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xfs: create new metadata UUID field and incompat flag

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This adds a new superblock field, sb_meta_uuid.  If set, along with
a new incompat flag, the code will use that field on a V5 filesystem
to compare to metadata UUIDs, which allows us to change the user-
visible UUID at will.  Userspace handles the setting and clearing
of the incompat flag as appropriate, as the UUID gets changed; i.e.
setting the user-visible UUID back to the original UUID (as stored in
the new field) will remove the incompatible feature flag.

If the incompat flag is not set, this copies the user-visible UUID into
into the meta_uuid slot in memory when the superblock is read from disk;
the meta_uuid field is not written back to disk in this case.

The remainder of this patch simply switches verifiers, initializers,
etc to use the new sb_meta_uuid field.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Eric Sandeen
2015-07-29 11:53:31 +10:00
committed by Dave Chinner
parent bc0195aad0
commit ce748eaa65
18 changed files with 66 additions and 36 deletions
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4
fs/xfs/libxfs/xfs_attr_leaf.c
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@@ -262,7 +262,7 @@ xfs_attr3_leaf_verify(
if (ichdr.magic != XFS_ATTR3_LEAF_MAGIC)
return false;
if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_uuid))
if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid))
return false;
if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
return false;
@@ -1056,7 +1056,7 @@ xfs_attr3_leaf_create(
hdr3->blkno = cpu_to_be64(bp->b_bn);
hdr3->owner = cpu_to_be64(dp->i_ino);
uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
ichdr.freemap[0].base = sizeof(struct xfs_attr3_leaf_hdr);
} else {