bmap.c 49.6 KB
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/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
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 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
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 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
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 * of the GNU General Public License version 2.
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 */

#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
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#include <linux/blkdev.h>
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#include <linux/gfs2_ondisk.h>
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#include <linux/crc32.h>
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#include <linux/iomap.h>
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#include "gfs2.h"
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#include "incore.h"
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#include "bmap.h"
#include "glock.h"
#include "inode.h"
#include "meta_io.h"
#include "quota.h"
#include "rgrp.h"
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#include "log.h"
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#include "super.h"
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#include "trans.h"
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#include "dir.h"
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#include "util.h"
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#include "trace_gfs2.h"
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/* This doesn't need to be that large as max 64 bit pointers in a 4k
 * block is 512, so __u16 is fine for that. It saves stack space to
 * keep it small.
 */
struct metapath {
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	struct buffer_head *mp_bh[GFS2_MAX_META_HEIGHT];
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	__u16 mp_list[GFS2_MAX_META_HEIGHT];
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	int mp_fheight; /* find_metapath height */
	int mp_aheight; /* actual height (lookup height) */
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};

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/**
 * gfs2_unstuffer_page - unstuff a stuffed inode into a block cached by a page
 * @ip: the inode
 * @dibh: the dinode buffer
 * @block: the block number that was allocated
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 * @page: The (optional) page. This is looked up if @page is NULL
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 *
 * Returns: errno
 */

static int gfs2_unstuffer_page(struct gfs2_inode *ip, struct buffer_head *dibh,
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			       u64 block, struct page *page)
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{
	struct inode *inode = &ip->i_inode;
	struct buffer_head *bh;
	int release = 0;

	if (!page || page->index) {
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		page = find_or_create_page(inode->i_mapping, 0, GFP_NOFS);
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		if (!page)
			return -ENOMEM;
		release = 1;
	}

	if (!PageUptodate(page)) {
		void *kaddr = kmap(page);
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		u64 dsize = i_size_read(inode);
 
		if (dsize > (dibh->b_size - sizeof(struct gfs2_dinode)))
			dsize = dibh->b_size - sizeof(struct gfs2_dinode);
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		memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
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		memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
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		kunmap(page);

		SetPageUptodate(page);
	}

	if (!page_has_buffers(page))
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		create_empty_buffers(page, BIT(inode->i_blkbits),
				     BIT(BH_Uptodate));
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	bh = page_buffers(page);

	if (!buffer_mapped(bh))
		map_bh(bh, inode->i_sb, block);

	set_buffer_uptodate(bh);
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	if (!gfs2_is_jdata(ip))
		mark_buffer_dirty(bh);
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	if (!gfs2_is_writeback(ip))
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		gfs2_trans_add_data(ip->i_gl, bh);
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	if (release) {
		unlock_page(page);
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		put_page(page);
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	}

	return 0;
}

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/**
 * gfs2_unstuff_dinode - Unstuff a dinode when the data has grown too big
 * @ip: The GFS2 inode to unstuff
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 * @page: The (optional) page. This is looked up if the @page is NULL
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 *
 * This routine unstuffs a dinode and returns it to a "normal" state such
 * that the height can be grown in the traditional way.
 *
 * Returns: errno
 */

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int gfs2_unstuff_dinode(struct gfs2_inode *ip, struct page *page)
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{
	struct buffer_head *bh, *dibh;
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	struct gfs2_dinode *di;
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	u64 block = 0;
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	int isdir = gfs2_is_dir(ip);
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	int error;

	down_write(&ip->i_rw_mutex);

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto out;
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	if (i_size_read(&ip->i_inode)) {
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		/* Get a free block, fill it with the stuffed data,
		   and write it out to disk */

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		unsigned int n = 1;
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		error = gfs2_alloc_blocks(ip, &block, &n, 0, NULL);
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		if (error)
			goto out_brelse;
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		if (isdir) {
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			gfs2_trans_add_unrevoke(GFS2_SB(&ip->i_inode), block, 1);
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			error = gfs2_dir_get_new_buffer(ip, block, &bh);
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			if (error)
				goto out_brelse;
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			gfs2_buffer_copy_tail(bh, sizeof(struct gfs2_meta_header),
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					      dibh, sizeof(struct gfs2_dinode));
			brelse(bh);
		} else {
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			error = gfs2_unstuffer_page(ip, dibh, block, page);
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			if (error)
				goto out_brelse;
		}
	}

	/*  Set up the pointer to the new block  */

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	gfs2_trans_add_meta(ip->i_gl, dibh);
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	di = (struct gfs2_dinode *)dibh->b_data;
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	gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));

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	if (i_size_read(&ip->i_inode)) {
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		*(__be64 *)(di + 1) = cpu_to_be64(block);
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		gfs2_add_inode_blocks(&ip->i_inode, 1);
		di->di_blocks = cpu_to_be64(gfs2_get_inode_blocks(&ip->i_inode));
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	}

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	ip->i_height = 1;
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	di->di_height = cpu_to_be16(1);
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out_brelse:
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	brelse(dibh);
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out:
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	up_write(&ip->i_rw_mutex);
	return error;
}


/**
 * find_metapath - Find path through the metadata tree
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 * @sdp: The superblock
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 * @mp: The metapath to return the result in
 * @block: The disk block to look up
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 * @height: The pre-calculated height of the metadata tree
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 *
 *   This routine returns a struct metapath structure that defines a path
 *   through the metadata of inode "ip" to get to block "block".
 *
 *   Example:
 *   Given:  "ip" is a height 3 file, "offset" is 101342453, and this is a
 *   filesystem with a blocksize of 4096.
 *
 *   find_metapath() would return a struct metapath structure set to:
 *   mp_offset = 101342453, mp_height = 3, mp_list[0] = 0, mp_list[1] = 48,
 *   and mp_list[2] = 165.
 *
 *   That means that in order to get to the block containing the byte at
 *   offset 101342453, we would load the indirect block pointed to by pointer
 *   0 in the dinode.  We would then load the indirect block pointed to by
 *   pointer 48 in that indirect block.  We would then load the data block
 *   pointed to by pointer 165 in that indirect block.
 *
 *             ----------------------------------------
 *             | Dinode |                             |
 *             |        |                            4|
 *             |        |0 1 2 3 4 5                 9|
 *             |        |                            6|
 *             ----------------------------------------
 *                       |
 *                       |
 *                       V
 *             ----------------------------------------
 *             | Indirect Block                       |
 *             |                                     5|
 *             |            4 4 4 4 4 5 5            1|
 *             |0           5 6 7 8 9 0 1            2|
 *             ----------------------------------------
 *                                |
 *                                |
 *                                V
 *             ----------------------------------------
 *             | Indirect Block                       |
 *             |                         1 1 1 1 1   5|
 *             |                         6 6 6 6 6   1|
 *             |0                        3 4 5 6 7   2|
 *             ----------------------------------------
 *                                           |
 *                                           |
 *                                           V
 *             ----------------------------------------
 *             | Data block containing offset         |
 *             |            101342453                 |
 *             |                                      |
 *             |                                      |
 *             ----------------------------------------
 *
 */

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static void find_metapath(const struct gfs2_sbd *sdp, u64 block,
			  struct metapath *mp, unsigned int height)
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{
	unsigned int i;

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	mp->mp_fheight = height;
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	for (i = height; i--;)
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		mp->mp_list[i] = do_div(block, sdp->sd_inptrs);
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}

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static inline unsigned int metapath_branch_start(const struct metapath *mp)
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{
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	if (mp->mp_list[0] == 0)
		return 2;
	return 1;
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}

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/**
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 * metaptr1 - Return the first possible metadata pointer in a metapath buffer
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 * @height: The metadata height (0 = dinode)
 * @mp: The metapath
 */
static inline __be64 *metaptr1(unsigned int height, const struct metapath *mp)
{
	struct buffer_head *bh = mp->mp_bh[height];
	if (height == 0)
		return ((__be64 *)(bh->b_data + sizeof(struct gfs2_dinode)));
	return ((__be64 *)(bh->b_data + sizeof(struct gfs2_meta_header)));
}

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/**
 * metapointer - Return pointer to start of metadata in a buffer
 * @height: The metadata height (0 = dinode)
 * @mp: The metapath
 *
 * Return a pointer to the block number of the next height of the metadata
 * tree given a buffer containing the pointer to the current height of the
 * metadata tree.
 */

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static inline __be64 *metapointer(unsigned int height, const struct metapath *mp)
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{
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	__be64 *p = metaptr1(height, mp);
	return p + mp->mp_list[height];
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}

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static void gfs2_metapath_ra(struct gfs2_glock *gl, struct metapath *mp,
			     unsigned int height)
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{
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	struct buffer_head *bh = mp->mp_bh[height];
	const __be64 *pos = metapointer(height, mp);
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	const __be64 *endp = (const __be64 *)(bh->b_data + bh->b_size);
	const __be64 *t;

	for (t = pos; t < endp; t++) {
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		struct buffer_head *rabh;

