NVMe: Handle bios that contain non-virtually contiguous addresses

NVMe scatterlists must be virtually contiguous, like almost all I/Os.
However, when the filesystem lays out files with a hole, it can be that
adjacent LBAs map to non-adjacent virtual addresses.  Handle this by
submitting one NVMe command at a time for each virtually discontiguous
range.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index d99b400..2409227 100644 (file)
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -315,7 +315,14 @@ static void bio_completion(struct nvme_queue *nvmeq, void *ctx,
        dma_unmap_sg(nvmeq->q_dmadev, nbio->sg, nbio->nents,
                        bio_data_dir(bio) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
        free_nbio(nvmeq, nbio);
-       bio_endio(bio, status ? -EIO : 0);
+       if (status)
+               bio_endio(bio, -EIO);
+       if (bio->bi_vcnt > bio->bi_idx) {
+               bio_list_add(&nvmeq->sq_cong, bio);
+               wake_up_process(nvme_thread);
+       } else {
+               bio_endio(bio, 0);
+       }
 }
 
 /* length is in bytes */
@@ -393,29 +400,41 @@ static struct nvme_prps *nvme_setup_prps(struct nvme_dev *dev,
        return prps;
 }
 
+/* NVMe scatterlists require no holes in the virtual address */
+#define BIOVEC_NOT_VIRT_MERGEABLE(vec1, vec2)  ((vec2)->bv_offset || \
+                       (((vec1)->bv_offset + (vec1)->bv_len) % PAGE_SIZE))
+
 static int nvme_map_bio(struct device *dev, struct nvme_bio *nbio,
                struct bio *bio, enum dma_data_direction dma_dir, int psegs)
 {
        struct bio_vec *bvec, *bvprv = NULL;
        struct scatterlist *sg = NULL;
-       int i, nsegs = 0;
+       int i, old_idx, length = 0, nsegs = 0;
 
        sg_init_table(nbio->sg, psegs);
+       old_idx = bio->bi_idx;
        bio_for_each_segment(bvec, bio, i) {
                if (bvprv && BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) {
                        sg->length += bvec->bv_len;
                } else {
-                       /* Check bvprv && offset == 0 */
+                       if (bvprv && BIOVEC_NOT_VIRT_MERGEABLE(bvprv, bvec))
+                               break;
                        sg = sg ? sg + 1 : nbio->sg;
                        sg_set_page(sg, bvec->bv_page, bvec->bv_len,
                                                        bvec->bv_offset);
                        nsegs++;
                }
+               length += bvec->bv_len;
                bvprv = bvec;
        }
+       bio->bi_idx = i;
        nbio->nents = nsegs;
        sg_mark_end(sg);
-       return dma_map_sg(dev, nbio->sg, nbio->nents, dma_dir);
+       if (dma_map_sg(dev, nbio->sg, nbio->nents, dma_dir) == 0) {
+               bio->bi_idx = old_idx;
+               return -ENOMEM;
+       }
+       return length;
 }
 
 static int nvme_submit_flush(struct nvme_queue *nvmeq, struct nvme_ns *ns,
@@ -451,7 +470,7 @@ static int nvme_submit_bio_queue(struct nvme_queue *nvmeq, struct nvme_ns *ns,
        struct nvme_command *cmnd;
        struct nvme_bio *nbio;
        enum dma_data_direction dma_dir;
-       int cmdid, result = -ENOMEM;
+       int cmdid, length, result = -ENOMEM;
        u16 control;
        u32 dsmgmt;
        int psegs = bio_phys_segments(ns->queue, bio);
@@ -496,16 +515,17 @@ static int nvme_submit_bio_queue(struct nvme_queue *nvmeq, struct nvme_ns *ns,
                dma_dir = DMA_FROM_DEVICE;
        }
 
-       result = -ENOMEM;
-       if (nvme_map_bio(nvmeq->q_dmadev, nbio, bio, dma_dir, psegs) == 0)
+       result = nvme_map_bio(nvmeq->q_dmadev, nbio, bio, dma_dir, psegs);
+       if (result < 0)
                goto free_nbio;
+       length = result;
 
        cmnd->rw.command_id = cmdid;
        cmnd->rw.nsid = cpu_to_le32(ns->ns_id);
        nbio->prps = nvme_setup_prps(nvmeq->dev, &cmnd->common, nbio->sg,
-                                                               bio->bi_size);
+                                                               length);
        cmnd->rw.slba = cpu_to_le64(bio->bi_sector >> (ns->lba_shift - 9));
-       cmnd->rw.length = cpu_to_le16((bio->bi_size >> ns->lba_shift) - 1);
+       cmnd->rw.length = cpu_to_le16((length >> ns->lba_shift) - 1);
        cmnd->rw.control = cpu_to_le16(control);
        cmnd->rw.dsmgmt = cpu_to_le32(dsmgmt);