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| author | Dave Chinner <dchinner@redhat.com> | 2024-04-03 00:28:30 +0300 |
|---|---|---|
| committer | Chandan Babu R <chandanbabu@kernel.org> | 2024-04-22 10:21:43 +0300 |
| commit | 27a7a9d903a0473cb763afa662c38debf6f65bfa (patch) | |
| tree | 94547966ca80a849f3b26074ba93a19e00c39459 /fs/xfs/scrub | |
| parent | 2c03d9560ecebf2865b963e457ba89299c5f1966 (diff) | |
| download | linux-27a7a9d903a0473cb763afa662c38debf6f65bfa.tar.xz | |
xfs: silence sparse warning when checking version number
Scrub checks the superblock version number against the known good
feature bits that can be set in the version mask. It calculates
the version mask to compare like so:
vernum_mask = cpu_to_be16(~XFS_SB_VERSION_OKBITS |
XFS_SB_VERSION_NUMBITS |
XFS_SB_VERSION_ALIGNBIT |
XFS_SB_VERSION_DALIGNBIT |
XFS_SB_VERSION_SHAREDBIT |
XFS_SB_VERSION_LOGV2BIT |
XFS_SB_VERSION_SECTORBIT |
XFS_SB_VERSION_EXTFLGBIT |
XFS_SB_VERSION_DIRV2BIT);
This generates a sparse warning:
fs/xfs/scrub/agheader.c:168:23: warning: cast truncates bits from constant value (ffff3f8f becomes 3f8f)
This is because '~XFS_SB_VERSION_OKBITS' is considered a 32 bit
constant, even though it's value is always under 16 bits.
This is a kinda silly thing to do, because:
/*
* Supported feature bit list is just all bits in the versionnum field because
* we've used them all up and understand them all. Except, of course, for the
* shared superblock bit, which nobody knows what it does and so is unsupported.
*/
#define XFS_SB_VERSION_OKBITS \
((XFS_SB_VERSION_NUMBITS | XFS_SB_VERSION_ALLFBITS) & \
~XFS_SB_VERSION_SHAREDBIT)
#define XFS_SB_VERSION_NUMBITS 0x000f
#define XFS_SB_VERSION_ALLFBITS 0xfff0
#define XFS_SB_VERSION_SHAREDBIT 0x0200
XFS_SB_VERSION_OKBITS has a value of 0xfdff, and so
~XFS_SB_VERSION_OKBITS == XFS_SB_VERSION_SHAREDBIT. The calculated
mask already sets XFS_SB_VERSION_SHAREDBIT, so starting with
~XFS_SB_VERSION_OKBITS is completely redundant....
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Diffstat (limited to 'fs/xfs/scrub')
| -rw-r--r-- | fs/xfs/scrub/agheader.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c index 1528f14bd925..f8e5b67128d2 100644 --- a/fs/xfs/scrub/agheader.c +++ b/fs/xfs/scrub/agheader.c @@ -166,8 +166,7 @@ xchk_superblock( xchk_block_set_corrupt(sc, bp); /* Check sb_versionnum bits that are set at mkfs time. */ - vernum_mask = cpu_to_be16(~XFS_SB_VERSION_OKBITS | - XFS_SB_VERSION_NUMBITS | + vernum_mask = cpu_to_be16(XFS_SB_VERSION_NUMBITS | XFS_SB_VERSION_ALIGNBIT | XFS_SB_VERSION_DALIGNBIT | XFS_SB_VERSION_SHAREDBIT | |