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		if (!*t)
			continue;

		rabh = gfs2_getbuf(gl, be64_to_cpu(*t), CREATE);
		if (trylock_buffer(rabh)) {
			if (!buffer_uptodate(rabh)) {
				rabh->b_end_io = end_buffer_read_sync;
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				submit_bh(REQ_OP_READ,
					  REQ_RAHEAD | REQ_META | REQ_PRIO,
					  rabh);
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				continue;
			}
			unlock_buffer(rabh);
		}
		brelse(rabh);
	}
}

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static int __fillup_metapath(struct gfs2_inode *ip, struct metapath *mp,
			     unsigned int x, unsigned int h)
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{
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	for (; x < h; x++) {
		__be64 *ptr = metapointer(x, mp);
		u64 dblock = be64_to_cpu(*ptr);
		int ret;
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		if (!dblock)
			break;
		ret = gfs2_meta_indirect_buffer(ip, x + 1, dblock, &mp->mp_bh[x + 1]);
		if (ret)
			return ret;
	}
	mp->mp_aheight = x + 1;
	return 0;
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}

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/**
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 * lookup_metapath - Walk the metadata tree to a specific point
 * @ip: The inode
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 * @mp: The metapath
 *
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 * Assumes that the inode's buffer has already been looked up and
 * hooked onto mp->mp_bh[0] and that the metapath has been initialised
 * by find_metapath().
 *
 * If this function encounters part of the tree which has not been
 * allocated, it returns the current height of the tree at the point
 * at which it found the unallocated block. Blocks which are found are
 * added to the mp->mp_bh[] list.
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 *
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 * Returns: error
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 */

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static int lookup_metapath(struct gfs2_inode *ip, struct metapath *mp)
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{
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	return __fillup_metapath(ip, mp, 0, ip->i_height - 1);
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}

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/**
 * fillup_metapath - fill up buffers for the metadata path to a specific height
 * @ip: The inode
 * @mp: The metapath
 * @h: The height to which it should be mapped
 *
 * Similar to lookup_metapath, but does lookups for a range of heights
 *
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 * Returns: error or the number of buffers filled
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 */

static int fillup_metapath(struct gfs2_inode *ip, struct metapath *mp, int h)
{
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	unsigned int x = 0;
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	int ret;
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	if (h) {
		/* find the first buffer we need to look up. */
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		for (x = h - 1; x > 0; x--) {
			if (mp->mp_bh[x])
				break;
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		}
	}
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	ret = __fillup_metapath(ip, mp, x, h);
	if (ret)
		return ret;
	return mp->mp_aheight - x - 1;
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}

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static inline void release_metapath(struct metapath *mp)
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{
	int i;

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	for (i = 0; i < GFS2_MAX_META_HEIGHT; i++) {
		if (mp->mp_bh[i] == NULL)
			break;
		brelse(mp->mp_bh[i]);
	}
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}

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/**
 * gfs2_extent_length - Returns length of an extent of blocks
 * @start: Start of the buffer
 * @len: Length of the buffer in bytes
 * @ptr: Current position in the buffer
 * @limit: Max extent length to return (0 = unlimited)
 * @eob: Set to 1 if we hit "end of block"
 *
 * If the first block is zero (unallocated) it will return the number of
 * unallocated blocks in the extent, otherwise it will return the number
 * of contiguous blocks in the extent.
 *
 * Returns: The length of the extent (minimum of one block)
 */

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static inline unsigned int gfs2_extent_length(void *start, unsigned int len, __be64 *ptr, size_t limit, int *eob)
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{
	const __be64 *end = (start + len);
	const __be64 *first = ptr;
	u64 d = be64_to_cpu(*ptr);

	*eob = 0;
	do {
		ptr++;
		if (ptr >= end)
			break;
		if (limit && --limit == 0)
			break;
		if (d)
			d++;
	} while(be64_to_cpu(*ptr) == d);
	if (ptr >= end)
		*eob = 1;
	return (ptr - first);
}

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static inline void bmap_lock(struct gfs2_inode *ip, int create)
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{
	if (create)
		down_write(&ip->i_rw_mutex);
	else
		down_read(&ip->i_rw_mutex);
}

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static inline void bmap_unlock(struct gfs2_inode *ip, int create)
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{
	if (create)
		up_write(&ip->i_rw_mutex);
	else
		up_read(&ip->i_rw_mutex);
}

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static inline __be64 *gfs2_indirect_init(struct metapath *mp,
					 struct gfs2_glock *gl, unsigned int i,
					 unsigned offset, u64 bn)
{
	__be64 *ptr = (__be64 *)(mp->mp_bh[i - 1]->b_data +
		       ((i > 1) ? sizeof(struct gfs2_meta_header) :
				 sizeof(struct gfs2_dinode)));
	BUG_ON(i < 1);
	BUG_ON(mp->mp_bh[i] != NULL);
	mp->mp_bh[i] = gfs2_meta_new(gl, bn);
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	gfs2_trans_add_meta(gl, mp->mp_bh[i]);
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	gfs2_metatype_set(mp->mp_bh[i], GFS2_METATYPE_IN, GFS2_FORMAT_IN);
	gfs2_buffer_clear_tail(mp->mp_bh[i], sizeof(struct gfs2_meta_header));
	ptr += offset;
	*ptr = cpu_to_be64(bn);
	return ptr;
}

enum alloc_state {
	ALLOC_DATA = 0,
	ALLOC_GROW_DEPTH = 1,
	ALLOC_GROW_HEIGHT = 2,
	/* ALLOC_UNSTUFF = 3,   TBD and rather complicated */
};

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static inline unsigned int hptrs(struct gfs2_sbd *sdp, const unsigned int hgt)
{
	if (hgt)
		return sdp->sd_inptrs;
	return sdp->sd_diptrs;
}

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/**
 * gfs2_bmap_alloc - Build a metadata tree of the requested height
 * @inode: The GFS2 inode
 * @lblock: The logical starting block of the extent
 * @bh_map: This is used to return the mapping details
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 * @zero_new: True if newly allocated blocks should be zeroed
 * @mp: The metapath, with proper height information calculated
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 * @maxlen: The max number of data blocks to alloc
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 * @dblock: Pointer to return the resulting new block
 * @dblks: Pointer to return the number of blocks allocated
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 *
 * In this routine we may have to alloc:
 *   i) Indirect blocks to grow the metadata tree height
 *  ii) Indirect blocks to fill in lower part of the metadata tree
 * iii) Data blocks
 *
 * The function is in two parts. The first part works out the total
 * number of blocks which we need. The second part does the actual
 * allocation asking for an extent at a time (if enough contiguous free
 * blocks are available, there will only be one request per bmap call)
 * and uses the state machine to initialise the blocks in order.
 *
 * Returns: errno on error
 */

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static int gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap,
			    unsigned flags, struct metapath *mp)
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{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
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	struct super_block *sb = sdp->sd_vfs;
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	struct buffer_head *dibh = mp->mp_bh[0];
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	u64 bn;
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	unsigned n, i, blks, alloced = 0, iblks = 0, branch_start = 0;
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	unsigned dblks = 0;
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	unsigned ptrs_per_blk;
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	const unsigned end_of_metadata = mp->mp_fheight - 1;
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	int ret;
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	enum alloc_state state;
	__be64 *ptr;
	__be64 zero_bn = 0;
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	size_t maxlen = iomap->length >> inode->i_blkbits;
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	BUG_ON(mp->mp_aheight < 1);
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	BUG_ON(dibh == NULL);

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	gfs2_trans_add_meta(ip->i_gl, dibh);
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	if (mp->mp_fheight == mp->mp_aheight) {
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		struct buffer_head *bh;
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		int eob;

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		/* Bottom indirect block exists, find unalloced extent size */
		ptr = metapointer(end_of_metadata, mp);
		bh = mp->mp_bh[end_of_metadata];
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		dblks = gfs2_extent_length(bh->b_data, bh->b_size, ptr,
					   maxlen, &eob);
		BUG_ON(dblks < 1);
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		state = ALLOC_DATA;
	} else {
		/* Need to allocate indirect blocks */
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		ptrs_per_blk = mp->mp_fheight > 1 ? sdp->sd_inptrs :
			sdp->sd_diptrs;
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		dblks = min(maxlen, (size_t)(ptrs_per_blk -
					     mp->mp_list[end_of_metadata]));
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		if (mp->mp_fheight == ip->i_height) {
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			/* Writing into existing tree, extend tree down */
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			iblks = mp->mp_fheight - mp->mp_aheight;
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			state = ALLOC_GROW_DEPTH;
		} else {
			/* Building up tree height */
			state = ALLOC_GROW_HEIGHT;
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			iblks = mp->mp_fheight - ip->i_height;
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			branch_start = metapath_branch_start(mp);
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			iblks += (mp->mp_fheight - branch_start);
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		}
	}

