[PATCH] Btrfs: do not check inode's runtime flags under root->orphan_lock

[PATCH] Btrfs: do not check inode's runtime flags under root->orphan_lock

[Liu Bo]

It's not necessary to hold ->orphan_lock when checking inode's runtime
flags.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
---
 fs/btrfs/inode.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b3fe0a8..1511db2 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3354,14 +3354,6 @@ int btrfs_orphan_add(struct btrfs_trans_handle *trans,
 			return -ENOMEM;
 	}
 
-	spin_lock(&root->orphan_lock);
-	if (!root->orphan_block_rsv) {
-		root->orphan_block_rsv = block_rsv;
-	} else if (block_rsv) {
-		btrfs_free_block_rsv(fs_info, block_rsv);
-		block_rsv = NULL;
-	}
-
 	if (!test_and_set_bit(BTRFS_INODE_HAS_ORPHAN_ITEM,
 			      &inode->runtime_flags)) {
 #if 0
@@ -3376,12 +3368,23 @@ int btrfs_orphan_add(struct btrfs_trans_handle *trans,
 			insert = 1;
 #endif
 		insert = 1;
-		atomic_inc(&root->orphan_inodes);
 	}
 
 	if (!test_and_set_bit(BTRFS_INODE_ORPHAN_META_RESERVED,
 			      &inode->runtime_flags))
 		reserve = 1;
+
+	spin_lock(&root->orphan_lock);
+	/* If someone has created ->orphan_block_rsv, be happy to use it. */
+	if (!root->orphan_block_rsv) {
+		root->orphan_block_rsv = block_rsv;
+	} else if (block_rsv) {
+		btrfs_free_block_rsv(fs_info, block_rsv);
+		block_rsv = NULL;
+	}
+
+	if (insert)
+		atomic_inc(&root->orphan_inodes);
 	spin_unlock(&root->orphan_lock);
 
 	/* grab metadata reservation from transaction handle */
-- 
2.9.4

Re: [PATCH] Btrfs: do not check inode's runtime flags under root->orphan_lock

[Josef Bacik]

On Thu, Jan 25, 2018 at 11:02:55AM -0700, Liu Bo wrote:
> It's not necessary to hold ->orphan_lock when checking inode's runtime
> flags.
> 
> Signed-off-by: Liu Bo <bo.li.liu@oracle.com>

Reviewed-by: Josef Bacik <jbacik@fb.com>

Thanks,

Josef