Release 4.10 fs/gfs2/aops.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/mpage.h>
#include <linux/fs.h>
#include <linux/writeback.h>
#include <linux/swap.h>
#include <linux/gfs2_ondisk.h>
#include <linux/backing-dev.h>
#include <linux/uio.h>
#include <trace/events/writeback.h>

#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "glock.h"
#include "inode.h"
#include "log.h"
#include "meta_io.h"
#include "quota.h"
#include "trans.h"
#include "rgrp.h"
#include "super.h"
#include "util.h"
#include "glops.h"




static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
				   unsigned int from, unsigned int to)
{
	struct buffer_head *head = page_buffers(page);
	unsigned int bsize = head->b_size;
	struct buffer_head *bh;
	unsigned int start, end;

	for (bh = head, start = 0; bh != head || !start;
	     bh = bh->b_this_page, start = end) {
		end = start + bsize;
		if (end <= from || start >= to)
			continue;
		if (gfs2_is_jdata(ip))
			set_buffer_uptodate(bh);
		gfs2_trans_add_data(ip->i_gl, bh);
	}
}

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benjamin marzinski
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1
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robert s. peterson
robert s. peterson
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/**
 * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
 * @inode: The inode
 * @lblock: The block number to look up
 * @bh_result: The buffer head to return the result in
 * @create: Non-zero if we may add block to the file
 *
 * Returns: errno
 */



static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
				  struct buffer_head *bh_result, int create)
{
	int error;

	error = gfs2_block_map(inode, lblock, bh_result, 0);
	if (error)
		return error;
	if (!buffer_mapped(bh_result))
		return -EIO;
	return 0;
}

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david teigland
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steven whitehouse
steven whitehouse
6
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2
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wendy cheng
wendy cheng
4
6.67%
1
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robert s. peterson
robert s. peterson
2
3.33%
1
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static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
				 struct buffer_head *bh_result, int create)
{
	return gfs2_block_map(inode, lblock, bh_result, 0);
}

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steven whitehouse
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robert s. peterson
2
5.88%
1
33.33%
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34
100.00%
3
100.00%

/**
 * gfs2_writepage_common - Common bits of writepage
 * @page: The page to be written
 * @wbc: The writeback control
 *
 * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
 */



static int gfs2_writepage_common(struct page *page,
				 struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	loff_t i_size = i_size_read(inode);
	pgoff_t end_index = i_size >> PAGE_SHIFT;
	unsigned offset;

	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
		goto out;
	if (current->journal_info)
		goto redirty;
	/* Is the page fully outside i_size? (truncate in progress) */
	offset = i_size & (PAGE_SIZE-1);
	if (page->index > end_index || (page->index == end_index && !offset)) {
		page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
		goto out;
	}
	return 1;
redirty:
	redirty_page_for_writepage(wbc, page);
out:
	unlock_page(page);
	return 0;
}

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steven whitehouse
103
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6
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david teigland
david teigland
56
34.36%
1
11.11%
kirill a. shutemov
kirill a. shutemov
3
1.84%
1
11.11%
lukas czerner
lukas czerner
1
0.61%
1
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/**
 * gfs2_writepage - Write page for writeback mappings
 * @page: The page
 * @wbc: The writeback control
 *
 */



static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
{
	int ret;

	ret = gfs2_writepage_common(page, wbc);
	if (ret <= 0)
		return ret;

	return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
}

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/* This is the same as calling block_write_full_page, but it also
 * writes pages outside of i_size
 */


int gfs2_write_full_page(struct page *page, get_block_t *get_block,
			 struct writeback_control *wbc)
{
	struct inode * const inode = page->mapping->host;
	loff_t i_size = i_size_read(inode);
	const pgoff_t end_index = i_size >> PAGE_SHIFT;
	unsigned offset;

	/*
         * The page straddles i_size.  It must be zeroed out on each and every
         * writepage invocation because it may be mmapped.  "A file is mapped
         * in multiples of the page size.  For a file that is not a multiple of
         * the  page size, the remaining memory is zeroed when mapped, and
         * writes to that region are not written out to the file."
         */
	offset = i_size & (PAGE_SIZE-1);
	if (page->index == end_index && offset)
		zero_user_segment(page, offset, PAGE_SIZE);

	return __block_write_full_page(inode, page, get_block, wbc,
				       end_buffer_async_write);
}

