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Btrfs: fix delalloc accounting after copy_from_user faults

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Commit 56244ef151 was almost but not quite enough to fix the
reservation math after btrfs_copy_from_user returned partial copies.

Some users are still seeing warnings in btrfs_destroy_inode, and with a
long enough test run I'm able to trigger them as well.

This patch fixes the accounting math again, bringing it much closer to
the way it was before the sectorsize conversion Chandan did.  The
problem is accounting for the offset into the page/sector when we do a
partial copy.  This one just uses the dirty_sectors variable which
should already be updated properly.

Signed-off-by: Chris Mason <clm@fb.com>
cc: stable@vger.kernel.org # v4.6+
This commit is contained in:
Chris Mason 2016-07-19 05:52:36 -07:00
parent bac357dcec
commit 8b8b08cbfb
1 changed files with 5 additions and 7 deletions
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12
fs/btrfs/file.c
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@ -1629,13 +1629,11 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
* managed to copy.
*/
if (num_sectors > dirty_sectors) {
/*
* we round down because we don't want to count
* any partial blocks actually sent through the
* IO machines
*/
release_bytes = round_down(release_bytes - copied,
root->sectorsize);
/* release everything except the sectors we dirtied */
release_bytes -= dirty_sectors <<
root->fs_info->sb->s_blocksize_bits;
if (copied > 0) {
spin_lock(&BTRFS_I(inode)->lock);
BTRFS_I(inode)->outstanding_extents++;