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authorQu Wenruo <wqu@suse.com>2019-09-16 20:02:39 +0800
committerDavid Sterba <dsterba@suse.com>2019-09-27 15:24:34 +0200
commitd4e204948fe3e0dc8e1fbf3f8f3290c9c2823be3 (patch)
tree06439f29ac19eb4436afbeb2c4b3e0a4503dbb38 /fs
parentbab32fc069ce8829c416e8737c119f62a57970f9 (diff)
btrfs: qgroup: Fix reserved data space leak if we have multiple reserve calls
[BUG] The following script can cause btrfs qgroup data space leak: mkfs.btrfs -f $dev mount $dev -o nospace_cache $mnt btrfs subv create $mnt/subv btrfs quota en $mnt btrfs quota rescan -w $mnt btrfs qgroup limit 128m $mnt/subv for (( i = 0; i < 3; i++)); do # Create 3 64M holes for latter fallocate to fail truncate -s 192m $mnt/subv/file xfs_io -c "pwrite 64m 4k" $mnt/subv/file > /dev/null xfs_io -c "pwrite 128m 4k" $mnt/subv/file > /dev/null sync # it's supposed to fail, and each failure will leak at least 64M # data space xfs_io -f -c "falloc 0 192m" $mnt/subv/file &> /dev/null rm $mnt/subv/file sync done # Shouldn't fail after we removed the file xfs_io -f -c "falloc 0 64m" $mnt/subv/file [CAUSE] Btrfs qgroup data reserve code allow multiple reservations to happen on a single extent_changeset: E.g: btrfs_qgroup_reserve_data(inode, &data_reserved, 0, SZ_1M); btrfs_qgroup_reserve_data(inode, &data_reserved, SZ_1M, SZ_2M); btrfs_qgroup_reserve_data(inode, &data_reserved, 0, SZ_4M); Btrfs qgroup code has its internal tracking to make sure we don't double-reserve in above example. The only pattern utilizing this feature is in the main while loop of btrfs_fallocate() function. However btrfs_qgroup_reserve_data()'s error handling has a bug in that on error it clears all ranges in the io_tree with EXTENT_QGROUP_RESERVED flag but doesn't free previously reserved bytes. This bug has a two fold effect: - Clearing EXTENT_QGROUP_RESERVED ranges This is the correct behavior, but it prevents btrfs_qgroup_check_reserved_leak() to catch the leakage as the detector is purely EXTENT_QGROUP_RESERVED flag based. - Leak the previously reserved data bytes. The bug manifests when N calls to btrfs_qgroup_reserve_data are made and the last one fails, leaking space reserved in the previous ones. [FIX] Also free previously reserved data bytes when btrfs_qgroup_reserve_data fails. Fixes: 524725537023 ("btrfs: qgroup: Introduce btrfs_qgroup_reserve_data function") CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/qgroup.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 4ab85555a947..c4bb69941c77 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -3442,6 +3442,9 @@ cleanup:
while ((unode = ulist_next(&reserved->range_changed, &uiter)))
clear_extent_bit(&BTRFS_I(inode)->io_tree, unode->val,
unode->aux, EXTENT_QGROUP_RESERVED, 0, 0, NULL);
+ /* Also free data bytes of already reserved one */
+ btrfs_qgroup_free_refroot(root->fs_info, root->root_key.objectid,
+ orig_reserved, BTRFS_QGROUP_RSV_DATA);
extent_changeset_release(reserved);
return ret;
}

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