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fat: avoid stack overflow warning

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Building the fat kunit tests on with -fsanitize=alignment reveals some
rather excessive stack usage:

fs/fat/fat_test.c: In function 'fat_clus_to_blknr_test':
fs/fat/fat_test.c:33:1: error: the frame size of 4736 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]
   33 | }
      | ^
fs/fat/fat_test.c: In function 'fat_get_blknr_offset_test':
fs/fat/fat_test.c:52:1: error: the frame size of 4800 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]

The problem is clearly related to the on-stack copy of a local
msdos_sb_info structure.  Avoid this by making that copy 'static const'
and changing the called functions to accept a constant input.

Link: https://lore.kernel.org/20260515204456.2692208-1-arnd@kernel.org
Fixes: 410002f813 ("kunit: fat: test cluster and directory i_pos layout helpers")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Adi Nata <adinata.softwareengineer@gmail.com>
Cc: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Arnd Bergmann
2026-05-15 22:44:46 +02:00
committed by Andrew Morton
parent 1292c0ecb1
commit e1a1729419
2 changed files with 4 additions and 4 deletions
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4
fs/fat/fat.h
View File

@@ -249,13 +249,13 @@ static inline unsigned char fat_checksum(const __u8 *name)
return s;
}
static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus)
static inline sector_t fat_clus_to_blknr(const struct msdos_sb_info *sbi, int clus)
{
return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus
+ sbi->data_start;
}
static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi,
static inline void fat_get_blknr_offset(const struct msdos_sb_info *sbi,
loff_t i_pos, sector_t *blknr, int *offset)
{
*blknr = i_pos >> sbi->dir_per_block_bits;

4
fs/fat/fat_test.c
View File

@@ -22,7 +22,7 @@ static void fat_checksum_test(struct kunit *test)
static void fat_clus_to_blknr_test(struct kunit *test)
{
struct msdos_sb_info sbi = {
static const struct msdos_sb_info sbi = {
.sec_per_clus = 4,
.data_start = 100,
};
@@ -34,7 +34,7 @@ static void fat_clus_to_blknr_test(struct kunit *test)
static void fat_get_blknr_offset_test(struct kunit *test)
{
struct msdos_sb_info sbi = {
static const struct msdos_sb_info sbi = {
.dir_per_block = 16,
.dir_per_block_bits = 4,
};