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benjamin marzinski
benjamin marzinski
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/**
 * __gfs2_jdata_writepage - The core of jdata writepage
 * @page: The page to write
 * @wbc: The writeback control
 *
 * This is shared between writepage and writepages and implements the
 * core of the writepage operation. If a transaction is required then
 * PageChecked will have been set and the transaction will have
 * already been started before this is called.
 */



static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);

	if (PageChecked(page)) {
		ClearPageChecked(page);
		if (!page_has_buffers(page)) {
			create_empty_buffers(page, inode->i_sb->s_blocksize,
					     BIT(BH_Dirty)|BIT(BH_Uptodate));
		}
		gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
	}
	return gfs2_write_full_page(page, gfs2_get_block_noalloc, wbc);
}

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steven whitehouse
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fabian frederick
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33.33%
benjamin marzinski
benjamin marzinski
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/**
 * gfs2_jdata_writepage - Write complete page
 * @page: Page to write
 * @wbc: The writeback control
 *
 * Returns: errno
 *
 */



static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	int ret;

	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
		goto out;
	if (PageChecked(page) || current->journal_info)
		goto out_ignore;
	ret = __gfs2_jdata_writepage(page, wbc);
	return ret;

out_ignore:
	redirty_page_for_writepage(wbc, page);
out:
	unlock_page(page);
	return 0;
}

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benjamin marzinski
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/**
 * gfs2_writepages - Write a bunch of dirty pages back to disk
 * @mapping: The mapping to write
 * @wbc: Write-back control
 *
 * Used for both ordered and writeback modes.
 */


static int gfs2_writepages(struct address_space *mapping,
			   struct writeback_control *wbc)
{
	return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
}

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/**
 * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 * @mapping: The mapping
 * @wbc: The writeback control
 * @pvec: The vector of pages
 * @nr_pages: The number of pages to write
 * @end: End position
 * @done_index: Page index
 *
 * Returns: non-zero if loop should terminate, zero otherwise
 */



static int gfs2_write_jdata_pagevec(struct address_space *mapping,
				    struct writeback_control *wbc,
				    struct pagevec *pvec,
				    int nr_pages, pgoff_t end,
				    pgoff_t *done_index)
{
	struct inode *inode = mapping->host;
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	unsigned nrblocks = nr_pages * (PAGE_SIZE/inode->i_sb->s_blocksize);
	int i;
	int ret;

	ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
	if (ret < 0)
		return ret;

	for(i = 0; i < nr_pages; i++) {
		struct page *page = pvec->pages[i];

		/*
                 * At this point, the page may be truncated or
                 * invalidated (changing page->mapping to NULL), or
                 * even swizzled back from swapper_space to tmpfs file
                 * mapping. However, page->index will not change
                 * because we have a reference on the page.
                 */
		if (page->index > end) {
			/*
                         * can't be range_cyclic (1st pass) because
                         * end == -1 in that case.
                         */
			ret = 1;
			break;
		}

		*done_index = page->index;

		lock_page(page);

		if (unlikely(page->mapping != mapping)) {
continue_unlock:
			unlock_page(page);
			continue;
		}

		if (!PageDirty(page)) {
			/* someone wrote it for us */
			goto continue_unlock;
		}

		if (PageWriteback(page)) {
			if (wbc->sync_mode != WB_SYNC_NONE)
				wait_on_page_writeback(page);
			else
				goto continue_unlock;
		}

		BUG_ON(PageWriteback(page));
		if (!clear_page_dirty_for_io(page))
			goto continue_unlock;

		trace_wbc_writepage(wbc, inode_to_bdi(inode));

		ret = __gfs2_jdata_writepage(page, wbc);
		if (unlikely(ret)) {
			if (ret == AOP_WRITEPAGE_ACTIVATE) {
				unlock_page(page);
				ret = 0;
			} else {

				/*
                                 * done_index is set past this page,
                                 * so media errors will not choke
                                 * background writeout for the entire
                                 * file. This has consequences for
                                 * range_cyclic semantics (ie. it may
                                 * not be suitable for data integrity
                                 * writeout).
                                 */
				*done_index = page->index + 1;
				ret = 1;
				break;
			}
		}

		/*
                 * We stop writing back only if we are not doing
                 * integrity sync. In case of integrity sync we have to
                 * keep going until we have written all the pages
                 * we tagged for writeback prior to entering this loop.
                 */
		if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
			ret = 1;
			break;
		}

