != head);
}


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#if defined(XFS_RW_TRACE)
void
xfs_page_trace(
	int		tag,
	struct inode	*inode,
	struct page	*page,
	int		mask)
{
	xfs_inode_t	*ip;
	vnode_t		*vp = LINVFS_GET_VP(inode);
	loff_t		isize = i_size_read(inode);
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	loff_t		offset = page_offset(page);
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	int		delalloc = -1, unmapped = -1, unwritten = -1;

	if (page_has_buffers(page))
		xfs_count_page_state(page, &delalloc, &unmapped, &unwritten);

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	ip = xfs_vtoi(vp);
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	if (!ip->i_rwtrace)
		return;

	ktrace_enter(ip->i_rwtrace,
		(void *)((unsigned long)tag),
		(void *)ip,
		(void *)inode,
		(void *)page,
		(void *)((unsigned long)mask),
		(void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
		(void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
		(void *)((unsigned long)((isize >> 32) & 0xffffffff)),
		(void *)((unsigned long)(isize & 0xffffffff)),
		(void *)((unsigned long)((offset >> 32) & 0xffffffff)),
		(void *)((unsigned long)(offset & 0xffffffff)),
		(void *)((unsigned long)delalloc),
		(void *)((unsigned long)unmapped),
		(void *)((unsigned long)unwritten),
		(void *)NULL,
		(void *)NULL);
}
#else
#define xfs_page_trace(tag, inode, page, mask)
#endif

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/*
 * Schedule IO completion handling on a xfsdatad if this was
 * the final hold on this ioend.
 */
STATIC void
xfs_finish_ioend(
	xfs_ioend_t		*ioend)
{
	if (atomic_dec_and_test(&ioend->io_remaining))
		queue_work(xfsdatad_workqueue, &ioend->io_work);
}

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/*
 * We're now finished for good with this ioend structure.
 * Update the page state via the associated buffer_heads,
 * release holds on the inode and bio, and finally free
 * up memory.  Do not use the ioend after this.
 */
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STATIC void
xfs_destroy_ioend(
	xfs_ioend_t		*ioend)
{
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	struct buffer_head	*bh, *next;

	for (bh = ioend->io_buffer_head; bh; bh = next) {
		next = bh->b_private;
		bh->b_end_io(bh, ioend->io_uptodate);
	}

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	vn_iowake(ioend->io_vnode);
	mempool_free(ioend, xfs_ioend_pool);
}

/*
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 * Buffered IO write completion for delayed allocate extents.
 * TODO: Update ondisk isize now that we know the file data
 * has been flushed (i.e. the notorious "NULL file" problem).
 */
STATIC void
xfs_end_bio_delalloc(
	void			*data)
{
	xfs_ioend_t		*ioend = data;

	xfs_destroy_ioend(ioend);
}

/*
 * Buffered IO write completion for regular, written extents.
 */
STATIC void
xfs_end_bio_written(
	void			*data)
{
	xfs_ioend_t		*ioend = data;

	xfs_destroy_ioend(ioend);
}

/*
 * IO write completion for unwritten extents.
 *
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 * Issue transactions to convert a buffer range from unwritten
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 * to written extents.
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 */
STATIC void
xfs_end_bio_unwritten(
	void			*data)
{
	xfs_ioend_t		*ioend = data;
	vnode_t			*vp = ioend->io_vnode;
	xfs_off_t		offset = ioend->io_offset;
	size_t			size = ioend->io_size;
	int			error;

	if (ioend->io_uptodate)
		VOP_BMAP(vp, offset, size, BMAPI_UNWRITTEN, NULL, NULL, error);
	xfs_destroy_ioend(ioend);
}

/*
 * Allocate and initialise an IO completion structure.
 * We need to track unwritten extent write completion here initially.
 * We'll need to extend this for updating the ondisk inode size later
 * (vs. incore size).
 */
STATIC xfs_ioend_t *
xfs_alloc_ioend(
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	struct inode		*inode,
	unsigned int		type)
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{
	xfs_ioend_t		*ioend;

	ioend = mempool_alloc(xfs_ioend_pool, GFP_NOFS);

	/*
	 * Set the count to 1 initially, which will prevent an I/O
	 * completion callback from happening before we have started
	 * all the I/O from calling the completion routine too early.
	 */
	atomic_set(&ioend->io_remaining, 1);
	ioend->io_uptodate = 1; /* cleared if any I/O fails */
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	ioend->io_list = NULL;
	ioend->io_type = type;
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	ioend->io_vnode = LINVFS_GET_VP(inode);
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	ioend->io_buffer_head = NULL;
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	ioend->io_buffer_tail = NULL;
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	atomic_inc(&ioend->io_vnode->v_iocount);
	ioend->io_offset = 0;
	ioend->io_size = 0;

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	if (type == IOMAP_UNWRITTEN)
		INIT_WORK(&ioend->io_work, xfs_end_bio_unwritten, ioend);
	else if (type == IOMAP_DELAY)
		INIT_WORK(&ioend->io_work, xfs_end_bio_delalloc, ioend);
	else
		INIT_WORK(&ioend->io_work, xfs_end_bio_written, ioend);
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	return ioend;
}

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STATIC int
xfs_map_blocks(
	struct inode		*inode,
	loff_t			offset,
	ssize_t			count,
	xfs_iomap_t		*mapp,
	int			flags)
{
	vnode_t			*vp = LINVFS_GET_VP(inode);
	int			error, nmaps = 1;

