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author | Boaz Harrosh <bharrosh@panasas.com> | 2007-12-13 13:50:53 +0200 |
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committer | James Bottomley <James.Bottomley@HansenPartnership.com> | 2008-01-30 13:03:41 -0600 |
commit | 6f9a35e2dafa0f855ab051c11bdbf739745ff6f5 (patch) | |
tree | 5ca273c98b61a4d329653ef30faa2c0414eccd2b /drivers/scsi/wd7000.c | |
parent | 30b0c37b27485a9cb897bfe3824f6f517b8c80d6 (diff) | |
download | op-kernel-dev-6f9a35e2dafa0f855ab051c11bdbf739745ff6f5.zip op-kernel-dev-6f9a35e2dafa0f855ab051c11bdbf739745ff6f5.tar.gz |
[SCSI] bidirectional command support
At the block level bidi request uses req->next_rq pointer for a second
bidi_read request.
At Scsi-midlayer a second scsi_data_buffer structure is used for the
bidi_read part. This bidi scsi_data_buffer is put on
request->next_rq->special. Struct scsi_cmnd is not changed.
- Define scsi_bidi_cmnd() to return true if it is a bidi request and a
second sgtable was allocated.
- Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer
from this command This API is to isolate users from the mechanics of
bidi.
- Define scsi_end_bidi_request() to do what scsi_end_request() does but
for a bidi request. This is necessary because bidi commands are a bit
tricky here. (See comments in body)
- scsi_release_buffers() will also release the bidi_read scsi_data_buffer
- scsi_io_completion() on bidi commands will now call
scsi_end_bidi_request() and return.
- The previous work done in scsi_init_io() is now done in a new
scsi_init_sgtable() (which is 99% identical to old scsi_init_io())
The new scsi_init_io() will call the above twice if needed also for
the bidi_read command. Only at this point is a command bidi.
- In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not
confused by a get-sense command that looks like bidi. This is done
by puting NULL at request->next_rq, and restoring.
[jejb: update to sg_table and resolve conflicts
also update to blk-end-request and resolve conflicts]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Diffstat (limited to 'drivers/scsi/wd7000.c')
0 files changed, 0 insertions, 0 deletions