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authorQu Wenruo <quwenruo@cn.fujitsu.com>2017-02-27 15:10:37 +0800
committerDavid Sterba <dsterba@suse.com>2017-06-29 20:17:02 +0200
commita12b877b557dde885bdb6978cec86bf761e63c9a (patch)
tree7c1466560dc4a5da520786b463851671c4449646 /fs
parent7bc329c1836866ffac8b2613f780a51b3ffe786d (diff)
downloadlinux-a12b877b557dde885bdb6978cec86bf761e63c9a.tar.bz2
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.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 86cac431864b..b66ea03a3a1c 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);