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Ignore "safe" flag differences when e2fsck compares superblocks 

Recent e2fsprogs (1.40.3 and higher) fsck compares primary superblock to
backups, and if things differ, it forces a full check.  However, the
kernel has a penchant for updating flags the first time a feature is
used - attributes, large files, etc.

This is a bad idea, and we should break the kernel of this habit,
especially for the ext4 feature flags.  But for now, let's make e2fsck
avoid forcing a full check and backup except when absolutely
necessary.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
bitmap-optimize
Theodore Ts'o 2008-01-26 23:17:50 -05:00
parent 2921332fd8
commit a8cde73acb
1 changed files with 30 additions and 4 deletions
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34
e2fsck/super.c
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@ -773,8 +773,26 @@ void check_super_block(e2fsck_t ctx)
/*
* Check to see if we should backup the master sb to the backup super
* blocks.
* blocks. Returns non-zero if the sb should be backed up.
*/
/*
* A few flags are set on the fly by the kernel, but only in the
* primary superblock. This is actually a bad thing, and we should
* try to discourage it in the future. In particular, for the newer
* ext4 files, especially EXT4_FEATURE_RO_COMPAT_DIR_NLINK and
* EXT3_FEATURE_INCOMPAT_EXTENTS. So some of these may go away in the
* future.
*
* The kernel will set EXT2_FEATURE_COMPAT_EXT_ATTR, but
* unfortunately, we shouldn't ignore it since if it's not set in the
* backup, the extended attributes in the filesystem will be stripped
* away.
*/
#define FEATURE_RO_COMPAT_IGNORE (EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
EXT4_FEATURE_RO_COMPAT_DIR_NLINK)
#define FEATURE_INCOMPAT_IGNORE (EXT3_FEATURE_INCOMPAT_EXTENTS)
int check_backup_super_block(e2fsck_t ctx)
{
ext2_filsys fs = ctx->fs;
@ -814,10 +832,18 @@ int check_backup_super_block(e2fsck_t ctx)
continue;
}
#define SUPER_DIFFERENT(x) (fs->super->x != tfs->super->x)
#define SUPER_INCOMPAT_DIFFERENT(x) \
(( fs->super->x & ~FEATURE_INCOMPAT_IGNORE) != \
(tfs->super->x & ~FEATURE_INCOMPAT_IGNORE))
#define SUPER_RO_COMPAT_DIFFERENT(x) \
(( fs->super->x & ~FEATURE_RO_COMPAT_IGNORE) != \
(tfs->super->x & ~FEATURE_RO_COMPAT_IGNORE))
#define SUPER_DIFFERENT(x) \
(fs->super->x != tfs->super->x)
if (SUPER_DIFFERENT(s_feature_compat) ||
SUPER_DIFFERENT(s_feature_incompat) ||
SUPER_DIFFERENT(s_feature_ro_compat) ||
SUPER_INCOMPAT_DIFFERENT(s_feature_incompat) ||
SUPER_RO_COMPAT_DIFFERENT(s_feature_ro_compat) ||
SUPER_DIFFERENT(s_blocks_count) ||
SUPER_DIFFERENT(s_inodes_count) ||
memcmp(fs->super->s_uuid, tfs->super->s_uuid,