[PATCH] block: support larger block pc requests
This patch modifies blk_rq_map/unmap_user() and the cdrom and scsi_ioctl.c
users so that it supports requests larger than bio by chaining them together.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 9eaee66..0f82e12 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -2322,6 +2322,84 @@
EXPORT_SYMBOL(blk_insert_request);
+static int __blk_rq_unmap_user(struct bio *bio)
+{
+ int ret = 0;
+
+ if (bio) {
+ if (bio_flagged(bio, BIO_USER_MAPPED))
+ bio_unmap_user(bio);
+ else
+ ret = bio_uncopy_user(bio);
+ }
+
+ return ret;
+}
+
+static int __blk_rq_map_user(request_queue_t *q, struct request *rq,
+ void __user *ubuf, unsigned int len)
+{
+ unsigned long uaddr;
+ struct bio *bio, *orig_bio;
+ int reading, ret;
+
+ reading = rq_data_dir(rq) == READ;
+
+ /*
+ * if alignment requirement is satisfied, map in user pages for
+ * direct dma. else, set up kernel bounce buffers
+ */
+ uaddr = (unsigned long) ubuf;
+ if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
+ bio = bio_map_user(q, NULL, uaddr, len, reading);
+ else
+ bio = bio_copy_user(q, uaddr, len, reading);
+
+ if (IS_ERR(bio)) {
+ return PTR_ERR(bio);
+ }
+
+ orig_bio = bio;
+ blk_queue_bounce(q, &bio);
+ /*
+ * We link the bounce buffer in and could have to traverse it
+ * later so we have to get a ref to prevent it from being freed
+ */
+ bio_get(bio);
+
+ /*
+ * for most (all? don't know of any) queues we could
+ * skip grabbing the queue lock here. only drivers with
+ * funky private ->back_merge_fn() function could be
+ * problematic.
+ */
+ spin_lock_irq(q->queue_lock);
+ if (!rq->bio)
+ blk_rq_bio_prep(q, rq, bio);
+ else if (!q->back_merge_fn(q, rq, bio)) {
+ ret = -EINVAL;
+ spin_unlock_irq(q->queue_lock);
+ goto unmap_bio;
+ } else {
+ rq->biotail->bi_next = bio;
+ rq->biotail = bio;
+
+ rq->nr_sectors += bio_sectors(bio);
+ rq->hard_nr_sectors = rq->nr_sectors;
+ rq->data_len += bio->bi_size;
+ }
+ spin_unlock_irq(q->queue_lock);
+
+ return bio->bi_size;
+
+unmap_bio:
+ /* if it was boucned we must call the end io function */
+ bio_endio(bio, bio->bi_size, 0);
+ __blk_rq_unmap_user(orig_bio);
+ bio_put(bio);
+ return ret;
+}
+
/**
* blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
* @q: request queue where request should be inserted
@@ -2343,42 +2421,44 @@
* unmapping.
*/
int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf,
- unsigned int len)
+ unsigned long len)
{
- unsigned long uaddr;
- struct bio *bio;
- int reading;
+ unsigned long bytes_read = 0;
+ int ret;
if (len > (q->max_hw_sectors << 9))
return -EINVAL;
if (!len || !ubuf)
return -EINVAL;
- reading = rq_data_dir(rq) == READ;
+ while (bytes_read != len) {
+ unsigned long map_len, end, start;
- /*
- * if alignment requirement is satisfied, map in user pages for
- * direct dma. else, set up kernel bounce buffers
- */
- uaddr = (unsigned long) ubuf;
- if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
- bio = bio_map_user(q, NULL, uaddr, len, reading);
- else
- bio = bio_copy_user(q, uaddr, len, reading);
+ map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
+ end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
+ >> PAGE_SHIFT;
+ start = (unsigned long)ubuf >> PAGE_SHIFT;
- if (!IS_ERR(bio)) {
- rq->bio = rq->biotail = bio;
- blk_rq_bio_prep(q, rq, bio);
+ /*
+ * A bad offset could cause us to require BIO_MAX_PAGES + 1
+ * pages. If this happens we just lower the requested
+ * mapping len by a page so that we can fit
+ */
+ if (end - start > BIO_MAX_PAGES)
+ map_len -= PAGE_SIZE;
- rq->buffer = rq->data = NULL;
- rq->data_len = len;
- return 0;
+ ret = __blk_rq_map_user(q, rq, ubuf, map_len);
+ if (ret < 0)
+ goto unmap_rq;
+ bytes_read += ret;
+ ubuf += ret;
}
- /*
- * bio is the err-ptr
- */
- return PTR_ERR(bio);
+ rq->buffer = rq->data = NULL;
+ return 0;
+unmap_rq:
+ blk_rq_unmap_user(rq);
+ return ret;
}
EXPORT_SYMBOL(blk_rq_map_user);
@@ -2404,7 +2484,7 @@
* unmapping.
