[SCSI] Convert SCSI mid-layer to scsi_execute_async

Add scsi helpers to create really-large-requests and convert
scsi-ml to scsi_execute_async().

Per Jens's previous comments, I placed this function in scsi_lib.c.
I made it follow all the queue's limits - I think I did at least :), so
I removed the warning on the function header.

I think the scsi_execute_* functions should eventually take a request_queue
and be placed some place where the dm-multipath hw_handler can use them
if that failover code is going to stay in the kernel. That conversion
patch will be sent in another mail though.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

6 files changed, 233 insertions, 73 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 18c5d2523014..53ea62d3b53d 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1315,23 +1315,6 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
 }
 
 /**
- * scsi_eh_lock_done - done function for eh door lock request
- * @scmd:       SCSI command block for the door lock request
- *
- * Notes:
- *      We completed the asynchronous door lock request, and it has either
- *      locked the door or failed.  We must free the command structures
- *      associated with this request.
- **/
-static void scsi_eh_lock_done(struct scsi_cmnd *scmd)
-{
-        struct scsi_request *sreq = scmd->sc_request;
-
-        scsi_release_request(sreq);
-}
-
-
-/**
  * scsi_eh_lock_door - Prevent medium removal for the specified device
  * @sdev:       SCSI device to prevent medium removal
  *
@@ -1353,29 +1336,17 @@ static void scsi_eh_lock_done(struct scsi_cmnd *scmd)
  **/
 static void scsi_eh_lock_door(struct scsi_device *sdev)
 {
-        struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
+        unsigned char cmnd[MAX_COMMAND_SIZE];
 
-        if (unlikely(!sreq)) {
-                printk(KERN_ERR "%s: request allocate failed,"
-                       "prevent media removal cmd not sent\n", __FUNCTION__);
-                return;
-        }
+        cmnd[0] = ALLOW_MEDIUM_REMOVAL;
+        cmnd[1] = 0;
+        cmnd[2] = 0;
+        cmnd[3] = 0;
+        cmnd[4] = SCSI_REMOVAL_PREVENT;
+        cmnd[5] = 0;
 
-        sreq->sr_cmnd[0] = ALLOW_MEDIUM_REMOVAL;
-        sreq->sr_cmnd[1] = 0;
-        sreq->sr_cmnd[2] = 0;
-        sreq->sr_cmnd[3] = 0;
-        sreq->sr_cmnd[4] = SCSI_REMOVAL_PREVENT;
-        sreq->sr_cmnd[5] = 0;
-        sreq->sr_data_direction = DMA_NONE;
-        sreq->sr_bufflen = 0;
-        sreq->sr_buffer = NULL;
-        sreq->sr_allowed = 5;
-        sreq->sr_done = scsi_eh_lock_done;
-        sreq->sr_timeout_per_command = 10 * HZ;
-        sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
-
-        scsi_insert_special_req(sreq, 1);
+        scsi_execute_async(sdev, cmnd, DMA_NONE, NULL, 0, 0, 10 * HZ,
+                           5, NULL, NULL, GFP_KERNEL);
 }
 
 
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 1f2782767ca9..eb0cfbfbcf8f 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -63,39 +63,6 @@ static struct scsi_host_sg_pool scsi_sg_pools[] = {
 };      
 #undef SP
 
-
-/*
- * Function:    scsi_insert_special_req()
- *
- * Purpose:     Insert pre-formed request into request queue.
- *
- * Arguments:   sreq    - request that is ready to be queued.
- *              at_head - boolean.  True if we should insert at head
- *                        of queue, false if we should insert at tail.
- *
- * Lock status: Assumed that lock is not held upon entry.
- *
- * Returns:     Nothing
- *
- * Notes:       This function is called from character device and from
- *              ioctl types of functions where the caller knows exactly
- *              what SCSI command needs to be issued.   The idea is that
- *              we merely inject the command into the queue (at the head
- *              for now), and then call the queue request function to actually
- *              process it.
- */
-int scsi_insert_special_req(struct scsi_request *sreq, int at_head)
-{
-        /*
-         * Because users of this function are apt to reuse requests with no
-         * modification, we have to sanitise the request flags here
-         */
-        sreq->sr_request->flags &= ~REQ_DONTPREP;
-        blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
-                           at_head, sreq);
-        return 0;
-}
-
 static void scsi_run_queue(struct request_queue *q);
 
 /*
@@ -249,8 +216,13 @@ void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
 
         /*
          * head injection *required* here otherwise quiesce won't work
+         *
+         * Because users of this function are apt to reuse requests with no
+         * modification, we have to sanitise the request flags here
          */
-        scsi_insert_special_req(sreq, 1);
+        sreq->sr_request->flags &= ~REQ_DONTPREP;
+        blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
+                           1, sreq);
 }
 EXPORT_SYMBOL(scsi_do_req);
 
