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authorMike Christie <michaelc@cs.wisc.edu>2011-07-31 22:05:09 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-07-31 22:05:09 +0200
commitaa387cc895672b00f807ad7c734a2defaf677712 (patch)
tree31c2c3f3e0d58ff2524cdf8f94abecc394f5eb49 /block/bsg-lib.c
parent24c3047095fa3954f114bfff2e37b8fcbb216396 (diff)
downloadlinux-stericsson-aa387cc895672b00f807ad7c734a2defaf677712.tar.gz
block: add bsg helper library
This moves the FC classes bsg code to the block layer and makes it a lib so that other classes like iscsi and SAS can use it. It is helpful because working with the request queue, bios, creating scatterlists, etc are a pain that the LLD does not have to worry about with normal IOs and should not have to worry about for bsg requests. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block/bsg-lib.c')
-rw-r--r--block/bsg-lib.c297
1 files changed, 297 insertions, 0 deletions
diff --git a/block/bsg-lib.c b/block/bsg-lib.c
new file mode 100644
index 000000000000..f8c0a61a529c
--- /dev/null
+++ b/block/bsg-lib.c
@@ -0,0 +1,297 @@
+/*
+ * BSG helper library
+ *
+ * Copyright (C) 2008 James Smart, Emulex Corporation
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2011 Mike Christie
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/scatterlist.h>
+#include <linux/bsg-lib.h>
+#include <scsi/scsi_cmnd.h>
+
+/**
+ * bsg_destroy_job - routine to teardown/delete a bsg job
+ * @job: bsg_job that is to be torn down
+ */
+static void bsg_destroy_job(struct bsg_job *job)
+{
+ put_device(job->dev); /* release reference for the request */
+
+ kfree(job->request_payload.sg_list);
+ kfree(job->reply_payload.sg_list);
+ kfree(job);
+}
+
+/**
+ * bsg_job_done - completion routine for bsg requests
+ * @job: bsg_job that is complete
+ * @result: job reply result
+ * @reply_payload_rcv_len: length of payload recvd
+ *
+ * The LLD should call this when the bsg job has completed.
+ */
+void bsg_job_done(struct bsg_job *job, int result,
+ unsigned int reply_payload_rcv_len)
+{
+ struct request *req = job->req;
+ struct request *rsp = req->next_rq;
+ int err;
+
+ err = job->req->errors = result;
+ if (err < 0)
+ /* we're only returning the result field in the reply */
+ job->req->sense_len = sizeof(u32);
+ else
+ job->req->sense_len = job->reply_len;
+ /* we assume all request payload was transferred, residual == 0 */
+ req->resid_len = 0;
+
+ if (rsp) {
+ WARN_ON(reply_payload_rcv_len > rsp->resid_len);
+
+ /* set reply (bidi) residual */
+ rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
+ }
+ blk_complete_request(req);
+}
+EXPORT_SYMBOL_GPL(bsg_job_done);
+
+/**
+ * bsg_softirq_done - softirq done routine for destroying the bsg requests
+ * @rq: BSG request that holds the job to be destroyed
+ */
+static void bsg_softirq_done(struct request *rq)
+{
+ struct bsg_job *job = rq->special;
+
+ blk_end_request_all(rq, rq->errors);
+ bsg_destroy_job(job);
+}
+
+static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
+{
+ size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
+
+ BUG_ON(!req->nr_phys_segments);
+
+ buf->sg_list = kzalloc(sz, GFP_KERNEL);
+ if (!buf->sg_list)
+ return -ENOMEM;
+ sg_init_table(buf->sg_list, req->nr_phys_segments);
+ buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
+ buf->payload_len = blk_rq_bytes(req);
+ return 0;
+}
+
+/**
+ * bsg_create_job - create the bsg_job structure for the bsg request
+ * @dev: device that is being sent the bsg request
+ * @req: BSG request that needs a job structure
+ */
+static int bsg_create_job(struct device *dev, struct request *req)
+{
+ struct request *rsp = req->next_rq;
+ struct request_queue *q = req->q;
+ struct bsg_job *job;
+ int ret;
+
+ BUG_ON(req->special);
+
+ job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
+ if (!job)
+ return -ENOMEM;
+
+ req->special = job;
+ job->req = req;
+ if (q->bsg_job_size)
+ job->dd_data = (void *)&job[1];
+ job->request = req->cmd;
+ job->request_len = req->cmd_len;
+ job->reply = req->sense;
+ job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
+ * allocated */
+ if (req->bio) {
+ ret = bsg_map_buffer(&job->request_payload, req);
+ if (ret)
+ goto failjob_rls_job;
+ }
+ if (rsp && rsp->bio) {
+ ret = bsg_map_buffer(&job->reply_payload, rsp);
+ if (ret)
+ goto failjob_rls_rqst_payload;
+ }
+ job->dev = dev;
+ /* take a reference for the request */
+ get_device(job->dev);
+ return 0;
+
+failjob_rls_rqst_payload:
+ kfree(job->request_payload.sg_list);
+failjob_rls_job:
+ kfree(job);
+ return -ENOMEM;
+}
+
+/*
+ * bsg_goose_queue - restart queue in case it was stopped
+ * @q: request q to be restarted
+ */
+void bsg_goose_queue(struct request_queue *q)
+{
+ if (!q)
+ return;
+
+ blk_run_queue_async(q);
+}
+EXPORT_SYMBOL_GPL(bsg_goose_queue);
+
+/**
+ * bsg_request_fn - generic handler for bsg requests
+ * @q: request queue to manage
+ *
+ * On error the create_bsg_job function should return a -Exyz error value
+ * that will be set to the req->errors.
