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-rw-r--r--fs/bio.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/fs/bio.c b/fs/bio.c
index 3a1472a..707b9af 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -701,6 +701,71 @@ void bio_unmap_user(struct bio *bio)
bio_put(bio);
}
+static struct bio *__bio_map_kern(request_queue_t *q, void *data,
+ unsigned int len, unsigned int gfp_mask)
+{
+ unsigned long kaddr = (unsigned long)data;
+ unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ unsigned long start = kaddr >> PAGE_SHIFT;
+ const int nr_pages = end - start;
+ int offset, i;
+ struct bio *bio;
+
+ bio = bio_alloc(gfp_mask, nr_pages);
+ if (!bio)
+ return ERR_PTR(-ENOMEM);
+
+ offset = offset_in_page(kaddr);
+ for (i = 0; i < nr_pages; i++) {
+ unsigned int bytes = PAGE_SIZE - offset;
+
+ if (len <= 0)
+ break;
+
+ if (bytes > len)
+ bytes = len;
+
+ if (__bio_add_page(q, bio, virt_to_page(data), bytes,
+ offset) < bytes)
+ break;
+
+ data += bytes;
+ len -= bytes;
+ offset = 0;
+ }
+
+ return bio;
+}
+
+/**
+ * bio_map_kern - map kernel address into bio
+ * @q: the request_queue_t for the bio
+ * @data: pointer to buffer to map
+ * @len: length in bytes
+ * @gfp_mask: allocation flags for bio allocation
+ *
+ * Map the kernel address into a bio suitable for io to a block
+ * device. Returns an error pointer in case of error.
+ */
+struct bio *bio_map_kern(request_queue_t *q, void *data, unsigned int len,
+ unsigned int gfp_mask)
+{
+ struct bio *bio;
+
+ bio = __bio_map_kern(q, data, len, gfp_mask);
+ if (IS_ERR(bio))
+ return bio;
+
+ if (bio->bi_size == len)
+ return bio;
+
+ /*
+ * Don't support partial mappings.
+ */
+ bio_put(bio);
+ return ERR_PTR(-EINVAL);
+}
+
/*
* bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
* for performing direct-IO in BIOs.
@@ -1088,6 +1153,7 @@ EXPORT_SYMBOL(bio_add_page);
EXPORT_SYMBOL(bio_get_nr_vecs);
EXPORT_SYMBOL(bio_map_user);
EXPORT_SYMBOL(bio_unmap_user);
+EXPORT_SYMBOL(bio_map_kern);
EXPORT_SYMBOL(bio_pair_release);
EXPORT_SYMBOL(bio_split);
EXPORT_SYMBOL(bio_split_pool);