	}
	gfs2_trans_end(sdp);
	return ret;
}

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christoph hellwig
4
1.25%
1
20.00%
abhijith das
abhijith das
1
0.31%
1
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kirill a. shutemov
kirill a. shutemov
1
0.31%
1
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/**
 * gfs2_write_cache_jdata - Like write_cache_pages but different
 * @mapping: The mapping to write
 * @wbc: The writeback control
 *
 * The reason that we use our own function here is that we need to
 * start transactions before we grab page locks. This allows us
 * to get the ordering right.
 */



static int gfs2_write_cache_jdata(struct address_space *mapping,
				  struct writeback_control *wbc)
{
	int ret = 0;
	int done = 0;
	struct pagevec pvec;
	int nr_pages;
	pgoff_t uninitialized_var(writeback_index);
	pgoff_t index;
	pgoff_t end;
	pgoff_t done_index;
	int cycled;
	int range_whole = 0;
	int tag;

	pagevec_init(&pvec, 0);
	if (wbc->range_cyclic) {
		writeback_index = mapping->writeback_index; /* prev offset */
		index = writeback_index;
		if (index == 0)
			cycled = 1;
		else
			cycled = 0;
		end = -1;
	} else {
		index = wbc->range_start >> PAGE_SHIFT;
		end = wbc->range_end >> PAGE_SHIFT;
		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
			range_whole = 1;
		cycled = 1; /* ignore range_cyclic tests */
	}
	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
		tag = PAGECACHE_TAG_TOWRITE;
	else
		tag = PAGECACHE_TAG_DIRTY;

retry:
	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
		tag_pages_for_writeback(mapping, index, end);
	done_index = index;
	while (!done && (index <= end)) {
		nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
			      min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
		if (nr_pages == 0)
			break;

		ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, end, &done_index);
		if (ret)
			done = 1;
		if (ret > 0)
			ret = 0;
		pagevec_release(&pvec);
		cond_resched();
	}

	if (!cycled && !done) {
		/*
                 * range_cyclic:
                 * We hit the last page and there is more work to be done: wrap
                 * back to the start of the file
                 */
		cycled = 1;
		index = 0;
		end = writeback_index - 1;
		goto retry;
	}

	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
		mapping->writeback_index = done_index;

	return ret;
}


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kirill a. shutemov
2
0.58%
1
25.00%
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346
100.00%
4
100.00%

/**
 * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 * @mapping: The mapping to write
 * @wbc: The writeback control
 * 
 */



static int gfs2_jdata_writepages(struct address_space *mapping,
				 struct writeback_control *wbc)
{
	struct gfs2_inode *ip = GFS2_I(mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
	int ret;

	ret = gfs2_write_cache_jdata(mapping, wbc);
	if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
		gfs2_log_flush(sdp, ip->i_gl, NORMAL_FLUSH);
		ret = gfs2_write_cache_jdata(mapping, wbc);
	}
	return ret;
}

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steven whitehouse
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david teigland
7
7.87%
1
16.67%
benjamin marzinski
benjamin marzinski
2
2.25%
1
16.67%
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89
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6
100.00%

/**
 * stuffed_readpage - Fill in a Linux page with stuffed file data
 * @ip: the inode
 * @page: the page
 *
 * Returns: errno
 */



static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
{
	struct buffer_head *dibh;
	u64 dsize = i_size_read(&ip->i_inode);
	void *kaddr;
	int error;

	/*
         * Due to the order of unstuffing files and ->fault(), we can be
         * asked for a zero page in the case of a stuffed file being extended,
         * so we need to supply one here. It doesn't happen often.
         */
	if (unlikely(page->index)) {
		zero_user(page, 0, PAGE_SIZE);
		SetPageUptodate(page);
		return 0;
	}

