Commit 9c1d9c20 authored by Martin K. Petersen's avatar Martin K. Petersen

sd: Reject optimal transfer length smaller than page size

Eryu Guan reported that loading scsi_debug would fail. This turned out
to be caused by scsi_debug reporting an optimal I/O size of 32KB which
is smaller than the 64KB page size on the PowerPC system in question.

Add a check to ensure that we only use the device-reported OPTIMAL
TRANSFER LENGTH if it is bigger than or equal to the page cache size.
Reported-by: default avatarEryu Guan <guaneryu@gmail.com>
Reported-by: default avatarMing Lei <tom.leiming@gmail.com>
Reviewed-by: default avatarDouglas Gilbert <dgilbert@interlog.com>
Reviewed-by: default avatarEwan Milne <emilne@redhat.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 1c69d3b6
......@@ -2885,10 +2885,13 @@ static int sd_revalidate_disk(struct gendisk *disk)
/*
* Use the device's preferred I/O size for reads and writes
* unless the reported value is unreasonably large (or garbage).
* unless the reported value is unreasonably small, large, or
* garbage.
*/
if (sdkp->opt_xfer_blocks && sdkp->opt_xfer_blocks <= dev_max &&
sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS)
if (sdkp->opt_xfer_blocks &&
sdkp->opt_xfer_blocks <= dev_max &&
sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&
sdkp->opt_xfer_blocks * sdp->sector_size >= PAGE_CACHE_SIZE)
rw_max = q->limits.io_opt =
logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
else
......
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