	VOP_BMAP(vp, offset, count, flags, mapp, &nmaps, error);
	if (!error && (flags & (BMAPI_WRITE|BMAPI_ALLOCATE)))
		VMODIFY(vp);
	return -error;
}

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STATIC inline int
xfs_iomap_valid(
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	xfs_iomap_t		*iomapp,
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	loff_t			offset)
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{
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	return offset >= iomapp->iomap_offset &&
		offset < iomapp->iomap_offset + iomapp->iomap_bsize;
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}

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/*
 * BIO completion handler for buffered IO.
 */
STATIC int
xfs_end_bio(
	struct bio		*bio,
	unsigned int		bytes_done,
	int			error)
{
	xfs_ioend_t		*ioend = bio->bi_private;

	if (bio->bi_size)
		return 1;

	ASSERT(ioend);
	ASSERT(atomic_read(&bio->bi_cnt) >= 1);

	/* Toss bio and pass work off to an xfsdatad thread */
	if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
		ioend->io_uptodate = 0;
	bio->bi_private = NULL;
	bio->bi_end_io = NULL;

	bio_put(bio);
	xfs_finish_ioend(ioend);
	return 0;
}

STATIC void
xfs_submit_ioend_bio(
	xfs_ioend_t	*ioend,
	struct bio	*bio)
{
	atomic_inc(&ioend->io_remaining);

	bio->bi_private = ioend;
	bio->bi_end_io = xfs_end_bio;

	submit_bio(WRITE, bio);
	ASSERT(!bio_flagged(bio, BIO_EOPNOTSUPP));
	bio_put(bio);
}

STATIC struct bio *
xfs_alloc_ioend_bio(
	struct buffer_head	*bh)
{
	struct bio		*bio;
	int			nvecs = bio_get_nr_vecs(bh->b_bdev);

	do {
		bio = bio_alloc(GFP_NOIO, nvecs);
		nvecs >>= 1;
	} while (!bio);

	ASSERT(bio->bi_private == NULL);
	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
	bio->bi_bdev = bh->b_bdev;
	bio_get(bio);
	return bio;
}

STATIC void
xfs_start_buffer_writeback(
	struct buffer_head	*bh)
{
	ASSERT(buffer_mapped(bh));
	ASSERT(buffer_locked(bh));
	ASSERT(!buffer_delay(bh));
	ASSERT(!buffer_unwritten(bh));

	mark_buffer_async_write(bh);
	set_buffer_uptodate(bh);
	clear_buffer_dirty(bh);
}

STATIC void
xfs_start_page_writeback(
	struct page		*page,
	struct writeback_control *wbc,
	int			clear_dirty,
	int			buffers)
{
	ASSERT(PageLocked(page));
	ASSERT(!PageWriteback(page));
	set_page_writeback(page);
	if (clear_dirty)
		clear_page_dirty(page);
	unlock_page(page);
	if (!buffers) {
		end_page_writeback(page);
		wbc->pages_skipped++;	/* We didn't write this page */
	}
}

static inline int bio_add_buffer(struct bio *bio, struct buffer_head *bh)
{
	return bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
}

/*
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 * Submit all of the bios for all of the ioends we have saved up, covering the
 * initial writepage page and also any probed pages.
 *
 * Because we may have multiple ioends spanning a page, we need to start
 * writeback on all the buffers before we submit them for I/O. If we mark the
 * buffers as we got, then we can end up with a page that only has buffers
 * marked async write and I/O complete on can occur before we mark the other
 * buffers async write.
 *
 * The end result of this is that we trip a bug in end_page_writeback() because
 * we call it twice for the one page as the code in end_buffer_async_write()
 * assumes that all buffers on the page are started at the same time.
 *
 * The fix is two passes across the ioend list - one to start writeback on the
 * bufferheads, and then the second one submit them for I/O.
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 */
STATIC void
xfs_submit_ioend(
	xfs_ioend_t		*ioend)
{
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	xfs_ioend_t		*head = ioend;
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	xfs_ioend_t		*next;
	struct buffer_head	*bh;
	struct bio		*bio;
	sector_t		lastblock = 0;

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	/* Pass 1 - start writeback */
	do {
		next = ioend->io_list;
		for (bh = ioend->io_buffer_head; bh; bh = bh->b_private) {
			xfs_start_buffer_writeback(bh);
		}
	} while ((ioend = next) != NULL);

	/* Pass 2 - submit I/O */
	ioend = head;
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	do {
		next = ioend->io_list;
		bio = NULL;

		for (bh = ioend->io_buffer_head; bh; bh = bh->b_private) {

			if (!bio) {
 retry:
				bio = xfs_alloc_ioend_bio(bh);
			} else if (bh->b_blocknr != lastblock + 1) {
				xfs_submit_ioend_bio(ioend, bio);
				goto retry;
			}

			if (bio_add_buffer(bio, bh) != bh->b_size) {
				xfs_submit_ioend_bio(ioend, bio);
				goto retry;
			}

			lastblock = bh->b_blocknr;
		}
		if (bio)
			xfs_submit_ioend_bio(ioend, bio);
		xfs_finish_ioend(ioend);
	} while ((ioend = next) != NULL);
}

/*
 * Cancel submission of all buffer_heads so far in this endio.
 * Toss the endio too.  Only ever called for the initial page
 * in a writepage request, so only ever one page.
 */
STATIC void
xfs_cancel_ioend(
	xfs_ioend_t		*ioend)
{
	xfs_ioend_t		*next;
	struct buffer_head	*bh, *next_bh;

	do {
		next = ioend->io_list;
		bh = ioend->io_buffer_head;
		do {
			next_bh = bh->b_private;
			clear_buffer_async_write(bh);
			unlock_buffer(bh);
		} while ((bh = next_bh) != NULL);

		vn_iowake(ioend->io_vnode);
		mempool_free(ioend, xfs_ioend_pool);
	} while ((ioend = next) != NULL);
}

