1 files changed, 68 insertions, 57 deletions

diff --git a/fs/bio.c b/fs/bio.c
index e0c9e545bbfa..98711647ece4 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -175,14 +175,6 @@ struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
         struct bio_vec *bvl;
 
         /*
-         * If 'bs' is given, lookup the pool and do the mempool alloc.
-         * If not, this is a bio_kmalloc() allocation and just do a
-         * kzalloc() for the exact number of vecs right away.
-         */
-        if (!bs)
-                bvl = kmalloc(nr * sizeof(struct bio_vec), gfp_mask);
-
-        /*
          * see comment near bvec_array define!
          */
         switch (nr) {
@@ -260,21 +252,6 @@ void bio_free(struct bio *bio, struct bio_set *bs)
         mempool_free(p, bs->bio_pool);
 }
 
-/*
- * default destructor for a bio allocated with bio_alloc_bioset()
- */
-static void bio_fs_destructor(struct bio *bio)
-{
-        bio_free(bio, fs_bio_set);
-}
-
-static void bio_kmalloc_destructor(struct bio *bio)
-{
-        if (bio_has_allocated_vec(bio))
-                kfree(bio->bi_io_vec);
-        kfree(bio);
-}
-
 void bio_init(struct bio *bio)
 {
         memset(bio, 0, sizeof(*bio));
@@ -301,21 +278,15 @@ void bio_init(struct bio *bio)
  **/
 struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
 {
+        unsigned long idx = BIO_POOL_NONE;
         struct bio_vec *bvl = NULL;
-        struct bio *bio = NULL;
-        unsigned long idx = 0;
-        void *p = NULL;
-
-        if (bs) {
-                p = mempool_alloc(bs->bio_pool, gfp_mask);
-                if (!p)
-                        goto err;
-                bio = p + bs->front_pad;
-        } else {
-                bio = kmalloc(sizeof(*bio), gfp_mask);
-                if (!bio)
-                        goto err;
-        }
+        struct bio *bio;
+        void *p;
+
+        p = mempool_alloc(bs->bio_pool, gfp_mask);
+        if (unlikely(!p))
+                return NULL;
+        bio = p + bs->front_pad;
 
         bio_init(bio);
 
@@ -332,22 +303,33 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
 
                 nr_iovecs = bvec_nr_vecs(idx);
         }
+out_set:
         bio->bi_flags |= idx << BIO_POOL_OFFSET;
         bio->bi_max_vecs = nr_iovecs;
-out_set:
         bio->bi_io_vec = bvl;
-
         return bio;
 
 err_free:
-        if (bs)
-                mempool_free(p, bs->bio_pool);
-        else
-                kfree(bio);
-err:
+        mempool_free(p, bs->bio_pool);
         return NULL;
 }
 
+static void bio_fs_destructor(struct bio *bio)
+{
+        bio_free(bio, fs_bio_set);
+}
+
+/**
+ *      bio_alloc - allocate a new bio, memory pool backed
+ *      @gfp_mask: allocation mask to use
+ *      @nr_iovecs: number of iovecs
+ *
+ *      Allocate a new bio with @nr_iovecs bvecs.  If @gfp_mask
+ *      contains __GFP_WAIT, the allocation is guaranteed to succeed.
+ *
+ *      RETURNS:
+ *      Pointer to new bio on success, NULL on failure.
+ */
 struct bio *bio_alloc(gfp_t gfp_mask, int nr_iovecs)
 {
         struct bio *bio = bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
@@ -358,19 +340,45 @@ struct bio *bio_alloc(gfp_t gfp_mask, int nr_iovecs)
         return bio;
 }
 
-/*
- * Like bio_alloc(), but doesn't use a mempool backing. This means that
- * it CAN fail, but while bio_alloc() can only be used for allocations
- * that have a short (finite) life span, bio_kmalloc() should be used
- * for more permanent bio allocations (like allocating some bio's for
- * initalization or setup purposes).
- */
+static void bio_kmalloc_destructor(struct bio *bio)
+{
+        if (bio_integrity(bio))
+                bio_integrity_free(bio);
+        kfree(bio);
+}
+
+/**
+ * bio_alloc - allocate a bio for I/O
+ * @gfp_mask:   the GFP_ mask given to the slab allocator
+ * @nr_iovecs:  number of iovecs to pre-allocate
+ *
+ * Description:
+ *   bio_alloc will allocate a bio and associated bio_vec array that can hold
+ *   at least @nr_iovecs entries. Allocations will be done from the
+ *   fs_bio_set. Also see @bio_alloc_bioset.
+ *
+ *   If %__GFP_WAIT is set, then bio_alloc will always be able to allocate
+ *   a bio. This is due to the mempool guarantees. To make this work, callers
+ *   must never allocate more than 1 bio at the time from this pool. Callers
+ *   that need to allocate more than 1 bio must always submit the previously
+ *   allocate bio for IO before attempting to allocate a new one. Failure to
+ *   do so can cause livelocks under memory pressure.
+ *
+ **/
 struct bio *bio_kmalloc(gfp_t gfp_mask, int nr_iovecs)
 {
-        struct bio *bio = bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
+        struct bio *bio;
 
-        if (bio)
-                bio->bi_destructor = bio_kmalloc_destructor;
+        bio = kmalloc(sizeof(struct bio) + nr_iovecs * sizeof(struct bio_vec),
+                      gfp_mask);
+        if (unlikely(!bio))
+                return NULL;
+
+        bio_init(bio);
+        bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET;
+        bio->bi_max_vecs = nr_iovecs;
+        bio->bi_io_vec = bio->bi_inline_vecs;
+        bio->bi_destructor = bio_kmalloc_destructor;
 
         return bio;
 }
@@ -809,12 +817,15 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
                 len += iov[i].iov_len;
         }
 
+        if (offset)
+                nr_pages++;
+
         bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
         if (!bmd)
                 return ERR_PTR(-ENOMEM);
 
         ret = -ENOMEM;
-        bio = bio_alloc(gfp_mask, nr_pages);
+        bio = bio_kmalloc(gfp_mask, nr_pages);
         if (!bio)
                 goto out_bmd;
 
@@ -938,7 +949,7 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
         if (!nr_pages)
                 return ERR_PTR(-EINVAL);
 
-        bio = bio_alloc(gfp_mask, nr_pages);
+        bio = bio_kmalloc(gfp_mask, nr_pages);
         if (!bio)
                 return ERR_PTR(-ENOMEM);
 
@@ -1122,7 +1133,7 @@ static struct bio *__bio_map_kern(struct request_queue *q, void *data,
         int offset, i;
         struct bio *bio;
 
-        bio = bio_alloc(gfp_mask, nr_pages);
+        bio = bio_kmalloc(gfp_mask, nr_pages);
         if (!bio)
                 return ERR_PTR(-ENOMEM);