+ *
+ * Drivers/subsys should pass this to the queue init function.
+ */
+void bsg_request_fn(struct request_queue *q)
+{
+ struct device *dev = q->queuedata;
+ struct request *req;
+ struct bsg_job *job;
+ int ret;
+
+ if (!get_device(dev))
+ return;
+
+ while (1) {
+ req = blk_fetch_request(q);
+ if (!req)
+ break;
+ spin_unlock_irq(q->queue_lock);
+
+ ret = bsg_create_job(dev, req);
+ if (ret) {
+ req->errors = ret;
+ blk_end_request_all(req, ret);
+ spin_lock_irq(q->queue_lock);
+ continue;
+ }
+
+ job = req->special;
+ ret = q->bsg_job_fn(job);
+ spin_lock_irq(q->queue_lock);
+ if (ret)
+ break;
+ }
+
+ spin_unlock_irq(q->queue_lock);
+ put_device(dev);
+ spin_lock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL_GPL(bsg_request_fn);
+
+/**
+ * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
+ * @dev: device to attach bsg device to
+ * @q: request queue setup by caller
+ * @name: device to give bsg device
+ * @job_fn: bsg job handler
+ * @dd_job_size: size of LLD data needed for each job
+ *
+ * The caller should have setup the reuqest queue with bsg_request_fn
+ * as the request_fn.
+ */
+int bsg_setup_queue(struct device *dev, struct request_queue *q,
+ char *name, bsg_job_fn *job_fn, int dd_job_size)
+{
+ int ret;
+
+ q->queuedata = dev;
+ q->bsg_job_size = dd_job_size;
+ q->bsg_job_fn = job_fn;
+ queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
+ blk_queue_softirq_done(q, bsg_softirq_done);
+ blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
+
+ ret = bsg_register_queue(q, dev, name, NULL);
+ if (ret) {
+ printk(KERN_ERR "%s: bsg interface failed to "
+ "initialize - register queue\n", dev->kobj.name);
+ return ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(bsg_setup_queue);
+
+/**
+ * bsg_remove_queue - Deletes the bsg dev from the q
+ * @q: the request_queue that is to be torn down.
+ *
+ * Notes:
+ * Before unregistering the queue empty any requests that are blocked
+ */
+void bsg_remove_queue(struct request_queue *q)
+{
+ struct request *req; /* block request */
+ int counts; /* totals for request_list count and starved */
+
+ if (!q)
+ return;
+
+ /* Stop taking in new requests */
+ spin_lock_irq(q->queue_lock);
+ blk_stop_queue(q);
+
+ /* drain all requests in the queue */
+ while (1) {
+ /* need the lock to fetch a request
+ * this may fetch the same reqeust as the previous pass
+ */
+ req = blk_fetch_request(q);
+ /* save requests in use and starved */
+ counts = q->rq.count[0] + q->rq.count[1] +
+ q->rq.starved[0] + q->rq.starved[1];
+ spin_unlock_irq(q->queue_lock);
+ /* any requests still outstanding? */
+ if (counts == 0)
+ break;
+
+ /* This may be the same req as the previous iteration,
+ * always send the blk_end_request_all after a prefetch.
+ * It is not okay to not end the request because the
+ * prefetch started the request.
+ */
+ if (req) {
+ /* return -ENXIO to indicate that this queue is
+ * going away
+ */
+ req->errors = -ENXIO;
+ blk_end_request_all(req, -ENXIO);
+ }
+
+ msleep(200); /* allow bsg to possibly finish */
+ spin_lock_irq(q->queue_lock);
+ }
+ bsg_unregister_queue(q);
+}
+EXPORT_SYMBOL_GPL(bsg_remove_queue);