@@ -327,6 +299,196 @@ int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
 }
 EXPORT_SYMBOL(scsi_execute_req);
 
+struct scsi_io_context {
+        void *data;
+        void (*done)(void *data, char *sense, int result, int resid);
+        char sense[SCSI_SENSE_BUFFERSIZE];
+};
+
+static void scsi_end_async(struct request *req)
+{
+        struct scsi_io_context *sioc = req->end_io_data;
+
+        if (sioc->done)
+                sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
+
+        kfree(sioc);
+        __blk_put_request(req->q, req);
+}
+
+static int scsi_merge_bio(struct request *rq, struct bio *bio)
+{
+        struct request_queue *q = rq->q;
+
+        bio->bi_flags &= ~(1 << BIO_SEG_VALID);
+        if (rq_data_dir(rq) == WRITE)
+                bio->bi_rw |= (1 << BIO_RW);
+        blk_queue_bounce(q, &bio);
+
+        if (!rq->bio)
+                blk_rq_bio_prep(q, rq, bio);
+        else if (!q->back_merge_fn(q, rq, bio))
+                return -EINVAL;
+        else {
+                rq->biotail->bi_next = bio;
+                rq->biotail = bio;
+                rq->hard_nr_sectors += bio_sectors(bio);
+                rq->nr_sectors = rq->hard_nr_sectors;
+        }
+
+        return 0;
+}
+
+static int scsi_bi_endio(struct bio *bio, unsigned int bytes_done, int error)
+{
+        if (bio->bi_size)
+                return 1;
+
+        bio_put(bio);
+        return 0;
+}
+
+/**
+ * scsi_req_map_sg - map a scatterlist into a request
+ * @rq:         request to fill
+ * @sg:         scatterlist
+ * @nsegs:      number of elements
+ * @bufflen:    len of buffer
+ * @gfp:        memory allocation flags
+ *
+ * scsi_req_map_sg maps a scatterlist into a request so that the
+ * request can be sent to the block layer. We do not trust the scatterlist
+ * sent to use, as some ULDs use that struct to only organize the pages.
+ */
+static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
+                           int nsegs, unsigned bufflen, gfp_t gfp)
+{
+        struct request_queue *q = rq->q;
+        int nr_pages = (bufflen + PAGE_SIZE - 1) >> PAGE_SHIFT;
+        unsigned int data_len = 0, len, bytes, off;
+        struct page *page;
+        struct bio *bio = NULL;
+        int i, err, nr_vecs = 0;
+
+        for (i = 0; i < nsegs; i++) {
+                page = sgl[i].page;
+                off = sgl[i].offset;
+                len = sgl[i].length;
+                data_len += len;
+
+                while (len > 0) {
+                        bytes = min_t(unsigned int, len, PAGE_SIZE - off);
+
+                        if (!bio) {
+                                nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
+                                nr_pages -= nr_vecs;
+
+                                bio = bio_alloc(gfp, nr_vecs);
+                                if (!bio) {
+                                        err = -ENOMEM;
+                                        goto free_bios;
+                                }
+                                bio->bi_end_io = scsi_bi_endio;
+                        }
+
+                        if (bio_add_pc_page(q, bio, page, bytes, off) !=
+                            bytes) {
+                                bio_put(bio);
+                                err = -EINVAL;
+                                goto free_bios;
+                        }
+
+                        if (bio->bi_vcnt >= nr_vecs) {
+                                err = scsi_merge_bio(rq, bio);
+                                if (err) {
+                                        bio_endio(bio, bio->bi_size, 0);
+                                        goto free_bios;
+                                }
+                                bio = NULL;
+                        }
+
+                        page++;
+                        len -= bytes;
+                        off = 0;
+                }
+        }
+
+        rq->buffer = rq->data = NULL;
+        rq->data_len = data_len;
+        return 0;
+
+free_bios:
+        while ((bio = rq->bio) != NULL) {
+                rq->bio = bio->bi_next;
+                /*
+                 * call endio instead of bio_put incase it was bounced
+                 */
+                bio_endio(bio, bio->bi_size, 0);
+        }
+
+        return err;
+}
+
+/**
+ * scsi_execute_async - insert request
+ * @sdev:       scsi device
+ * @cmd:        scsi command
+ * @data_direction: data direction
+ * @buffer:     data buffer (this can be a kernel buffer or scatterlist)
+ * @bufflen:    len of buffer
+ * @use_sg:     if buffer is a scatterlist this is the number of elements
+ * @timeout:    request timeout in seconds
+ * @retries:    number of times to retry request
+ * @flags:      or into request flags
+ **/
+int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
+                       int data_direction, void *buffer, unsigned bufflen,
+                       int use_sg, int timeout, int retries, void *privdata,
+                       void (*done)(void *, char *, int, int), gfp_t gfp)
+{
+        struct request *req;
+        struct scsi_io_context *sioc;
+        int err = 0;
+        int write = (data_direction == DMA_TO_DEVICE);
+
+        sioc = kzalloc(sizeof(*sioc), gfp);
+        if (!sioc)
+                return DRIVER_ERROR << 24;
+
+        req = blk_get_request(sdev->request_queue, write, gfp);
+        if (!req)
+                goto free_sense;
+
+        if (use_sg)
+                err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
+        else if (bufflen)
+                err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
+
+        if (err)
+                goto free_req;
+
+        req->cmd_len = COMMAND_SIZE(cmd[0]);
+        memcpy(req->cmd, cmd, req->cmd_len);
+        req->sense = sioc->sense;
+        req->sense_len = 0;
+        req->timeout = timeout;
+        req->flags |= REQ_BLOCK_PC | REQ_QUIET;
+        req->end_io_data = sioc;
+
+        sioc->data = privdata;
+        sioc->done = done;
+
+        blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
+        return 0;
+
+free_req:
+        blk_put_request(req);
+free_sense:
+        kfree(sioc);
+        return DRIVER_ERROR << 24;
+}
+EXPORT_SYMBOL_GPL(scsi_execute_async);
+
 /*
  * Function:    scsi_init_cmd_errh()
  *
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index a8d121c8fbcd..f04e7e11f57a 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -40,7 +40,6 @@ extern void scsi_exit_hosts(void);
 extern int scsi_dispatch_cmd(struct scsi_cmnd *cmd);
 extern int scsi_setup_command_freelist(struct Scsi_Host *shost);
 extern void scsi_destroy_command_freelist(struct Scsi_Host *shost);
-extern int scsi_insert_special_req(struct scsi_request *sreq, int);
 extern void scsi_init_cmd_from_req(struct scsi_cmnd *cmd,
                 struct scsi_request *sreq);
 extern void __scsi_release_request(struct scsi_request *sreq);
diff --git a/fs/bio.c b/fs/bio.c
index 460554b07ff9..4d21ee3873ec 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -386,6 +386,25 @@ static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
 }
 
