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scsi: core: Make SCSI Status CONDITION MET equivalent to GOOD

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The SCSI PRE-FETCH (10 or 16) command is present both on hard disks
and some SSDs. It is useful when the address of the next block(s) to
be read is known but it is not following the LBA of the current READ
(so read-ahead won't help). It returns two "good" SCSI Status values.
If the requested blocks have fitted (or will most likely fit (when
the IMMED bit is set)) into the disk's cache, it returns CONDITION
MET. If it didn't (or will not) fit then it returns GOOD status.

The goal of this patch is to stop the SCSI subsystem treating the
CONDITION MET SCSI status as an error. The current state makes the
PRE-FETCH command effectively unusable via pass-throughs.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Douglas Gilbert
2018-03-06 22:19:49 -05:00
committed by Martin K. Petersen
parent 217c55cd0c
commit 1875ede02e
2 changed files with 13 additions and 0 deletions
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include/scsi/scsi.h
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@@ -47,6 +47,8 @@ static inline int scsi_status_is_good(int status)
*/
status &= 0xfe;
return ((status == SAM_STAT_GOOD) ||
(status == SAM_STAT_CONDITION_MET) ||
/* Next two "intermediate" statuses are obsolete in SAM-4 */
(status == SAM_STAT_INTERMEDIATE) ||
(status == SAM_STAT_INTERMEDIATE_CONDITION_MET) ||
/* FIXME: this is obsolete in SAM-3 */