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[XFS] Ensure "both" features2 slots are consistent 

Since older kernels may look in the sb_bad_features2 slot for flags,
rather than zeroing it out on fixup, we should make it equal to the
sb_features2 value.

Also, if the ATTR2 flag was not found prior to features2 fixup, it was not
set in the mount flags, so re-check after the fixup so that the current
session will use the feature.

Also fix up the comments to reflect these changes.

SGI-PV: 980085
SGI-Modid: xfs-linux-melb:xfs-kern:30778a

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
hifive-unleashed-5.1
Eric Sandeen 2008-04-10 12:19:34 +10:00 committed by Lachlan McIlroy
parent ee1c090825
commit e6957ea484
2 changed files with 29 additions and 15 deletions
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37
fs/xfs/xfs_mount.c
View File

@ -972,23 +972,35 @@ xfs_mountfs(
xfs_mount_common(mp, sbp);
/*
* Check for a bad features2 field alignment. This happened on
* some platforms due to xfs_sb_t not being 64bit size aligned
* when sb_features was added and hence the compiler put it in
* the wrong place.
* Check for a mismatched features2 values. Older kernels
* read & wrote into the wrong sb offset for sb_features2
* on some platforms due to xfs_sb_t not being 64bit size aligned
* when sb_features2 was added, which made older superblock
* reading/writing routines swap it as a 64-bit value.
*
* If we detect a bad field, we or the set bits into the existing
* features2 field in case it has already been modified and we
* don't want to lose any features. Zero the bad one and mark
* the two fields as needing updates once the transaction subsystem
* is online.
* For backwards compatibility, we make both slots equal.
*
* If we detect a mismatched field, we OR the set bits into the
* existing features2 field in case it has already been modified; we
* don't want to lose any features. We then update the bad location
* with the ORed value so that older kernels will see any features2
* flags, and mark the two fields as needing updates once the
* transaction subsystem is online.
*/
if (xfs_sb_has_bad_features2(sbp)) {
if (xfs_sb_has_mismatched_features2(sbp)) {
cmn_err(CE_WARN,
"XFS: correcting sb_features alignment problem");
sbp->sb_features2 |= sbp->sb_bad_features2;
sbp->sb_bad_features2 = 0;
sbp->sb_bad_features2 = sbp->sb_features2;
update_flags |= XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2;
/*
* Re-check for ATTR2 in case it was found in bad_features2
* slot.
*/
if (xfs_sb_version_hasattr2(&mp->m_sb))
mp->m_flags |= XFS_MOUNT_ATTR2;
}
/*
@ -1896,7 +1908,8 @@ xfs_uuid_unmount(
/*
* Used to log changes to the superblock unit and width fields which could
* be altered by the mount options. Only the first superblock is updated.
* be altered by the mount options, as well as any potential sb_features2
* fixup. Only the first superblock is updated.
*/
STATIC void
xfs_mount_log_sb(

7
fs/xfs/xfs_sb.h
View File

@ -320,11 +320,12 @@ static inline int xfs_sb_good_version(xfs_sb_t *sbp)
#endif /* __KERNEL__ */
/*
* Detect a bad features2 field
* Detect a mismatched features2 field. Older kernels read/wrote
* this into the wrong slot, so to be safe we keep them in sync.
*/
static inline int xfs_sb_has_bad_features2(xfs_sb_t *sbp)
static inline int xfs_sb_has_mismatched_features2(xfs_sb_t *sbp)
{
return (sbp->sb_bad_features2 != 0);
return (sbp->sb_bad_features2 != sbp->sb_features2);
}
static inline unsigned xfs_sb_version_tonew(unsigned v)