Btrfs: Fix data=ordered vs wait_on_inode deadlock on older kernels

Using ilookup5 during data=ordered writeback could deadlock on I_LOCK.  This
saves a pointer to the inode instead.

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

1 files changed, 13 insertions, 17 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 08f7a188dc3e..b6bbfc179c29 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -490,19 +490,17 @@ int btrfs_write_ordered_inodes(struct btrfs_trans_handle *trans,
         while(1) {
                 ret = btrfs_find_first_ordered_inode(
                                 &cur_trans->ordered_inode_tree,
-                                &root_objectid, &objectid);
+                                &root_objectid, &objectid, &inode);
                 if (!ret)
                         break;
 
                 mutex_unlock(&root->fs_info->trans_mutex);
                 mutex_unlock(&root->fs_info->fs_mutex);
-                inode = btrfs_ilookup(root->fs_info->sb, objectid,
-                                      root_objectid);
-                if (inode) {
-                        if (S_ISREG(inode->i_mode))
-                                filemap_fdatawrite(inode->i_mapping);
-                        iput(inode);
-                }
+
+                if (S_ISREG(inode->i_mode))
+                        filemap_fdatawrite(inode->i_mapping);
+                iput(inode);
+
                 mutex_lock(&root->fs_info->fs_mutex);
                 mutex_lock(&root->fs_info->trans_mutex);
         }
@@ -511,19 +509,17 @@ int btrfs_write_ordered_inodes(struct btrfs_trans_handle *trans,
                 objectid = 0;
                 ret = btrfs_find_del_first_ordered_inode(
                                 &cur_trans->ordered_inode_tree,
-                                &root_objectid, &objectid);
+                                &root_objectid, &objectid, &inode);
                 if (!ret)
                         break;
                 mutex_unlock(&root->fs_info->trans_mutex);
                 mutex_unlock(&root->fs_info->fs_mutex);
-                inode = btrfs_ilookup(root->fs_info->sb, objectid,
-                                      root_objectid);
-                if (inode) {
-                        if (S_ISREG(inode->i_mode))
-                                filemap_write_and_wait(inode->i_mapping);
-                        atomic_dec(&inode->i_count);
-                        iput(inode);
-                }
+
+                if (S_ISREG(inode->i_mode))
+                        filemap_write_and_wait(inode->i_mapping);
+                atomic_dec(&inode->i_count);
+                iput(inode);
+
                 mutex_lock(&root->fs_info->fs_mutex);
                 mutex_lock(&root->fs_info->trans_mutex);
         }