Btrfs: Add delayed iput

iput() can trigger new transactions if we are dropping the
final reference, so calling it in btrfs_commit_transaction
may end up deadlock. This patch adds delayed iput to avoid
the issue.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 9b16073bb875..b10a49d4bc6a 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -352,7 +352,8 @@ int btrfs_remove_ordered_extent(struct inode *inode,
  * wait for all the ordered extents in a root.  This is done when balancing
  * space between drives.
  */
-int btrfs_wait_ordered_extents(struct btrfs_root *root, int nocow_only)
+int btrfs_wait_ordered_extents(struct btrfs_root *root,
+                               int nocow_only, int delay_iput)
 {
         struct list_head splice;
         struct list_head *cur;
@@ -389,7 +390,10 @@ int btrfs_wait_ordered_extents(struct btrfs_root *root, int nocow_only)
                 if (inode) {
                         btrfs_start_ordered_extent(inode, ordered, 1);
                         btrfs_put_ordered_extent(ordered);
-                        iput(inode);
+                        if (delay_iput)
+                                btrfs_add_delayed_iput(inode);
+                        else
+                                iput(inode);
                 } else {
                         btrfs_put_ordered_extent(ordered);
                 }
@@ -447,7 +451,7 @@ again:
                                 btrfs_wait_ordered_range(inode, 0, (u64)-1);
                         else
                                 filemap_flush(inode->i_mapping);
-                        iput(inode);
+                        btrfs_add_delayed_iput(inode);
                 }
 
                 cond_resched();