xfs: improve FSGROWFSRT precondition checking

Improve the checking at the start of a realtime grow operation so that
we avoid accidentally set a new extent size that is too large and avoid
adding an rt volume to a filesystem with rmap or reflink because we
don't support rt rmap or reflink yet.

While we're at it, separate the checks so that we're only testing one
aspect at a time.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 4e7be6b4ca8e85c3cbdf1546d5b5473678931e13..8f6a05db44686e5f63ae3fa1733503948cedc8be 100644 (file)
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -923,16 +923,41 @@ xfs_growfs_rt(
        uint8_t         *rsum_cache;    /* old summary cache */
 
        sbp = &mp->m_sb;
-       /*
-        * Initial error checking.
-        */
+
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
-       if (mp->m_rtdev_targp == NULL || mp->m_rbmip == NULL ||
-           (nrblocks = in->newblocks) <= sbp->sb_rblocks ||
-           (sbp->sb_rblocks && (in->extsize != sbp->sb_rextsize)))
+
+       /* Needs to have been mounted with an rt device. */
+       if (!XFS_IS_REALTIME_MOUNT(mp))
+               return -EINVAL;
+       /*
+        * Mount should fail if the rt bitmap/summary files don't load, but
+        * we'll check anyway.
+        */
+       if (!mp->m_rbmip || !mp->m_rsumip)
+               return -EINVAL;
+
+       /* Shrink not supported. */
+       if (in->newblocks <= sbp->sb_rblocks)
+               return -EINVAL;
+
+       /* Can only change rt extent size when adding rt volume. */
+       if (sbp->sb_rblocks > 0 && in->extsize != sbp->sb_rextsize)
+               return -EINVAL;
+
+       /* Range check the extent size. */
+       if (XFS_FSB_TO_B(mp, in->extsize) > XFS_MAX_RTEXTSIZE ||
+           XFS_FSB_TO_B(mp, in->extsize) < XFS_MIN_RTEXTSIZE)
                return -EINVAL;
-       if ((error = xfs_sb_validate_fsb_count(sbp, nrblocks)))
+
+       /* Unsupported realtime features. */
+       if (xfs_sb_version_hasrmapbt(&mp->m_sb) ||
+           xfs_sb_version_hasreflink(&mp->m_sb))
+               return -EOPNOTSUPP;
+
+       nrblocks = in->newblocks;
+       error = xfs_sb_validate_fsb_count(sbp, nrblocks);
+       if (error)
                return error;
        /*
         * Read in the last block of the device, make sure it exists.