/*
 * Test to see if we've been building up a completion structure for
 * earlier buffers -- if so, we try to append to this ioend if we
 * can, otherwise we finish off any current ioend and start another.
 * Return true if we've finished the given ioend.
 */
STATIC void
xfs_add_to_ioend(
	struct inode		*inode,
	struct buffer_head	*bh,
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	xfs_off_t		offset,
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	unsigned int		type,
	xfs_ioend_t		**result,
	int			need_ioend)
{
	xfs_ioend_t		*ioend = *result;

	if (!ioend || need_ioend || type != ioend->io_type) {
		xfs_ioend_t	*previous = *result;

		ioend = xfs_alloc_ioend(inode, type);
		ioend->io_offset = offset;
		ioend->io_buffer_head = bh;
		ioend->io_buffer_tail = bh;
		if (previous)
			previous->io_list = ioend;
		*result = ioend;
	} else {
		ioend->io_buffer_tail->b_private = bh;
		ioend->io_buffer_tail = bh;
	}

	bh->b_private = NULL;
	ioend->io_size += bh->b_size;
}

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STATIC void
xfs_map_buffer(
	struct buffer_head	*bh,
	xfs_iomap_t		*mp,
	xfs_off_t		offset,
	uint			block_bits)
{
	sector_t		bn;

	ASSERT(mp->iomap_bn != IOMAP_DADDR_NULL);

	bn = (mp->iomap_bn >> (block_bits - BBSHIFT)) +
	      ((offset - mp->iomap_offset) >> block_bits);

	ASSERT(bn || (mp->iomap_flags & IOMAP_REALTIME));

	bh->b_blocknr = bn;
	set_buffer_mapped(bh);
}

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STATIC void
xfs_map_at_offset(
	struct buffer_head	*bh,
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	loff_t			offset,
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	int			block_bits,
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	xfs_iomap_t		*iomapp)
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{
	ASSERT(!(iomapp->iomap_flags & IOMAP_HOLE));
	ASSERT(!(iomapp->iomap_flags & IOMAP_DELAY));

	lock_buffer(bh);
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	xfs_map_buffer(bh, iomapp, offset, block_bits);
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	bh->b_bdev = iomapp->iomap_target->bt_bdev;
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	set_buffer_mapped(bh);
	clear_buffer_delay(bh);
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	clear_buffer_unwritten(bh);
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}

/*
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 * Look for a page at index that is suitable for clustering.
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 */
STATIC unsigned int
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xfs_probe_page(
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	struct page		*page,
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	unsigned int		pg_offset,
	int			mapped)
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{
	int			ret = 0;

	if (PageWriteback(page))
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		return 0;
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	if (page->mapping && PageDirty(page)) {
		if (page_has_buffers(page)) {
			struct buffer_head	*bh, *head;

			bh = head = page_buffers(page);
			do {
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				if (!buffer_uptodate(bh))
					break;
				if (mapped != buffer_mapped(bh))
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					break;
				ret += bh->b_size;
				if (ret >= pg_offset)
					break;
			} while ((bh = bh->b_this_page) != head);
		} else
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			ret = mapped ? 0 : PAGE_CACHE_SIZE;
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	}

	return ret;
}

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STATIC size_t
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xfs_probe_cluster(
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	struct inode		*inode,
	struct page		*startpage,
	struct buffer_head	*bh,
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	struct buffer_head	*head,
	int			mapped)
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{
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	struct pagevec		pvec;
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	pgoff_t			tindex, tlast, tloff;
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	size_t			total = 0;
	int			done = 0, i;
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	/* First sum forwards in this page */
	do {
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		if (!buffer_uptodate(bh) || (mapped != buffer_mapped(bh)))
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			return total;
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		total += bh->b_size;
	} while ((bh = bh->b_this_page) != head);

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	/* if we reached the end of the page, sum forwards in following pages */
	tlast = i_size_read(inode) >> PAGE_CACHE_SHIFT;
	tindex = startpage->index + 1;

	/* Prune this back to avoid pathological behavior */
	tloff = min(tlast, startpage->index + 64);

	pagevec_init(&pvec, 0);
	while (!done && tindex <= tloff) {
		unsigned len = min_t(pgoff_t, PAGEVEC_SIZE, tlast - tindex + 1);

		if (!pagevec_lookup(&pvec, inode->i_mapping, tindex, len))
			break;

		for (i = 0; i < pagevec_count(&pvec); i++) {
			struct page *page = pvec.pages[i];
			size_t pg_offset, len = 0;

			if (tindex == tlast) {
				pg_offset =
				    i_size_read(inode) & (PAGE_CACHE_SIZE - 1);
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				if (!pg_offset) {
					done = 1;
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					break;
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				}
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			} else
				pg_offset = PAGE_CACHE_SIZE;

			if (page->index == tindex && !TestSetPageLocked(page)) {
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				len = xfs_probe_page(page, pg_offset, mapped);
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				unlock_page(page);
			}

			if (!len) {
				done = 1;
				break;
			}

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			total += len;
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			tindex++;
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		}
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		pagevec_release(&pvec);
		cond_resched();
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	}
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	return total;
}

