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authorTejun Heo <htejun@gmail.com>2008-02-19 11:36:35 +0100
committerJens Axboe <jens.axboe@oracle.com>2008-02-19 11:36:35 +0100
commit6b00769fe1502b4ad97bb327ef7ac971b208bfb5 (patch)
tree2ffc51176437ebf4f8a4ab13de59a32431043f15 /drivers/scsi/scsi_lib.c
parentblock: update bio according to DMA alignment padding (diff)
downloadlinux-6b00769fe1502b4ad97bb327ef7ac971b208bfb5.tar.xz
linux-6b00769fe1502b4ad97bb327ef7ac971b208bfb5.zip
block: add request->raw_data_len
With padding and draining moved into it, block layer now may extend requests as directed by queue parameters, so now a request has two sizes - the original request size and the extended size which matches the size of area pointed to by bios and later by sgs. The latter size is what lower layers are primarily interested in when allocating, filling up DMA tables and setting up the controller. Both padding and draining extend the data area to accomodate controller characteristics. As any controller which speaks SCSI can handle underflows, feeding larger data area is safe. So, this patch makes the primary data length field, request->data_len, indicate the size of full data area and add a separate length field, request->raw_data_len, for the unmodified request size. The latter is used to report to higher layer (userland) and where the original request size should be fed to the controller or device. Signed-off-by: Tejun Heo <htejun@gmail.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 135c1d054701..ba21d97d1855 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1014,10 +1014,6 @@ static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
}
req->buffer = NULL;
- if (blk_pc_request(req))
- sdb->length = req->data_len;
- else
- sdb->length = req->nr_sectors << 9;
/*
* Next, walk the list, and fill in the addresses and sizes of
@@ -1026,6 +1022,10 @@ static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
BUG_ON(count > sdb->table.nents);
sdb->table.nents = count;
+ if (blk_pc_request(req))
+ sdb->length = req->data_len;
+ else
+ sdb->length = req->nr_sectors << 9;
return BLKPREP_OK;
}