diff options
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 313 |
1 files changed, 166 insertions, 147 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 743f67ed764..ee35a62bb7a 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -995,25 +995,14 @@ static int scsi_init_io(struct scsi_cmnd *cmd) int count; /* - * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer - */ - if (blk_pc_request(req) && !req->bio) { - cmd->request_bufflen = req->data_len; - cmd->request_buffer = req->data; - req->buffer = req->data; - cmd->use_sg = 0; - return 0; - } - - /* - * we used to not use scatter-gather for single segment request, + * We used to not use scatter-gather for single segment request, * but now we do (it makes highmem I/O easier to support without * kmapping pages) */ cmd->use_sg = req->nr_phys_segments; /* - * if sg table allocation fails, requeue request later. + * If sg table allocation fails, requeue request later. */ sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC); if (unlikely(!sgpnt)) { @@ -1021,24 +1010,21 @@ static int scsi_init_io(struct scsi_cmnd *cmd) return BLKPREP_DEFER; } + req->buffer = NULL; cmd->request_buffer = (char *) sgpnt; - cmd->request_bufflen = req->nr_sectors << 9; if (blk_pc_request(req)) cmd->request_bufflen = req->data_len; - req->buffer = NULL; + else + cmd->request_bufflen = req->nr_sectors << 9; /* * Next, walk the list, and fill in the addresses and sizes of * each segment. */ count = blk_rq_map_sg(req->q, req, cmd->request_buffer); - - /* - * mapped well, send it off - */ if (likely(count <= cmd->use_sg)) { cmd->use_sg = count; - return 0; + return BLKPREP_OK; } printk(KERN_ERR "Incorrect number of segments after building list\n"); @@ -1068,6 +1054,27 @@ static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk, return -EOPNOTSUPP; } +static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev, + struct request *req) +{ + struct scsi_cmnd *cmd; + + if (!req->special) { + cmd = scsi_get_command(sdev, GFP_ATOMIC); + if (unlikely(!cmd)) + return NULL; + req->special = cmd; + } else { + cmd = req->special; + } + + /* pull a tag out of the request if we have one */ + cmd->tag = req->tag; + cmd->request = req; + + return cmd; +} + static void scsi_blk_pc_done(struct scsi_cmnd *cmd) { BUG_ON(!blk_pc_request(cmd->request)); @@ -1080,9 +1087,37 @@ static void scsi_blk_pc_done(struct scsi_cmnd *cmd) scsi_io_completion(cmd, cmd->request_bufflen); } -static void scsi_setup_blk_pc_cmnd(struct scsi_cmnd *cmd) +static int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req) { - struct request *req = cmd->request; + struct scsi_cmnd *cmd; + + cmd = scsi_get_cmd_from_req(sdev, req); + if (unlikely(!cmd)) + return BLKPREP_DEFER; + + /* + * BLOCK_PC requests may transfer data, in which case they must + * a bio attached to them. Or they might contain a SCSI command + * that does not transfer data, in which case they may optionally + * submit a request without an attached bio. + */ + if (req->bio) { + int ret; + + BUG_ON(!req->nr_phys_segments); + + ret = scsi_init_io(cmd); + if (unlikely(ret)) + return ret; + } else { + BUG_ON(req->data_len); + BUG_ON(req->data); + + cmd->request_bufflen = 0; + cmd->request_buffer = NULL; + cmd->use_sg = 0; + req->buffer = NULL; + } BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd)); memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd)); @@ -1098,154 +1133,138 @@ static void scsi_setup_blk_pc_cmnd(struct scsi_cmnd *cmd) cmd->allowed = req->retries; cmd->timeout_per_command = req->timeout; cmd->done = scsi_blk_pc_done; + return BLKPREP_OK; } -static int scsi_prep_fn(struct request_queue *q, struct request *req) +/* + * Setup a REQ_TYPE_FS command. These are simple read/write request + * from filesystems that still need to be translated to SCSI CDBs from + * the ULD. + */ +static int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req) { - struct scsi_device *sdev = q->queuedata; struct scsi_cmnd *cmd; - int specials_only = 0; + struct scsi_driver *drv; + int ret; /* - * Just check to see if the device is online. If it isn't, we - * refuse to process any commands. The device must be brought - * online before trying any recovery commands + * Filesystem requests must transfer data. */ - if (unlikely(!scsi_device_online(sdev))) { - sdev_printk(KERN_ERR, sdev, - "rejecting I/O to offline device\n"); - goto kill; - } - if (unlikely(sdev->sdev_state != SDEV_RUNNING)) { - /* OK, we're not in a running state don't prep - * user commands */ - if (sdev->sdev_state == SDEV_DEL) { - /* Device is fully deleted, no commands - * at all allowed down */ - sdev_printk(KERN_ERR, sdev, - "rejecting I/O to dead device\n"); - goto kill; - } - /* OK, we only allow special commands (i.e. not - * user initiated ones */ - specials_only = sdev->sdev_state; + BUG_ON(!req->nr_phys_segments); + + cmd = scsi_get_cmd_from_req(sdev, req); + if (unlikely(!cmd)) + return BLKPREP_DEFER; + + ret = scsi_init_io(cmd); + if (unlikely(ret)) + return ret; + + /* + * Initialize the actual SCSI command for this request. + */ + drv = *(struct scsi_driver **)req->rq_disk->private_data; + if (unlikely(!drv->init_command(cmd))) { + scsi_release_buffers(cmd); + scsi_put_command(cmd); + return BLKPREP_KILL; } + return BLKPREP_OK; +} + +static int