/*
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 * Test if a given page is suitable for writing as part of an unwritten
 * or delayed allocate extent.
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 */
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STATIC int
xfs_is_delayed_page(
	struct page		*page,
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	unsigned int		type)
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{
	if (PageWriteback(page))
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		return 0;
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	if (page->mapping && page_has_buffers(page)) {
		struct buffer_head	*bh, *head;
		int			acceptable = 0;

		bh = head = page_buffers(page);
		do {
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			if (buffer_unwritten(bh))
				acceptable = (type == IOMAP_UNWRITTEN);
			else if (buffer_delay(bh))
				acceptable = (type == IOMAP_DELAY);
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			else if (buffer_mapped(bh))
				acceptable = (type == 0);
655
			else
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				break;
		} while ((bh = bh->b_this_page) != head);

		if (acceptable)
660
			return 1;
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	}

663
	return 0;
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}

/*
 * Allocate & map buffers for page given the extent map. Write it out.
 * except for the original page of a writepage, this is called on
 * delalloc/unwritten pages only, for the original page it is possible
 * that the page has no mapping at all.
 */
672
STATIC int
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xfs_convert_page(
	struct inode		*inode,
	struct page		*page,
676
	loff_t			tindex,
677
	xfs_iomap_t		*mp,
678
	xfs_ioend_t		**ioendp,
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	struct writeback_control *wbc,
	int			startio,
	int			all_bh)
{
683
	struct buffer_head	*bh, *head;
684 685
	xfs_off_t		end_offset;
	unsigned long		p_offset;
686
	unsigned int		type;
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	int			bbits = inode->i_blkbits;
688
	int			len, page_dirty;
689
	int			count = 0, done = 0, uptodate = 1;
690
 	xfs_off_t		offset = page_offset(page);
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692 693 694 695 696 697 698 699 700 701 702
	if (page->index != tindex)
		goto fail;
	if (TestSetPageLocked(page))
		goto fail;
	if (PageWriteback(page))
		goto fail_unlock_page;
	if (page->mapping != inode->i_mapping)
		goto fail_unlock_page;
	if (!xfs_is_delayed_page(page, (*ioendp)->io_type))
		goto fail_unlock_page;

703 704 705
	/*
	 * page_dirty is initially a count of buffers on the page before
	 * EOF and is decrememted as we move each into a cleanable state.
706 707 708 709 710 711 712 713 714
	 *
	 * Derivation:
	 *
	 * End offset is the highest offset that this page should represent.
	 * If we are on the last page, (end_offset & (PAGE_CACHE_SIZE - 1))
	 * will evaluate non-zero and be less than PAGE_CACHE_SIZE and
	 * hence give us the correct page_dirty count. On any other page,
	 * it will be zero and in that case we need page_dirty to be the
	 * count of buffers on the page.
715
	 */
716 717 718 719
	end_offset = min_t(unsigned long long,
			(xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
			i_size_read(inode));

720
	len = 1 << inode->i_blkbits;
721 722 723 724
	p_offset = min_t(unsigned long, end_offset & (PAGE_CACHE_SIZE - 1),
					PAGE_CACHE_SIZE);
	p_offset = p_offset ? roundup(p_offset, len) : PAGE_CACHE_SIZE;
	page_dirty = p_offset / len;
725

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	bh = head = page_buffers(page);
	do {
728
		if (offset >= end_offset)
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			break;
730 731 732 733
		if (!buffer_uptodate(bh))
			uptodate = 0;
		if (!(PageUptodate(page) || buffer_uptodate(bh))) {
			done = 1;
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			continue;
735 736
		}

737 738 739 740 741 742 743
		if (buffer_unwritten(bh) || buffer_delay(bh)) {
			if (buffer_unwritten(bh))
				type = IOMAP_UNWRITTEN;
			else
				type = IOMAP_DELAY;

			if (!xfs_iomap_valid(mp, offset)) {
744
				done = 1;
745 746 747 748 749 750 751 752
				continue;
			}

			ASSERT(!(mp->iomap_flags & IOMAP_HOLE));
			ASSERT(!(mp->iomap_flags & IOMAP_DELAY));

			xfs_map_at_offset(bh, offset, bbits, mp);
			if (startio) {
753
				xfs_add_to_ioend(inode, bh, offset,
754 755 756 757 758 759 760 761 762 763 764
						type, ioendp, done);
			} else {
				set_buffer_dirty(bh);
				unlock_buffer(bh);
				mark_buffer_dirty(bh);
			}
			page_dirty--;
			count++;
		} else {
			type = 0;
			if (buffer_mapped(bh) && all_bh && startio) {
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				lock_buffer(bh);
766
				xfs_add_to_ioend(inode, bh, offset,
767 768
						type, ioendp, done);
				count++;
769
				page_dirty--;
770 771
			} else {
				done = 1;
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			}
		}
774
	} while (offset += len, (bh = bh->b_this_page) != head);
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776 777 778 779
	if (uptodate && bh == head)
		SetPageUptodate(page);

	if (startio) {
780 781 782 783
		if (count) {
			struct backing_dev_info *bdi;

			bdi = inode->i_mapping->backing_dev_info;
784
			wbc->nr_to_write--;
785 786 787
			if (bdi_write_congested(bdi)) {
				wbc->encountered_congestion = 1;
				done = 1;
788
			} else if (wbc->nr_to_write <= 0) {
789 790 791
				done = 1;
			}
		}
792
		xfs_start_page_writeback(page, wbc, !page_dirty, count);
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	}
794 795

	return done;
796 797 798 799
 fail_unlock_page:
	unlock_page(page);
 fail:
	return 1;
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}

