xfs: refactor ratelimited buffer error messages into helper

XFS has some inconsistent log message rate limiting with respect to
buffer alerts. The metadata I/O error notification uses the generic
ratelimited alert, the buffer push code uses a custom rate limit and
the similar quiesce time failure checks are not rate limited at all
(when they should be).

The custom rate limit defined in the buf item code is specifically
crafted for buffer alerts. It is more aggressive than generic rate
limiting code because it must accommodate a high frequency of I/O
error events in a relative short timeframe.

Factor out the custom rate limit state from the buf item code into a
per-buftarg rate limit so various alerts are limited based on the
target. Define a buffer alert helper function and use it for the
buffer alerts that are already ratelimited.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_buf.c

@@ -1244,10 +1244,10 @@ xfs_buf_ioerror_alert(
 	struct xfs_buf		*bp,
 	xfs_failaddr_t		func)
 {
-	xfs_alert_ratelimited(bp->b_mount,
-"metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
-			func, (uint64_t)XFS_BUF_ADDR(bp), bp->b_length,
-			-bp->b_error);
+	xfs_buf_alert_ratelimited(bp, "XFS: metadata IO error",
+		"metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
+				  func, (uint64_t)XFS_BUF_ADDR(bp),
+				  bp->b_length, -bp->b_error);
 }
 
 /*
@@ -1828,6 +1828,13 @@ xfs_alloc_buftarg(
 	btp->bt_bdev = bdev;
 	btp->bt_daxdev = dax_dev;
 
+	/*
+	 * Buffer IO error rate limiting. Limit it to no more than 10 messages
+	 * per 30 seconds so as to not spam logs too much on repeated errors.
+	 */
+	ratelimit_state_init(&btp->bt_ioerror_rl, 30 * HZ,
+			     DEFAULT_RATELIMIT_BURST);
+
 	if (xfs_setsize_buftarg_early(btp, bdev))
 		goto error_free;
 

fs/xfs/xfs_buf.h

@@ -91,6 +91,7 @@ typedef struct xfs_buftarg {
 	struct list_lru		bt_lru;
 
 	struct percpu_counter	bt_io_count;
+	struct ratelimit_state	bt_ioerror_rl;
 } xfs_buftarg_t;
 
 struct xfs_buf;

fs/xfs/xfs_buf_item.c

@@ -481,14 +481,6 @@ xfs_buf_item_unpin(
 	}
 }
 
-/*
- * Buffer IO error rate limiting. Limit it to no more than 10 messages per 30
- * seconds so as to not spam logs too much on repeated detection of the same
- * buffer being bad..
- */
-
-static DEFINE_RATELIMIT_STATE(xfs_buf_write_fail_rl_state, 30 * HZ, 10);
-
 STATIC uint
 xfs_buf_item_push(
 	struct xfs_log_item	*lip,
@@ -518,10 +510,9 @@ xfs_buf_item_push(
 	trace_xfs_buf_item_push(bip);
 
 	/* has a previous flush failed due to IO errors? */
-	if ((bp->b_flags & XBF_WRITE_FAIL) &&
-	    ___ratelimit(&xfs_buf_write_fail_rl_state, "XFS: Failing async write")) {
-		xfs_warn(bp->b_mount,
-"Failing async write on buffer block 0x%llx. Retrying async write.",
+	if (bp->b_flags & XBF_WRITE_FAIL) {
+		xfs_buf_alert_ratelimited(bp, "XFS: Failing async write",
+	    "Failing async write on buffer block 0x%llx. Retrying async write.",
 					  (long long)bp->b_bn);
 	}
 

fs/xfs/xfs_message.c

@@ -117,3 +117,25 @@ xfs_hex_dump(const void *p, int length)
 {
 	print_hex_dump(KERN_ALERT, "", DUMP_PREFIX_OFFSET, 16, 1, p, length, 1);
 }
+
+void
+xfs_buf_alert_ratelimited(
+	struct xfs_buf		*bp,
+	const char		*rlmsg,
+	const char		*fmt,
+	...)
+{
+	struct xfs_mount	*mp = bp->b_mount;
+	struct va_format	vaf;
+	va_list			args;
+
+	/* use the more aggressive per-target rate limit for buffers */
+	if (!___ratelimit(&bp->b_target->bt_ioerror_rl, rlmsg))
+		return;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+	__xfs_printk(KERN_ALERT, mp, &vaf);
+	va_end(args);
+}

fs/xfs/xfs_message.h

@@ -79,4 +79,7 @@ void asswarn(struct xfs_mount *mp, char *expr, char *f, int l);
 
 extern void xfs_hex_dump(const void *p, int length);
 
+void xfs_buf_alert_ratelimited(struct xfs_buf *bp, const char *rlmsg,
+			       const char *fmt, ...);
+
 #endif	/* __XFS_MESSAGE_H */