[PATCH v2 07/11] xfs_repair: force not-so-bad bmbt blocks back through the verifier

[Darrick J. Wong]

If during prefetch we encounter a bmbt block that fails the CRC check
due to corruption in the unused part of the block, force the buffer
back through the non-prefetch verifiers later so that the CRC is
updated.  Otherwise, the bad checksum goes unfixed and the kernel will
still flag the bmbt block as invalid.

v2: Halt all readahead on the bmapbt if any of its blocks produce an
error.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 repair/prefetch.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/repair/prefetch.c b/repair/prefetch.c
index 1de3ec0..32ec55e 100644
--- a/repair/prefetch.c
+++ b/repair/prefetch.c
@@ -276,6 +276,18 @@ pf_scan_lbtree(
 
 	XFS_BUF_SET_PRIORITY(bp, isadir ? B_DIR_BMAP : B_BMAP);
 
+	/*
+	 * If the verifier flagged a problem with the buffer, we can't trust
+	 * its contents for the purposes of reading ahead.  Stop prefetching
+	 * the tree and mark the buffer unchecked so that the next read of the
+	 * buffer will retain the error status and be acted upon appropriately.
+	 */
+	if (bp->b_error) {
+		bp->b_flags |= LIBXFS_B_UNCHECKED;
+		libxfs_putbuf(bp);
+		return 0;
+	}
+
 	rc = (*func)(XFS_BUF_TO_BLOCK(bp), level - 1, isadir, args);
 
 	libxfs_putbuf(bp);