/*
 * Convert & write out a cluster of pages in the same extent as defined
 * by mp and following the start page.
 */
STATIC void
xfs_cluster_write(
	struct inode		*inode,
	pgoff_t			tindex,
	xfs_iomap_t		*iomapp,
811
	xfs_ioend_t		**ioendp,
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	struct writeback_control *wbc,
	int			startio,
	int			all_bh,
	pgoff_t			tlast)
{
817 818
	struct pagevec		pvec;
	int			done = 0, i;
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820 821 822 823 824
	pagevec_init(&pvec, 0);
	while (!done && tindex <= tlast) {
		unsigned len = min_t(pgoff_t, PAGEVEC_SIZE, tlast - tindex + 1);

		if (!pagevec_lookup(&pvec, inode->i_mapping, tindex, len))
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			break;
826 827 828 829 830 831 832 833 834 835

		for (i = 0; i < pagevec_count(&pvec); i++) {
			done = xfs_convert_page(inode, pvec.pages[i], tindex++,
					iomapp, ioendp, wbc, startio, all_bh);
			if (done)
				break;
		}

		pagevec_release(&pvec);
		cond_resched();
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	}
}

/*
 * Calling this without startio set means we are being asked to make a dirty
 * page ready for freeing it's buffers.  When called with startio set then
 * we are coming from writepage.
 *
 * When called with startio set it is important that we write the WHOLE
 * page if possible.
 * The bh->b_state's cannot know if any of the blocks or which block for
 * that matter are dirty due to mmap writes, and therefore bh uptodate is
 * only vaild if the page itself isn't completely uptodate.  Some layers
 * may clear the page dirty flag prior to calling write page, under the
 * assumption the entire page will be written out; by not writing out the
 * whole page the page can be reused before all valid dirty data is
 * written out.  Note: in the case of a page that has been dirty'd by
 * mapwrite and but partially setup by block_prepare_write the
 * bh->b_states's will not agree and only ones setup by BPW/BCW will have
 * valid state, thus the whole page must be written out thing.
 */

STATIC int
xfs_page_state_convert(
	struct inode	*inode,
	struct page	*page,
	struct writeback_control *wbc,
	int		startio,
	int		unmapped) /* also implies page uptodate */
{
866
	struct buffer_head	*bh, *head;
867
	xfs_iomap_t		iomap;
868
	xfs_ioend_t		*ioend = NULL, *iohead = NULL;
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	loff_t			offset;
	unsigned long           p_offset = 0;
871
	unsigned int		type;
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	__uint64_t              end_offset;
	pgoff_t                 end_index, last_index, tlast;
874 875
	ssize_t			size, len;
	int			flags, err, iomap_valid = 0, uptodate = 1;
876
	int			page_dirty, count = 0, trylock_flag = 0;
877
	int			all_bh = unmapped;
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879
	/* wait for other IO threads? */
880
	if (startio && (wbc->sync_mode == WB_SYNC_NONE && wbc->nonblocking))
881
		trylock_flag |= BMAPI_TRYLOCK;
882

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	/* Is this page beyond the end of the file? */
	offset = i_size_read(inode);
	end_index = offset >> PAGE_CACHE_SHIFT;
	last_index = (offset - 1) >> PAGE_CACHE_SHIFT;
	if (page->index >= end_index) {
		if ((page->index >= end_index + 1) ||
		    !(i_size_read(inode) & (PAGE_CACHE_SIZE - 1))) {
890 891 892
			if (startio)
				unlock_page(page);
			return 0;
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		}
	}

	/*
897 898
	 * page_dirty is initially a count of buffers on the page before
	 * EOF and is decrememted as we move each into a cleanable state.
899 900 901 902 903 904 905 906 907 908 909 910
	 *
	 * Derivation:
	 *
	 * End offset is the highest offset that this page should represent.
	 * If we are on the last page, (end_offset & (PAGE_CACHE_SIZE - 1))
	 * will evaluate non-zero and be less than PAGE_CACHE_SIZE and
	 * hence give us the correct page_dirty count. On any other page,
	 * it will be zero and in that case we need page_dirty to be the
	 * count of buffers on the page.
 	 */
	end_offset = min_t(unsigned long long,
			(xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT, offset);
911
	len = 1 << inode->i_blkbits;
912 913 914
	p_offset = min_t(unsigned long, end_offset & (PAGE_CACHE_SIZE - 1),
					PAGE_CACHE_SIZE);
	p_offset = p_offset ? roundup(p_offset, len) : PAGE_CACHE_SIZE;
915 916 917
	page_dirty = p_offset / len;

	bh = head = page_buffers(page);
918
	offset = page_offset(page);
919 920
	flags = -1;
	type = 0;
921 922

	/* TODO: cleanup count and page_dirty */
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	do {
		if (offset >= end_offset)
			break;
		if (!buffer_uptodate(bh))
			uptodate = 0;
929
		if (!(PageUptodate(page) || buffer_uptodate(bh)) && !startio) {
930 931 932 933 934
			/*
			 * the iomap is actually still valid, but the ioend
			 * isn't.  shouldn't happen too often.
			 */
			iomap_valid = 0;
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			continue;
936
		}
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938 939
		if (iomap_valid)
			iomap_valid = xfs_iomap_valid(&iomap, offset);
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		/*
		 * First case, map an unwritten extent and prepare for
		 * extent state conversion transaction on completion.
944
		 *
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		 * Second case, allocate space for a delalloc buffer.
		 * We can return EAGAIN here in the release page case.
947 948 949 950 951 952 953
		 *
		 * Third case, an unmapped buffer was found, and we are
		 * in a path where we need to write the whole page out.
 		 */
		if (buffer_unwritten(bh) || buffer_delay(bh) ||
		    ((buffer_uptodate(bh) || PageUptodate(page)) &&
		     !buffer_mapped(bh) && (unmapped || startio))) {
954 955 956 957 958 959
		     	/*
			 * Make sure we don't use a read-only iomap
			 */
		     	if (flags == BMAPI_READ)
				iomap_valid = 0;

