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| author | Qu Wenruo <wqu@suse.com> | 2017-12-12 15:34:36 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2018-03-31 02:01:05 +0200 |
| commit | 0b78877a2adadc8f41f2bd959a3ffdc9c3bc0294 (patch) | |
| tree | d1d4f403fcc45f10de912dbdf5faaf18802e5f07 /fs/btrfs | |
| parent | 4ee0d8832c2ecd08fd4ccbaa55484e6a500f2f34 (diff) | |
| download | linux-0b78877a2adadc8f41f2bd959a3ffdc9c3bc0294.tar.bz2 | |
Revert "btrfs: qgroups: Retry after commit on getting EDQUOT"
This reverts commit 48a89bc4f2ceab87bc858a8eb189636b09c846a7.
The idea to commit transaction and free some space after hitting qgroup
limit is good, although the problem is it can easily cause deadlocks.
One deadlock example is caused by trying to flush data while still
holding it:
Call Trace:
__schedule+0x49d/0x10f0
schedule+0xc6/0x290
schedule_timeout+0x187/0x1c0
wait_for_completion+0x204/0x3a0
btrfs_wait_ordered_extents+0xa40/0xaf0 [btrfs]
qgroup_reserve+0x913/0xa10 [btrfs]
btrfs_qgroup_reserve_data+0x3ef/0x580 [btrfs]
btrfs_check_data_free_space+0x96/0xd0 [btrfs]
__btrfs_buffered_write+0x3ac/0xd40 [btrfs]
btrfs_file_write_iter+0x62a/0xba0 [btrfs]
__vfs_write+0x320/0x430
vfs_write+0x107/0x270
SyS_write+0xbf/0x150
do_syscall_64+0x1b0/0x3d0
entry_SYSCALL64_slow_path+0x25/0x25
Another can be caused by trying to commit one transaction while nesting
with trans handle held by ourselves:
btrfs_start_transaction()
|- btrfs_qgroup_reserve_meta_pertrans()
|- qgroup_reserve()
|- btrfs_join_transaction()
|- btrfs_commit_transaction()
The retry is causing more problems than exppected when limit is enabled.
At least a graceful EDQUOT is way better than deadlock.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/qgroup.c | 23 |
1 files changed, 0 insertions, 23 deletions
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 92e2c9f15951..c8ca5483226e 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2406,7 +2406,6 @@ static int qgroup_reserve(struct btrfs_root *root, u64 num_bytes, bool enforce, struct btrfs_fs_info *fs_info = root->fs_info; u64 ref_root = root->root_key.objectid; int ret = 0; - int retried = 0; struct ulist_node *unode; struct ulist_iterator uiter; @@ -2420,7 +2419,6 @@ static int qgroup_reserve(struct btrfs_root *root, u64 num_bytes, bool enforce, capable(CAP_SYS_RESOURCE)) enforce = false; -retry: spin_lock(&fs_info->qgroup_lock); quota_root = fs_info->quota_root; if (!quota_root) @@ -2447,27 +2445,6 @@ retry: qg = unode_aux_to_qgroup(unode); if (enforce && !qgroup_check_limits(qg, num_bytes)) { - /* - * Commit the tree and retry, since we may have - * deletions which would free up space. - */ - if (!retried && qgroup_rsv_total(qg) > 0) { - struct btrfs_trans_handle *trans; - - spin_unlock(&fs_info->qgroup_lock); - ret = btrfs_start_delalloc_inodes(root, 0); - if (ret) - return ret; - btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1); - trans = btrfs_join_transaction(root); - if (IS_ERR(trans)) - return PTR_ERR(trans); - ret = btrfs_commit_transaction(trans); - if (ret) - return ret; - retried++; - goto retry; - } ret = -EDQUOT; goto out; } |