From 18351070b86d155713cf790b26af4f21b1fd0b29 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 5 Aug 2008 21:42:21 -0700 Subject: Re-introduce "[SCSI] extend the last_sector_bug flag to cover more sectors" This re-introduces commit 2b142900784c6e38c8d39fa57d5f95ef08e735d8, which was reverted due to the regression it caused by commit fca082c9f1e11ec07efa8d2f9f13688521253f36. That regression was not root-caused by the original commit, it was just uncovered by it, and the real fix was done by Alan Stern in commit 580da34847488b404218d1d7f53b156f245f5555 ("Fix USB storage hang on command abort"). We can thus re-introduce the change that was confirmed by Alan Jenkins to be still required by his odd card reader. Cc: Alan Jenkins Cc: Alan Stern Cc: James Bottomley Signed-off-by: Linus Torvalds --- drivers/scsi/sd.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) (limited to 'drivers/scsi/sd.c') diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 8e08d51a0f05..e5e7d7856454 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)); -- cgit v1.2.3