Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  xen/blkfront: use blk_rq_map_sg to generate ring entries
  block: reduce stack footprint of blk_recount_segments()
  cciss: shorten 30s timeout on controller reset
  block: add documentation for register_blkdev()
  block: fix bogus gcc warning for uninitialized var usage

6 files changed, 94 insertions, 60 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index b92f5b0866b0..a104593e70c3 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -38,72 +38,84 @@ void blk_recalc_rq_sectors(struct request *rq, int nsect)
         }
 }
 
-void blk_recalc_rq_segments(struct request *rq)
+static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
+                                             struct bio *bio,
+                                             unsigned int *seg_size_ptr)
 {
-        int nr_phys_segs;
         unsigned int phys_size;
         struct bio_vec *bv, *bvprv = NULL;
-        int seg_size;
-        int cluster;
-        struct req_iterator iter;
-        int high, highprv = 1;
-        struct request_queue *q = rq->q;
+        int cluster, i, high, highprv = 1;
+        unsigned int seg_size, nr_phys_segs;
+        struct bio *fbio;
 
-        if (!rq->bio)
-                return;
+        if (!bio)
+                return 0;
 
+        fbio = bio;
         cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
         seg_size = 0;
         phys_size = nr_phys_segs = 0;
-        rq_for_each_segment(bv, rq, iter) {
-                /*
-                 * the trick here is making sure that a high page is never
-                 * considered part of another segment, since that might
-                 * change with the bounce page.
-                 */
-                high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
-                if (high || highprv)
-                        goto new_segment;
-                if (cluster) {
-                        if (seg_size + bv->bv_len > q->max_segment_size)
-                                goto new_segment;
-                        if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
-                                goto new_segment;
-                        if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
+        for_each_bio(bio) {
+                bio_for_each_segment(bv, bio, i) {
+                        /*
+                         * the trick here is making sure that a high page is
+                         * never considered part of another segment, since that
+                         * might change with the bounce page.
+                         */
+                        high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
+                        if (high || highprv)
                                 goto new_segment;
+                        if (cluster) {
+                                if (seg_size + bv->bv_len > q->max_segment_size)
+                                        goto new_segment;
+                                if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
+                                        goto new_segment;
+                                if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
+                                        goto new_segment;
+
+                                seg_size += bv->bv_len;
+                                bvprv = bv;
+                                continue;
+                        }
+new_segment:
+                        if (nr_phys_segs == 1 && seg_size >
+                            fbio->bi_seg_front_size)
+                                fbio->bi_seg_front_size = seg_size;
 
-                        seg_size += bv->bv_len;
+                        nr_phys_segs++;
                         bvprv = bv;
-                        continue;
+                        seg_size = bv->bv_len;
+                        highprv = high;
                 }
-new_segment:
-                if (nr_phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
-                        rq->bio->bi_seg_front_size = seg_size;
-
-                nr_phys_segs++;
-                bvprv = bv;
-                seg_size = bv->bv_len;
-                highprv = high;
         }
 
-        if (nr_phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
+        if (seg_size_ptr)
+                *seg_size_ptr = seg_size;
+
+        return nr_phys_segs;
+}
+
+void blk_recalc_rq_segments(struct request *rq)
+{
+        unsigned int seg_size = 0, phys_segs;
+
+        phys_segs = __blk_recalc_rq_segments(rq->q, rq->bio, &seg_size);
+
+        if (phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
                 rq->bio->bi_seg_front_size = seg_size;
         if (seg_size > rq->biotail->bi_seg_back_size)
                 rq->biotail->bi_seg_back_size = seg_size;
 
-        rq->nr_phys_segments = nr_phys_segs;
+        rq->nr_phys_segments = phys_segs;
 }
 
 void blk_recount_segments(struct request_queue *q, struct bio *bio)
 {
-        struct request rq;
         struct bio *nxt = bio->bi_next;
-        rq.q = q;
-        rq.bio = rq.biotail = bio;
+
         bio->bi_next = NULL;
-        blk_recalc_rq_segments(&rq);
+        bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, NULL);
         bio->bi_next = nxt;
-        bio->bi_phys_segments = rq.nr_phys_segments;
         bio->bi_flags |= (1 << BIO_SEG_VALID);
 }
 EXPORT_SYMBOL(blk_recount_segments);
diff --git a/block/genhd.c b/block/genhd.c
index e1eadcc9546a..a9ec910974c1 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -256,6 +256,22 @@ void blkdev_show(struct seq_file *seqf, off_t offset)
 }
 #endif /* CONFIG_PROC_FS */
 
