From: Jeongjun Park Date: Thu, 3 Oct 2024 12:53:37 +0000 (+0900) Subject: ext4: supress data-race warnings in ext4_free_inodes_{count,set}() X-Git-Tag: v4.19.325~38 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=319bf0c0b825f00d35cf3c1e3c1c7444ae6dad78;p=thirdparty%2Fkernel%2Fstable.git ext4: supress data-race warnings in ext4_free_inodes_{count,set}() commit 902cc179c931a033cd7f4242353aa2733bf8524c upstream. 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 Reviewed-by: Andreas Dilger Link: https://patch.msgid.link/20241003125337.47283-1-aha310510@gmail.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 926063a6d2321..f89c9bec5f116 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -258,9 +258,9 @@ __u32 ext4_free_group_clusters(struct super_block *sb, __u32 ext4_free_inodes_count(struct super_block *sb, 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 ? - (__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, @@ -314,9 +314,9 @@ void ext4_free_group_clusters_set(struct super_block *sb, void ext4_free_inodes_set(struct super_block *sb, 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) - 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,