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SubjectRe: [PATCH 5/6] fuse: rework fuse_perform_write()
Date
Maxim Patlasov <mpatlasov@parallels.com> writes:

> The patch allocates as many page pointers in fuse_req as needed to cover
> interval [pos .. pos+len-1]. FUSE_WR_PAGES macro is introduced to hide this
> cumbersome arithmetics.

Please don't ever use a macro for something which you can use an inline
function.

> ---
> fs/fuse/file.c | 15 +++++++++++----
> 1 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 9a6dcc6..84cc83c 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -815,7 +815,8 @@ static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
>
> static ssize_t fuse_fill_write_pages(struct fuse_req *req,
> struct address_space *mapping,
> - struct iov_iter *ii, loff_t pos)
> + struct iov_iter *ii, loff_t pos,
> + unsigned nr_pages)
> {
> struct fuse_conn *fc = get_fuse_conn(mapping->host);
> unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
> @@ -875,11 +876,16 @@ static ssize_t fuse_fill_write_pages(struct fuse_req *req,
> if (!fc->big_writes)
> break;
> } while (iov_iter_count(ii) && count < fc->max_write &&
> - req->num_pages < FUSE_MAX_PAGES_PER_REQ && offset == 0);
> + req->num_pages < nr_pages && offset == 0);
>
> return count > 0 ? count : err;
> }
>
> +#define FUSE_WR_PAGES(pos, len) min_t(unsigned, \
> + ((pos + len - 1) >> PAGE_CACHE_SHIFT) - \
> + (pos >> PAGE_CACHE_SHIFT) + 1, \
> + FUSE_MAX_PAGES_PER_REQ)
> +
> static ssize_t fuse_perform_write(struct file *file,
> struct address_space *mapping,
> struct iov_iter *ii, loff_t pos)
> @@ -895,14 +901,15 @@ static ssize_t fuse_perform_write(struct file *file,
> do {
> struct fuse_req *req;
> ssize_t count;
> + unsigned nr_pages = FUSE_WR_PAGES(pos, iov_iter_count(ii));
>
> - req = fuse_get_req_multipage(fc, FUSE_MAX_PAGES_PER_REQ);
> + req = fuse_get_req_multipage(fc, nr_pages);
> if (IS_ERR(req)) {
> err = PTR_ERR(req);
> break;
> }
>
> - count = fuse_fill_write_pages(req, mapping, ii, pos);
> + count = fuse_fill_write_pages(req, mapping, ii, pos, nr_pages);
> if (count <= 0) {
> err = count;
> } else {


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