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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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5
fs/xfs/libxfs/xfs_bmap_btree.c
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@ -349,7 +349,8 @@ xfs_bmbt_to_bmdr(
if (xfs_sb_version_hascrc(&mp->m_sb)) {
ASSERT(rblock->bb_magic == cpu_to_be32(XFS_BMAP_CRC_MAGIC));
ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid));
ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid,
&mp->m_sb.sb_meta_uuid));
ASSERT(rblock->bb_u.l.bb_blkno ==
cpu_to_be64(XFS_BUF_DADDR_NULL));
} else
@ -647,7 +648,7 @@ xfs_bmbt_verify(
case cpu_to_be32(XFS_BMAP_CRC_MAGIC):
if (!xfs_sb_version_hascrc(&mp->m_sb))
return false;
if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid))
if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid))
return false;
if (be64_to_cpu(block->bb_u.l.bb_blkno) != bp->b_bn)
return false;