dm integrity: limit the rate of error messages

When using dm-integrity underneath md-raid, some tests with raid
auto-correction trigger large amounts of integrity failures - and all
these failures print an error message. These messages can bring the
system to a halt if the system is using serial console.

Fix this by limiting the rate of error messages - it improves the speed
of raid recovery and avoids the hang.

Fixes: 7eada909 ("dm: add integrity target")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-integrity.c

@@ -1368,8 +1368,8 @@ static void integrity_metadata(struct work_struct *w)
 						checksums_ptr - checksums, !dio->write ? TAG_CMP : TAG_WRITE);
 			if (unlikely(r)) {
 				if (r > 0) {
-					DMERR("Checksum failed at sector 0x%llx",
-					      (unsigned long long)(sector - ((r + ic->tag_size - 1) / ic->tag_size)));
+					DMERR_LIMIT("Checksum failed at sector 0x%llx",
+						    (unsigned long long)(sector - ((r + ic->tag_size - 1) / ic->tag_size)));
 					r = -EILSEQ;
 					atomic64_inc(&ic->number_of_mismatches);
 				}
@@ -1561,8 +1561,8 @@ static bool __journal_read_write(struct dm_integrity_io *dio, struct bio *bio,
 
 					integrity_sector_checksum(ic, logical_sector, mem + bv.bv_offset, checksums_onstack);
 					if (unlikely(memcmp(checksums_onstack, journal_entry_tag(ic, je), ic->tag_size))) {
-						DMERR("Checksum failed when reading from journal, at sector 0x%llx",
-						      (unsigned long long)logical_sector);
+						DMERR_LIMIT("Checksum failed when reading from journal, at sector 0x%llx",
+							    (unsigned long long)logical_sector);
 					}
 				}
 #endif