[XFS] Don't grow filesystems past the size they can index.

When growing a filesystem we don't check to see if the new size overflows
the page cache index range, so we can do silly things like grow a
filesystem page 16TB on a 32bit. Check new filesystem sizes against the
limits the kernel can support.

SGI-PV: 957886
SGI-Modid: xfs-linux-melb:xfs-kern:28563a
Signed-Off-By: Nathan Scott <nscott@aconex.com>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>

fs/xfs/xfs_fsops.c

@@ -140,6 +140,8 @@ xfs_growfs_data_private(
 	pct = in->imaxpct;
 	if (nb < mp->m_sb.sb_dblocks || pct < 0 || pct > 100)
 		return XFS_ERROR(EINVAL);
+	if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
+		return error;
 	dpct = pct - mp->m_sb.sb_imax_pct;
 	error = xfs_read_buf(mp, mp->m_ddev_targp,
 			XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),

fs/xfs/xfs_mount.c

@@ -202,6 +202,27 @@ xfs_mount_free(
 	kmem_free(mp, sizeof(xfs_mount_t));
 }
 
+/*
+ * Check size of device based on the (data/realtime) block count.
+ * Note: this check is used by the growfs code as well as mount.
+ */
+int
+xfs_sb_validate_fsb_count(
+	xfs_sb_t	*sbp,
+	__uint64_t	nblocks)
+{
+	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
+	ASSERT(sbp->sb_blocklog >= BBSHIFT);
+
+#if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
+	if (nblocks >> (PAGE_CACHE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
+		return E2BIG;
+#else                  /* Limited by UINT_MAX of sectors */
+	if (nblocks << (sbp->sb_blocklog - BBSHIFT) > UINT_MAX)
+		return E2BIG;
+#endif
+	return 0;
+}
 
 /*
  * Check the validity of the SB found.
@@ -284,18 +305,8 @@ xfs_mount_validate_sb(
 		return XFS_ERROR(EFSCORRUPTED);
 	}
 
-	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
-	ASSERT(sbp->sb_blocklog >= BBSHIFT);
-
-#if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
-	if (unlikely(
-	    (sbp->sb_dblocks >> (PAGE_SHIFT - sbp->sb_blocklog)) > ULONG_MAX ||
-	    (sbp->sb_rblocks >> (PAGE_SHIFT - sbp->sb_blocklog)) > ULONG_MAX)) {
-#else                  /* Limited by UINT_MAX of sectors */
-	if (unlikely(
-	    (sbp->sb_dblocks << (sbp->sb_blocklog - BBSHIFT)) > UINT_MAX ||
-	    (sbp->sb_rblocks << (sbp->sb_blocklog - BBSHIFT)) > UINT_MAX)) {
-#endif
+	if (xfs_sb_validate_fsb_count(sbp, sbp->sb_dblocks) ||
+	    xfs_sb_validate_fsb_count(sbp, sbp->sb_rblocks)) {
 		xfs_fs_mount_cmn_err(flags,
 			"file system too large to be mounted on this system.");
 		return XFS_ERROR(E2BIG);

fs/xfs/xfs_mount.h

@@ -624,6 +624,7 @@ extern int	xfs_sync_inodes(xfs_mount_t *, int, int *);
 extern xfs_agnumber_t	xfs_initialize_perag(struct bhv_vfs *, xfs_mount_t *,
 						xfs_agnumber_t);
 extern void	xfs_xlatesb(void *, struct xfs_sb *, int, __int64_t);
+extern int	xfs_sb_validate_fsb_count(struct xfs_sb *, __uint64_t);
 
 extern struct xfs_dmops xfs_dmcore_stub;
 extern struct xfs_qmops xfs_qmcore_stub;

fs/xfs/xfs_rtalloc.c

@@ -1882,11 +1882,13 @@ xfs_growfs_rt(
 	    (nrblocks = in->newblocks) <= sbp->sb_rblocks ||
 	    (sbp->sb_rblocks && (in->extsize != sbp->sb_rextsize)))
 		return XFS_ERROR(EINVAL);
+	if ((error = xfs_sb_validate_fsb_count(sbp, nrblocks)))
+		return error;
 	/*
 	 * Read in the last block of the device, make sure it exists.
 	 */
 	error = xfs_read_buf(mp, mp->m_rtdev_targp,
-			XFS_FSB_TO_BB(mp, in->newblocks - 1),
+			XFS_FSB_TO_BB(mp, nrblocks - 1),
 			XFS_FSB_TO_BB(mp, 1), 0, &bp);
 	if (error)
 		return error;