[PATCH v4 5/5] block: add __must_check attribute to sb_min_blocksize()

[Yongpeng Yang <yangyongpeng.storage@gmail.com>]

From: Yongpeng Yang <yangyongpeng@xiaomi.com>

When sb_min_blocksize() returns 0 and the return value is not checked,
it may lead to a situation where sb->s_blocksize is 0 when
accessing the filesystem super block. After commit a64e5a596067bd
("bdev: add back PAGE_SIZE block size validation for
sb_set_blocksize()"), this becomes more likely to happen when the
block device’s logical_block_size is larger than PAGE_SIZE and the
filesystem is unformatted. Add the __must_check attribute to ensure
callers always check the return value.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>
---
 block/bdev.c       | 2 +-
 include/linux/fs.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/bdev.c b/block/bdev.c
index 810707cca970..638f0cd458ae 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -231,7 +231,7 @@ int sb_set_blocksize(struct super_block *sb, int size)
 
 EXPORT_SYMBOL(sb_set_blocksize);
 
-int sb_min_blocksize(struct super_block *sb, int size)
+int __must_check sb_min_blocksize(struct super_block *sb, int size)
 {
 	int minsize = bdev_logical_block_size(sb->s_bdev);
 	if (size < minsize)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c895146c1444..26d4ca0f859a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3424,7 +3424,7 @@ extern void inode_sb_list_add(struct inode *inode);
 extern void inode_add_lru(struct inode *inode);
 
 extern int sb_set_blocksize(struct super_block *, int);
-extern int sb_min_blocksize(struct super_block *, int);
+extern int __must_check sb_min_blocksize(struct super_block *, int);
 
 int generic_file_mmap(struct file *, struct vm_area_struct *);
 int generic_file_mmap_prepare(struct vm_area_desc *desc);
-- 
2.43.0