@@ -2416,7 +2416,6 @@ 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;
@@ -2430,7 +2429,6 @@ 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)
@@ -2457,27 +2455,6 @@ static int qgroup_reserve(struct btrfs_root *root, u64 num_bytes, bool enforce,
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;
}
This reverts commit 48a89bc4f2ceab87bc858a8eb189636b09c846a7. The idea to commit transaction and free some space after hitting qgroup limit is good, although the problem is it will 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 case can be caused by trying to commit one transaction while nesting with trans handler hold by ourselves: btrfs_start_transaction() |- btrfs_qgroup_reserve_meta_pertrans() |- qgroup_reserve() |- btrfs_join_transaction() |- btrfs_commit_transaction() The retry is causing more problem than expectation when limit is enabled. At least graceful EDQUOT is way better than kernel deadlock. Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/qgroup.c | 23 ----------------------- 1 file changed, 23 deletions(-)