github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-11-06 21:58:01 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

ext2: Make sbi an proper alias for EXT2_SB(sb) in ext2_fill_super()

Browse Source 
A recent LLVM change to fix parsing and validating __guarded_by on
structure members [1] reveals a couple of warnings in ext2_fill_super()
from the annotations added by commit 023051c2d0 ("ext2: mark
s_mount_state as guarded by s_lock") and commit c23746524f ("ext2:
annotate s_rsv_window_root as requiring s_rsv_window_lock"):

  fs/ext2/super.c:1040:7: error: writing variable 's_mount_state' requires holding spinlock '_res->s_lock' exclusively [-Werror,-Wthread-safety-precise]
   1040 |         sbi->s_mount_state = le16_to_cpu(es->s_state);
        |              ^
  fs/ext2/super.c:1040:7: note: found near match 'EXT2_SB(sb).s_lock'
  fs/ext2/super.c:1138:8: error: writing variable 's_rsv_window_root' requires holding spinlock '_res->s_rsv_window_lock' exclusively [-Werror,-Wthread-safety-precise]
   1138 |                 sbi->s_rsv_window_root = RB_ROOT;
        |                      ^
  fs/ext2/super.c:1138:8: note: found near match 'EXT2_SB(sb).s_rsv_window_lock'

Context analysis does very minimal alias detection [2], so it is not
able to figure out that sbi == sb->s_fs_info == EXT2_SB(sb). The only
reason there were no warnings before the above LLVM change is because
the annotation was not parsed and verified correctly.

Rework the allocation and assignment of sbi to have a direct assignment
of EXT2_SB(sb) to sbi so that the analysis knows that sbi and
EXT2_SB(sb) refer to the same object, clearing up the warnings.

Fixes: 9708538ba2 ("ext2: enable context analysis support for ext2 filesystem")
Link: 217e229a1f [1]
Link: https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#no-alias-analysis [2]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Marco Elver <elver@google.com>
Link: https://patch.msgid.link/20261023-ext2-fix-context-analysis-clang-24-v2-1-a33961453899@kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Nathan Chancellor 2026-10-23 14:25:02 -07:00 committed by Jan Kara
parent 0415c2624f
commit afb28ca1f1
1 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
fs/ext2/super.c
View File

@ -883,17 +883,18 @@ static int ext2_fill_super(struct super_block *sb, struct fs_context *fc)
__le32 features;
int err;
sbi = kzalloc_obj(*sbi);
if (!sbi)
sb->s_fs_info = kzalloc_obj(*sbi);
if (!sb->s_fs_info)
return -ENOMEM;
sbi = EXT2_SB(sb);
sbi->s_blockgroup_lock =
kzalloc_obj(struct blockgroup_lock);
if (!sbi->s_blockgroup_lock) {
kfree(sbi);
kfree(sb->s_fs_info);
sb->s_fs_info = NULL;
return -ENOMEM;
}
sb->s_fs_info = sbi;
sbi->s_sb_block = sb_block;
guard(spinlock_init)(&EXT2_SB(sb)->s_lock);