+/**
+ * register_blkdev - register a new block device
+ *
+ * @major: the requested major device number [1..255]. If @major=0, try to
+ *         allocate any unused major number.
+ * @name: the name of the new block device as a zero terminated string
+ *
+ * The @name must be unique within the system.
+ *
+ * The return value depends on the @major input parameter.
+ *  - if a major device number was requested in range [1..255] then the
+ *    function returns zero on success, or a negative error code
+ *  - if any unused major number was requested with @major=0 parameter
+ *    then the return value is the allocated major number in range
+ *    [1..255] or a negative error code otherwise
+ */
 int register_blkdev(unsigned int major, const char *name)
 {
         struct blk_major_name **n, *p;
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index d2cb67b61176..b5a061114630 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -3611,11 +3611,15 @@ static int __devinit cciss_init_one(struct pci_dev *pdev,
                 schedule_timeout_uninterruptible(30*HZ);
 
                 /* Now try to get the controller to respond to a no-op */
-                for (i=0; i<12; i++) {
+                for (i=0; i<30; i++) {
                         if (cciss_noop(pdev) == 0)
                                 break;
-                        else
-                                printk("cciss: no-op failed%s\n", (i < 11 ? "; re-trying" : ""));
+
+                        schedule_timeout_uninterruptible(HZ);
+                }
+                if (i == 30) {
+                        printk(KERN_ERR "cciss: controller seems dead\n");
+                        return -EBUSY;
                 }
         }
 
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 918ef725de41..b6c8ce254359 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -40,6 +40,7 @@
 #include <linux/hdreg.h>
 #include <linux/cdrom.h>
 #include <linux/module.h>
+#include <linux/scatterlist.h>
 
 #include <xen/xenbus.h>
 #include <xen/grant_table.h>
@@ -82,6 +83,7 @@ struct blkfront_info
         enum blkif_state connected;
         int ring_ref;
         struct blkif_front_ring ring;
+        struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
         unsigned int evtchn, irq;
         struct request_queue *rq;
         struct work_struct work;
@@ -204,12 +206,11 @@ static int blkif_queue_request(struct request *req)
         struct blkfront_info *info = req->rq_disk->private_data;
         unsigned long buffer_mfn;
         struct blkif_request *ring_req;
-        struct req_iterator iter;
-        struct bio_vec *bvec;
         unsigned long id;
         unsigned int fsect, lsect;
-        int ref;
+        int i, ref;
         grant_ref_t gref_head;
+        struct scatterlist *sg;
 
         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
                 return 1;
@@ -238,12 +239,13 @@ static int blkif_queue_request(struct request *req)
         if (blk_barrier_rq(req))
                 ring_req->operation = BLKIF_OP_WRITE_BARRIER;
 
-        ring_req->nr_segments = 0;
-        rq_for_each_segment(bvec, req, iter) {
-                BUG_ON(ring_req->nr_segments == BLKIF_MAX_SEGMENTS_PER_REQUEST);
-                buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page));
-                fsect = bvec->bv_offset >> 9;
-                lsect = fsect + (bvec->bv_len >> 9) - 1;
+        ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
+        BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
+
+        for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
+                buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
+                fsect = sg->offset >> 9;
+                lsect = fsect + (sg->length >> 9) - 1;
                 /* install a grant reference. */
                 ref = gnttab_claim_grant_reference(&gref_head);
                 BUG_ON(ref == -ENOSPC);
@@ -254,16 +256,12 @@ static int blkif_queue_request(struct request *req)
                                 buffer_mfn,
                                 rq_data_dir(req) );
 
-                info->shadow[id].frame[ring_req->nr_segments] =
-                                mfn_to_pfn(buffer_mfn);
-
-                ring_req->seg[ring_req->nr_segments] =
+                info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
+                ring_req->seg[i] =
                                 (struct blkif_request_segment) {
                                         .gref       = ref,
                                         .first_sect = fsect,
                                         .last_sect  = lsect };
-
-                ring_req->nr_segments++;
         }
 
         info->ring.req_prod_pvt++;
@@ -622,6 +620,8 @@ static int setup_blkring(struct xenbus_device *dev,
         SHARED_RING_INIT(sring);
         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 
+        sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
+
         err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
         if (err < 0) {
                 free_page((unsigned long)sring);
diff --git a/fs/bio.c b/fs/bio.c
index 72ab251cdb9c..124b95c4d582 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -302,7 +302,7 @@ void bio_init(struct bio *bio)
 struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
 {
         struct bio *bio = NULL;
-        void *p;
+        void *uninitialized_var(p);
 
         if (bs) {
                 p = mempool_alloc(bs->bio_pool, gfp_mask);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index dcaa0fd84b02..465d6babc847 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -708,6 +708,8 @@ struct req_iterator {
 };
 
 /* This should not be used directly - use rq_for_each_segment */
+#define for_each_bio(_bio)              \
+        for (; _bio; _bio = _bio->bi_next)
 #define __rq_for_each_bio(_bio, rq)     \
         if ((rq->bio))                  \
                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)