*/
int blk_rq_map_user_iov(request_queue_t *q, struct request *rq,
- struct sg_iovec *iov, int iov_count)
+ struct sg_iovec *iov, int iov_count, unsigned int len)
{
struct bio *bio;
@@ -2418,10 +2498,15 @@
if (IS_ERR(bio))
return PTR_ERR(bio);
- rq->bio = rq->biotail = bio;
+ if (bio->bi_size != len) {
+ bio_endio(bio, bio->bi_size, 0);
+ bio_unmap_user(bio);
+ return -EINVAL;
+ }
+
+ bio_get(bio);
blk_rq_bio_prep(q, rq, bio);
rq->buffer = rq->data = NULL;
- rq->data_len = bio->bi_size;
return 0;
}
@@ -2429,23 +2514,26 @@
/**
* blk_rq_unmap_user - unmap a request with user data
- * @bio: bio to be unmapped
- * @ulen: length of user buffer
+ * @rq: rq to be unmapped
*
* Description:
- * Unmap a bio previously mapped by blk_rq_map_user().
+ * Unmap a rq previously mapped by blk_rq_map_user().
+ * rq->bio must be set to the original head of the request.
*/
-int blk_rq_unmap_user(struct bio *bio, unsigned int ulen)
+int blk_rq_unmap_user(struct request *rq)
{
- int ret = 0;
+ struct bio *bio, *mapped_bio;
- if (bio) {
- if (bio_flagged(bio, BIO_USER_MAPPED))
- bio_unmap_user(bio);
+ while ((bio = rq->bio)) {
+ if (bio_flagged(bio, BIO_BOUNCED))
+ mapped_bio = bio->bi_private;
else
- ret = bio_uncopy_user(bio);
- }
+ mapped_bio = bio;
+ __blk_rq_unmap_user(mapped_bio);
+ rq->bio = bio->bi_next;
+ bio_put(bio);
+ }
return 0;
}
@@ -2476,11 +2564,8 @@
if (rq_data_dir(rq) == WRITE)
bio->bi_rw |= (1 << BIO_RW);
- rq->bio = rq->biotail = bio;
blk_rq_bio_prep(q, rq, bio);
-
rq->buffer = rq->data = NULL;
- rq->data_len = len;
return 0;
}
@@ -3495,6 +3580,7 @@
rq->hard_cur_sectors = rq->current_nr_sectors;
rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
rq->buffer = bio_data(bio);
+ rq->data_len = bio->bi_size;
rq->bio = rq->biotail = bio;
}
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index e55a756..5493c2f 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -226,7 +226,6 @@
unsigned long start_time;
int writing = 0, ret = 0;
struct request *rq;
- struct bio *bio;
char sense[SCSI_SENSE_BUFFERSIZE];
unsigned char cmd[BLK_MAX_CDB];
@@ -258,6 +257,32 @@
if (!rq)
return -ENOMEM;
+ /*
+ * fill in request structure
+ */
+ rq->cmd_len = hdr->cmd_len;
+ memset(rq->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
+ memcpy(rq->cmd, cmd, hdr->cmd_len);
+
+ memset(sense, 0, sizeof(sense));
+ rq->sense = sense;
+ rq->sense_len = 0;
+
+ rq->cmd_type = REQ_TYPE_BLOCK_PC;
+
+ /*
+ * bounce this after holding a reference to the original bio, it's
+ * needed for proper unmapping
+ */
+ if (rq->bio)
+ blk_queue_bounce(q, &rq->bio);
+
+ rq->timeout = (hdr->timeout * HZ) / 1000;
+ if (!rq->timeout)
+ rq->timeout = q->sg_timeout;
+ if (!rq->timeout)
+ rq->timeout = BLK_DEFAULT_TIMEOUT;
+
if (hdr->iovec_count) {
const int size = sizeof(struct sg_iovec) * hdr->iovec_count;
struct sg_iovec *iov;
@@ -274,7 +299,8 @@
goto out;
}
- ret = blk_rq_map_user_iov(q, rq, iov, hdr->iovec_count);
+ ret = blk_rq_map_user_iov(q, rq, iov, hdr->iovec_count,
+ hdr->dxfer_len);
kfree(iov);
} else if (hdr->dxfer_len)
ret = blk_rq_map_user(q, rq, hdr->dxferp, hdr->dxfer_len);
@@ -282,33 +308,6 @@
if (ret)
goto out;
- /*
- * fill in request structure
- */
- rq->cmd_len = hdr->cmd_len;
- memset(rq->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
- memcpy(rq->cmd, cmd, hdr->cmd_len);
-
- memset(sense, 0, sizeof(sense));
- rq->sense = sense;
- rq->sense_len = 0;
-
- rq->cmd_type = REQ_TYPE_BLOCK_PC;
- bio = rq->bio;
-
- /*
- * bounce this after holding a reference to the original bio, it's
- * needed for proper unmapping
- */
- if (rq->bio)
- blk_queue_bounce(q, &rq->bio);
-
- rq->timeout = (hdr->timeout * HZ) / 1000;
- if (!rq->timeout)
- rq->timeout = q->sg_timeout;
- if (!rq->timeout)
- rq->timeout = BLK_DEFAULT_TIMEOUT;
-
rq->retries = 0;
start_time = jiffies;
@@ -339,7 +338,7 @@
hdr->sb_len_wr = len;
}
- if (blk_rq_unmap_user(bio, hdr->dxfer_len))
+ if (blk_rq_unmap_user(rq))
ret = -EFAULT;
/* may not have succeeded, but output values written to control