	/* start of the second part of the function (state machine) */

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	blks = dblks + iblks;
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	i = mp->mp_aheight;
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	do {
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		int error;
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		n = blks - alloced;
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		error = gfs2_alloc_blocks(ip, &bn, &n, 0, NULL);
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		if (error)
			return error;
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		alloced += n;
		if (state != ALLOC_DATA || gfs2_is_jdata(ip))
			gfs2_trans_add_unrevoke(sdp, bn, n);
		switch (state) {
		/* Growing height of tree */
		case ALLOC_GROW_HEIGHT:
			if (i == 1) {
				ptr = (__be64 *)(dibh->b_data +
						 sizeof(struct gfs2_dinode));
				zero_bn = *ptr;
			}
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			for (; i - 1 < mp->mp_fheight - ip->i_height && n > 0;
			     i++, n--)
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				gfs2_indirect_init(mp, ip->i_gl, i, 0, bn++);
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			if (i - 1 == mp->mp_fheight - ip->i_height) {
578 579 580 581 582 583 584 585 586 587 588
				i--;
				gfs2_buffer_copy_tail(mp->mp_bh[i],
						sizeof(struct gfs2_meta_header),
						dibh, sizeof(struct gfs2_dinode));
				gfs2_buffer_clear_tail(dibh,
						sizeof(struct gfs2_dinode) +
						sizeof(__be64));
				ptr = (__be64 *)(mp->mp_bh[i]->b_data +
					sizeof(struct gfs2_meta_header));
				*ptr = zero_bn;
				state = ALLOC_GROW_DEPTH;
589
				for(i = branch_start; i < mp->mp_fheight; i++) {
590 591 592 593 594
					if (mp->mp_bh[i] == NULL)
						break;
					brelse(mp->mp_bh[i]);
					mp->mp_bh[i] = NULL;
				}
595
				i = branch_start;
596 597 598 599 600
			}
			if (n == 0)
				break;
		/* Branching from existing tree */
		case ALLOC_GROW_DEPTH:
601
			if (i > 1 && i < mp->mp_fheight)
602
				gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[i-1]);
603
			for (; i < mp->mp_fheight && n > 0; i++, n--)
604 605
				gfs2_indirect_init(mp, ip->i_gl, i,
						   mp->mp_list[i-1], bn++);
606
			if (i == mp->mp_fheight)
607 608 609 610 611
				state = ALLOC_DATA;
			if (n == 0)
				break;
		/* Tree complete, adding data blocks */
		case ALLOC_DATA:
B
Bob Peterson 已提交
612
			BUG_ON(n > dblks);
613
			BUG_ON(mp->mp_bh[end_of_metadata] == NULL);
614
			gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[end_of_metadata]);
B
Bob Peterson 已提交
615
			dblks = n;
616
			ptr = metapointer(end_of_metadata, mp);
B
Bob Peterson 已提交
617 618
			iomap->addr = bn << inode->i_blkbits;
			iomap->flags |= IOMAP_F_NEW;
619 620
			while (n-- > 0)
				*ptr++ = cpu_to_be64(bn++);
B
Bob Peterson 已提交
621 622 623
			if (flags & IOMAP_ZERO) {
				ret = sb_issue_zeroout(sb, iomap->addr >> inode->i_blkbits,
						       dblks, GFP_NOFS);
624 625 626
				if (ret) {
					fs_err(sdp,
					       "Failed to zero data buffers\n");
B
Bob Peterson 已提交
627
					flags &= ~IOMAP_ZERO;
628 629
				}
			}
630 631
			break;
		}
B
Bob Peterson 已提交
632
	} while (iomap->addr == IOMAP_NULL_ADDR);
633

B
Bob Peterson 已提交
634
	iomap->length = (u64)dblks << inode->i_blkbits;
635
	ip->i_height = mp->mp_fheight;
636 637 638 639 640
	gfs2_add_inode_blocks(&ip->i_inode, alloced);
	gfs2_dinode_out(ip, mp->mp_bh[0]->b_data);
	return 0;
}

D
David Teigland 已提交
641
/**
B
Bob Peterson 已提交
642
 * hole_size - figure out the size of a hole
S
Steven Whitehouse 已提交
643
 * @inode: The inode
B
Bob Peterson 已提交
644 645
 * @lblock: The logical starting block number
 * @mp: The metapath
D
David Teigland 已提交
646
 *
B
Bob Peterson 已提交
647
 * Returns: The hole size in bytes
D
David Teigland 已提交
648 649
 *
 */
B
Bob Peterson 已提交
650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688
static u64 hole_size(struct inode *inode, sector_t lblock, struct metapath *mp)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	struct metapath mp_eof;
	u64 factor = 1;
	int hgt;
	u64 holesz = 0;
	const __be64 *first, *end, *ptr;
	const struct buffer_head *bh;
	u64 lblock_stop = (i_size_read(inode) - 1) >> inode->i_blkbits;
	int zeroptrs;
	bool done = false;

	/* Get another metapath, to the very last byte */
	find_metapath(sdp, lblock_stop, &mp_eof, ip->i_height);
	for (hgt = ip->i_height - 1; hgt >= 0 && !done; hgt--) {
		bh = mp->mp_bh[hgt];
		if (bh) {
			zeroptrs = 0;
			first = metapointer(hgt, mp);
			end = (const __be64 *)(bh->b_data + bh->b_size);

			for (ptr = first; ptr < end; ptr++) {
				if (*ptr) {
					done = true;
					break;
				} else {
					zeroptrs++;
				}
			}
		} else {
			zeroptrs = sdp->sd_inptrs;
		}
		if (factor * zeroptrs >= lblock_stop - lblock + 1) {
			holesz = lblock_stop - lblock + 1;
			break;
		}
		holesz += factor * zeroptrs;
D
David Teigland 已提交
689

B
Bob Peterson 已提交
690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720
		factor *= sdp->sd_inptrs;
		if (hgt && (mp->mp_list[hgt - 1] < mp_eof.mp_list[hgt - 1]))
			(mp->mp_list[hgt - 1])++;
	}
	return holesz << inode->i_blkbits;
}

static void gfs2_stuffed_iomap(struct inode *inode, struct iomap *iomap)
{
	struct gfs2_inode *ip = GFS2_I(inode);

	iomap->addr = (ip->i_no_addr << inode->i_blkbits) +
		      sizeof(struct gfs2_dinode);
	iomap->offset = 0;
	iomap->length = i_size_read(inode);
	iomap->type = IOMAP_MAPPED;
	iomap->flags = IOMAP_F_DATA_INLINE;
}

/**
 * gfs2_iomap_begin - Map blocks from an inode to disk blocks
 * @inode: The inode
 * @pos: Starting position in bytes
 * @length: Length to map, in bytes
 * @flags: iomap flags
 * @iomap: The iomap structure
 *
 * Returns: errno
 */
int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
		     unsigned flags, struct iomap *iomap)
D
David Teigland 已提交
721
{
722 723
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
B
Bob Peterson 已提交
724
	struct metapath mp = { .mp_aheight = 1, };
725
	unsigned int factor = sdp->sd_sb.sb_bsize;
726
	const u64 *arr = sdp->sd_heightsize;
727
	__be64 *ptr;
B
Bob Peterson 已提交
728 729
	sector_t lblock;
	sector_t lend;
730 731 732 733 734
	int ret;
	int eob;
	unsigned int len;
	struct buffer_head *bh;
	u8 height;
S
Steven Whitehouse 已提交
735

B
Bob Peterson 已提交
736 737 738 739 740
	trace_gfs2_iomap_start(ip, pos, length, flags);
	if (!length) {
		ret = -EINVAL;
		goto out;
	}
D
David Teigland 已提交
741

B
Bob Peterson 已提交
742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758
	if ((flags & IOMAP_REPORT) && gfs2_is_stuffed(ip)) {
		gfs2_stuffed_iomap(inode, iomap);
		if (pos >= iomap->length)
			return -ENOENT;
		ret = 0;
		goto out;
	}

	lblock = pos >> inode->i_blkbits;
	lend = (pos + length + sdp->sd_sb.sb_bsize - 1) >> inode->i_blkbits;

	iomap->offset = lblock << inode->i_blkbits;
	iomap->addr = IOMAP_NULL_ADDR;
	iomap->type = IOMAP_HOLE;
	iomap->length = (u64)(lend - lblock) << inode->i_blkbits;
	iomap->flags = IOMAP_F_MERGED;
	bmap_lock(ip, 0);
759 760 761 762 763 764

	/*
	 * Directory data blocks have a struct gfs2_meta_header header, so the
	 * remaining size is smaller than the filesystem block size.  Logical
	 * block numbers for directories are in units of this remaining size!
	 */
765
	if (gfs2_is_dir(ip)) {
766
		factor = sdp->sd_jbsize;
767 768
		arr = sdp->sd_jheightsize;
	}
769