960 961 962
			if (buffer_unwritten(bh)) {
				type = IOMAP_UNWRITTEN;
				flags = BMAPI_WRITE|BMAPI_IGNSTATE;
963
			} else if (buffer_delay(bh)) {
964 965 966 967
				type = IOMAP_DELAY;
				flags = BMAPI_ALLOCATE;
				if (!startio)
					flags |= trylock_flag;
968
			} else {
969
				type = IOMAP_NEW;
970
				flags = BMAPI_WRITE|BMAPI_MMAP;
971 972
			}

973
			if (!iomap_valid) {
974 975 976
				if (type == IOMAP_NEW) {
					size = xfs_probe_cluster(inode,
							page, bh, head, 0);
977 978 979 980 981 982
				} else {
					size = len;
				}

				err = xfs_map_blocks(inode, offset, size,
						&iomap, flags);
983
				if (err)
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984
					goto error;
985
				iomap_valid = xfs_iomap_valid(&iomap, offset);
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			}
987 988 989
			if (iomap_valid) {
				xfs_map_at_offset(bh, offset,
						inode->i_blkbits, &iomap);
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				if (startio) {
991
					xfs_add_to_ioend(inode, bh, offset,
992 993
							type, &ioend,
							!iomap_valid);
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				} else {
					set_buffer_dirty(bh);
					unlock_buffer(bh);
					mark_buffer_dirty(bh);
				}
				page_dirty--;
1000
				count++;
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			}
1002
		} else if (buffer_uptodate(bh) && startio) {
1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
			/*
			 * we got here because the buffer is already mapped.
			 * That means it must already have extents allocated
			 * underneath it. Map the extent by reading it.
			 */
			if (!iomap_valid || type != 0) {
				flags = BMAPI_READ;
				size = xfs_probe_cluster(inode, page, bh,
								head, 1);
				err = xfs_map_blocks(inode, offset, size,
						&iomap, flags);
				if (err)
					goto error;
				iomap_valid = xfs_iomap_valid(&iomap, offset);
			}
1018

1019
			type = 0;
1020 1021
			if (!test_and_set_bit(BH_Lock, &bh->b_state)) {
				ASSERT(buffer_mapped(bh));
1022 1023
				if (iomap_valid)
					all_bh = 1;
1024
				xfs_add_to_ioend(inode, bh, offset, type,
1025 1026 1027
						&ioend, !iomap_valid);
				page_dirty--;
				count++;
1028
			} else {
1029
				iomap_valid = 0;
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1030
			}
1031 1032 1033
		} else if ((buffer_uptodate(bh) || PageUptodate(page)) &&
			   (unmapped || startio)) {
			iomap_valid = 0;
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1034
		}
1035 1036 1037 1038 1039

		if (!iohead)
			iohead = ioend;

	} while (offset += len, ((bh = bh->b_this_page) != head));
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	if (uptodate && bh == head)
		SetPageUptodate(page);

1044 1045
	if (startio)
		xfs_start_page_writeback(page, wbc, 1, count);
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1047 1048
	if (ioend && iomap_valid) {
		offset = (iomap.iomap_offset + iomap.iomap_bsize - 1) >>
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1049
					PAGE_CACHE_SHIFT;
1050
		tlast = min_t(pgoff_t, offset, last_index);
1051
		xfs_cluster_write(inode, page->index + 1, &iomap, &ioend,
1052
					wbc, startio, all_bh, tlast);
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1053 1054
	}

1055 1056 1057
	if (iohead)
		xfs_submit_ioend(iohead);

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1058 1059 1060
	return page_dirty;

error:
1061 1062
	if (iohead)
		xfs_cancel_ioend(iohead);
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1063 1064 1065 1066 1067 1068 1069

	/*
	 * If it's delalloc and we have nowhere to put it,
	 * throw it away, unless the lower layers told
	 * us to try again.
	 */
	if (err != -EAGAIN) {
1070
		if (!unmapped)
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1071 1072 1073 1074 1075 1076
			block_invalidatepage(page, 0);
		ClearPageUptodate(page);
	}
	return err;
}

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 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224
/*
 * writepage: Called from one of two places:
 *
 * 1. we are flushing a delalloc buffer head.
 *
 * 2. we are writing out a dirty page. Typically the page dirty
 *    state is cleared before we get here. In this case is it
 *    conceivable we have no buffer heads.
 *
 * For delalloc space on the page we need to allocate space and
 * flush it. For unmapped buffer heads on the page we should
 * allocate space if the page is uptodate. For any other dirty
 * buffer heads on the page we should flush them.
 *
 * If we detect that a transaction would be required to flush
 * the page, we have to check the process flags first, if we
 * are already in a transaction or disk I/O during allocations
 * is off, we need to fail the writepage and redirty the page.
 */

STATIC int
linvfs_writepage(
	struct page		*page,
	struct writeback_control *wbc)
{
	int			error;
	int			need_trans;
	int			delalloc, unmapped, unwritten;
	struct inode		*inode = page->mapping->host;

	xfs_page_trace(XFS_WRITEPAGE_ENTER, inode, page, 0);

