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[SCSI] sd/scsi_lib simplify sd_rw_intr and scsi_io_completion
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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>
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Luben Tuikov authored and James Bottomley committed Jun 26, 2006
1 parent f89d0a4 commit 03aba2f
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Showing 4 changed files with 106 additions and 149 deletions.
108 changes: 42 additions & 66 deletions drivers/scsi/scsi_lib.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -855,8 +855,7 @@ static void scsi_release_buffers(struct scsi_cmnd *cmd)
* b) We can just use scsi_requeue_command() here. This would
* be used if we just wanted to retry, for example.
*/
void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
unsigned int block_bytes)
void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
{
int result = cmd->result;
int this_count = cmd->bufflen;
Expand Down Expand Up @@ -921,87 +920,72 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
* Next deal with any sectors which we were able to correctly
* handle.
*/
if (good_bytes >= 0) {
SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
if (good_bytes > 0) {
SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
"%d bytes done.\n",
req->nr_sectors, good_bytes));
SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));

if (clear_errors)
req->errors = 0;
/*
* If multiple sectors are requested in one buffer, then
* they will have been finished off by the first command.
* If not, then we have a multi-buffer command.
*
* If block_bytes != 0, it means we had a medium error
* of some sort, and that we want to mark some number of
* sectors as not uptodate. Thus we want to inhibit
* requeueing right here - we will requeue down below
* when we handle the bad sectors.
*/

/*
* If the command completed without error, then either
* finish off the rest of the command, or start a new one.
/* A number of bytes were successfully read. If there
* is leftovers and there is some kind of error
* (result != 0), retry the rest.
*/
if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
if (scsi_end_request(cmd, 1, good_bytes, !!result) == NULL)
return;
}
/*
* Now, if we were good little boys and girls, Santa left us a request
* sense buffer. We can extract information from this, so we
* can choose a block to remap, etc.

/* good_bytes = 0, or (inclusive) there were leftovers and
* result = 0, so scsi_end_request couldn't retry.
*/
if (sense_valid && !sense_deferred) {
switch (sshdr.sense_key) {
case UNIT_ATTENTION:
if (cmd->device->removable) {
/* detected disc change. set a bit
/* Detected disc change. Set a bit
* and quietly refuse further access.
*/
cmd->device->changed = 1;
scsi_end_request(cmd, 0,
this_count, 1);
scsi_end_request(cmd, 0, this_count, 1);
return;
} else {
/*
* Must have been a power glitch, or a
* bus reset. Could not have been a
* media change, so we just retry the
* request and see what happens.
*/
/* Must have been a power glitch, or a
* bus reset. Could not have been a
* media change, so we just retry the
* request and see what happens.
*/
scsi_requeue_command(q, cmd);
return;
}
break;
case ILLEGAL_REQUEST:
/*
* If we had an ILLEGAL REQUEST returned, then we may
* have performed an unsupported command. The only
* thing this should be would be a ten byte read where
* only a six byte read was supported. Also, on a
* system where READ CAPACITY failed, we may have read
* past the end of the disk.
*/
/* If we had an ILLEGAL REQUEST returned, then
* we may have performed an unsupported
* command. The only thing this should be
* would be a ten byte read where only a six
* byte read was supported. Also, on a system
* where READ CAPACITY failed, we may have
* read past the end of the disk.
*/
if ((cmd->device->use_10_for_rw &&
sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
(cmd->cmnd[0] == READ_10 ||
cmd->cmnd[0] == WRITE_10)) {
cmd->device->use_10_for_rw = 0;
/*
* This will cause a retry with a 6-byte
* command.
/* This will cause a retry with a
* 6-byte command.
*/
scsi_requeue_command(q, cmd);
result = 0;
return;
} else {
scsi_end_request(cmd, 0, this_count, 1);
return;
}
break;
case NOT_READY:
/*
* If the device is in the process of becoming
/* If the device is in the process of becoming
* ready, or has a temporary blockage, retry.
*/
if (sshdr.asc == 0x04) {
Expand All @@ -1021,51 +1005,43 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
}
if (!(req->flags & REQ_QUIET)) {
scmd_printk(KERN_INFO, cmd,
"Device not ready: ");
"Device not ready: ");
scsi_print_sense_hdr("", &sshdr);
}
scsi_end_request(cmd, 0, this_count, 1);
return;
case VOLUME_OVERFLOW:
if (!(req->flags & REQ_QUIET)) {
scmd_printk(KERN_INFO, cmd,
"Volume overflow, CDB: ");
"Volume overflow, CDB: ");
__scsi_print_command(cmd->data_cmnd);
scsi_print_sense("", cmd);
}
scsi_end_request(cmd, 0, block_bytes, 1);
/* See SSC3rXX or current. */
scsi_end_request(cmd, 0, this_count, 1);
return;
default:
break;
}
} /* driver byte != 0 */
}
if (host_byte(result) == DID_RESET) {
/*
* Third party bus reset or reset for error
* recovery reasons. Just retry the request
* and see what happens.
/* Third party bus reset or reset for error recovery
* reasons. Just retry the request and see what
* happens.
*/
scsi_requeue_command(q, cmd);
return;
}
if (result) {
if (!(req->flags & REQ_QUIET)) {
scmd_printk(KERN_INFO, cmd,
"SCSI error: return code = 0x%x\n", result);

"SCSI error: return code = 0x%08x\n",
result);
if (driver_byte(result) & DRIVER_SENSE)
scsi_print_sense("", cmd);
}
/*
* Mark a single buffer as not uptodate. Queue the remainder.
* We sometimes get this cruft in the event that a medium error
* isn't properly reported.
*/
block_bytes = req->hard_cur_sectors << 9;
if (!block_bytes)
block_bytes = req->data_len;
scsi_end_request(cmd, 0, block_bytes, 1);
}
scsi_end_request(cmd, 0, this_count, !result);
}
EXPORT_SYMBOL(scsi_io_completion);

Expand Down Expand Up @@ -1169,7 +1145,7 @@ static void scsi_blk_pc_done(struct scsi_cmnd *cmd)
* successfully. Since this is a REQ_BLOCK_PC command the
* caller should check the request's errors value
*/
scsi_io_completion(cmd, cmd->bufflen, 0);
scsi_io_completion(cmd, cmd->bufflen);
}

static void scsi_setup_blk_pc_cmnd(struct scsi_cmnd *cmd)
Expand Down
143 changes: 62 additions & 81 deletions drivers/scsi/sd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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));
Expand All @@ -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,
Expand Down
2 changes: 1 addition & 1 deletion drivers/scsi/sr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -292,7 +292,7 @@ static void rw_intr(struct scsi_cmnd * SCpnt)
* how many actual sectors finished, and how many sectors we need
* to say have failed.
*/
scsi_io_completion(SCpnt, good_bytes, block_sectors << 9);
scsi_io_completion(SCpnt, good_bytes);
}

static int sr_init_command(struct scsi_cmnd * SCpnt)
Expand Down
2 changes: 1 addition & 1 deletion include/scsi/scsi_cmnd.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,7 @@ struct scsi_cmnd {

extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t);
extern void scsi_put_command(struct scsi_cmnd *);
extern void scsi_io_completion(struct scsi_cmnd *, unsigned int, unsigned int);
extern void scsi_io_completion(struct scsi_cmnd *, unsigned int);
extern void scsi_finish_command(struct scsi_cmnd *cmd);
extern void scsi_req_abort_cmd(struct scsi_cmnd *cmd);

Expand Down

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