770 771
	ret = gfs2_meta_inode_buffer(ip, &mp.mp_bh[0]);
	if (ret)
B
Bob Peterson 已提交
772
		goto out_release;
D
David Teigland 已提交
773

774
	height = ip->i_height;
B
Bob Peterson 已提交
775
	while ((lblock + 1) * factor > arr[height])
776 777 778 779
		height++;
	find_metapath(sdp, lblock, &mp, height);
	if (height > ip->i_height || gfs2_is_stuffed(ip))
		goto do_alloc;
B
Bob Peterson 已提交
780

781
	ret = lookup_metapath(ip, &mp);
782
	if (ret)
B
Bob Peterson 已提交
783 784
		goto out_release;

785
	if (mp.mp_aheight != ip->i_height)
786
		goto do_alloc;
B
Bob Peterson 已提交
787

788 789 790
	ptr = metapointer(ip->i_height - 1, &mp);
	if (*ptr == 0)
		goto do_alloc;
B
Bob Peterson 已提交
791 792 793 794

	iomap->type = IOMAP_MAPPED;
	iomap->addr = be64_to_cpu(*ptr) << inode->i_blkbits;

795
	bh = mp.mp_bh[ip->i_height - 1];
B
Bob Peterson 已提交
796
	len = gfs2_extent_length(bh->b_data, bh->b_size, ptr, lend - lblock, &eob);
797
	if (eob)
B
Bob Peterson 已提交
798 799 800
		iomap->flags |= IOMAP_F_BOUNDARY;
	iomap->length = (u64)len << inode->i_blkbits;

801
	ret = 0;
B
Bob Peterson 已提交
802 803

out_release:
804
	release_metapath(&mp);
B
Bob Peterson 已提交
805 806 807
	bmap_unlock(ip, 0);
out:
	trace_gfs2_iomap_end(ip, iomap, ret);
808
	return ret;
809

810
do_alloc:
B
Bob Peterson 已提交
811 812 813 814 815
	if (!(flags & IOMAP_WRITE)) {
		if (pos >= i_size_read(inode)) {
			ret = -ENOENT;
			goto out_release;
		}
816
		ret = 0;
B
Bob Peterson 已提交
817 818
		iomap->length = hole_size(inode, lblock, &mp);
		goto out_release;
D
David Teigland 已提交
819
	}
820

B
Bob Peterson 已提交
821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852
	ret = gfs2_iomap_alloc(inode, iomap, flags, &mp);
	goto out_release;
}

/**
 * gfs2_block_map - Map a block from an inode to a disk block
 * @inode: The inode
 * @lblock: The logical block number
 * @bh_map: The bh to be mapped
 * @create: True if its ok to alloc blocks to satify the request
 *
 * Sets buffer_mapped() if successful, sets buffer_boundary() if a
 * read of metadata will be required before the next block can be
 * mapped. Sets buffer_new() if new blocks were allocated.
 *
 * Returns: errno
 */

int gfs2_block_map(struct inode *inode, sector_t lblock,
		   struct buffer_head *bh_map, int create)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct iomap iomap;
	int ret, flags = 0;

	clear_buffer_mapped(bh_map);
	clear_buffer_new(bh_map);
	clear_buffer_boundary(bh_map);
	trace_gfs2_bmap(ip, bh_map, lblock, create, 1);

	if (create)
		flags |= IOMAP_WRITE;
853
	if (buffer_zeronew(bh_map))
B
Bob Peterson 已提交
854 855 856 857 858 859 860 861 862 863 864 865 866 867
		flags |= IOMAP_ZERO;
	ret = gfs2_iomap_begin(inode, (loff_t)lblock << inode->i_blkbits,
			       bh_map->b_size, flags, &iomap);
	if (ret) {
		if (!create && ret == -ENOENT) {
			/* Return unmapped buffer beyond the end of file.  */
			ret = 0;
		}
		goto out;
	}

	if (iomap.length > bh_map->b_size) {
		iomap.length = bh_map->b_size;
		iomap.flags &= ~IOMAP_F_BOUNDARY;
868
	}
B
Bob Peterson 已提交
869 870 871 872 873 874 875 876 877 878 879
	if (iomap.addr != IOMAP_NULL_ADDR)
		map_bh(bh_map, inode->i_sb, iomap.addr >> inode->i_blkbits);
	bh_map->b_size = iomap.length;
	if (iomap.flags & IOMAP_F_BOUNDARY)
		set_buffer_boundary(bh_map);
	if (iomap.flags & IOMAP_F_NEW)
		set_buffer_new(bh_map);

out:
	trace_gfs2_bmap(ip, bh_map, lblock, create, ret);
	return ret;
S
Steven Whitehouse 已提交
880 881
}

882 883 884
/*
 * Deprecated: do not use in new code
 */
S
Steven Whitehouse 已提交
885 886
int gfs2_extent_map(struct inode *inode, u64 lblock, int *new, u64 *dblock, unsigned *extlen)
{
887
	struct buffer_head bh = { .b_state = 0, .b_blocknr = 0 };
888
	int ret;
S
Steven Whitehouse 已提交
889 890 891 892 893 894
	int create = *new;

	BUG_ON(!extlen);
	BUG_ON(!dblock);
	BUG_ON(!new);

F
Fabian Frederick 已提交
895
	bh.b_size = BIT(inode->i_blkbits + (create ? 0 : 5));
896
	ret = gfs2_block_map(inode, lblock, &bh, create);
897 898 899 900 901 902 903
	*extlen = bh.b_size >> inode->i_blkbits;
	*dblock = bh.b_blocknr;
	if (buffer_new(&bh))
		*new = 1;
	else
		*new = 0;
	return ret;
D
David Teigland 已提交
904 905
}

S
Steven Whitehouse 已提交
906
/**
907
 * gfs2_block_zero_range - Deal with zeroing out data
S
Steven Whitehouse 已提交
908 909 910
 *
 * This is partly borrowed from ext3.
 */
911 912
static int gfs2_block_zero_range(struct inode *inode, loff_t from,
				 unsigned int length)
S
Steven Whitehouse 已提交
913
{
914
	struct address_space *mapping = inode->i_mapping;
S
Steven Whitehouse 已提交
915
	struct gfs2_inode *ip = GFS2_I(inode);
916 917
	unsigned long index = from >> PAGE_SHIFT;
	unsigned offset = from & (PAGE_SIZE-1);
918
	unsigned blocksize, iblock, pos;
S
Steven Whitehouse 已提交
919 920 921 922
	struct buffer_head *bh;
	struct page *page;
	int err;

923
	page = find_or_create_page(mapping, index, GFP_NOFS);
S
Steven Whitehouse 已提交
924 925 926 927
	if (!page)
		return 0;

	blocksize = inode->i_sb->s_blocksize;
928
	iblock = index << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
S
Steven Whitehouse 已提交
929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944

	if (!page_has_buffers(page))
		create_empty_buffers(page, blocksize, 0);

	/* Find the buffer that contains "offset" */
	bh = page_buffers(page);
	pos = blocksize;
	while (offset >= pos) {
		bh = bh->b_this_page;
		iblock++;
		pos += blocksize;
	}

	err = 0;

	if (!buffer_mapped(bh)) {
945
		gfs2_block_map(inode, iblock, bh, 0);
S
Steven Whitehouse 已提交
946 947 948 949 950 951 952 953 954 955 956
		/* unmapped? It's a hole - nothing to do */
		if (!buffer_mapped(bh))
			goto unlock;
	}

	/* Ok, it's mapped. Make sure it's up-to-date */
	if (PageUptodate(page))
		set_buffer_uptodate(bh);

	if (!buffer_uptodate(bh)) {
		err = -EIO;
957
		ll_rw_block(REQ_OP_READ, 0, 1, &bh);
S
Steven Whitehouse 已提交
958 959 960 961
		wait_on_buffer(bh);
		/* Uhhuh. Read error. Complain and punt. */
		if (!buffer_uptodate(bh))
			goto unlock;
962
		err = 0;
S
Steven Whitehouse 已提交
963 964
	}

965
	if (!gfs2_is_writeback(ip))
966
		gfs2_trans_add_data(ip->i_gl, bh);
S
Steven Whitehouse 已提交
967

968
	zero_user(page, offset, length);
969
	mark_buffer_dirty(bh);
S
Steven Whitehouse 已提交
970 971
unlock:
	unlock_page(page);
972
	put_page(page);
S
Steven Whitehouse 已提交
973 974 975
	return err;
}

976 977
#define GFS2_JTRUNC_REVOKES 8192

978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996
/**
 * gfs2_journaled_truncate - Wrapper for truncate_pagecache for jdata files
 * @inode: The inode being truncated
 * @oldsize: The original (larger) size
 * @newsize: The new smaller size
 *
 * With jdata files, we have to journal a revoke for each block which is
 * truncated. As a result, we need to split this into separate transactions
 * if the number of pages being truncated gets too large.
 */

static int gfs2_journaled_truncate(struct inode *inode, u64 oldsize, u64 newsize)
{
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	u64 max_chunk = GFS2_JTRUNC_REVOKES * sdp->sd_vfs->s_blocksize;
	u64 chunk;
	int error;

	while (oldsize != newsize) {
997 998 999
		struct gfs2_trans *tr;
		unsigned int offs;