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		return error;

	kaddr = kmap_atomic(page);
	if (dsize > (dibh->b_size - sizeof(struct gfs2_dinode)))
		dsize = (dibh->b_size - sizeof(struct gfs2_dinode));
	memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
	memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
	kunmap_atomic(kaddr);
	flush_dcache_page(page);
	brelse(dibh);
	SetPageUptodate(page);

	return 0;
}


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david teigland
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steven whitehouse
steven whitehouse
72
41.14%
4
40.00%
abhijith das
abhijith das
5
2.86%
1
10.00%
kirill a. shutemov
kirill a. shutemov
2
1.14%
1
10.00%
russell cattelan
russell cattelan
1
0.57%
1
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christoph lameter
christoph lameter
1
0.57%
1
10.00%
nick piggin
nick piggin
1
0.57%
1
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175
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10
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/**
 * __gfs2_readpage - readpage
 * @file: The file to read a page for
 * @page: The page to read
 *
 * This is the core of gfs2's readpage. Its used by the internal file
 * reading code as in that case we already hold the glock. Also its
 * called by gfs2_readpage() once the required lock has been granted.
 *
 */



static int __gfs2_readpage(void *file, struct page *page)
{
	struct gfs2_inode *ip = GFS2_I(page->mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
	int error;

	if (gfs2_is_stuffed(ip)) {
		error = stuffed_readpage(ip, page);
		unlock_page(page);
	} else {
		error = mpage_readpage(page, gfs2_block_map);
	}

	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
		return -EIO;

	return error;
}

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steven whitehouse
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89.32%
3
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david teigland
10
9.71%
1
20.00%
robert s. peterson
robert s. peterson
1
0.97%
1
20.00%
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103
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5
100.00%

/**
 * gfs2_readpage - read a page of a file
 * @file: The file to read
 * @page: The page of the file
 *
 * This deals with the locking required. We have to unlock and
 * relock the page in order to get the locking in the right
 * order.
 */



static int gfs2_readpage(struct file *file, struct page *page)
{
	struct address_space *mapping = page->mapping;
	struct gfs2_inode *ip = GFS2_I(mapping->host);
	struct gfs2_holder gh;
	int error;

	unlock_page(page);
	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
	error = gfs2_glock_nq(&gh);
	if (unlikely(error))
		goto out;
	error = AOP_TRUNCATED_PAGE;
	lock_page(page);
	if (page->mapping == mapping && !PageUptodate(page))
		error = __gfs2_readpage(file, page);
	else
		unlock_page(page);
	gfs2_glock_dq(&gh);
out:
	gfs2_holder_uninit(&gh);
	if (error && error != AOP_TRUNCATED_PAGE)
		lock_page(page);
	return error;
}

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steven whitehouse
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71.43%
david teigland
david teigland
15
10.07%
1
14.29%
russell cattelan
russell cattelan
4
2.68%
1
14.29%
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149
100.00%
7
100.00%

/**
 * gfs2_internal_read - read an internal file
 * @ip: The gfs2 inode
 * @buf: The buffer to fill
 * @pos: The file position
 * @size: The amount to read
 *
 */



int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
                       unsigned size)
{
	struct address_space *mapping = ip->i_inode.i_mapping;
	unsigned long index = *pos / PAGE_SIZE;
	unsigned offset = *pos & (PAGE_SIZE - 1);
	unsigned copied = 0;
	unsigned amt;
	struct page *page;
	void *p;

	do {
		amt = size - copied;
		if (offset + size > PAGE_SIZE)
			amt = PAGE_SIZE - offset;
		page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
		if (IS_ERR(page))
			return PTR_ERR(page);
		p = kmap_atomic(page);
		memcpy(buf + copied, p + offset, amt);
		kunmap_atomic(p);
		put_page(page);
		copied += amt;
		index++;
		offset = 0;
	} while(copied < size);
	(*pos) += size;
	return size;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
steven whitehouse
steven whitehouse
166
93.79%
3
50.00%
kirill a. shutemov
kirill a. shutemov
5
2.82%
1
16.67%
josef whiter
josef whiter
5
2.82%
1
16.67%
david teigland
david teigland
1
0.56%
1
16.67%
Total
177
100.00%
6
100.00%

/**
 * gfs2_readpages - Read a bunch of pages at once
 * @file: The file to read from
 * @mapping: Address space info
 * @pages: List of pages to read
 * @nr_pages: Number of pages to read
 *
 * Some notes:
 * 1. This is only for readahead, so we can simply ignore any things
 *    which are slightly inconvenient (such as locking conflicts between
 *    the page lock and the glock) and return having done no I/O. Its
 *    obviously not something we'd want to do on too regular a basis.
 *    Any I/O we ignore at this time will be done via readpage later.
 * 2. We don't handle stuffed files here we let readpage do the honours.
 * 3. mpage_readpages() does most of the heavy lifting in the common case.
 * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 */



static int gfs2_readpages(struct file *file, struct address_space *mapping,
			  struct list_head *pages, unsigned nr_pages)
{
	struct inode *inode = mapping->host;
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	struct gfs2_holder gh;
	int ret;

