Btrfs: Add drop inode func to avoid data=ordered deadlock

Signed-off-by: Chris Mason <chris.mason@oracle.com>

3 files changed, 21 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f65b258344d4..a2c2d6d82c5e 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1144,6 +1144,7 @@ int btrfs_check_free_space(struct btrfs_root *root, u64 num_required,
 int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page);
 int btrfs_readpage(struct file *file, struct page *page);
 void btrfs_delete_inode(struct inode *inode);
+void btrfs_drop_inode(struct inode *inode);
 void btrfs_read_locked_inode(struct inode *inode);
 int btrfs_write_inode(struct inode *inode, int wait);
 void btrfs_dirty_inode(struct inode *inode);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5260b4708158..e53d20331646 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -990,6 +990,25 @@ out:
 fail:
         return err;
 }
+
+void btrfs_drop_inode(struct inode *inode)
+{
+        struct btrfs_trans_handle *trans;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+
+        if (!BTRFS_I(inode)->ordered_trans) {
+                generic_drop_inode(inode);
+                return;
+        }
+        /* nasty, but it prevents a deadlock with data=ordered by preventing
+         * a commit until after this inode is done
+         */
+        trans = btrfs_start_transaction(root, 1);
+        generic_drop_inode(inode);
+        /* note, the inode is now untouchable */
+        btrfs_end_transaction(trans, root);
+}
+
 void btrfs_delete_inode(struct inode *inode)
 {
         struct btrfs_trans_handle *trans;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 9ab4086d463c..4deea393ca94 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -425,6 +425,7 @@ static struct file_system_type btrfs_fs_type = {
 
 static struct super_operations btrfs_super_ops = {
         .delete_inode   = btrfs_delete_inode,
+        .drop_inode     = btrfs_drop_inode,
         .put_super      = btrfs_put_super,
         .read_inode     = btrfs_read_locked_inode,
         .write_super    = btrfs_write_super,