[SCSI] sd/scsi_lib simplify sd_rw_intr and scsi_io_completion

This patch simplifies "good_bytes" computation in sd_rw_intr().
sd: "good_bytes" computation is always done in terms of the resolution
of the device's medium, since after that it is the number of good bytes
we pass around and other layers/contexts (as opposed ot sd) can translate
that to their own resolution (block layer:512).  It also makes
scsi_io_completion() processing more straightforward, eliminating the
3rd argument to the function.

It also fixes a couple of bugs like not checking return value,
using "break" instead of "return;", etc.

I've been running with this patch for some time now on a
test (do-it-all) system.

Signed-off-by: Luben Tuikov <ltuikov@yahoo.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 62 insertions, 81 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 354199011246..f899ff0cf005 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -891,11 +891,10 @@ static struct block_device_operations sd_fops = {
 static void sd_rw_intr(struct scsi_cmnd * SCpnt)
 {
         int result = SCpnt->result;
-        int this_count = SCpnt->request_bufflen;
-        int good_bytes = (result == 0 ? this_count : 0);
-        sector_t block_sectors = 1;
-        u64 first_err_block;
-        sector_t error_sector;
+        unsigned int xfer_size = SCpnt->request_bufflen;
+        unsigned int good_bytes = result ? 0 : xfer_size;
+        u64 start_lba = SCpnt->request->sector;
+        u64 bad_lba;
         struct scsi_sense_hdr sshdr;
         int sense_valid = 0;
         int sense_deferred = 0;
@@ -906,7 +905,6 @@ static void sd_rw_intr(struct scsi_cmnd * SCpnt)
                 if (sense_valid)
                         sense_deferred = scsi_sense_is_deferred(&sshdr);
         }
-
 #ifdef CONFIG_SCSI_LOGGING
         SCSI_LOG_HLCOMPLETE(1, printk("sd_rw_intr: %s: res=0x%x\n", 
                                 SCpnt->request->rq_disk->disk_name, result));
@@ -916,89 +914,72 @@ static void sd_rw_intr(struct scsi_cmnd * SCpnt)
                                 sshdr.sense_key, sshdr.asc, sshdr.ascq));
         }
 #endif
-        /*
-           Handle MEDIUM ERRORs that indicate partial success.  Since this is a
-           relatively rare error condition, no care is taken to avoid
-           unnecessary additional work such as memcpy's that could be avoided.
-         */
-        if (driver_byte(result) != 0 &&
-                 sense_valid && !sense_deferred) {
-                switch (sshdr.sense_key) {
-                case MEDIUM_ERROR:
-                        if (!blk_fs_request(SCpnt->request))
-                                break;
-                        info_valid = scsi_get_sense_info_fld(
-                                SCpnt->sense_buffer, SCSI_SENSE_BUFFERSIZE,
-                                &first_err_block);
-                        /*
-                         * May want to warn and skip if following cast results
-                         * in actual truncation (if sector_t < 64 bits)
-                         */
-                        error_sector = (sector_t)first_err_block;
-                        if (SCpnt->request->bio != NULL)
-                                block_sectors = bio_sectors(SCpnt->request->bio);
-                        switch (SCpnt->device->sector_size) {
-                        case 1024:
-                                error_sector <<= 1;
-                                if (block_sectors < 2)
-                                        block_sectors = 2;
-                                break;
-                        case 2048:
-                                error_sector <<= 2;
-                                if (block_sectors < 4)
-                                        block_sectors = 4;
-                                break;
-                        case 4096:
-                                error_sector <<=3;
-                                if (block_sectors < 8)
-                                        block_sectors = 8;
-                                break;
-                        case 256:
-                                error_sector >>= 1;
-                                break;
-                        default:
-                                break;
-                        }
+        if (driver_byte(result) != DRIVER_SENSE &&
+            (!sense_valid || sense_deferred))
+                goto out;
 
-                        error_sector &= ~(block_sectors - 1);
-                        good_bytes = (error_sector - SCpnt->request->sector) << 9;
-                        if (good_bytes < 0 || good_bytes >= this_count)
-                                good_bytes = 0;
+        switch (sshdr.sense_key) {
+        case HARDWARE_ERROR:
+        case MEDIUM_ERROR:
+                if (!blk_fs_request(SCpnt->request))
+                        goto out;
+                info_valid = scsi_get_sense_info_fld(SCpnt->sense_buffer,
+                                                     SCSI_SENSE_BUFFERSIZE,
+                                                     &bad_lba);
+                if (!info_valid)
+                        goto out;
+                if (xfer_size <= SCpnt->device->sector_size)
+                        goto out;
+                switch (SCpnt->device->sector_size) {
+                case 256:
+                        start_lba <<= 1;
                         break;
-
-                case RECOVERED_ERROR: /* an error occurred, but it recovered */
-                case NO_SENSE: /* LLDD got sense data */
-                        /*
-                         * Inform the user, but make sure that it's not treated
-                         * as a hard error.
-                         */
-                        scsi_print_sense("sd", SCpnt);
-                        SCpnt->result = 0;
-                        memset(SCpnt->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
-                        good_bytes = this_count;
+                case 512:
                         break;
-
-                case ILLEGAL_REQUEST:
-                        if (SCpnt->device->use_10_for_rw &&
-                            (SCpnt->cmnd[0] == READ_10 ||
-                             SCpnt->cmnd[0] == WRITE_10))
-                                SCpnt->device->use_10_for_rw = 0;
-                        if (SCpnt->device->use_10_for_ms &&
-                            (SCpnt->cmnd[0] == MODE_SENSE_10 ||
-                             SCpnt->cmnd[0] == MODE_SELECT_10))
-                                SCpnt->device->use_10_for_ms = 0;
+                case 1024:
+                        start_lba >>= 1;
+                        break;
+                case 2048:
+                        start_lba >>= 2;
+                        break;
+                case 4096:
+                        start_lba >>= 3;
                         break;
-
                 default:
+                        /* Print something here with limiting frequency. */
+                        goto out;
                         break;
                 }
+                /* This computation should always be done in terms of
+                 * the resolution of the device's medium.
+                 */
+                good_bytes = (bad_lba - start_lba)*SCpnt->device->sector_size;
+                break;
+        case RECOVERED_ERROR:
+        case NO_SENSE:
+                /* Inform the user, but make sure that it's not treated
+                 * as a hard error.
+                 */
+                scsi_print_sense("sd", SCpnt);
+                SCpnt->result = 0;
+                memset(SCpnt->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
+                good_bytes = xfer_size;
+                break;
+        case ILLEGAL_REQUEST:
+                if (SCpnt->device->use_10_for_rw &&
+                    (SCpnt->cmnd[0] == READ_10 ||
+                     SCpnt->cmnd[0] == WRITE_10))
+                        SCpnt->device->use_10_for_rw = 0;
+                if (SCpnt->device->use_10_for_ms &&
+                    (SCpnt->cmnd[0] == MODE_SENSE_10 ||
+                     SCpnt->cmnd[0] == MODE_SELECT_10))
+                        SCpnt->device->use_10_for_ms = 0;
+                break;
+        default:
+                break;
         }
-        /*
-         * This calls the generic completion function, now that we know
-         * how many actual sectors finished, and how many sectors we need
-         * to say have failed.
-         */
-        scsi_io_completion(SCpnt, good_bytes, block_sectors << 9);
+ out:
+        scsi_io_completion(SCpnt, good_bytes);
 }
 
 static int media_not_present(struct scsi_disk *sdkp,