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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 /include
parent40b01b9bbdf51ae543a04744283bf2d56c4a6afa (diff)
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 'include')
-rw-r--r--include/linux/blkdev.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e1888cc5b8a..f1fe9fbf1c0 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -216,6 +216,7 @@ struct request {
unsigned int cmd_len;
unsigned char cmd[BLK_MAX_CDB];
+ unsigned int raw_data_len;
unsigned int data_len;
unsigned int sense_len;
void *data;