Btrfs: clean up error handling in btrfs_truncate()

btrfs_truncate() uses two variables for error handling, ret and err (if
this sounds familiar, it's because btrfs_truncate_inode_items() did
something similar). This is error prone, as was made evident by "Btrfs:
fix error handling in btrfs_truncate()". We only have err because we
don't want to mask an error if we call btrfs_update_inode() and
btrfs_end_transaction(), so let's make that its own scoped return
variable and use ret everywhere else.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 880431ae5e594c2792ccd432c36c904438bf3418..89b2082017830942e040063a2ca000d1a10f75df 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9030,8 +9030,7 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_block_rsv *rsv;
-       int ret = 0;
-       int err = 0;
+       int ret;
        struct btrfs_trans_handle *trans;
        u64 mask = fs_info->sectorsize - 1;
        u64 min_size = btrfs_calc_trunc_metadata_size(fs_info, 1);
@@ -9083,7 +9082,7 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
         */
        trans = btrfs_start_transaction(root, 2);
        if (IS_ERR(trans)) {
-               err = PTR_ERR(trans);
+               ret = PTR_ERR(trans);
                goto out;
        }
 
@@ -9107,24 +9106,19 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
                                                 inode->i_size,
                                                 BTRFS_EXTENT_DATA_KEY);
                trans->block_rsv = &fs_info->trans_block_rsv;
-               if (ret != -ENOSPC && ret != -EAGAIN) {
-                       if (ret < 0)
-                               err = ret;
+               if (ret != -ENOSPC && ret != -EAGAIN)
                        break;
-               }
 
                ret = btrfs_update_inode(trans, root, inode);
-               if (ret) {
-                       err = ret;
+               if (ret)
                        break;
-               }
 
                btrfs_end_transaction(trans);
                btrfs_btree_balance_dirty(fs_info);
 
                trans = btrfs_start_transaction(root, 2);
                if (IS_ERR(trans)) {
-                       ret = err = PTR_ERR(trans);
+                       ret = PTR_ERR(trans);
                        trans = NULL;
                        break;
                }
@@ -9158,21 +9152,22 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
        }
 
        if (trans) {
+               int ret2;
+
                trans->block_rsv = &fs_info->trans_block_rsv;
-               ret = btrfs_update_inode(trans, root, inode);
-               if (ret && !err)
-                       err = ret;
+               ret2 = btrfs_update_inode(trans, root, inode);
+               if (ret2 && !ret)
+                       ret = ret2;
 
-               ret = btrfs_end_transaction(trans);
+               ret2 = btrfs_end_transaction(trans);
+               if (ret2 && !ret)
+                       ret = ret2;
                btrfs_btree_balance_dirty(fs_info);
        }
 out:
        btrfs_free_block_rsv(fs_info, rsv);
 
-       if (ret && !err)
-               err = ret;
-
-       return err;
+       return ret;
 }
 
 /*