 /**
+ *      bio_add_pc_page -       attempt to add page to bio
+ *      @bio: destination bio
+ *      @page: page to add
+ *      @len: vec entry length
+ *      @offset: vec entry offset
+ *
+ *      Attempt to add a page to the bio_vec maplist. This can fail for a
+ *      number of reasons, such as the bio being full or target block
+ *      device limitations. The target block device must allow bio's
+ *      smaller than PAGE_SIZE, so it is always possible to add a single
+ *      page to an empty bio. This should only be used by REQ_PC bios.
+ */
+int bio_add_pc_page(request_queue_t *q, struct bio *bio, struct page *page,
+                    unsigned int len, unsigned int offset)
+{
+        return __bio_add_page(q, bio, page, len, offset);
+}
+
+/**
  *      bio_add_page    -       attempt to add page to bio
  *      @bio: destination bio
  *      @page: page to add
@@ -1228,6 +1247,7 @@ EXPORT_SYMBOL(bio_clone);
 EXPORT_SYMBOL(bio_phys_segments);
 EXPORT_SYMBOL(bio_hw_segments);
 EXPORT_SYMBOL(bio_add_page);
+EXPORT_SYMBOL(bio_add_pc_page);
 EXPORT_SYMBOL(bio_get_nr_vecs);
 EXPORT_SYMBOL(bio_map_user);
 EXPORT_SYMBOL(bio_unmap_user);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 685fd3720df5..b60ffe32cd21 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -292,6 +292,8 @@ extern struct bio *bio_clone(struct bio *, gfp_t);
 extern void bio_init(struct bio *);
 
 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
+extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
+                           unsigned int, unsigned int);
 extern int bio_get_nr_vecs(struct block_device *);
 extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
                                 unsigned long, unsigned int, int);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 063e32fe036c..e94ca4d36035 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -274,6 +274,12 @@ extern int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 extern int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
                             int data_direction, void *buffer, unsigned bufflen,
                             struct scsi_sense_hdr *, int timeout, int retries);
+extern int scsi_execute_async(struct scsi_device *sdev,
+                              const unsigned char *cmd, int data_direction,
+                              void *buffer, unsigned bufflen, int use_sg,
+                              int timeout, int retries, void *privdata,
+                              void (*done)(void *, char *, int, int),
+                              gfp_t gfp);
 
 static inline unsigned int sdev_channel(struct scsi_device *sdev)
 {