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[PATCH] block: support larger block pc requests
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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 <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Mike Christie authored and Jens Axboe committed Dec 1, 2006
1 parent ad2d722 commit 0e75f90
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Showing 5 changed files with 160 additions and 90 deletions.
166 changes: 126 additions & 40 deletions block/ll_rw_blk.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2322,6 +2322,84 @@ void blk_insert_request(request_queue_t *q, struct request *rq,

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
Expand All @@ -2343,42 +2421,44 @@ EXPORT_SYMBOL(blk_insert_request);
* 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);
Expand All @@ -2404,7 +2484,7 @@ EXPORT_SYMBOL(blk_rq_map_user);
* 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;

Expand All @@ -2418,34 +2498,42 @@ int blk_rq_map_user_iov(request_queue_t *q, struct request *rq,
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;
}

EXPORT_SYMBOL(blk_rq_map_user_iov);

/**
* 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;
}

Expand Down Expand Up @@ -2476,11 +2564,8 @@ int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf,
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;
}

Expand Down Expand Up @@ -3495,6 +3580,7 @@ void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio)
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;
}
Expand Down
53 changes: 26 additions & 27 deletions block/scsi_ioctl.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -226,7 +226,6 @@ static int sg_io(struct file *file, request_queue_t *q,
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];

Expand Down Expand Up @@ -258,30 +257,6 @@ static int sg_io(struct file *file, request_queue_t *q,
if (!rq)
return -ENOMEM;

if (hdr->iovec_count) {
const int size = sizeof(struct sg_iovec) * hdr->iovec_count;
struct sg_iovec *iov;

iov = kmalloc(size, GFP_KERNEL);
if (!iov) {
ret = -ENOMEM;
goto out;
}

if (copy_from_user(iov, hdr->dxferp, size)) {
kfree(iov);
ret = -EFAULT;
goto out;
}

ret = blk_rq_map_user_iov(q, rq, iov, hdr->iovec_count);
kfree(iov);
} else if (hdr->dxfer_len)
ret = blk_rq_map_user(q, rq, hdr->dxferp, hdr->dxfer_len);

if (ret)
goto out;

/*
* fill in request structure
*/
Expand All @@ -294,7 +269,6 @@ static int sg_io(struct file *file, request_queue_t *q,
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
Expand All @@ -309,6 +283,31 @@ static int sg_io(struct file *file, request_queue_t *q,
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;

iov = kmalloc(size, GFP_KERNEL);
if (!iov) {
ret = -ENOMEM;
goto out;
}

if (copy_from_user(iov, hdr->dxferp, size)) {
kfree(iov);
ret = -EFAULT;
goto out;
}

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);

if (ret)
goto out;

rq->retries = 0;

start_time = jiffies;
Expand Down Expand Up @@ -339,7 +338,7 @@ static int sg_io(struct file *file, request_queue_t *q,
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
Expand Down
6 changes: 2 additions & 4 deletions drivers/cdrom/cdrom.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2133,16 +2133,14 @@ static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
rq->timeout = 60 * HZ;
bio = rq->bio;

if (rq->bio)
blk_queue_bounce(q, &rq->bio);

if (blk_execute_rq(q, cdi->disk, rq, 0)) {
struct request_sense *s = rq->sense;
ret = -EIO;
cdi->last_sense = s->sense_key;
}

if (blk_rq_unmap_user(bio, len))
rq->bio = bio;
if (blk_rq_unmap_user(rq))
ret = -EFAULT;

if (ret)
Expand Down
18 changes: 2 additions & 16 deletions fs/bio.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -560,10 +560,8 @@ struct bio *bio_copy_user(request_queue_t *q, unsigned long uaddr,
break;
}

if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes) {
ret = -EINVAL;
if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
break;
}

len -= bytes;
}
Expand Down Expand Up @@ -750,7 +748,6 @@ struct bio *bio_map_user_iov(request_queue_t *q, struct block_device *bdev,
int write_to_vm)
{
struct bio *bio;
int len = 0, i;

bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm);

Expand All @@ -765,18 +762,7 @@ struct bio *bio_map_user_iov(request_queue_t *q, struct block_device *bdev,
*/
bio_get(bio);

for (i = 0; i < iov_count; i++)
len += iov[i].iov_len;

if (bio->bi_size == len)
return bio;

/*
* don't support partial mappings
*/
bio_endio(bio, bio->bi_size, 0);
bio_unmap_user(bio);
return ERR_PTR(-EINVAL);
return bio;
}

static void __bio_unmap_user(struct bio *bio)
Expand Down
7 changes: 4 additions & 3 deletions include/linux/blkdev.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -678,10 +678,11 @@ extern void __blk_stop_queue(request_queue_t *q);
extern void blk_run_queue(request_queue_t *);
extern void blk_start_queueing(request_queue_t *);
extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned int);
extern int blk_rq_unmap_user(struct bio *, unsigned int);
extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned long);
extern int blk_rq_unmap_user(struct request *);
extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, gfp_t);
extern int blk_rq_map_user_iov(request_queue_t *, struct request *, struct sg_iovec *, int);
extern int blk_rq_map_user_iov(request_queue_t *, struct request *,
struct sg_iovec *, int, unsigned int);
extern int blk_execute_rq(request_queue_t *, struct gendisk *,
struct request *, int);
extern void blk_execute_rq_nowait(request_queue_t *, struct gendisk *,
Expand Down

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