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| author | Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com> | 2016-09-07 14:17:38 +0200 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2017-01-19 18:00:58 +0100 |
| commit | 47b5d64691350e116093c9b47b55ca6b9433bc50 (patch) | |
| tree | 1882c38d550baab0c3b788f1c7e1df19db8cd7a8 /fs | |
| parent | Merge branch 'tracepoint-updates-4.10' of git://git.kernel.org/pub/scm/linux/... (diff) | |
| download | linux-47b5d64691350e116093c9b47b55ca6b9433bc50.tar.xz linux-47b5d64691350e116093c9b47b55ca6b9433bc50.zip | |
btrfs: fix false enospc error when truncating heavily reflinked file
Below test script can reveal this bug:
dd if=/dev/zero of=fs.img bs=$((1024*1024)) count=100
dev=$(losetup --show -f fs.img)
mkdir -p /mnt/mntpoint
mkfs.btrfs -f $dev
mount $dev /mnt/mntpoint
cd /mnt/mntpoint
echo "workdir is: /mnt/mntpoint"
blocksize=$((128 * 1024))
dd if=/dev/zero of=testfile bs=$blocksize count=1
sync
count=$((17*1024*1024*1024/blocksize))
echo "file size is:" $((count*blocksize))
for ((i = 1; i <= $count; i++)); do
dst_offset=$((blocksize * i))
xfs_io -f -c "reflink testfile 0 $dst_offset $blocksize"\
testfile > /dev/null
done
sync
truncate --size 0 testfile
The last truncate operation will fail for ENOSPC reason, but indeed
it should not fail.
In btrfs_truncate(), we use a temporary block_rsv to do truncate
operation. With every btrfs_truncate_inode_items() call, we migrate space
to this block_rsv, but forget to cleanup previous reservation, which
will make this block_rsv's reserved bytes keep growing, and this reserved
space will only be released in the end of btrfs_truncate(), this metadata
leak will impact other's metadata reservation. In this case, it's
"btrfs_start_transaction(root, 2);" fails for enospc error, which make
this truncate operation fail.
Call btrfs_block_rsv_release() to fix this bug.
Signed-off-by: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/inode.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 128e52489f81..415a6ad5ba22 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -9215,6 +9215,7 @@ static int btrfs_truncate(struct inode *inode) break; } + btrfs_block_rsv_release(fs_info, rsv, -1); ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv, min_size, 0); BUG_ON(ret); /* shouldn't happen */ |