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authorQu Wenruo <wqu@suse.com>2017-12-12 15:34:36 +0800
committerDavid Sterba <dsterba@suse.com>2018-03-31 02:01:05 +0200
commit0b78877a2adadc8f41f2bd959a3ffdc9c3bc0294 (patch)
treed1d4f403fcc45f10de912dbdf5faaf18802e5f07 /fs/btrfs
parent4ee0d8832c2ecd08fd4ccbaa55484e6a500f2f34 (diff)
downloadlinux-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.c23
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;
}