[PATCH] btrfs: free-space-cache: Fix error return code in __load_free_space_cache

[PATCH] btrfs: free-space-cache: Fix error return code in __load_free_space_cache

[Zhihao Cheng]

Fix to return the error code(instead always 0) when memory allocating
failed in __load_free_space_cache().

Fixes: a67509c30079f4c50 ("Btrfs: add a io_ctl struct and helpers ...")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/btrfs/free-space-cache.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index af0013d3df63..ae4059ce2f84 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -744,8 +744,10 @@ static int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 	while (num_entries) {
 		e = kmem_cache_zalloc(btrfs_free_space_cachep,
 				      GFP_NOFS);
-		if (!e)
+		if (!e) {
+			ret = -ENOMEM;
 			goto free_cache;
+		}
 
 		ret = io_ctl_read_entry(&io_ctl, e, &type);
 		if (ret) {
@@ -764,6 +766,7 @@ static int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 			e->trim_state = BTRFS_TRIM_STATE_TRIMMED;
 
 		if (!e->bytes) {
+			ret = -1;
 			kmem_cache_free(btrfs_free_space_cachep, e);
 			goto free_cache;
 		}
@@ -784,6 +787,7 @@ static int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 			e->bitmap = kmem_cache_zalloc(
 					btrfs_free_space_bitmap_cachep, GFP_NOFS);
 			if (!e->bitmap) {
+				ret = -ENOMEM;
 				kmem_cache_free(
 					btrfs_free_space_cachep, e);
 				goto free_cache;
-- 
2.25.4

Re: [PATCH] btrfs: free-space-cache: Fix error return code in __load_free_space_cache

[David Sterba]

On Fri, Nov 20, 2020 at 09:08:04AM +0800, Zhihao Cheng wrote:
> Fix to return the error code(instead always 0) when memory allocating
> failed in __load_free_space_cache().

Hm right the error handling flow in that function is a mess and the
error values are not set. Your patch is a minimal fix so I'll add it,
the function could use some cleanups though. Thanks.

Re: [PATCH] btrfs: free-space-cache: Fix error return code in __load_free_space_cache

[David Sterba]

On Fri, Nov 20, 2020 at 09:08:04AM +0800, Zhihao Cheng wrote:
> Fix to return the error code(instead always 0) when memory allocating
> failed in __load_free_space_cache().

This lacks the analysis of consequences, so there's only one caller and
that will treat values <=0 as 'cache not loaded'. There's no functional
change but otherwise the error values should be there for clarity.
Changelog updated.

> Fixes: a67509c30079f4c50 ("Btrfs: add a io_ctl struct and helpers ...")

BTW, please don't trim the patch subject in the Fixes line.