Kernel/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-01-16 09:56:46 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

ext4: supress data-race warnings in ext4_free_inodes_{count,set}()

Browse Source 
find_group_other() and find_group_orlov() read *_lo, *_hi with
ext4_free_inodes_count without additional locking. This can cause
data-race warning, but since the lock is held for most writes and free
inodes value is generally not a problem even if it is incorrect, it is
more appropriate to use READ_ONCE()/WRITE_ONCE() than to add locking.

==================================================================
BUG: KCSAN: data-race in ext4_free_inodes_count / ext4_free_inodes_set

write to 0xffff88810404300e of 2 bytes by task 6254 on cpu 1:
 ext4_free_inodes_set+0x1f/0x80 fs/ext4/super.c:405
 __ext4_new_inode+0x15ca/0x2200 fs/ext4/ialloc.c:1216
 ext4_symlink+0x242/0x5a0 fs/ext4/namei.c:3391
 vfs_symlink+0xca/0x1d0 fs/namei.c:4615
 do_symlinkat+0xe3/0x340 fs/namei.c:4641
 __do_sys_symlinkat fs/namei.c:4657 [inline]
 __se_sys_symlinkat fs/namei.c:4654 [inline]
 __x64_sys_symlinkat+0x5e/0x70 fs/namei.c:4654
 x64_sys_call+0x1dda/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:267
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

read to 0xffff88810404300e of 2 bytes by task 6257 on cpu 0:
 ext4_free_inodes_count+0x1c/0x80 fs/ext4/super.c:349
 find_group_other fs/ext4/ialloc.c:594 [inline]
 __ext4_new_inode+0x6ec/0x2200 fs/ext4/ialloc.c:1017
 ext4_symlink+0x242/0x5a0 fs/ext4/namei.c:3391
 vfs_symlink+0xca/0x1d0 fs/namei.c:4615
 do_symlinkat+0xe3/0x340 fs/namei.c:4641
 __do_sys_symlinkat fs/namei.c:4657 [inline]
 __se_sys_symlinkat fs/namei.c:4654 [inline]
 __x64_sys_symlinkat+0x5e/0x70 fs/namei.c:4654
 x64_sys_call+0x1dda/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:267
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Cc: stable@vger.kernel.org
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://patch.msgid.link/20241003125337.47283-1-aha310510@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jeongjun Park 2024-10-03 21:53:37 +09:00 committed by Theodore Ts'o
parent d431a2cd28
commit 902cc179c9
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
fs/ext4/super.c
View File

@ -346,9 +346,9 @@ __u32 ext4_free_group_clusters(struct super_block *sb,
__u32 ext4_free_inodes_count(struct super_block *sb, __u32 ext4_free_inodes_count(struct super_block *sb,
struct ext4_group_desc *bg) struct ext4_group_desc *bg)
{ {
return le16_to_cpu(bg->bg_free_inodes_count_lo) | return le16_to_cpu(READ_ONCE(bg->bg_free_inodes_count_lo)) |
(EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ? (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
(__u32)le16_to_cpu(bg->bg_free_inodes_count_hi) << 16 : 0); (__u32)le16_to_cpu(READ_ONCE(bg->bg_free_inodes_count_hi)) << 16 : 0);
} }
__u32 ext4_used_dirs_count(struct super_block *sb, __u32 ext4_used_dirs_count(struct super_block *sb,
@ -402,9 +402,9 @@ void ext4_free_group_clusters_set(struct super_block *sb,
void ext4_free_inodes_set(struct super_block *sb, void ext4_free_inodes_set(struct super_block *sb,
struct ext4_group_desc *bg, __u32 count) struct ext4_group_desc *bg, __u32 count)
{ {
bg->bg_free_inodes_count_lo = cpu_to_le16((__u16)count); WRITE_ONCE(bg->bg_free_inodes_count_lo, cpu_to_le16((__u16)count));
if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT) if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
bg->bg_free_inodes_count_hi = cpu_to_le16(count >> 16); WRITE_ONCE(bg->bg_free_inodes_count_hi, cpu_to_le16(count >> 16));
} }
void ext4_used_dirs_set(struct super_block *sb, void ext4_used_dirs_set(struct super_block *sb,