[PATCH v12 16/20] scsi: sd: Have scsi-ml retry read_capacity_10 errors

Mike Christie
2023-11-14T01:39:25Z

This has read_capacity_10 have scsi-ml retry errors instead of driving
them itself.

There are 2 behavior changes with this patch:
1. There is one behavior change where we no longer retry when
scsi_execute_cmd returns < 0, but we should be ok. We don't need to retry
for failures like the queue being removed, and for the case where there
are no tags/reqs since the block layer waits/retries for us. For possible
memory allocation failures from blk_rq_map_kern we use GFP_NOIO, so
retrying will probably not help.
2. For the specific UAs we checked for and retried, we would get
READ_CAPACITY_RETRIES_ON_RESET retries plus whatever retries were left
from the main loop's retries. Each UA now gets
READ_CAPACITY_RETRIES_ON_RESET reties, and the other errors get up to 3
retries. This is most likely ok, because READ_CAPACITY_RETRIES_ON_RESET
is already 10 and is not based on anything specific like a spec or
device, so the extra 3 we got from the main loop was probably just an
accident and is not going to help.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
drivers/scsi/sd.c | 62 +++++++++++++++++++++++++++++------------------
1 file changed, 39 insertions(+), 23 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 87a8feabc2b4..cd6a6b31433c 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2622,42 +2622,58 @@ static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp,
static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp,
unsigned char *buffer)
{
- unsigned char cmd[16];
+ static const u8 cmd[10] = { READ_CAPACITY };
struct scsi_sense_hdr sshdr;
+ struct scsi_failure failure_defs[] = {
+ /* Do not retry Medium Not Present */
+ {
+ .sense = UNIT_ATTENTION,
+ .asc = 0x3A,
+ .result = SAM_STAT_CHECK_CONDITION,
+ },
+ {
+ .sense = NOT_READY,
+ .asc = 0x3A,
+ .result = SAM_STAT_CHECK_CONDITION,
+ },
+ /* Device reset might occur several times so retry a lot */
+ {
+ .sense = UNIT_ATTENTION,
+ .asc = 0x29,
+ .allowed = READ_CAPACITY_RETRIES_ON_RESET,
+ .result = SAM_STAT_CHECK_CONDITION,
+ },
+ /* Any other error not listed above retry 3 times */
+ {
+ .result = SCMD_FAILURE_RESULT_ANY,
+ .allowed = 3,
+ },
+ {}
+ };
+ struct scsi_failures failures = {
+ .failure_definitions = failure_defs,
+ };
const struct scsi_exec_args exec_args = {
.sshdr = &sshdr,
+ .failures = &failures,
};
int sense_valid = 0;
int the_result;
- int retries = 3, reset_retries = READ_CAPACITY_RETRIES_ON_RESET;
sector_t lba;
unsigned sector_size;

- do {
- cmd[0] = READ_CAPACITY;
- memset(&cmd[1], 0, 9);
- memset(buffer, 0, 8);
+ memset(buffer, 0, 8);
+
+ the_result = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN, buffer,
+ 8, SD_TIMEOUT, sdkp->max_retries,
+ &exec_args);

- the_result = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN, buffer,
- 8, SD_TIMEOUT, sdkp->max_retries,
- &exec_args);
+ if (the_result > 0) {
+ sense_valid = scsi_sense_valid(&sshdr);

if (media_not_present(sdkp, &sshdr))
return -ENODEV;
-
- if (the_result > 0) {
- sense_valid = scsi_sense_valid(&sshdr);
- if (sense_valid &&
- sshdr.sense_key == UNIT_ATTENTION &&
- sshdr.asc == 0x29 && sshdr.ascq == 0x00)
- /* Device reset might occur several times,
- * give it one more chance */
- if (--reset_retries > 0)
- continue;
- }
- retries--;
-
- } while (the_result && retries);
+ }

if (the_result) {
sd_print_result(sdkp, "Read Capacity(10) failed", the_result);
--
2.34.1