btrfs: fix return value check of btrfs_start_transaction()

The error check of btrfs_start_transaction() is added, and the mistake
of the error check on several places is corrected.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

7 files changed, 37 insertions, 6 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 9de4ff03882a..f07ba21cbf06 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6271,6 +6271,8 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
         BUG_ON(!wc);
 
         trans = btrfs_start_transaction(tree_root, 0);
+        BUG_ON(IS_ERR(trans));
+
         if (block_rsv)
                 trans->block_rsv = block_rsv;
 
@@ -6368,6 +6370,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
 
                         btrfs_end_transaction_throttle(trans, tree_root);
                         trans = btrfs_start_transaction(tree_root, 0);
+                        BUG_ON(IS_ERR(trans));
                         if (block_rsv)
                                 trans->block_rsv = block_rsv;
                 }
@@ -7587,7 +7590,7 @@ int btrfs_cleanup_reloc_trees(struct btrfs_root *root)
 
         if (found) {
                 trans = btrfs_start_transaction(root, 1);
-                BUG_ON(!trans);
+                BUG_ON(IS_ERR(trans));
                 ret = btrfs_commit_transaction(trans, root);
                 BUG_ON(ret);
         }
@@ -7831,7 +7834,7 @@ static noinline int relocate_one_extent(struct btrfs_root *extent_root,
 
 
         trans = btrfs_start_transaction(extent_root, 1);
-        BUG_ON(!trans);
+        BUG_ON(IS_ERR(trans));
 
         if (extent_key->objectid == 0) {
                 ret = del_extent_zero(trans, extent_root, path, extent_key);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5621818921f8..36bc3f49ebf9 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2357,6 +2357,7 @@ void btrfs_orphan_cleanup(struct btrfs_root *root)
                  */
                 if (is_bad_inode(inode)) {
                         trans = btrfs_start_transaction(root, 0);
+                        BUG_ON(IS_ERR(trans));
                         btrfs_orphan_del(trans, inode);
                         btrfs_end_transaction(trans, root);
                         iput(inode);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 12dabe28cf54..02d224e8c83f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -907,6 +907,10 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
 
         if (new_size > old_size) {
                 trans = btrfs_start_transaction(root, 0);
+                if (IS_ERR(trans)) {
+                        ret = PTR_ERR(trans);
+                        goto out_unlock;
+                }
                 ret = btrfs_grow_device(trans, device, new_size);
                 btrfs_commit_transaction(trans, root);
         } else {
@@ -2141,9 +2145,9 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
         path->leave_spinning = 1;
 
         trans = btrfs_start_transaction(root, 1);
-        if (!trans) {
+        if (IS_ERR(trans)) {
                 btrfs_free_path(path);
-                return -ENOMEM;
+                return PTR_ERR(trans);
         }
 
         dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
@@ -2337,6 +2341,8 @@ static noinline long btrfs_ioctl_start_sync(struct file *file, void __user *argp
         u64 transid;
 
         trans = btrfs_start_transaction(root, 0);
+        if (IS_ERR(trans))
+                return PTR_ERR(trans);
         transid = trans->transid;
         btrfs_commit_transaction_async(trans, root, 0);
 
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index ea9965430241..1f5556acb530 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2028,6 +2028,7 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
 
         while (1) {
                 trans = btrfs_start_transaction(root, 0);
+                BUG_ON(IS_ERR(trans));
                 trans->block_rsv = rc->block_rsv;
 
                 ret = btrfs_block_rsv_check(trans, root, rc->block_rsv,
@@ -3665,6 +3666,7 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 
         while (1) {
                 trans = btrfs_start_transaction(rc->extent_root, 0);
+                BUG_ON(IS_ERR(trans));
 
                 if (update_backref_cache(trans, &rc->backref_cache)) {
                         btrfs_end_transaction(trans, rc->extent_root);
@@ -4033,6 +4035,7 @@ static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
         int ret;
 
         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
+        BUG_ON(IS_ERR(trans));
 
         memset(&root->root_item.drop_progress, 0,
                 sizeof(root->root_item.drop_progress));
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f4e45fdded30..0209b5fc772c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -623,6 +623,8 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
         btrfs_wait_ordered_extents(root, 0, 0);
 
         trans = btrfs_start_transaction(root, 0);
+        if (IS_ERR(trans))
+                return PTR_ERR(trans);
         ret = btrfs_commit_transaction(trans, root);
         return ret;
 }
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 6d66e5caff97..a4bbb854dfd2 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3112,6 +3112,7 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
         BUG_ON(!path);
 
         trans = btrfs_start_transaction(fs_info->tree_root, 0);
+        BUG_ON(IS_ERR(trans));
 
         wc.trans = trans;
         wc.pin = 1;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f2d2f4ccc738..7cad59353b09 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1212,6 +1212,10 @@ static int btrfs_rm_dev_item(struct btrfs_root *root,
                 return -ENOMEM;
 
         trans = btrfs_start_transaction(root, 0);
+        if (IS_ERR(trans)) {
+                btrfs_free_path(path);
+                return PTR_ERR(trans);
+        }
         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
         key.type = BTRFS_DEV_ITEM_KEY;
         key.offset = device->devid;
@@ -1604,6 +1608,12 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         }
 
         trans = btrfs_start_transaction(root, 0);
+        if (IS_ERR(trans)) {
+                kfree(device);
+                ret = PTR_ERR(trans);
+                goto error;
+        }
+
         lock_chunks(root);
 
         device->barriers = 1;
@@ -1872,7 +1882,7 @@ static int btrfs_relocate_chunk(struct btrfs_root *root,
                 return ret;
 
         trans = btrfs_start_transaction(root, 0);
-        BUG_ON(!trans);
+        BUG_ON(IS_ERR(trans));
 
         lock_chunks(root);
 
@@ -2046,7 +2056,7 @@ int btrfs_balance(struct btrfs_root *dev_root)
                 BUG_ON(ret);
 
                 trans = btrfs_start_transaction(dev_root, 0);
-                BUG_ON(!trans);
+                BUG_ON(IS_ERR(trans));
 
                 ret = btrfs_grow_device(trans, device, old_size);
                 BUG_ON(ret);
@@ -2212,6 +2222,11 @@ again:
 
         /* Shrinking succeeded, else we would be at "done". */
         trans = btrfs_start_transaction(root, 0);
+        if (IS_ERR(trans)) {
+                ret = PTR_ERR(trans);
+                goto done;
+        }
+
         lock_chunks(root);
 
         device->disk_total_bytes = new_size;