Re: [PATCH 05/17] bio: cleanup rw usage

From: Boaz Harrosh
Date: Thu Apr 02 2009 - 04:39:18 EST


On 04/01/2009 04:44 PM, Tejun Heo wrote:
> Impact: cleanup
>
> bio confusingly uses @write_to_vm and @reading for data directions,
> both of which mean the opposite of the usual block/bio convention of
> using READ and WRITE w.r.t. IO devices. The only place where the
> inversion is necessary is when caling get_user_pages_fast() in
> bio_copy_user_iov() as the gup uses the VM convention of read/write
> w.r.t. VM.
>
> This patch converts all bio functions to use READ/WRITE rw parameter
> and let the one place where inversion is necessary to rw == READ.
>

Hi one more nit picking just if you are at it. If you want
I can do the work and send it to you so you can squash it into this patch.
See bellow

> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> ---
> block/blk-map.c | 10 +++++-----
> fs/bio.c | 50 +++++++++++++++++++++++++-------------------------
> include/linux/bio.h | 18 +++++++++---------
> 3 files changed, 39 insertions(+), 39 deletions(-)
>
> diff --git a/block/blk-map.c b/block/blk-map.c
> index b0b65ef..29aa60d 100644
> --- a/block/blk-map.c
> +++ b/block/blk-map.c
> @@ -68,15 +68,15 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
> int iov_count, unsigned int len, gfp_t gfp_mask)
> {
> struct bio *bio = ERR_PTR(-EINVAL);
> - int read = rq_data_dir(rq) == READ;
> + int rw = rq_data_dir(rq);
>
> if (!iov || iov_count <= 0)
> return -EINVAL;
>
> if (!map_data)
> - bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);
> + bio = bio_map_user_iov(q, NULL, iov, iov_count, rw, gfp_mask);
> if (bio == ERR_PTR(-EINVAL))
> - bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,
> + bio = bio_copy_user_iov(q, map_data, iov, iov_count, rw,
> gfp_mask);
> if (IS_ERR(bio))
> return PTR_ERR(bio);
> @@ -177,7 +177,7 @@ EXPORT_SYMBOL(blk_rq_unmap_user);
> int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
> unsigned int len, gfp_t gfp_mask)
> {
> - int reading = rq_data_dir(rq) == READ;
> + int rw = rq_data_dir(rq);
> int do_copy = 0;
> struct bio *bio;
>
> @@ -188,7 +188,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
>
> do_copy = !blk_rq_aligned(q, kbuf, len) || object_is_on_stack(kbuf);
> if (do_copy)
> - bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
> + bio = bio_copy_kern(q, kbuf, len, gfp_mask, rw);
> else
> bio = bio_map_kern(q, kbuf, len, gfp_mask);
>
> diff --git a/fs/bio.c b/fs/bio.c
> index 80f61ed..70e5153 100644
> --- a/fs/bio.c
> +++ b/fs/bio.c
> @@ -780,7 +780,7 @@ int bio_uncopy_user(struct bio *bio)
> * @map_data: pointer to the rq_map_data holding pages (if necessary)
> * @iov: the iovec.
> * @iov_count: number of elements in the iovec
> - * @write_to_vm: bool indicating writing to pages or not
> + * @rw: READ or WRITE
> * @gfp_mask: memory allocation flags
> *
> * Prepares and returns a bio for indirect user io, bouncing data
> @@ -789,8 +789,8 @@ int bio_uncopy_user(struct bio *bio)
> */
> struct bio *bio_copy_user_iov(struct request_queue *q,
> struct rq_map_data *map_data,
> - struct sg_iovec *iov, int iov_count,
> - int write_to_vm, gfp_t gfp_mask)
> + struct sg_iovec *iov, int iov_count, int rw,
> + gfp_t gfp_mask)
> {
> struct bio_map_data *bmd;
> struct bio_vec *bvec;
> @@ -823,7 +823,8 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
> if (!bio)
> goto out_bmd;
>
> - bio->bi_rw |= (!write_to_vm << BIO_RW);
> + if (rw == WRITE)
> + bio->bi_rw |= 1 << BIO_RW;

can we pleas have an inline that does that? Like bio_set_dir()?
and change all users. You will be surprised how many there are.

It gives me an hart attack every time I have to write yet another
one.

>
> ret = 0;
>
> @@ -872,7 +873,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
> */
> if (unlikely(map_data && map_data->null_mapped))
> bio->bi_flags |= (1 << BIO_NULL_MAPPED);
> - else if (!write_to_vm) {
> + else if (rw == WRITE) {
> ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 0);
> if (ret)
> goto cleanup;
> @@ -897,7 +898,7 @@ out_bmd:
> * @map_data: pointer to the rq_map_data holding pages (if necessary)
> * @uaddr: start of user address
> * @len: length in bytes
> - * @write_to_vm: bool indicating writing to pages or not
> + * @rw: READ or WRITE
> * @gfp_mask: memory allocation flags
> *
> * Prepares and returns a bio for indirect user io, bouncing data
> @@ -905,21 +906,21 @@ out_bmd:
> * call bio_uncopy_user() on io completion.
> */
> struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
> - unsigned long uaddr, unsigned int len,
> - int write_to_vm, gfp_t gfp_mask)
> + unsigned long uaddr, unsigned int len, int rw,
> + gfp_t gfp_mask)
> {
> struct sg_iovec iov;
>
> iov.iov_base = (void __user *)uaddr;
> iov.iov_len = len;
>
> - return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
> + return bio_copy_user_iov(q, map_data, &iov, 1, rw, gfp_mask);
> }
>
> static struct bio *__bio_map_user_iov(struct request_queue *q,
> struct block_device *bdev,
> struct sg_iovec *iov, int iov_count,
> - int write_to_vm, gfp_t gfp_mask)
> + int rw, gfp_t gfp_mask)
> {
> int i, j;
> size_t tot_len = 0;
> @@ -967,8 +968,8 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
> const int local_nr_pages = end - start;
> const int page_limit = cur_page + local_nr_pages;
>
> - ret = get_user_pages_fast(uaddr, local_nr_pages,
> - write_to_vm, &pages[cur_page]);
> + ret = get_user_pages_fast(uaddr, local_nr_pages, rw == READ,
> + &pages[cur_page]);
> if (ret < local_nr_pages) {
> ret = -EFAULT;
> goto out_unmap;
> @@ -1008,7 +1009,7 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
> /*
> * set data direction, and check if mapped pages need bouncing
> */
> - if (!write_to_vm)
> + if (rw == WRITE)
> bio->bi_rw |= (1 << BIO_RW);