1000 1001 1002
		chunk = oldsize - newsize;
		if (chunk > max_chunk)
			chunk = max_chunk;
1003 1004 1005 1006 1007

		offs = oldsize & ~PAGE_MASK;
		if (offs && chunk > PAGE_SIZE)
			chunk = offs + ((chunk - offs) & PAGE_MASK);

1008
		truncate_pagecache(inode, oldsize - chunk);
1009
		oldsize -= chunk;
1010 1011 1012 1013 1014

		tr = current->journal_info;
		if (!test_bit(TR_TOUCHED, &tr->tr_flags))
			continue;

1015 1016 1017 1018 1019 1020 1021 1022 1023
		gfs2_trans_end(sdp);
		error = gfs2_trans_begin(sdp, RES_DINODE, GFS2_JTRUNC_REVOKES);
		if (error)
			return error;
	}

	return 0;
}

1024
static int trunc_start(struct inode *inode, u64 newsize)
D
David Teigland 已提交
1025
{
S
Steven Whitehouse 已提交
1026 1027
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
1028
	struct buffer_head *dibh = NULL;
D
David Teigland 已提交
1029
	int journaled = gfs2_is_jdata(ip);
1030
	u64 oldsize = inode->i_size;
D
David Teigland 已提交
1031 1032
	int error;

1033 1034 1035 1036
	if (journaled)
		error = gfs2_trans_begin(sdp, RES_DINODE + RES_JDATA, GFS2_JTRUNC_REVOKES);
	else
		error = gfs2_trans_begin(sdp, RES_DINODE, 0);
D
David Teigland 已提交
1037 1038 1039 1040 1041 1042 1043
	if (error)
		return error;

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto out;

1044
	gfs2_trans_add_meta(ip->i_gl, dibh);
S
Steven Whitehouse 已提交
1045

D
David Teigland 已提交
1046
	if (gfs2_is_stuffed(ip)) {
S
Steven Whitehouse 已提交
1047
		gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode) + newsize);
D
David Teigland 已提交
1048
	} else {
1049 1050 1051 1052 1053
		unsigned int blocksize = i_blocksize(inode);
		unsigned int offs = newsize & (blocksize - 1);
		if (offs) {
			error = gfs2_block_zero_range(inode, newsize,
						      blocksize - offs);
S
Steven Whitehouse 已提交
1054
			if (error)
1055
				goto out;
D
David Teigland 已提交
1056
		}
S
Steven Whitehouse 已提交
1057
		ip->i_diskflags |= GFS2_DIF_TRUNC_IN_PROG;
D
David Teigland 已提交
1058 1059
	}

S
Steven Whitehouse 已提交
1060
	i_size_write(inode, newsize);
1061
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
S
Steven Whitehouse 已提交
1062
	gfs2_dinode_out(ip, dibh->b_data);
D
David Teigland 已提交
1063

1064 1065 1066
	if (journaled)
		error = gfs2_journaled_truncate(inode, oldsize, newsize);
	else
1067
		truncate_pagecache(inode, newsize);
1068

1069
out:
1070 1071 1072
	brelse(dibh);
	if (current->journal_info)
		gfs2_trans_end(sdp);
D
David Teigland 已提交
1073 1074 1075
	return error;
}

B
Bob Peterson 已提交
1076 1077 1078 1079 1080 1081 1082
/**
 * sweep_bh_for_rgrps - find an rgrp in a meta buffer and free blocks therein
 * @ip: inode
 * @rg_gh: holder of resource group glock
 * @mp: current metapath fully populated with buffers
 * @btotal: place to keep count of total blocks freed
 * @hgt: height we're processing
1083
 * @keep_start: preserve the first meta pointer
B
Bob Peterson 已提交
1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098
 *
 * We sweep a metadata buffer (provided by the metapath) for blocks we need to
 * free, and free them all. However, we do it one rgrp at a time. If this
 * block has references to multiple rgrps, we break it into individual
 * transactions. This allows other processes to use the rgrps while we're
 * focused on a single one, for better concurrency / performance.
 * At every transaction boundary, we rewrite the inode into the journal.
 * That way the bitmaps are kept consistent with the inode and we can recover
 * if we're interrupted by power-outages.
 *
 * Returns: 0, or return code if an error occurred.
 *          *btotal has the total number of blocks freed
 */
static int sweep_bh_for_rgrps(struct gfs2_inode *ip, struct gfs2_holder *rd_gh,
			      const struct metapath *mp, u32 *btotal, int hgt,
1099
			      bool keep_start)
D
David Teigland 已提交
1100
{
1101
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
B
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1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123
	struct gfs2_rgrpd *rgd;
	struct gfs2_trans *tr;
	struct buffer_head *bh = mp->mp_bh[hgt];
	__be64 *top, *bottom, *p;
	int blks_outside_rgrp;
	u64 bn, bstart, isize_blks;
	s64 blen; /* needs to be s64 or gfs2_add_inode_blocks breaks */
	int meta = ((hgt != ip->i_height - 1) ? 1 : 0);
	int ret = 0;
	bool buf_in_tr = false; /* buffer was added to transaction */

	if (gfs2_metatype_check(sdp, bh,
				(hgt ? GFS2_METATYPE_IN : GFS2_METATYPE_DI)))
		return -EIO;

more_rgrps:
	blks_outside_rgrp = 0;
	bstart = 0;
	blen = 0;
	top = metapointer(hgt, mp); /* first ptr from metapath */
	/* If we're keeping some data at the truncation point, we've got to
	   preserve the metadata tree by adding 1 to the starting metapath. */
1124
	if (keep_start)
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1125 1126 1127 1128 1129 1130 1131 1132 1133
		top++;

	bottom = (__be64 *)(bh->b_data + bh->b_size);

	for (p = top; p < bottom; p++) {
		if (!*p)
			continue;
		bn = be64_to_cpu(*p);
		if (gfs2_holder_initialized(rd_gh)) {
1134
			rgd = gfs2_glock2rgrp(rd_gh->gh_gl);
B
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1135 1136 1137
			gfs2_assert_withdraw(sdp,
				     gfs2_glock_is_locked_by_me(rd_gh->gh_gl));
		} else {
1138
			rgd = gfs2_blk2rgrpd(sdp, bn, true);
B
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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 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235
			ret = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_EXCLUSIVE,
						 0, rd_gh);
			if (ret)
				goto out;

			/* Must be done with the rgrp glock held: */
			if (gfs2_rs_active(&ip->i_res) &&
			    rgd == ip->i_res.rs_rbm.rgd)
				gfs2_rs_deltree(&ip->i_res);
		}

		if (!rgrp_contains_block(rgd, bn)) {
			blks_outside_rgrp++;
			continue;
		}

		/* The size of our transactions will be unknown until we
		   actually process all the metadata blocks that relate to
		   the rgrp. So we estimate. We know it can't be more than
		   the dinode's i_blocks and we don't want to exceed the
		   journal flush threshold, sd_log_thresh2. */
		if (current->journal_info == NULL) {
			unsigned int jblocks_rqsted, revokes;

			jblocks_rqsted = rgd->rd_length + RES_DINODE +
				RES_INDIRECT;
			isize_blks = gfs2_get_inode_blocks(&ip->i_inode);
			if (isize_blks > atomic_read(&sdp->sd_log_thresh2))
				jblocks_rqsted +=
					atomic_read(&sdp->sd_log_thresh2);
			else
				jblocks_rqsted += isize_blks;
			revokes = jblocks_rqsted;
			if (meta)
				revokes += hptrs(sdp, hgt);
			else if (ip->i_depth)
				revokes += sdp->sd_inptrs;
			ret = gfs2_trans_begin(sdp, jblocks_rqsted, revokes);
			if (ret)
				goto out_unlock;
			down_write(&ip->i_rw_mutex);
		}
		/* check if we will exceed the transaction blocks requested */
		tr = current->journal_info;
		if (tr->tr_num_buf_new + RES_STATFS +
		    RES_QUOTA >= atomic_read(&sdp->sd_log_thresh2)) {
			/* We set blks_outside_rgrp to ensure the loop will
			   be repeated for the same rgrp, but with a new
			   transaction. */
			blks_outside_rgrp++;
			/* This next part is tricky. If the buffer was added
			   to the transaction, we've already set some block
			   pointers to 0, so we better follow through and free
			   them, or we will introduce corruption (so break).
			   This may be impossible, or at least rare, but I
			   decided to cover the case regardless.

