[PATCH 1/2] xfs: improve FSGROWFSRT precondition checking

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

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>
---
 fs/xfs/xfs_rtalloc.c |   20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)


diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 4e7be6b4ca8e..8920bce4fb0a 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -928,11 +928,23 @@ xfs_growfs_rt(
 	 */
 	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)))
+	if (mp->m_rtdev_targp == NULL || !mp->m_rbmip || !mp->m_rsumip)
 		return -EINVAL;
-	if ((error = xfs_sb_validate_fsb_count(sbp, nrblocks)))
+	if (in->newblocks <= sbp->sb_rblocks)
+		return -EINVAL;
+	if (xfs_sb_version_hasrealtime(&mp->m_sb) &&
+	    in->extsize != sbp->sb_rextsize)
+		return -EINVAL;
+	if (XFS_FSB_TO_B(mp, in->extsize) > XFS_MAX_RTEXTSIZE ||
+	    XFS_FSB_TO_B(mp, in->extsize) < XFS_MIN_RTEXTSIZE)
+		return -EINVAL;
+	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.