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| author | Bharath Vedartham <linux.bhar@gmail.com> | 2019-05-15 00:44:29 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-15 04:52:50 +0200 |
| commit | 672cdd56f0ae95069e399db790dbf2e303ac72b7 (patch) | |
| tree | d68d174568a9992051a49a9886e4cca991050a73 /fs/reiserfs | |
| parent | autofs: add description of ignore pseudo mount option (diff) | |
| download | linux-672cdd56f0ae95069e399db790dbf2e303ac72b7.tar.xz linux-672cdd56f0ae95069e399db790dbf2e303ac72b7.zip | |
reiserfs: add comment to explain endianness issue in xattr_hash
csum_partial() gives different results for little-endian and big-endian
hosts. This causes images created on little-endian hosts and mounted on
big endian hosts to see csum mismatches. This causes an endianness bug.
Sparse gives a warning as csum_partial returns a restricted integer type
__wsum_t and xattr_hash expects __u32. This warning acts as a reminder
for this bug and should not be suppressed.
This comment aims to convey these endianness issues.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20190423161831.GA15387@bharath12345-Inspiron-5559
Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/reiserfs')
| -rw-r--r-- | fs/reiserfs/xattr.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c index 32d8986c26fb..b5b26d8a192c 100644 --- a/fs/reiserfs/xattr.c +++ b/fs/reiserfs/xattr.c @@ -450,6 +450,15 @@ fail: static inline __u32 xattr_hash(const char *msg, int len) { + /* + * csum_partial() gives different results for little-endian and + * big endian hosts. Images created on little-endian hosts and + * mounted on big-endian hosts(and vice versa) will see csum mismatches + * when trying to fetch xattrs. Treating the hash as __wsum_t would + * lower the frequency of mismatch. This is an endianness bug in + * reiserfs. The return statement would result in a sparse warning. Do + * not fix the sparse warning so as to not hide a reminder of the bug. + */ return csum_partial(msg, len, 0); } |