			   If the buffer was not added to the transaction
			   (this call), doing so would exceed our transaction
			   size, so we need to end the transaction and start a
			   new one (so goto). */

			if (buf_in_tr)
				break;
			goto out_unlock;
		}

		gfs2_trans_add_meta(ip->i_gl, bh);
		buf_in_tr = true;
		*p = 0;
		if (bstart + blen == bn) {
			blen++;
			continue;
		}
		if (bstart) {
			__gfs2_free_blocks(ip, bstart, (u32)blen, meta);
			(*btotal) += blen;
			gfs2_add_inode_blocks(&ip->i_inode, -blen);
		}
		bstart = bn;
		blen = 1;
	}
	if (bstart) {
		__gfs2_free_blocks(ip, bstart, (u32)blen, meta);
		(*btotal) += blen;
		gfs2_add_inode_blocks(&ip->i_inode, -blen);
	}
out_unlock:
	if (!ret && blks_outside_rgrp) { /* If buffer still has non-zero blocks
					    outside the rgrp we just processed,
					    do it all over again. */
		if (current->journal_info) {
			struct buffer_head *dibh = mp->mp_bh[0];

			/* Every transaction boundary, we rewrite the dinode
			   to keep its di_blocks current in case of failure. */
			ip->i_inode.i_mtime = ip->i_inode.i_ctime =
1236
				current_time(&ip->i_inode);
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1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266
			gfs2_trans_add_meta(ip->i_gl, dibh);
			gfs2_dinode_out(ip, dibh->b_data);
			up_write(&ip->i_rw_mutex);
			gfs2_trans_end(sdp);
		}
		gfs2_glock_dq_uninit(rd_gh);
		cond_resched();
		goto more_rgrps;
	}
out:
	return ret;
}

/**
 * find_nonnull_ptr - find a non-null pointer given a metapath and height
 * assumes the metapath is valid (with buffers) out to height h
 * @mp: starting metapath
 * @h: desired height to search
 *
 * Returns: true if a non-null pointer was found in the metapath buffer
 *          false if all remaining pointers are NULL in the buffer
 */
static bool find_nonnull_ptr(struct gfs2_sbd *sdp, struct metapath *mp,
			     unsigned int h)
{
	__be64 *ptr;
	unsigned int ptrs = hptrs(sdp, h) - 1;

	while (true) {
		ptr = metapointer(h, mp);
1267 1268 1269 1270 1271 1272 1273
		if (*ptr) { /* if we have a non-null pointer */
			/* Now zero the metapath after the current height. */
			h++;
			if (h < GFS2_MAX_META_HEIGHT)
				memset(&mp->mp_list[h], 0,
				       (GFS2_MAX_META_HEIGHT - h) *
				       sizeof(mp->mp_list[0]));
B
Bob Peterson 已提交
1274
			return true;
1275
		}
B
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1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289

		if (mp->mp_list[h] < ptrs)
			mp->mp_list[h]++;
		else
			return false; /* no more pointers in this buffer */
	}
}

enum dealloc_states {
	DEALLOC_MP_FULL = 0,    /* Strip a metapath with all buffers read in */
	DEALLOC_MP_LOWER = 1,   /* lower the metapath strip height */
	DEALLOC_FILL_MP = 2,  /* Fill in the metapath to the given height. */
	DEALLOC_DONE = 3,       /* process complete */
};
D
David Teigland 已提交
1290

1291
static bool mp_eq_to_hgt(struct metapath *mp, __u16 *list, unsigned int h)
1292
{
1293
	if (memcmp(mp->mp_list, list, h * sizeof(mp->mp_list[0])))
1294 1295 1296 1297
		return false;
	return true;
}

B
Bob Peterson 已提交
1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314
/**
 * trunc_dealloc - truncate a file down to a desired size
 * @ip: inode to truncate
 * @newsize: The desired size of the file
 *
 * This function truncates a file to newsize. It works from the
 * bottom up, and from the right to the left. In other words, it strips off
 * the highest layer (data) before stripping any of the metadata. Doing it
 * this way is best in case the operation is interrupted by power failure, etc.
 * The dinode is rewritten in every transaction to guarantee integrity.
 */
static int trunc_dealloc(struct gfs2_inode *ip, u64 newsize)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct metapath mp;
	struct buffer_head *dibh, *bh;
	struct gfs2_holder rd_gh;
1315 1316 1317 1318
	unsigned int bsize_shift = sdp->sd_sb.sb_bsize_shift;
	u64 lblock = (newsize + (1 << bsize_shift) - 1) >> bsize_shift;
	__u16 start_list[GFS2_MAX_META_HEIGHT]; /* new beginning of truncation */
	unsigned int start_aligned;
B
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1319 1320 1321 1322 1323
	unsigned int strip_h = ip->i_height - 1;
	u32 btotal = 0;
	int ret, state;
	int mp_h; /* metapath buffers are read in to this height */
	u64 prev_bnr = 0;
1324
	bool keep_start; /* need to preserve the first meta pointer? */
D
David Teigland 已提交
1325

B
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	memset(&mp, 0, sizeof(mp));
1327
	find_metapath(sdp, lblock, &mp, ip->i_height);
D
David Teigland 已提交
1328

1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343
	memcpy(start_list, mp.mp_list, sizeof(start_list));

	/*
	 * Set start_aligned to the metadata height up to which the truncate
	 * point is aligned to the metadata tree (i.e., the truncate point is a
	 * multiple of the granularity at the height above).  This determines
	 * at which heights an additional meta pointer needs to be preserved:
	 * an additional meta pointer is needed at a given height if
	 * height < start_aligned.
	 */
	for (mp_h = ip->i_height - 1; mp_h > 0; mp_h--) {
		if (start_list[mp_h])
			break;
	}
	start_aligned = mp_h;
B
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1344 1345 1346 1347

	ret = gfs2_meta_inode_buffer(ip, &dibh);
	if (ret)
		return ret;
D
David Teigland 已提交
1348

B
Bob Peterson 已提交
1349 1350
	mp.mp_bh[0] = dibh;
	ret = lookup_metapath(ip, &mp);
1351 1352
	if (ret)
		goto out_metapath;
1353 1354 1355 1356 1357

	/* issue read-ahead on metadata */
	for (mp_h = 0; mp_h < mp.mp_aheight - 1; mp_h++)
		gfs2_metapath_ra(ip->i_gl, &mp, mp_h);

1358
	if (mp.mp_aheight == ip->i_height)
B
Bob Peterson 已提交
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		state = DEALLOC_MP_FULL; /* We have a complete metapath */
	else
		state = DEALLOC_FILL_MP; /* deal with partial metapath */
D
David Teigland 已提交
1362

B
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1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389
	ret = gfs2_rindex_update(sdp);
	if (ret)
		goto out_metapath;

	ret = gfs2_quota_hold(ip, NO_UID_QUOTA_CHANGE, NO_GID_QUOTA_CHANGE);
	if (ret)
		goto out_metapath;
	gfs2_holder_mark_uninitialized(&rd_gh);

	mp_h = strip_h;

	while (state != DEALLOC_DONE) {
		switch (state) {
		/* Truncate a full metapath at the given strip height.
		 * Note that strip_h == mp_h in order to be in this state. */
		case DEALLOC_MP_FULL:
			bh = mp.mp_bh[mp_h];
			gfs2_assert_withdraw(sdp, bh);
			if (gfs2_assert_withdraw(sdp,
						 prev_bnr != bh->b_blocknr)) {
				printk(KERN_EMERG "GFS2: fsid=%s:inode %llu, "
				       "block:%llu, i_h:%u, s_h:%u, mp_h:%u\n",
				       sdp->sd_fsname,
				       (unsigned long long)ip->i_no_addr,
				       prev_bnr, ip->i_height, strip_h, mp_h);
			}
			prev_bnr = bh->b_blocknr;
1390 1391 1392 1393

			keep_start = mp_h < start_aligned &&
				     mp_eq_to_hgt(&mp, start_list, mp_h);

B
Bob Peterson 已提交
1394
			ret = sweep_bh_for_rgrps(ip, &rd_gh, &mp, &btotal,
1395
						 mp_h, keep_start);
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1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418
			/* If we hit an error or just swept dinode buffer,
			   just exit. */
			if (ret || !mp_h) {
				state = DEALLOC_DONE;
				break;
			}
			state = DEALLOC_MP_LOWER;
			break;

		/* lower the metapath strip height */
		case DEALLOC_MP_LOWER:
			/* We're done with the current buffer, so release it,
			   unless it's the dinode buffer. Then back up to the
			   previous pointer. */
			if (mp_h) {
				brelse(mp.mp_bh[mp_h]);
				mp.mp_bh[mp_h] = NULL;
			}
			/* If we can't get any lower in height, we've stripped
			   off all we can. Next step is to back up and start
			   stripping the previous level of metadata. */
			if (mp_h == 0) {
				strip_h--;
1419
				memcpy(mp.mp_list, start_list, sizeof(start_list));
B
Bob Peterson 已提交
1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443
				mp_h = strip_h;
				state = DEALLOC_FILL_MP;
				break;
			}
			mp.mp_list[mp_h] = 0;
			mp_h--; /* search one metadata height down */
			if (mp.mp_list[mp_h] >= hptrs(sdp, mp_h) - 1)
				break; /* loop around in the same state */
			mp.mp_list[mp_h]++;
			/* Here we've found a part of the metapath that is not
			 * allocated. We need to search at that height for the
			 * next non-null pointer. */
			if (find_nonnull_ptr(sdp, &mp, mp_h)) {
				state = DEALLOC_FILL_MP;
				mp_h++;
			}
			/* No more non-null pointers at this height. Back up
			   to the previous height and try again. */
			break; /* loop around in the same state */

