From 6f9a35e2dafa0f855ab051c11bdbf739745ff6f5 Mon Sep 17 00:00:00 2001 From: Boaz Harrosh Date: Thu, 13 Dec 2007 13:50:53 +0200 Subject: [PATCH] [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 Signed-off-by: James Bottomley --- drivers/scsi/scsi_error.c | 3 ++ drivers/scsi/scsi_lib.c | 106 ++++++++++++++++++++++++++++++++------ include/scsi/scsi_cmnd.h | 19 ++++++- include/scsi/scsi_eh.h | 1 + 4 files changed, 113 insertions(+), 16 deletions(-) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 4f4edc388c0..045a0868fc7 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -618,9 +618,11 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses, memcpy(ses->cmnd, scmd->cmnd, sizeof(scmd->cmnd)); ses->data_direction = scmd->sc_data_direction; ses->sdb = scmd->sdb; + ses->next_rq = scmd->request->next_rq; ses->result = scmd->result; memset(&scmd->sdb, 0, sizeof(scmd->sdb)); + scmd->request->next_rq = NULL; if (sense_bytes) { scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE, @@ -673,6 +675,7 @@ void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses) memcpy(scmd->cmnd, ses->cmnd, sizeof(scmd->cmnd)); scmd->sc_data_direction = ses->data_direction; scmd->sdb = ses->sdb; + scmd->request->next_rq = ses->next_rq; scmd->result = ses->result; } EXPORT_SYMBOL(scsi_eh_restore_cmnd); diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index d5e77e9b3a9..681ed1b830f 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); /* @@ -790,9 +792,37 @@ 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() * @@ -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); diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index c6478bb6f96..de28aab820b 100644 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -2,12 +2,12 @@ #define _SCSI_SCSI_CMND_H #include +#include #include #include #include #include -struct request; struct Scsi_Host; struct scsi_device; @@ -158,4 +158,21 @@ static inline int scsi_get_resid(struct scsi_cmnd *cmd) #define scsi_for_each_sg(cmd, sg, nseg, __i) \ for_each_sg(scsi_sglist(cmd), sg, nseg, __i) +static inline int scsi_bidi_cmnd(struct scsi_cmnd *cmd) +{ + return blk_bidi_rq(cmd->request) && + (cmd->request->next_rq->special != NULL); +} + +static inline struct scsi_data_buffer *scsi_in(struct scsi_cmnd *cmd) +{ + return scsi_bidi_cmnd(cmd) ? + cmd->request->next_rq->special : &cmd->sdb; +} + +static inline struct scsi_data_buffer *scsi_out(struct scsi_cmnd *cmd) +{ + return &cmd->sdb; +} + #endif /* _SCSI_SCSI_CMND_H */ diff --git a/include/scsi/scsi_eh.h b/include/scsi/scsi_eh.h index 1e08be1466e..25071d5d9bf 100644 --- a/include/scsi/scsi_eh.h +++ b/include/scsi/scsi_eh.h @@ -74,6 +74,7 @@ struct scsi_eh_save { unsigned char cmd_len; unsigned char cmnd[MAX_COMMAND_SIZE]; struct scsi_data_buffer sdb; + struct request *next_rq; /* new command support */ struct scatterlist sense_sgl; -- 2.41.1