xfs: hoist recovered bmap intent checks out of xfs_bui_item_recover

When we recover a bmap intent from the log, we need to validate its
contents before we try to replay them.  Hoist the checking code into a
separate function in preparation to refactor this code to use validation
helpers.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>

fs/xfs/xfs_bmap_item.c

@@ -417,6 +417,49 @@ const struct xfs_defer_op_type xfs_bmap_update_defer_type = {
 	.cancel_item	= xfs_bmap_update_cancel_item,
 };
 
+/* Is this recovered BUI ok? */
+static inline bool
+xfs_bui_validate(
+	struct xfs_mount		*mp,
+	struct xfs_bui_log_item		*buip)
+{
+	struct xfs_map_extent		*bmap;
+	xfs_fsblock_t			startblock_fsb;
+	xfs_fsblock_t			inode_fsb;
+
+	/* Only one mapping operation per BUI... */
+	if (buip->bui_format.bui_nextents != XFS_BUI_MAX_FAST_EXTENTS)
+		return false;
+
+	bmap = &buip->bui_format.bui_extents[0];
+	startblock_fsb = XFS_BB_TO_FSB(mp,
+			XFS_FSB_TO_DADDR(mp, bmap->me_startblock));
+	inode_fsb = XFS_BB_TO_FSB(mp, XFS_FSB_TO_DADDR(mp,
+			XFS_INO_TO_FSB(mp, bmap->me_owner)));
+
+	if (bmap->me_flags & ~XFS_BMAP_EXTENT_FLAGS)
+		return false;
+
+	switch (bmap->me_flags & XFS_BMAP_EXTENT_TYPE_MASK) {
+	case XFS_BMAP_MAP:
+	case XFS_BMAP_UNMAP:
+		break;
+	default:
+		return false;
+	}
+
+	if (startblock_fsb == 0 ||
+	    bmap->me_len == 0 ||
+	    inode_fsb == 0 ||
+	    startblock_fsb >= mp->m_sb.sb_dblocks ||
+	    bmap->me_len >= mp->m_sb.sb_agblocks ||
+	    inode_fsb >= mp->m_sb.sb_dblocks ||
+	    (bmap->me_flags & ~XFS_BMAP_EXTENT_FLAGS))
+		return false;
+
+	return true;
+}
+
 /*
  * Process a bmap update intent item that was recovered from the log.
  * We need to update some inode's bmbt.
@@ -433,47 +476,24 @@ xfs_bui_item_recover(
 	struct xfs_mount		*mp = lip->li_mountp;
 	struct xfs_map_extent		*bmap;
 	struct xfs_bud_log_item		*budp;
-	xfs_fsblock_t			startblock_fsb;
-	xfs_fsblock_t			inode_fsb;
 	xfs_filblks_t			count;
 	xfs_exntst_t			state;
 	unsigned int			bui_type;
 	int				whichfork;
 	int				error = 0;
 
-	/* Only one mapping operation per BUI... */
-	if (buip->bui_format.bui_nextents != XFS_BUI_MAX_FAST_EXTENTS)
+	if (!xfs_bui_validate(mp, buip)) {
+		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+				&buip->bui_format, sizeof(buip->bui_format));
 		return -EFSCORRUPTED;
+	}
 
-	/*
-	 * First check the validity of the extent described by the
-	 * BUI.  If anything is bad, then toss the BUI.
-	 */
 	bmap = &buip->bui_format.bui_extents[0];
-	startblock_fsb = XFS_BB_TO_FSB(mp,
-			   XFS_FSB_TO_DADDR(mp, bmap->me_startblock));
-	inode_fsb = XFS_BB_TO_FSB(mp, XFS_FSB_TO_DADDR(mp,
-			XFS_INO_TO_FSB(mp, bmap->me_owner)));
 	state = (bmap->me_flags & XFS_BMAP_EXTENT_UNWRITTEN) ?
 			XFS_EXT_UNWRITTEN : XFS_EXT_NORM;
 	whichfork = (bmap->me_flags & XFS_BMAP_EXTENT_ATTR_FORK) ?
 			XFS_ATTR_FORK : XFS_DATA_FORK;
 	bui_type = bmap->me_flags & XFS_BMAP_EXTENT_TYPE_MASK;
-	switch (bui_type) {
-	case XFS_BMAP_MAP:
-	case XFS_BMAP_UNMAP:
-		break;
-	default:
-		return -EFSCORRUPTED;
-	}
-	if (startblock_fsb == 0 ||
-	    bmap->me_len == 0 ||
-	    inode_fsb == 0 ||
-	    startblock_fsb >= mp->m_sb.sb_dblocks ||
-	    bmap->me_len >= mp->m_sb.sb_agblocks ||
-	    inode_fsb >= mp->m_sb.sb_dblocks ||
-	    (bmap->me_flags & ~XFS_BMAP_EXTENT_FLAGS))
-		return -EFSCORRUPTED;
 
 	/* Grab the inode. */
 	error = xfs_iget(mp, NULL, bmap->me_owner, 0, 0, &ip);