	/*
	 * We need a transaction if:
	 *  1. There are delalloc buffers on the page
	 *  2. The page is uptodate and we have unmapped buffers
	 *  3. The page is uptodate and we have no buffers
	 *  4. There are unwritten buffers on the page
	 */

	if (!page_has_buffers(page)) {
		unmapped = 1;
		need_trans = 1;
	} else {
		xfs_count_page_state(page, &delalloc, &unmapped, &unwritten);
		if (!PageUptodate(page))
			unmapped = 0;
		need_trans = delalloc + unmapped + unwritten;
	}

	/*
	 * If we need a transaction and the process flags say
	 * we are already in a transaction, or no IO is allowed
	 * then mark the page dirty again and leave the page
	 * as is.
	 */
	if (PFLAGS_TEST_FSTRANS() && need_trans)
		goto out_fail;

	/*
	 * Delay hooking up buffer heads until we have
	 * made our go/no-go decision.
	 */
	if (!page_has_buffers(page))
		create_empty_buffers(page, 1 << inode->i_blkbits, 0);

	/*
	 * Convert delayed allocate, unwritten or unmapped space
	 * to real space and flush out to disk.
	 */
	error = xfs_page_state_convert(inode, page, wbc, 1, unmapped);
	if (error == -EAGAIN)
		goto out_fail;
	if (unlikely(error < 0))
		goto out_unlock;

	return 0;

out_fail:
	redirty_page_for_writepage(wbc, page);
	unlock_page(page);
	return 0;
out_unlock:
	unlock_page(page);
	return error;
}

/*
 * Called to move a page into cleanable state - and from there
 * to be released. Possibly the page is already clean. We always
 * have buffer heads in this call.
 *
 * Returns 0 if the page is ok to release, 1 otherwise.
 *
 * Possible scenarios are:
 *
 * 1. We are being called to release a page which has been written
 *    to via regular I/O. buffer heads will be dirty and possibly
 *    delalloc. If no delalloc buffer heads in this case then we
 *    can just return zero.
 *
 * 2. We are called to release a page which has been written via
 *    mmap, all we need to do is ensure there is no delalloc
 *    state in the buffer heads, if not we can let the caller
 *    free them and we should come back later via writepage.
 */
STATIC int
linvfs_release_page(
	struct page		*page,
	gfp_t			gfp_mask)
{
	struct inode		*inode = page->mapping->host;
	int			dirty, delalloc, unmapped, unwritten;
	struct writeback_control wbc = {
		.sync_mode = WB_SYNC_ALL,
		.nr_to_write = 1,
	};

	xfs_page_trace(XFS_RELEASEPAGE_ENTER, inode, page, gfp_mask);

	xfs_count_page_state(page, &delalloc, &unmapped, &unwritten);
	if (!delalloc && !unwritten)
		goto free_buffers;

	if (!(gfp_mask & __GFP_FS))
		return 0;

	/* If we are already inside a transaction or the thread cannot
	 * do I/O, we cannot release this page.
	 */
	if (PFLAGS_TEST_FSTRANS())
		return 0;

	/*
	 * Convert delalloc space to real space, do not flush the
	 * data out to disk, that will be done by the caller.
	 * Never need to allocate space here - we will always
	 * come back to writepage in that case.
	 */
	dirty = xfs_page_state_convert(inode, page, &wbc, 0, 0);
	if (dirty == 0 && !unwritten)
		goto free_buffers;
	return 0;

free_buffers:
	return try_to_free_buffers(page);
}

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STATIC int
__linvfs_get_block(
	struct inode		*inode,
	sector_t		iblock,
	unsigned long		blocks,
	struct buffer_head	*bh_result,
	int			create,
	int			direct,
	bmapi_flags_t		flags)
{
	vnode_t			*vp = LINVFS_GET_VP(inode);
	xfs_iomap_t		iomap;
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	xfs_off_t		offset;
	ssize_t			size;
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	int			retpbbm = 1;
	int			error;

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	offset = (xfs_off_t)iblock << inode->i_blkbits;
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	if (blocks)
		size = (ssize_t) min_t(xfs_off_t, LONG_MAX,
					(xfs_off_t)blocks << inode->i_blkbits);
	else
		size = 1 << inode->i_blkbits;
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	VOP_BMAP(vp, offset, size,
		create ? flags : BMAPI_READ, &iomap, &retpbbm, error);
	if (error)
		return -error;

	if (retpbbm == 0)
		return 0;

	if (iomap.iomap_bn != IOMAP_DADDR_NULL) {
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		/*
		 * For unwritten extents do not report a disk address on
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		 * the read case (treat as if we're reading into a hole).
		 */
		if (create || !(iomap.iomap_flags & IOMAP_UNWRITTEN)) {
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			xfs_map_buffer(bh_result, &iomap, offset,
				       inode->i_blkbits);
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		}
		if (create && (iomap.iomap_flags & IOMAP_UNWRITTEN)) {
			if (direct)
				bh_result->b_private = inode;
			set_buffer_unwritten(bh_result);
			set_buffer_delay(bh_result);
		}
	}

