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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_symlink_remote.c
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@@ -63,7 +63,7 @@ xfs_symlink_hdr_set(
dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
dsl->sl_offset = cpu_to_be32(offset);
dsl->sl_bytes = cpu_to_be32(size);
uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
dsl->sl_owner = cpu_to_be64(ino);
dsl->sl_blkno = cpu_to_be64(bp->b_bn);
bp->b_ops = &xfs_symlink_buf_ops;
@@ -107,7 +107,7 @@ xfs_symlink_verify(
return false;
if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
return false;
if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
return false;
if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
return false;