xfs: use unhashed buffers for size checks

When we are checking we can access the last block of each device, we
do not need to use cached buffers as they will be tossed away
immediately. Use uncached buffers for size checks so that all IO
prior to full in-memory structure initialisation does not use the
buffer cache.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>

1 files changed, 16 insertions, 23 deletions

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index fbca293326e5..912101d280bf 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -980,42 +980,35 @@ xfs_check_sizes(xfs_mount_t *mp)
 {
         xfs_buf_t       *bp;
         xfs_daddr_t     d;
-        int             error;
 
         d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
         if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {
-                cmn_err(CE_WARN, "XFS: size check 1 failed");
+                cmn_err(CE_WARN, "XFS: filesystem size mismatch detected");
                 return XFS_ERROR(EFBIG);
         }
-        error = xfs_read_buf(mp, mp->m_ddev_targp,
-                             d - XFS_FSS_TO_BB(mp, 1),
-                             XFS_FSS_TO_BB(mp, 1), 0, &bp);
-        if (!error) {
-                xfs_buf_relse(bp);
-        } else {
-                cmn_err(CE_WARN, "XFS: size check 2 failed");
-                if (error == ENOSPC)
-                        error = XFS_ERROR(EFBIG);
-                return error;
+        bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
+                                        d - XFS_FSS_TO_BB(mp, 1),
+                                        BBTOB(XFS_FSS_TO_BB(mp, 1)), 0);
+        if (!bp) {
+                cmn_err(CE_WARN, "XFS: last sector read failed");
+                return EIO;
         }
+        xfs_buf_relse(bp);
 
         if (mp->m_logdev_targp != mp->m_ddev_targp) {
                 d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
                 if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {
-                        cmn_err(CE_WARN, "XFS: size check 3 failed");
+                        cmn_err(CE_WARN, "XFS: log size mismatch detected");
                         return XFS_ERROR(EFBIG);
                 }
-                error = xfs_read_buf(mp, mp->m_logdev_targp,
-                                     d - XFS_FSB_TO_BB(mp, 1),
-                                     XFS_FSB_TO_BB(mp, 1), 0, &bp);
-                if (!error) {
-                        xfs_buf_relse(bp);
-                } else {
-                        cmn_err(CE_WARN, "XFS: size check 3 failed");
-                        if (error == ENOSPC)
-                                error = XFS_ERROR(EFBIG);
-                        return error;
+                bp = xfs_buf_read_uncached(mp, mp->m_logdev_targp,
+                                        d - XFS_FSB_TO_BB(mp, 1),
+                                        XFS_FSB_TO_B(mp, 1), 0);
+                if (!bp) {
+                        cmn_err(CE_WARN, "XFS: log device read failed");
+                        return EIO;
                 }
+                xfs_buf_relse(bp);
         }
         return 0;
 }