[PATCH] scsi: core: Rate limit "rejecting I/O" messages

[Daniel Wagner <dwagner@suse.de>]

Prevent excessive logging by rate limiting the "rejecting I/O"
messages. For example in setups where remote syslog is used the link
is saturated by those messages when a storage controller/disk
misbehaves.

Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/scsi/scsi_lib.c    |  4 ++--
 include/scsi/scsi_device.h | 10 ++++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 47835c4b4ee0..01c35c58c6f3 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1217,7 +1217,7 @@ scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
 		 */
 		if (!sdev->offline_already) {
 			sdev->offline_already = true;
-			sdev_printk(KERN_ERR, sdev,
+			sdev_printk_ratelimited(KERN_ERR, sdev,
 				    "rejecting I/O to offline device\n");
 		}
 		return BLK_STS_IOERR;
@@ -1226,7 +1226,7 @@ scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
 		 * If the device is fully deleted, we refuse to
 		 * process any commands as well.
 		 */
-		sdev_printk(KERN_ERR, sdev,
+		sdev_printk_ratelimited(KERN_ERR, sdev,
 			    "rejecting I/O to dead device\n");
 		return BLK_STS_IOERR;
 	case SDEV_BLOCK:
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index c3cba2aaf934..8be40b0e1b8f 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -257,6 +257,16 @@ sdev_prefix_printk(const char *, const struct scsi_device *, const char *,
 #define sdev_printk(l, sdev, fmt, a...)				\
 	sdev_prefix_printk(l, sdev, NULL, fmt, ##a)
 
+#define sdev_printk_ratelimited(l, sdev, fmt, a...)			\
+({									\
+	static DEFINE_RATELIMIT_STATE(_rs,				\
+				      DEFAULT_RATELIMIT_INTERVAL,	\
+				      DEFAULT_RATELIMIT_BURST);		\
+									\
+	if (__ratelimit(&_rs))						\
+		sdev_prefix_printk(l, sdev, NULL, fmt, ##a);		\
+})
+
 __printf(3, 4) void
 scmd_printk(const char *, const struct scsi_cmnd *, const char *, ...);
 
-- 
2.16.4