block: Add bio_alloc_pages()

More utility code to replace stuff that's getting open coded.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: NeilBrown <neilb@suse.de>

3 files changed, 32 insertions, 13 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index a7ea954abe1d..aeb4e3f74791 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -92,7 +92,6 @@ static void r1bio_pool_free(void *r1_bio, void *data)
 static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
 {
         struct pool_info *pi = data;
-        struct page *page;
         struct r1bio *r1_bio;
         struct bio *bio;
         int i, j;
@@ -122,14 +121,10 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
                 j = 1;
         while(j--) {
                 bio = r1_bio->bios[j];
-                for (i = 0; i < RESYNC_PAGES; i++) {
-                        page = alloc_page(gfp_flags);
-                        if (unlikely(!page))
-                                goto out_free_pages;
+                bio->bi_vcnt = RESYNC_PAGES;
 
-                        bio->bi_io_vec[i].bv_page = page;
-                        bio->bi_vcnt = i+1;
-                }
+                if (bio_alloc_pages(bio, gfp_flags))
+                        goto out_free_bio;
         }
         /* If not user-requests, copy the page pointers to all bios */
         if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
@@ -143,11 +138,6 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
 
         return r1_bio;
 
-out_free_pages:
-        for (j=0 ; j < pi->raid_disks; j++)
-                for (i=0; i < r1_bio->bios[j]->bi_vcnt ; i++)
-                        put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
-        j = -1;
 out_free_bio:
         while (++j < pi->raid_disks)
                 bio_put(r1_bio->bios[j]);
diff --git a/fs/bio.c b/fs/bio.c
index fe3aee90c988..e545a440d376 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -830,6 +830,34 @@ void bio_advance(struct bio *bio, unsigned bytes)
 EXPORT_SYMBOL(bio_advance);
 
 /**
+ * bio_alloc_pages - allocates a single page for each bvec in a bio
+ * @bio: bio to allocate pages for
+ * @gfp_mask: flags for allocation
+ *
+ * Allocates pages up to @bio->bi_vcnt.
+ *
+ * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
+ * freed.
+ */
+int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
+{
+        int i;
+        struct bio_vec *bv;
+
+        bio_for_each_segment_all(bv, bio, i) {
+                bv->bv_page = alloc_page(gfp_mask);
+                if (!bv->bv_page) {
+                        while (--bv >= bio->bi_io_vec)
+                                __free_page(bv->bv_page);
+                        return -ENOMEM;
+                }
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL(bio_alloc_pages);
+
+/**
  * bio_copy_data - copy contents of data buffers from one chain of bios to
  * another
  * @src: source bio list
diff --git a/include/linux/bio.h b/include/linux/bio.h
index be2efa09f9bf..e25378f2f408 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -298,6 +298,7 @@ static inline void bio_flush_dcache_pages(struct bio *bi)
 #endif
 
 extern void bio_copy_data(struct bio *dst, struct bio *src);
+extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 
 extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
                                  unsigned long, unsigned int, int, gfp_t);