aboutsummaryrefslogtreecommitdiffstats
path: root/block/bsg.c
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2009-05-07 09:24:37 -0400
committerJens Axboe <jens.axboe@oracle.com>2009-05-11 03:50:53 -0400
commitc3a4d78c580de4edc9ef0f7c59812fb02ceb037f (patch)
tree916ca44287100707508678e2cc0eff0c43b9ca39 /block/bsg.c
parent9720aef2539c10e3a872e9a92beec225030d99db (diff)
block: add rq->resid_len
rq->data_len served two purposes - the length of data buffer on issue and the residual count on completion. This duality creates some headaches. First of all, block layer and low level drivers can't really determine what rq->data_len contains while a request is executing. It could be the total request length or it coulde be anything else one of the lower layers is using to keep track of residual count. This complicates things because blk_rq_bytes() and thus [__]blk_end_request_all() relies on rq->data_len for PC commands. Drivers which want to report residual count should first cache the total request length, update rq->data_len and then complete the request with the cached data length. Secondly, it makes requests default to reporting full residual count, ie. reporting that no data transfer occurred. The residual count is an exception not the norm; however, the driver should clear rq->data_len to zero to signify the normal cases while leaving it alone means no data transfer occurred at all. This reverse default behavior complicates code unnecessarily and renders block PC on some drivers (ide-tape/floppy) unuseable. This patch adds rq->resid_len which is used only for residual count. While at it, remove now unnecessasry blk_rq_bytes() caching in ide_pc_intr() as rq->data_len is not changed anymore. Boaz : spotted missing conversion in osd Sergei : spotted too early conversion to blk_rq_bytes() in ide-tape [ Impact: cleanup residual count handling, report 0 resid by default ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Mike Miller <mike.miller@hp.com> Cc: Eric Moore <Eric.Moore@lsi.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Doug Gilbert <dgilbert@interlog.com> Cc: Mike Miller <mike.miller@hp.com> Cc: Eric Moore <Eric.Moore@lsi.com> Cc: Darrick J. Wong <djwong@us.ibm.com> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/bsg.c')
-rw-r--r--block/bsg.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/block/bsg.c b/block/bsg.c
index 206060e795da..2d746e34f4c2 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -445,14 +445,14 @@ static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
445 } 445 }
446 446
447 if (rq->next_rq) { 447 if (rq->next_rq) {
448 hdr->dout_resid = rq->data_len; 448 hdr->dout_resid = rq->resid_len;
449 hdr->din_resid = rq->next_rq->data_len; 449 hdr->din_resid = rq->next_rq->resid_len;
450 blk_rq_unmap_user(bidi_bio); 450 blk_rq_unmap_user(bidi_bio);
451 blk_put_request(rq->next_rq); 451 blk_put_request(rq->next_rq);
452 } else if (rq_data_dir(rq) == READ) 452 } else if (rq_data_dir(rq) == READ)
453 hdr->din_resid = rq->data_len; 453 hdr->din_resid = rq->resid_len;
454 else 454 else
455 hdr->dout_resid = rq->data_len; 455 hdr->dout_resid = rq->resid_len;
456 456
457 /* 457 /*
458 * If the request generated a negative error number, return it 458 * If the request generated a negative error number, return it