	/* If this is a realtime file, data might be on a new device */
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	bh_result->b_bdev = iomap.iomap_target->bt_bdev;
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	/* If we previously allocated a block out beyond eof and
	 * we are now coming back to use it then we will need to
	 * flag it as new even if it has a disk address.
	 */
	if (create &&
	    ((!buffer_mapped(bh_result) && !buffer_uptodate(bh_result)) ||
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	     (offset >= i_size_read(inode)) || (iomap.iomap_flags & IOMAP_NEW)))
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		set_buffer_new(bh_result);

	if (iomap.iomap_flags & IOMAP_DELAY) {
		BUG_ON(direct);
		if (create) {
			set_buffer_uptodate(bh_result);
			set_buffer_mapped(bh_result);
			set_buffer_delay(bh_result);
		}
	}

	if (blocks) {
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		ASSERT(iomap.iomap_bsize - iomap.iomap_delta > 0);
		offset = min_t(xfs_off_t,
				iomap.iomap_bsize - iomap.iomap_delta,
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				(xfs_off_t)blocks << inode->i_blkbits);
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		bh_result->b_size = (u32) min_t(xfs_off_t, UINT_MAX, offset);
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	}

	return 0;
}

int
linvfs_get_block(
	struct inode		*inode,
	sector_t		iblock,
	struct buffer_head	*bh_result,
	int			create)
{
	return __linvfs_get_block(inode, iblock, 0, bh_result,
					create, 0, BMAPI_WRITE);
}

STATIC int
linvfs_get_blocks_direct(
	struct inode		*inode,
	sector_t		iblock,
	unsigned long		max_blocks,
	struct buffer_head	*bh_result,
	int			create)
{
	return __linvfs_get_block(inode, iblock, max_blocks, bh_result,
					create, 1, BMAPI_WRITE|BMAPI_DIRECT);
}

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STATIC void
linvfs_end_io_direct(
	struct kiocb	*iocb,
	loff_t		offset,
	ssize_t		size,
	void		*private)
{
	xfs_ioend_t	*ioend = iocb->private;

	/*
	 * Non-NULL private data means we need to issue a transaction to
	 * convert a range from unwritten to written extents.  This needs
	 * to happen from process contect but aio+dio I/O completion
	 * happens from irq context so we need to defer it to a workqueue.
	 * This is not nessecary for synchronous direct I/O, but we do
	 * it anyway to keep the code uniform and simpler.
	 *
	 * The core direct I/O code might be changed to always call the
	 * completion handler in the future, in which case all this can
	 * go away.
	 */
	if (private && size > 0) {
		ioend->io_offset = offset;
		ioend->io_size = size;
		xfs_finish_ioend(ioend);
	} else {
		ASSERT(size >= 0);
		xfs_destroy_ioend(ioend);
	}

	/*
	 * blockdev_direct_IO can return an error even afer the I/O
	 * completion handler was called.  Thus we need to protect
	 * against double-freeing.
	 */
	iocb->private = NULL;
}

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STATIC ssize_t
linvfs_direct_IO(
	int			rw,
	struct kiocb		*iocb,
	const struct iovec	*iov,
	loff_t			offset,
	unsigned long		nr_segs)
{
	struct file	*file = iocb->ki_filp;
	struct inode	*inode = file->f_mapping->host;
	vnode_t		*vp = LINVFS_GET_VP(inode);
	xfs_iomap_t	iomap;
	int		maps = 1;
	int		error;
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	ssize_t		ret;
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	VOP_BMAP(vp, offset, 0, BMAPI_DEVICE, &iomap, &maps, error);
	if (error)
		return -error;

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	iocb->private = xfs_alloc_ioend(inode, IOMAP_UNWRITTEN);
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	ret = blockdev_direct_IO_own_locking(rw, iocb, inode,
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		iomap.iomap_target->bt_bdev,
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		iov, offset, nr_segs,
		linvfs_get_blocks_direct,
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		linvfs_end_io_direct);

	if (unlikely(ret <= 0 && iocb->private))
		xfs_destroy_ioend(iocb->private);
	return ret;
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}

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STATIC int
linvfs_prepare_write(
	struct file		*file,
	struct page		*page,
	unsigned int		from,
	unsigned int		to)
{
	return block_prepare_write(page, from, to, linvfs_get_block);
}
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STATIC sector_t
linvfs_bmap(
	struct address_space	*mapping,
	sector_t		block)
{
	struct inode		*inode = (struct inode *)mapping->host;
	vnode_t			*vp = LINVFS_GET_VP(inode);
	int			error;

	vn_trace_entry(vp, "linvfs_bmap", (inst_t *)__return_address);

	VOP_RWLOCK(vp, VRWLOCK_READ);
	VOP_FLUSH_PAGES(vp, (xfs_off_t)0, -1, 0, FI_REMAPF, error);
	VOP_RWUNLOCK(vp, VRWLOCK_READ);
	return generic_block_bmap(mapping, block, linvfs_get_block);
}

STATIC int
linvfs_readpage(
	struct file		*unused,
	struct page		*page)
{
	return mpage_readpage(page, linvfs_get_block);
}

STATIC int
linvfs_readpages(
	struct file		*unused,
	struct address_space	*mapping,
	struct list_head	*pages,
	unsigned		nr_pages)
{
	return mpage_readpages(mapping, pages, nr_pages, linvfs_get_block);
}

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STATIC int
linvfs_invalidate_page(
	struct page		*page,
	unsigned long		offset)
{
	xfs_page_trace(XFS_INVALIDPAGE_ENTER,
			page->mapping->host, page, offset);
	return block_invalidatepage(page, offset);
}

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struct address_space_operations linvfs_aops = {
	.readpage		= linvfs_readpage,
	.readpages		= linvfs_readpages,
	.writepage		= linvfs_writepage,
	.sync_page		= block_sync_page,
	.releasepage		= linvfs_release_page,
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	.invalidatepage		= linvfs_invalidate_page,
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	.prepare_write		= linvfs_prepare_write,
	.commit_write		= generic_commit_write,
	.bmap			= linvfs_bmap,
	.direct_IO		= linvfs_direct_IO,
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	.migratepage		= buffer_migrate_page,
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};