diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2010-02-26 11:49:39 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-03-02 14:55:07 -0800 |
| commit | 49d6271b85a3e18062eaf4d6f8d899abe00a7725 (patch) | |
| tree | 83b92caacf276bdd054a03320fd6f48cbe96c562 | |
| parent | efe7daf2231a6beb59f0f641461d19fa62fb83ab (diff) | |
usb-storage: use max_hw_sectors instead of max_sectors
This patch (as1347) makes some adjustments to the way usb-storage
handles the request-queue parameters.
USB host controllers are able to handle arbitrarily long
scatter-gather lists, since they are limited only by main memory and
not by the controller hardware. Hence the sg_tablesize field in the
host template can be increased to the maximum value.
Drivers like usb-storage aren't supposed to touch the queue's
max_sectors parameter; instead they are supposed to use the
max_hw_sectors value. Accordingly, the patch replaces calls of
queue_max_sectors() with calls of queue_max_hw_sectors(). Oddly
enough, the blk_queue_max_sectors() routine is nevertheless still
appropriate.
The existing code imposes a limit of SCSI_DEFAULT_MAX_SECTORS (1024)
on the values accepted by the max_sectors attribute file. There's no
reason not to accept larger values, so the limit is removed. (It
would be nice to change the file's name to max_hw_sectors, but the old
name is already a well-established API.)
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/usb/storage/scsiglue.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c index aadc16b5eed..4cc035562cc 100644 --- a/drivers/usb/storage/scsiglue.c +++ b/drivers/usb/storage/scsiglue.c @@ -133,7 +133,7 @@ static int slave_configure(struct scsi_device *sdev) if (us->fflags & US_FL_MAX_SECTORS_MIN) max_sectors = PAGE_CACHE_SIZE >> 9; - if (queue_max_sectors(sdev->request_queue) > max_sectors) + if (queue_max_hw_sectors(sdev->request_queue) > max_sectors) blk_queue_max_hw_sectors(sdev->request_queue, max_sectors); } else if (sdev->type == TYPE_TAPE) { @@ -484,7 +484,7 @@ static ssize_t show_max_sectors(struct device *dev, struct device_attribute *att { struct scsi_device *sdev = to_scsi_device(dev); - return sprintf(buf, "%u\n", queue_max_sectors(sdev->request_queue)); + return sprintf(buf, "%u\n", queue_max_hw_sectors(sdev->request_queue)); } /* Input routine for the sysfs max_sectors file */ @@ -494,9 +494,9 @@ static ssize_t store_max_sectors(struct device *dev, struct device_attribute *at struct scsi_device *sdev = to_scsi_device(dev); unsigned short ms; - if (sscanf(buf, "%hu", &ms) > 0 && ms <= SCSI_DEFAULT_MAX_SECTORS) { + if (sscanf(buf, "%hu", &ms) > 0) { blk_queue_max_hw_sectors(sdev->request_queue, ms); - return strlen(buf); + return count; } return -EINVAL; } @@ -539,7 +539,7 @@ struct scsi_host_template usb_stor_host_template = { .slave_configure = slave_configure, /* lots of sg segments can be handled */ - .sg_tablesize = SG_ALL, + .sg_tablesize = SCSI_MAX_SG_CHAIN_SEGMENTS, /* limit the total size of a transfer to 120 KB */ .max_sectors = 240, |