[PATCH 1/4] xfs: catch buffers written without verifiers attached

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

We recently had a bug where buffers were slipping through log
recovery without any verifier attached to them. This was resulting
in on-disk CRC mismatches for valid data. Add some warning code to
catch this occurrence so that we catch such bugs durin development
rather than not being aware they exist.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.c | 6 ++++++
 fs/xfs/xfs_log.c | 7 ++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index a6dc83e..95e5516 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1330,6 +1330,12 @@ _xfs_buf_ioapply(
 						   SHUTDOWN_CORRUPT_INCORE);
 				return;
 			}
+		} else if (bp->b_bn != -1LL) {
+			xfs_warn(bp->b_target->bt_mount,
+				"%s: no ops on block 0x%llx/0x%llx",
+				__func__, bp->b_bn, bp->b_maps[0].bm_bn);
+			xfs_hex_dump(bp->b_addr, 64);
+			dump_stack();
 		}
 	} else if (bp->b_flags & XBF_READ_AHEAD) {
 		rw = READA;
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 149a4a5..9dc92b3 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1378,8 +1378,13 @@ xlog_alloc_log(
 
 	xlog_get_iclog_buffer_size(mp, log);
 
+	/*
+	 * Use a block number of -1 for the extra log buffer used during splits
+	 * so that it will trigger errors if we ever try to do IO on it without
+	 * first having set it up properly.
+	 */
 	error = -ENOMEM;
-	bp = xfs_buf_alloc(mp->m_logdev_targp, 0, BTOBB(log->l_iclog_size), 0);
+	bp = xfs_buf_alloc(mp->m_logdev_targp, -1LL, BTOBB(log->l_iclog_size), 0);
 	if (!bp)
 		goto out_free_log;
 
-- 
2.0.0

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