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>

1 files changed, 14 insertions, 19 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 880431ae5e59..89b208201783 100644
--- 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;
 }
 
 /*