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>

1 files changed, 28 insertions, 0 deletions

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