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authorMike Christie <michaelc@cs.wisc.edu>2005-06-20 14:04:44 +0200
committerJens Axboe <axboe@suse.de>2005-06-20 14:04:44 +0200
commitdf46b9a44ceb5af2ea2351ce8e28ae7bd840b00f (patch)
tree30ab71759486f94d60af2283fc55bfffcc22155a /fs/bio.c
parent8b22c249e7de453961e4d253b19fc2a0bdd65d53 (diff)
downloadlinux-df46b9a44ceb5af2ea2351ce8e28ae7bd840b00f.tar.bz2
[PATCH] Add blk_rq_map_kern()
Add blk_rq_map_kern which takes a kernel buffer and maps it into a request and bio. This can be used by the dm hw_handlers, old sg_scsi_ioctl, and one day scsi special requests so all requests comming into scsi will have bios. All requests having bios should allow scsi to use scatter lists for all IO and allow it to use block layer functions. Signed-off-by: Jens Axboe <axboe@suse.de>
Diffstat (limited to 'fs/bio.c')
-rw-r--r--fs/bio.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/fs/bio.c b/fs/bio.c
index 3a1472acc361..707b9af2dd01 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);