		/* Fill the metapath with buffers to the given height. */
		case DEALLOC_FILL_MP:
			/* Fill the buffers out to the current height. */
			ret = fillup_metapath(ip, &mp, mp_h);
1444
			if (ret < 0)
B
Bob Peterson 已提交
1445
				goto out;
1446 1447 1448 1449 1450 1451 1452

			/* issue read-ahead on metadata */
			if (mp.mp_aheight > 1) {
				for (; ret > 1; ret--)
					gfs2_metapath_ra(ip->i_gl, &mp,
						mp.mp_aheight - ret);
			}
B
Bob Peterson 已提交
1453 1454

			/* If buffers found for the entire strip height */
1455
			if (mp.mp_aheight - 1 == strip_h) {
B
Bob Peterson 已提交
1456 1457 1458
				state = DEALLOC_MP_FULL;
				break;
			}
1459 1460
			if (mp.mp_aheight < ip->i_height) /* We have a partial height */
				mp_h = mp.mp_aheight - 1;
B
Bob Peterson 已提交
1461 1462 1463 1464 1465 1466 1467 1468

			/* If we find a non-null block pointer, crawl a bit
			   higher up in the metapath and try again, otherwise
			   we need to look lower for a new starting point. */
			if (find_nonnull_ptr(sdp, &mp, mp_h))
				mp_h++;
			else
				state = DEALLOC_MP_LOWER;
D
David Teigland 已提交
1469
			break;
B
Bob Peterson 已提交
1470
		}
D
David Teigland 已提交
1471 1472
	}

B
Bob Peterson 已提交
1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483
	if (btotal) {
		if (current->journal_info == NULL) {
			ret = gfs2_trans_begin(sdp, RES_DINODE + RES_STATFS +
					       RES_QUOTA, 0);
			if (ret)
				goto out;
			down_write(&ip->i_rw_mutex);
		}
		gfs2_statfs_change(sdp, 0, +btotal, 0);
		gfs2_quota_change(ip, -(s64)btotal, ip->i_inode.i_uid,
				  ip->i_inode.i_gid);
1484
		ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
B
Bob Peterson 已提交
1485 1486 1487 1488 1489
		gfs2_trans_add_meta(ip->i_gl, dibh);
		gfs2_dinode_out(ip, dibh->b_data);
		up_write(&ip->i_rw_mutex);
		gfs2_trans_end(sdp);
	}
D
David Teigland 已提交
1490

B
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1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502
out:
	if (gfs2_holder_initialized(&rd_gh))
		gfs2_glock_dq_uninit(&rd_gh);
	if (current->journal_info) {
		up_write(&ip->i_rw_mutex);
		gfs2_trans_end(sdp);
		cond_resched();
	}
	gfs2_quota_unhold(ip);
out_metapath:
	release_metapath(&mp);
	return ret;
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David Teigland 已提交
1503 1504 1505 1506
}

static int trunc_end(struct gfs2_inode *ip)
{
1507
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
D
David Teigland 已提交
1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520
	struct buffer_head *dibh;
	int error;

	error = gfs2_trans_begin(sdp, RES_DINODE, 0);
	if (error)
		return error;

	down_write(&ip->i_rw_mutex);

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto out;

S
Steven Whitehouse 已提交
1521
	if (!i_size_read(&ip->i_inode)) {
1522
		ip->i_height = 0;
1523
		ip->i_goal = ip->i_no_addr;
D
David Teigland 已提交
1524
		gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
1525
		gfs2_ordered_del_inode(ip);
D
David Teigland 已提交
1526
	}
1527
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
1528
	ip->i_diskflags &= ~GFS2_DIF_TRUNC_IN_PROG;
D
David Teigland 已提交
1529

1530
	gfs2_trans_add_meta(ip->i_gl, dibh);
1531
	gfs2_dinode_out(ip, dibh->b_data);
D
David Teigland 已提交
1532 1533
	brelse(dibh);

1534
out:
D
David Teigland 已提交
1535 1536 1537 1538 1539 1540 1541
	up_write(&ip->i_rw_mutex);
	gfs2_trans_end(sdp);
	return error;
}

/**
 * do_shrink - make a file smaller
S
Steven Whitehouse 已提交
1542 1543
 * @inode: the inode
 * @newsize: the size to make the file
D
David Teigland 已提交
1544
 *
S
Steven Whitehouse 已提交
1545 1546
 * Called with an exclusive lock on @inode. The @size must
 * be equal to or smaller than the current inode size.
D
David Teigland 已提交
1547 1548 1549 1550
 *
 * Returns: errno
 */

1551
static int do_shrink(struct inode *inode, u64 newsize)
D
David Teigland 已提交
1552
{
S
Steven Whitehouse 已提交
1553
	struct gfs2_inode *ip = GFS2_I(inode);
D
David Teigland 已提交
1554 1555
	int error;

1556
	error = trunc_start(inode, newsize);
D
David Teigland 已提交
1557 1558
	if (error < 0)
		return error;
S
Steven Whitehouse 已提交
1559
	if (gfs2_is_stuffed(ip))
D
David Teigland 已提交
1560 1561
		return 0;

S
Steven Whitehouse 已提交
1562 1563
	error = trunc_dealloc(ip, newsize);
	if (error == 0)
D
David Teigland 已提交
1564 1565 1566 1567 1568
		error = trunc_end(ip);

	return error;
}

S
Steven Whitehouse 已提交
1569
void gfs2_trim_blocks(struct inode *inode)
W
Wendy Cheng 已提交
1570
{
S
Steven Whitehouse 已提交
1571 1572
	int ret;

1573
	ret = do_shrink(inode, inode->i_size);
S
Steven Whitehouse 已提交
1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590
	WARN_ON(ret != 0);
}

/**
 * do_grow - Touch and update inode size
 * @inode: The inode
 * @size: The new size
 *
 * This function updates the timestamps on the inode and
 * may also increase the size of the inode. This function
 * must not be called with @size any smaller than the current
 * inode size.
 *
 * Although it is not strictly required to unstuff files here,
 * earlier versions of GFS2 have a bug in the stuffed file reading
 * code which will result in a buffer overrun if the size is larger
 * than the max stuffed file size. In order to prevent this from
L
Lucas De Marchi 已提交
1591
 * occurring, such files are unstuffed, but in other cases we can
S
Steven Whitehouse 已提交
1592 1593 1594 1595 1596 1597 1598 1599 1600
 * just update the inode size directly.
 *
 * Returns: 0 on success, or -ve on error
 */

static int do_grow(struct inode *inode, u64 size)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
1601
	struct gfs2_alloc_parms ap = { .target = 1, };
W
Wendy Cheng 已提交
1602 1603
	struct buffer_head *dibh;
	int error;
1604
	int unstuff = 0;
W
Wendy Cheng 已提交
1605

S
Steven Whitehouse 已提交
1606 1607
	if (gfs2_is_stuffed(ip) &&
	    (size > (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)))) {
1608
		error = gfs2_quota_lock_check(ip, &ap);
S
Steven Whitehouse 已提交
1609
		if (error)
1610
			return error;
S
Steven Whitehouse 已提交
1611

1612
		error = gfs2_inplace_reserve(ip, &ap);
S
Steven Whitehouse 已提交
1613 1614
		if (error)
			goto do_grow_qunlock;
1615
		unstuff = 1;
S
Steven Whitehouse 已提交
1616 1617
	}

1618 1619 1620
	error = gfs2_trans_begin(sdp, RES_DINODE + RES_STATFS + RES_RG_BIT +
				 (sdp->sd_args.ar_quota == GFS2_QUOTA_OFF ?
				  0 : RES_QUOTA), 0);
W
Wendy Cheng 已提交
1621
	if (error)
S
Steven Whitehouse 已提交
1622
		goto do_grow_release;
W
Wendy Cheng 已提交
1623

1624
	if (unstuff) {
S
Steven Whitehouse 已提交
1625 1626 1627 1628
		error = gfs2_unstuff_dinode(ip, NULL);
		if (error)
			goto do_end_trans;
	}
W
Wendy Cheng 已提交
1629 1630 1631

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
S
Steven Whitehouse 已提交
1632
		goto do_end_trans;
W
Wendy Cheng 已提交
1633