Here

>
> bio->bi_bdev = bdev;
> @@ -1033,14 +1034,14 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
> * @bdev: destination block device
> * @uaddr: start of user address
> * @len: length in bytes
> - * @write_to_vm: bool indicating writing to pages or not
> + * @rw: READ or WRITE
> * @gfp_mask: memory allocation flags
> *
> * Map the user space address into a bio suitable for io to a block
> * device. Returns an error pointer in case of error.
> */
> struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
> - unsigned long uaddr, unsigned int len, int write_to_vm,
> + unsigned long uaddr, unsigned int len, int rw,
> gfp_t gfp_mask)
> {
> struct sg_iovec iov;
> @@ -1048,7 +1049,7 @@ struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
> iov.iov_base = (void __user *)uaddr;
> iov.iov_len = len;
>
> - return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
> + return bio_map_user_iov(q, bdev, &iov, 1, rw, gfp_mask);
> }
>
> /**
> @@ -1057,20 +1058,19 @@ struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
> * @bdev: destination block device
> * @iov: the iovec.
> * @iov_count: number of elements in the iovec
> - * @write_to_vm: bool indicating writing to pages or not
> + * @rw: READ or WRITE
> * @gfp_mask: memory allocation flags
> *
> * Map the user space address into a bio suitable for io to a block
> * device. Returns an error pointer in case of error.
> */
> struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
> - struct sg_iovec *iov, int iov_count,
> - int write_to_vm, gfp_t gfp_mask)
> + struct sg_iovec *iov, int iov_count, int rw,
> + gfp_t gfp_mask)
> {
> struct bio *bio;
>
> - bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
> - gfp_mask);
> + bio = __bio_map_user_iov(q, bdev, iov, iov_count, rw, gfp_mask);
> if (IS_ERR(bio))
> return bio;
>
> @@ -1219,23 +1219,23 @@ static void bio_copy_kern_endio(struct bio *bio, int err)
> * @data: pointer to buffer to copy
> * @len: length in bytes
> * @gfp_mask: allocation flags for bio and page allocation
> - * @reading: data direction is READ
> + * @rw: READ or WRITE
> *
> * copy the kernel address into a bio suitable for io to a block
> * device. Returns an error pointer in case of error.
> */
> struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
> - gfp_t gfp_mask, int reading)
> + gfp_t gfp_mask, int rw)
> {
> struct bio *bio;
> struct bio_vec *bvec;
> int i;
>
> - bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
> + bio = bio_copy_user(q, NULL, (unsigned long)data, len, READ, gfp_mask);
> if (IS_ERR(bio))
> return bio;
>
> - if (!reading) {
> + if (rw == WRITE) {
> void *p = data;
>
> bio_for_each_segment(bvec, bio, i) {
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 4bf7442..45f56d2 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -387,24 +387,24 @@ int bio_get_nr_vecs(struct block_device *bdev);
> sector_t bio_sector_offset(struct bio *bio, unsigned short index,
> unsigned int offset);
> struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
> - unsigned long uaddr, unsigned int len,
> - int write_to_vm, gfp_t gfp_mask);
> + unsigned long uaddr, unsigned int len, int rw,
> + gfp_t gfp_mask);
> struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
> - struct sg_iovec *iov, int iov_count,
> - int write_to_vm, gfp_t gfp_mask);
> + struct sg_iovec *iov, int iov_count, int rw,
> + gfp_t gfp_mask);
> void bio_unmap_user(struct bio *bio);
> struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
> - unsigned long uaddr, unsigned int len,
> - int write_to_vm, gfp_t gfp_mask);
> + unsigned long uaddr, unsigned int len, int rw,
> + gfp_t gfp_mask);
> struct bio *bio_copy_user_iov(struct request_queue *q,
> struct rq_map_data *map_data,
> - struct sg_iovec *iov, int iov_count,
> - int write_to_vm, gfp_t gfp_mask);
> + struct sg_iovec *iov, int iov_count, int rw,
> + gfp_t gfp_mask);
> int bio_uncopy_user(struct bio *bio);
> struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
> gfp_t gfp_mask);
> struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
> - gfp_t gfp_mask, int reading);
> + gfp_t gfp_mask, int rw);
> void bio_set_pages_dirty(struct bio *bio);
> void bio_check_pages_dirty(struct bio *bio);
> void zero_fill_bio(struct bio *bio);

Boaz
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