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author | Qu Wenruo <quwenruo@cn.fujitsu.com> | 2017-02-27 15:10:37 +0800 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2017-06-29 20:17:02 +0200 |
commit | a12b877b557dde885bdb6978cec86bf761e63c9a (patch) | |
tree | 7c1466560dc4a5da520786b463851671c4449646 /fs | |
parent | 7bc329c1836866ffac8b2613f780a51b3ffe786d (diff) | |
download | op-kernel-dev-a12b877b557dde885bdb6978cec86bf761e63c9a.zip op-kernel-dev-a12b877b557dde885bdb6978cec86bf761e63c9a.tar.gz |
btrfs: qgroup: Fix qgroup reserved space underflow caused by buffered write and quotas being enabled
[BUG]
Under the following case, we can underflow qgroup reserved space.
Task A | Task B
---------------------------------------------------------------
Quota disabled |
Buffered write |
|- btrfs_check_data_free_space() |
| *NO* qgroup space is reserved |
| since quota is *DISABLED* |
|- All pages are copied to page |
cache |
| Enable quota
| Quota scan finished
|
| Sync_fs
| |- run_delalloc_range
| |- Write pages
| |- btrfs_finish_ordered_io
| |- insert_reserved_file_extent
| |- btrfs_qgroup_release_data()
| Since no qgroup space is
reserved in Task A, we
underflow qgroup reserved
space
This can be detected by fstest btrfs/104.
[CAUSE]
In insert_reserved_file_extent() we tell qgroup to release the @ram_bytes
size of qgroup reserved_space in all cases.
And btrfs_qgroup_release_data() will check if quotas are enabled.
However in the above case, the buffered write happens before quota is
enabled, so we don't have the reserved space for that range.
[FIX]
In insert_reserved_file_extent(), we tell qgroup to release the acctual
byte number it released.
In the above case, since we don't have the reserved space, we tell
qgroups to release 0 byte, so the problem can be fixed.
And thanks to the @reserved parameter introduced by the qgroup rework,
and previous patch to return released bytes, the fix can be as small as
10 lines.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
[ changelog updates ]
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/btrfs/inode.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 86cac43..b66ea03 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2145,6 +2145,7 @@ static int insert_reserved_file_extent(struct btrfs_trans_handle *trans, struct btrfs_path *path; struct extent_buffer *leaf; struct btrfs_key ins; + u64 qg_released; int extent_inserted = 0; int ret; @@ -2200,13 +2201,17 @@ static int insert_reserved_file_extent(struct btrfs_trans_handle *trans, ins.objectid = disk_bytenr; ins.offset = disk_num_bytes; ins.type = BTRFS_EXTENT_ITEM_KEY; - ret = btrfs_alloc_reserved_file_extent(trans, root->root_key.objectid, - btrfs_ino(BTRFS_I(inode)), file_pos, ram_bytes, &ins); + /* * Release the reserved range from inode dirty range map, as it is * already moved into delayed_ref_head */ - btrfs_qgroup_release_data(inode, file_pos, ram_bytes); + ret = btrfs_qgroup_release_data(inode, file_pos, ram_bytes); + if (ret < 0) + goto out; + qg_released = ret; + ret = btrfs_alloc_reserved_file_extent(trans, root->root_key.objectid, + btrfs_ino(BTRFS_I(inode)), file_pos, qg_released, &ins); out: btrfs_free_path(path); |