diff options
| -rw-r--r-- | drivers/scsi/sd.c | 21 | ||||
| -rw-r--r-- | drivers/scsi/sd.h | 6 | ||||
| -rw-r--r-- | include/scsi/scsi_device.h | 3 |
3 files changed, 23 insertions, 7 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 8e08d51a0f0..e5e7d785645 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -375,6 +375,7 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq) struct gendisk *disk = rq->rq_disk; struct scsi_disk *sdkp; sector_t block = rq->sector; + sector_t threshold; unsigned int this_count = rq->nr_sectors; unsigned int timeout = sdp->timeout; int ret; @@ -422,13 +423,21 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq) } /* - * Some devices (some sdcards for one) don't like it if the - * last sector gets read in a larger then 1 sector read. + * Some SD card readers can't handle multi-sector accesses which touch + * the last one or two hardware sectors. Split accesses as needed. */ - if (unlikely(sdp->last_sector_bug && - rq->nr_sectors > sdp->sector_size / 512 && - block + this_count == get_capacity(disk))) - this_count -= sdp->sector_size / 512; + threshold = get_capacity(disk) - SD_LAST_BUGGY_SECTORS * + (sdp->sector_size / 512); + + if (unlikely(sdp->last_sector_bug && block + this_count > threshold)) { + if (block < threshold) { + /* Access up to the threshold but not beyond */ + this_count = threshold - block; + } else { + /* Access only a single hardware sector */ + this_count = sdp->sector_size / 512; + } + } SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt, "block=%llu\n", (unsigned long long)block)); diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h index 550b2f70a1f..95b9f06534d 100644 --- a/drivers/scsi/sd.h +++ b/drivers/scsi/sd.h @@ -31,6 +31,12 @@ */ #define SD_BUF_SIZE 512 +/* + * Number of sectors at the end of the device to avoid multi-sector + * accesses to in the case of last_sector_bug + */ +#define SD_LAST_BUGGY_SECTORS 8 + struct scsi_disk { struct scsi_driver *driver; /* always &sd_template */ struct scsi_device *device; diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 9cecc409f0f..291d56a1916 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -140,7 +140,8 @@ struct scsi_device { unsigned fix_capacity:1; /* READ_CAPACITY is too high by 1 */ unsigned guess_capacity:1; /* READ_CAPACITY might be too high by 1 */ unsigned retry_hwerror:1; /* Retry HARDWARE_ERROR */ - unsigned last_sector_bug:1; /* Always read last sector in a 1 sector read */ + unsigned last_sector_bug:1; /* do not use multisector accesses on + SD_LAST_BUGGY_SECTORS */ DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */ struct list_head event_list; /* asserted events */ |