bio: fix bio_copy_kern() handling of bio->bv_len

The commit 68154e90c9d1492d570671ae181d9a8f8530da55 introduced
bio_copy_kern() to add bounce support to blk_rq_map_kern.

bio_copy_kern() uses bio->bv_len to copy data for READ commands after
the completion but it doesn't work with a request that partially
completed. SCSI always completes a PC request as a whole but seems
some don't.

This patch fixes bio_copy_kern to handle the above case. As
bio_copy_user does, bio_copy_kern uses struct bio_map_data to store
struct bio_vec.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reported-by: Nix <nix@esperi.org.uk>
Tested-by: Nix <nix@esperi.org.uk>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/fs/bio.c b/fs/bio.c
index 8000e2fa16cb21a12f8288b3f0b7eeb8d88ab042..8b1f5ee6f83c238a07166fed767ed27db1850d9d 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -469,20 +469,21 @@ static void bio_free_map_data(struct bio_map_data *bmd)
        kfree(bmd);
 }
 
-static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count)
+static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count,
+                                              gfp_t gfp_mask)
 {
-       struct bio_map_data *bmd = kmalloc(sizeof(*bmd), GFP_KERNEL);
+       struct bio_map_data *bmd = kmalloc(sizeof(*bmd), gfp_mask);
 
        if (!bmd)
                return NULL;
 
-       bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, GFP_KERNEL);
+       bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, gfp_mask);
        if (!bmd->iovecs) {
                kfree(bmd);
                return NULL;
        }
 
-       bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, GFP_KERNEL);
+       bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, gfp_mask);
        if (bmd->sgvecs)
                return bmd;
 
@@ -596,7 +597,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q, struct sg_iovec *iov,
                len += iov[i].iov_len;
        }
 
-       bmd = bio_alloc_map_data(nr_pages, iov_count);
+       bmd = bio_alloc_map_data(nr_pages, iov_count, GFP_KERNEL);
        if (!bmd)
                return ERR_PTR(-ENOMEM);
 
@@ -942,19 +943,22 @@ static void bio_copy_kern_endio(struct bio *bio, int err)
 {
        struct bio_vec *bvec;
        const int read = bio_data_dir(bio) == READ;
-       char *p = bio->bi_private;
+       struct bio_map_data *bmd = bio->bi_private;
        int i;
+       char *p = bmd->sgvecs[0].iov_base;
 
        __bio_for_each_segment(bvec, bio, i, 0) {
                char *addr = page_address(bvec->bv_page);
+               int len = bmd->iovecs[i].bv_len;
 
                if (read && !err)
-                       memcpy(p, addr, bvec->bv_len);
+                       memcpy(p, addr, len);
 
                __free_page(bvec->bv_page);
-               p += bvec->bv_len;
+               p += len;
        }
 
+       bio_free_map_data(bmd);
        bio_put(bio);
 }
 
@@ -978,11 +982,21 @@ struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
        const int nr_pages = end - start;
        struct bio *bio;
        struct bio_vec *bvec;
+       struct bio_map_data *bmd;
        int i, ret;
+       struct sg_iovec iov;
+
+       iov.iov_base = data;
+       iov.iov_len = len;
+
+       bmd = bio_alloc_map_data(nr_pages, 1, gfp_mask);
+       if (!bmd)
+               return ERR_PTR(-ENOMEM);
 
+       ret = -ENOMEM;
        bio = bio_alloc(gfp_mask, nr_pages);
        if (!bio)
-               return ERR_PTR(-ENOMEM);
+               goto out_bmd;
 
        while (len) {
                struct page *page;
@@ -1016,14 +1030,18 @@ struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
                }
        }
 
-       bio->bi_private = data;
+       bio->bi_private = bmd;
        bio->bi_end_io = bio_copy_kern_endio;
+
+       bio_set_map_data(bmd, bio, &iov, 1);
        return bio;
 cleanup:
        bio_for_each_segment(bvec, bio, i)
                __free_page(bvec->bv_page);
 
        bio_put(bio);
+out_bmd:
+       bio_free_map_data(bmd);
 
        return ERR_PTR(ret);
 }