	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
	ret = gfs2_glock_nq(&gh);
	if (unlikely(ret))
		goto out_uninit;
	if (!gfs2_is_stuffed(ip))
		ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
	gfs2_glock_dq(&gh);
out_uninit:
	gfs2_holder_uninit(&gh);
	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
		ret = -EIO;
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
steven whitehouse
steven whitehouse
102
68.00%
6
75.00%
david teigland
david teigland
47
31.33%
1
12.50%
robert s. peterson
robert s. peterson
1
0.67%
1
12.50%
Total
150
100.00%
8
100.00%

/**
 * gfs2_write_begin - Begin to write to a file
 * @file: The file to write to
 * @mapping: The mapping in which to write
 * @pos: The file offset at which to start writing
 * @len: Length of the write
 * @flags: Various flags
 * @pagep: Pointer to return the page
 * @fsdata: Pointer to return fs data (unused by GFS2)
 *
 * Returns: errno
 */



static int gfs2_write_begin(struct file *file, struct address_space *mapping,
			    loff_t pos, unsigned len, unsigned flags,
			    struct page **pagep, void **fsdata)
{
	struct gfs2_inode *ip = GFS2_I(mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
	struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
	unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
	unsigned requested = 0;
	int alloc_required;
	int error = 0;
	pgoff_t index = pos >> PAGE_SHIFT;
	unsigned from = pos & (PAGE_SIZE - 1);
	struct page *page;

	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
	error = gfs2_glock_nq(&ip->i_gh);
	if (unlikely(error))
		goto out_uninit;
	if (&ip->i_inode == sdp->sd_rindex) {
		error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
					   GL_NOCACHE, &m_ip->i_gh);
		if (unlikely(error)) {
			gfs2_glock_dq(&ip->i_gh);
			goto out_uninit;
		}
	}

	alloc_required = gfs2_write_alloc_required(ip, pos, len);

	if (alloc_required || gfs2_is_jdata(ip))
		gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);

	if (alloc_required) {
		struct gfs2_alloc_parms ap = { .aflags = 0, };
		requested = data_blocks + ind_blocks;
		ap.target = requested;
		error = gfs2_quota_lock_check(ip, &ap);
		if (error)
			goto out_unlock;

		error = gfs2_inplace_reserve(ip, &ap);
		if (error)
			goto out_qunlock;
	}

	rblocks = RES_DINODE + ind_blocks;
	if (gfs2_is_jdata(ip))
		rblocks += data_blocks ? data_blocks : 1;
	if (ind_blocks || data_blocks)
		rblocks += RES_STATFS + RES_QUOTA;
	if (&ip->i_inode == sdp->sd_rindex)
		rblocks += 2 * RES_STATFS;
	if (alloc_required)
		rblocks += gfs2_rg_blocks(ip, requested);

	error = gfs2_trans_begin(sdp, rblocks,
				 PAGE_SIZE/sdp->sd_sb.sb_bsize);
	if (error)
		goto out_trans_fail;

	error = -ENOMEM;
	flags |= AOP_FLAG_NOFS;
	page = grab_cache_page_write_begin(mapping, index, flags);
	*pagep = page;
	if (unlikely(!page))
		goto out_endtrans;

	if (gfs2_is_stuffed(ip)) {
		error = 0;
		if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
			error = gfs2_unstuff_dinode(ip, page);
			if (error == 0)
				goto prepare_write;
		} else if (!PageUptodate(page)) {
			error = stuffed_readpage(ip, page);
		}
		goto out;
	}

prepare_write:
	error = __block_write_begin(page, from, len, gfs2_block_map);
out:
	if (error == 0)
		return 0;

	unlock_page(page);
	put_page(page);

	gfs2_trans_end(sdp);
	if (pos + len > ip->i_inode.i_size)
		gfs2_trim_blocks(&ip->i_inode);
	goto out_trans_fail;

out_endtrans:
	gfs2_trans_end(sdp);
out_trans_fail:
	if (alloc_required) {
		gfs2_inplace_release(ip);