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author | Boaz Harrosh <bharrosh@panasas.com> | 2007-12-13 12:50:53 +0100 |
---|---|---|
committer | James Bottomley <James.Bottomley@HansenPartnership.com> | 2008-01-30 20:03:41 +0100 |
commit | 6f9a35e2dafa0f855ab051c11bdbf739745ff6f5 (patch) | |
tree | 5ca273c98b61a4d329653ef30faa2c0414eccd2b /drivers/scsi/scsi_lib.c | |
parent | [SCSI] implement scsi_data_buffer (diff) | |
download | linux-6f9a35e2dafa0f855ab051c11bdbf739745ff6f5.tar.xz linux-6f9a35e2dafa0f855ab051c11bdbf739745ff6f5.zip |
[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/scsi_lib.c')
-rw-r--r-- | drivers/scsi/scsi_lib.c | 106 |
1 files changed, 91 insertions, 15 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index d5e77e9b3a9c..681ed1b830f5 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -64,6 +64,8 @@ static struct scsi_host_sg_pool scsi_sg_pools[] = { }; #undef SP +static struct kmem_cache *scsi_bidi_sdb_cache; + static void scsi_run_queue(struct request_queue *q); /* @@ -790,10 +792,38 @@ void scsi_release_buffers(struct scsi_cmnd *cmd) scsi_free_sgtable(&cmd->sdb); memset(&cmd->sdb, 0, sizeof(cmd->sdb)); + + if (scsi_bidi_cmnd(cmd)) { + struct scsi_data_buffer *bidi_sdb = + cmd->request->next_rq->special; + scsi_free_sgtable(bidi_sdb); + kmem_cache_free(scsi_bidi_sdb_cache, bidi_sdb); + cmd->request->next_rq->special = NULL; + } } EXPORT_SYMBOL(scsi_release_buffers); /* + * Bidi commands Must be complete as a whole, both sides at once. + * If part of the bytes were written and lld returned + * scsi_in()->resid and/or scsi_out()->resid this information will be left + * in req->data_len and req->next_rq->data_len. The upper-layer driver can + * decide what to do with this information. + */ +void scsi_end_bidi_request(struct scsi_cmnd *cmd) +{ + blk_end_bidi_request(cmd->request, 0, scsi_out(cmd)->resid, + scsi_in(cmd)->resid); + scsi_release_buffers(cmd); + + /* + * This will goose the queue request function at the end, so we don't + * need to worry about launching another command. + */ + scsi_next_command(cmd); +} + +/* * Function: scsi_io_completion() * * Purpose: Completion processing for block device I/O requests. @@ -854,9 +884,15 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) req->sense_len = len; } } + if (scsi_bidi_cmnd(cmd)) { + /* will also release_buffers */ + scsi_end_bidi_request(cmd); + return; + } req->data_len = scsi_get_resid(cmd); } + BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */ scsi_release_buffers(cmd); /* @@ -982,28 +1018,16 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) scsi_end_request(cmd, -EIO, this_count, !result); } -/* - * Function: scsi_init_io() - * - * Purpose: SCSI I/O initialize function. - * - * Arguments: cmd - Command descriptor we wish to initialize - * - * Returns: 0 on success - * BLKPREP_DEFER if the failure is retryable - */ -int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) +static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb, + gfp_t gfp_mask) { - struct request *req = cmd->request; - int count; - struct scsi_data_buffer *sdb = &cmd->sdb; + int count; /* * If sg table allocation fails, requeue request later. */ if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments, gfp_mask))) { - scsi_unprep_request(req); return BLKPREP_DEFER; } @@ -1022,6 +1046,50 @@ int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) sdb->table.nents = count; return BLKPREP_OK; } + +/* + * Function: scsi_init_io() + * + * Purpose: SCSI I/O initialize function. + * + * Arguments: cmd - Command descriptor we wish to initialize + * + * Returns: 0 on success + * BLKPREP_DEFER if the failure is retryable + * BLKPREP_KILL if the failure is fatal + */ +int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) +{ + int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask); + if (error) + goto err_exit; + + if (blk_bidi_rq(cmd->request)) { + struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc( + scsi_bidi_sdb_cache, GFP_ATOMIC); + if (!bidi_sdb) { + error = BLKPREP_DEFER; + goto err_exit; + } + + cmd->request->next_rq->special = bidi_sdb; + error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb, + GFP_ATOMIC); + if (error) + goto err_exit; + } + + return BLKPREP_OK ; + +err_exit: + scsi_release_buffers(cmd); + if (error == BLKPREP_KILL) + scsi_put_command(cmd); + else /* BLKPREP_DEFER */ + scsi_unprep_request(cmd->request); + + return error; +} EXPORT_SYMBOL(scsi_init_io); static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev, @@ -1639,6 +1707,14 @@ int __init scsi_init_queue(void) return -ENOMEM; } + scsi_bidi_sdb_cache = kmem_cache_create("scsi_bidi_sdb", + sizeof(struct scsi_data_buffer), + 0, 0, NULL); + if (!scsi_bidi_sdb_cache) { + printk(KERN_ERR "SCSI: can't init scsi bidi sdb cache\n"); + return -ENOMEM; + } + for (i = 0; i < SG_MEMPOOL_NR; i++) { struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; int size = sgp->size * sizeof(struct scatterlist); |