scsi_prep_fn(struct request_queue *q, struct request *req) +{ + struct scsi_device *sdev = q->queuedata; + int ret = BLKPREP_OK; + /* - * Find the actual device driver associated with this command. - * The SPECIAL requests are things like character device or - * ioctls, which did not originate from ll_rw_blk. Note that - * the special field is also used to indicate the cmd for - * the remainder of a partially fulfilled request that can - * come up when there is a medium error. We have to treat - * these two cases differently. We differentiate by looking - * at request->cmd, as this tells us the real story. + * If the device is not in running state we will reject some + * or all commands. */ - if (blk_special_request(req) && req->special) - cmd = req->special; - else if (blk_pc_request(req) || blk_fs_request(req)) { - if (unlikely(specials_only) && !(req->cmd_flags & REQ_PREEMPT)){ - if (specials_only == SDEV_QUIESCE || - specials_only == SDEV_BLOCK) - goto defer; - + if (unlikely(sdev->sdev_state != SDEV_RUNNING)) { + switch (sdev->sdev_state) { + case SDEV_OFFLINE: + /* + * If the device is offline we refuse to process any + * commands. The device must be brought online + * before trying any recovery commands. + */ sdev_printk(KERN_ERR, sdev, - "rejecting I/O to device being removed\n"); - goto kill; + "rejecting I/O to offline device\n"); + ret = BLKPREP_KILL; + break; + case SDEV_DEL: + /* + * If the device is fully deleted, we refuse to + * process any commands as well. + */ + sdev_printk(KERN_ERR, sdev, + "rejecting I/O to dead device\n"); + ret = BLKPREP_KILL; + break; + case SDEV_QUIESCE: + case SDEV_BLOCK: + /* + * If the devices is blocked we defer normal commands. + */ + if (!(req->cmd_flags & REQ_PREEMPT)) + ret = BLKPREP_DEFER; + break; + default: + /* + * For any other not fully online state we only allow + * special commands. In particular any user initiated + * command is not allowed. + */ + if (!(req->cmd_flags & REQ_PREEMPT)) + ret = BLKPREP_KILL; + break; } - - /* - * Now try and find a command block that we can use. - */ - if (!req->special) { - cmd = scsi_get_command(sdev, GFP_ATOMIC); - if (unlikely(!cmd)) - goto defer; - } else - cmd = req->special; - - /* pull a tag out of the request if we have one */ - cmd->tag = req->tag; - } else { - blk_dump_rq_flags(req, "SCSI bad req"); - goto kill; + + if (ret != BLKPREP_OK) + goto out; } - - /* note the overloading of req->special. When the tag - * is active it always means cmd. If the tag goes - * back for re-queueing, it may be reset */ - req->special = cmd; - cmd->request = req; - - /* - * FIXME: drop the lock here because the functions below - * expect to be called without the queue lock held. Also, - * previously, we dequeued the request before dropping the - * lock. We hope REQ_STARTED prevents anything untoward from - * happening now. - */ - if (blk_fs_request(req) || blk_pc_request(req)) { - int ret; + switch (req->cmd_type) { + case REQ_TYPE_BLOCK_PC: + ret = scsi_setup_blk_pc_cmnd(sdev, req); + break; + case REQ_TYPE_FS: + ret = scsi_setup_fs_cmnd(sdev, req); + break; + default: /* - * This will do a couple of things: - * 1) Fill in the actual SCSI command. - * 2) Fill in any other upper-level specific fields - * (timeout). + * All other command types are not supported. * - * If this returns 0, it means that the request failed - * (reading past end of disk, reading offline device, - * etc). This won't actually talk to the device, but - * some kinds of consistency checking may cause the - * request to be rejected immediately. + * Note that these days the SCSI subsystem does not use + * REQ_TYPE_SPECIAL requests anymore. These are only used + * (directly or via blk_insert_request) by non-SCSI drivers. */ + blk_dump_rq_flags(req, "SCSI bad req"); + ret = BLKPREP_KILL; + break; + } - /* - * This sets up the scatter-gather table (allocating if - * required). - */ - ret = scsi_init_io(cmd); - switch(ret) { - /* For BLKPREP_KILL/DEFER the cmd was released */ - case BLKPREP_KILL: - goto kill; - case BLKPREP_DEFER: - goto defer; - } - + out: + switch (ret) { + case BLKPREP_KILL: + req->errors = DID_NO_CONNECT << 16; + break; + case BLKPREP_DEFER: /* - * Initialize the actual SCSI command for this request. + * If we defer, the elv_next_request() returns NULL, but the + * queue must be restarted, so we plug here if no returning + * command will automatically do that. */ - if (blk_pc_request(req)) { - scsi_setup_blk_pc_cmnd(cmd); - } else if (req->rq_disk) { - struct scsi_driver *drv; - - drv = *(struct scsi_driver **)req->rq_disk->private_data; - if (unlikely(!drv->init_command(cmd))) { - scsi_release_buffers(cmd); - scsi_put_command(cmd); - goto kill; - } - } + if (sdev->device_busy == 0) + blk_plug_device(q); + break; + default: + req->cmd_flags |= REQ_DONTPREP; } - /* - * The request is now prepped, no need to come back here - */ - req->cmd_flags |= REQ_DONTPREP; - return BLKPREP_OK; - - defer: - /* If we defer, the elv_next_request() returns NULL, but the - * queue must be restarted, so we plug here if no returning - * command will automatically do that. */ - if (sdev->device_busy == 0) - blk_plug_device(q); - return BLKPREP_DEFER; - kill: - req->errors = DID_NO_CONNECT << 16; - return BLKPREP_KILL; + return ret; } /* |