S
Steven Whitehouse 已提交
1634
	i_size_write(inode, size);
1635
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
1636
	gfs2_trans_add_meta(ip->i_gl, dibh);
W
Wendy Cheng 已提交
1637 1638 1639
	gfs2_dinode_out(ip, dibh->b_data);
	brelse(dibh);

S
Steven Whitehouse 已提交
1640
do_end_trans:
W
Wendy Cheng 已提交
1641
	gfs2_trans_end(sdp);
S
Steven Whitehouse 已提交
1642
do_grow_release:
1643
	if (unstuff) {
S
Steven Whitehouse 已提交
1644 1645 1646 1647
		gfs2_inplace_release(ip);
do_grow_qunlock:
		gfs2_quota_unlock(ip);
	}
W
Wendy Cheng 已提交
1648 1649 1650
	return error;
}

D
David Teigland 已提交
1651
/**
S
Steven Whitehouse 已提交
1652 1653 1654
 * gfs2_setattr_size - make a file a given size
 * @inode: the inode
 * @newsize: the size to make the file
D
David Teigland 已提交
1655
 *
S
Steven Whitehouse 已提交
1656 1657 1658
 * The file size can grow, shrink, or stay the same size. This
 * is called holding i_mutex and an exclusive glock on the inode
 * in question.
D
David Teigland 已提交
1659 1660 1661 1662
 *
 * Returns: errno
 */

S
Steven Whitehouse 已提交
1663
int gfs2_setattr_size(struct inode *inode, u64 newsize)
D
David Teigland 已提交
1664
{
1665
	struct gfs2_inode *ip = GFS2_I(inode);
S
Steven Whitehouse 已提交
1666
	int ret;
D
David Teigland 已提交
1667

S
Steven Whitehouse 已提交
1668
	BUG_ON(!S_ISREG(inode->i_mode));
D
David Teigland 已提交
1669

S
Steven Whitehouse 已提交
1670 1671 1672
	ret = inode_newsize_ok(inode, newsize);
	if (ret)
		return ret;
D
David Teigland 已提交
1673

1674 1675
	inode_dio_wait(inode);

1676
	ret = gfs2_rsqa_alloc(ip);
1677
	if (ret)
1678
		goto out;
1679

1680
	if (newsize >= inode->i_size) {
1681 1682 1683
		ret = do_grow(inode, newsize);
		goto out;
	}
S
Steven Whitehouse 已提交
1684

1685
	ret = do_shrink(inode, newsize);
1686
out:
1687
	gfs2_rsqa_delete(ip, NULL);
1688
	return ret;
D
David Teigland 已提交
1689 1690 1691 1692 1693
}

int gfs2_truncatei_resume(struct gfs2_inode *ip)
{
	int error;
S
Steven Whitehouse 已提交
1694
	error = trunc_dealloc(ip, i_size_read(&ip->i_inode));
D
David Teigland 已提交
1695 1696 1697 1698 1699 1700 1701 1702 1703 1704
	if (!error)
		error = trunc_end(ip);
	return error;
}

int gfs2_file_dealloc(struct gfs2_inode *ip)
{
	return trunc_dealloc(ip, 0);
}

1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725
/**
 * gfs2_free_journal_extents - Free cached journal bmap info
 * @jd: The journal
 *
 */

void gfs2_free_journal_extents(struct gfs2_jdesc *jd)
{
	struct gfs2_journal_extent *jext;

	while(!list_empty(&jd->extent_list)) {
		jext = list_entry(jd->extent_list.next, struct gfs2_journal_extent, list);
		list_del(&jext->list);
		kfree(jext);
	}
}

/**
 * gfs2_add_jextent - Add or merge a new extent to extent cache
 * @jd: The journal descriptor
 * @lblock: The logical block at start of new extent
1726
 * @dblock: The physical block at start of new extent
1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819
 * @blocks: Size of extent in fs blocks
 *
 * Returns: 0 on success or -ENOMEM
 */

static int gfs2_add_jextent(struct gfs2_jdesc *jd, u64 lblock, u64 dblock, u64 blocks)
{
	struct gfs2_journal_extent *jext;

	if (!list_empty(&jd->extent_list)) {
		jext = list_entry(jd->extent_list.prev, struct gfs2_journal_extent, list);
		if ((jext->dblock + jext->blocks) == dblock) {
			jext->blocks += blocks;
			return 0;
		}
	}

	jext = kzalloc(sizeof(struct gfs2_journal_extent), GFP_NOFS);
	if (jext == NULL)
		return -ENOMEM;
	jext->dblock = dblock;
	jext->lblock = lblock;
	jext->blocks = blocks;
	list_add_tail(&jext->list, &jd->extent_list);
	jd->nr_extents++;
	return 0;
}

/**
 * gfs2_map_journal_extents - Cache journal bmap info
 * @sdp: The super block
 * @jd: The journal to map
 *
 * Create a reusable "extent" mapping from all logical
 * blocks to all physical blocks for the given journal.  This will save
 * us time when writing journal blocks.  Most journals will have only one
 * extent that maps all their logical blocks.  That's because gfs2.mkfs
 * arranges the journal blocks sequentially to maximize performance.
 * So the extent would map the first block for the entire file length.
 * However, gfs2_jadd can happen while file activity is happening, so
 * those journals may not be sequential.  Less likely is the case where
 * the users created their own journals by mounting the metafs and
 * laying it out.  But it's still possible.  These journals might have
 * several extents.
 *
 * Returns: 0 on success, or error on failure
 */

int gfs2_map_journal_extents(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd)
{
	u64 lblock = 0;
	u64 lblock_stop;
	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
	struct buffer_head bh;
	unsigned int shift = sdp->sd_sb.sb_bsize_shift;
	u64 size;
	int rc;

	lblock_stop = i_size_read(jd->jd_inode) >> shift;
	size = (lblock_stop - lblock) << shift;
	jd->nr_extents = 0;
	WARN_ON(!list_empty(&jd->extent_list));

	do {
		bh.b_state = 0;
		bh.b_blocknr = 0;
		bh.b_size = size;
		rc = gfs2_block_map(jd->jd_inode, lblock, &bh, 0);
		if (rc || !buffer_mapped(&bh))
			goto fail;
		rc = gfs2_add_jextent(jd, lblock, bh.b_blocknr, bh.b_size >> shift);
		if (rc)
			goto fail;
		size -= bh.b_size;
		lblock += (bh.b_size >> ip->i_inode.i_blkbits);
	} while(size > 0);

	fs_info(sdp, "journal %d mapped with %u extents\n", jd->jd_jid,
		jd->nr_extents);
	return 0;

fail:
	fs_warn(sdp, "error %d mapping journal %u at offset %llu (extent %u)\n",
		rc, jd->jd_jid,
		(unsigned long long)(i_size_read(jd->jd_inode) - size),
		jd->nr_extents);
	fs_warn(sdp, "bmap=%d lblock=%llu block=%llu, state=0x%08lx, size=%llu\n",
		rc, (unsigned long long)lblock, (unsigned long long)bh.b_blocknr,
		bh.b_state, (unsigned long long)bh.b_size);
	gfs2_free_journal_extents(jd);
	return rc;
}

D
David Teigland 已提交
1820 1821 1822 1823 1824 1825
/**
 * gfs2_write_alloc_required - figure out if a write will require an allocation
 * @ip: the file being written to
 * @offset: the offset to write to
 * @len: the number of bytes being written
 *
1826
 * Returns: 1 if an alloc is required, 0 otherwise
D
David Teigland 已提交
1827 1828
 */

1829
int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
1830
			      unsigned int len)
D
David Teigland 已提交
1831
{
1832
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
1833 1834 1835
	struct buffer_head bh;
	unsigned int shift;
	u64 lblock, lblock_stop, size;
1836
	u64 end_of_file;
D
David Teigland 已提交
1837 1838 1839 1840 1841 1842 1843

	if (!len)
		return 0;

	if (gfs2_is_stuffed(ip)) {
		if (offset + len >
		    sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode))
1844
			return 1;
D
David Teigland 已提交
1845 1846 1847
		return 0;
	}

1848
	shift = sdp->sd_sb.sb_bsize_shift;
1849
	BUG_ON(gfs2_is_dir(ip));
S
Steven Whitehouse 已提交
1850
	end_of_file = (i_size_read(&ip->i_inode) + sdp->sd_sb.sb_bsize - 1) >> shift;
1851 1852 1853
	lblock = offset >> shift;
	lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
	if (lblock_stop > end_of_file)
1854
		return 1;
D
David Teigland 已提交
1855

1856 1857 1858 1859 1860 1861
	size = (lblock_stop - lblock) << shift;
	do {
		bh.b_state = 0;
		bh.b_size = size;
		gfs2_block_map(&ip->i_inode, lblock, &bh, 0);
		if (!buffer_mapped(&bh))
1862
			return 1;
1863 1864 1865
		size -= bh.b_size;
		lblock += (bh.b_size >> ip->i_inode.i_blkbits);
	} while(size > 0);
D
David Teigland 已提交
1866 1867 1868 1869

	return 0;
}