[PATCH 9/9] repair: detect and handle attribute tree CRC errors

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

Currently the attribute code will not detect and correct errors in
the attribute tree. It also fails to validate the CRCs and headers
on remote attribute blocks. Ensure that all the attribute blocks are
CRC checked and that the processing functions understand the correct
block formats for decoding.

Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 repair/attr_repair.c | 45 +++++++++++++++++++++++++++++++++++++--------
 1 file changed, 37 insertions(+), 8 deletions(-)

diff --git a/repair/attr_repair.c b/repair/attr_repair.c
index ba85ac2..9b57960 100644
--- a/repair/attr_repair.c
+++ b/repair/attr_repair.c
@@ -604,6 +604,7 @@ verify_da_path(xfs_mount_t	*mp,
 			libxfs_putbuf(bp);
 			return(1);
 		}
+
 		/*
 		 * update cursor, write out the *current* level if
 		 * required.  don't write out the descendant level
@@ -615,6 +616,8 @@ verify_da_path(xfs_mount_t	*mp,
 			libxfs_writebuf(cursor->level[this_level].bp, 0);
 		else
 			libxfs_putbuf(cursor->level[this_level].bp);
+
+		/* switch cursor to point at the new buffer we just read */
 		cursor->level[this_level].bp = bp;
 		cursor->level[this_level].dirty = 0;
 		cursor->level[this_level].bno = dabno;
@@ -624,6 +627,14 @@ verify_da_path(xfs_mount_t	*mp,
 		cursor->level[this_level].n = newnode;
 #endif
 		entry = cursor->level[this_level].index = 0;
+
+		/*
+		 * We want to rewrite the buffer a CRC error seeing as it
+		 * contains what appears to be a valid node block, but only if
+		 * we are fixing errors.
+		 */
+		if (bp->b_error == EFSBADCRC && !no_modify)
+			cursor->level[this_level].dirty++;
 	}
 	/*
 	 * ditto for block numbers
@@ -974,6 +985,10 @@ rmtval_get(xfs_mount_t *mp, xfs_ino_t ino, blkmap_t *blkmap,
 	xfs_dfsbno_t	bno;
 	xfs_buf_t	*bp;
 	int		clearit = 0, i = 0, length = 0, amountdone = 0;
+	int		hdrsize = 0;
+
+	if (xfs_sb_version_hascrc(&mp->m_sb))
+		hdrsize = sizeof(struct xfs_attr3_rmt_hdr);
 
 	/* ASSUMPTION: valuelen is a valid number, so use it for looping */
 	/* Note that valuelen is not a multiple of blocksize */
@@ -986,16 +1001,26 @@ rmtval_get(xfs_mount_t *mp, xfs_ino_t ino, blkmap_t *blkmap,
 			break;
 		}
 		bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, bno),
-				XFS_FSB_TO_BB(mp, 1), 0, NULL);
+				    XFS_FSB_TO_BB(mp, 1), 0,
+				    &xfs_attr3_rmt_buf_ops);
 		if (!bp) {
 			do_warn(
 	_("can't read remote block for attributes of inode %" PRIu64 "\n"), ino);
 			clearit = 1;
 			break;
 		}
+
+		if (bp->b_error == EFSBADCRC || bp->b_error == EFSCORRUPTED) {
+			do_warn(
+	_("Corrupt remote block for attributes of inode %" PRIu64 "\n"), ino);
+			clearit = 1;
+			break;
+		}
+
 		ASSERT(mp->m_sb.sb_blocksize == XFS_BUF_COUNT(bp));
-		length = MIN(XFS_BUF_COUNT(bp), valuelen - amountdone);
-		memmove(value, XFS_BUF_PTR(bp), length);
+
+		length = MIN(XFS_BUF_COUNT(bp) - hdrsize, valuelen - amountdone);
+		memmove(value, XFS_BUF_PTR(bp) + hdrsize, length);
 		amountdone += length;
 		value += length;
 		i++;
@@ -1143,7 +1168,6 @@ process_leaf_attr_block(
 
 	xfs_attr3_leaf_hdr_from_disk(&leafhdr, leaf);
 	clearit = usedbs = 0;
-	*repair = 0;
 	firstb = mp->m_sb.sb_blocksize;
 	stop = xfs_attr3_leaf_hdr_size(leaf);
 
@@ -1320,13 +1344,16 @@ process_leaf_attr_level(xfs_mount_t	*mp,
 		}
 
 		bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, dev_bno),
-					XFS_FSB_TO_BB(mp, 1), 0, NULL);
+				    XFS_FSB_TO_BB(mp, 1), 0,
+				    &xfs_attr3_leaf_buf_ops);
 		if (!bp) {
 			do_warn(
 	_("can't read file block %u (fsbno %" PRIu64 ") for attribute fork of inode %" PRIu64 "\n"),
 				da_bno, dev_bno, ino);
 			goto error_out;
 		}
+		if (bp->b_error == EFSBADCRC)
+			repair++;
 
 		leaf = bp->b_addr;
 		xfs_attr3_leaf_hdr_from_disk(&leafhdr, leaf);
@@ -1382,9 +1409,9 @@ process_leaf_attr_level(xfs_mount_t	*mp,
 
 		current_hashval = greatest_hashval;
 
-		if (repair && !no_modify) 
+		if (repair && !no_modify)
 			libxfs_writebuf(bp, 0);
-		else 
+		else
 			libxfs_putbuf(bp);
 	} while (da_bno != 0);
 
@@ -1512,6 +1539,8 @@ process_longform_attr(
 			ino);
 		return(1);
 	}
+	if (bp->b_error == EFSBADCRC)
+		(*repair)++;
 
 	/* verify leaf block */
 	leaf = (xfs_attr_leafblock_t *)XFS_BUF_PTR(bp);
@@ -1555,7 +1584,7 @@ process_longform_attr(
 	case XFS_DA_NODE_MAGIC:		/* btree-form attribute */
 	case XFS_DA3_NODE_MAGIC:
 		/* must do this now, to release block 0 before the traversal */
-		if (repairlinks) {
+		if (*repair || repairlinks) {
 			*repair = 1;
 			libxfs_writebuf(bp, 0);
 		} else
-- 
1.9.0