Commit f67da30c authored by Al Viro's avatar Al Viro
Browse files

new helper: iov_iter_npages() 



counts the pages covered by iov_iter, up to given limit.
do_block_direct_io() and fuse_iter_npages() switched to
it.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 5b46f25d

fs/direct-io.c

+1 −8
Original line number Diff line number Diff line
@@ -1100,7 +1100,6 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 
	get_block_t get_block, dio_iodone_t end_io,

	dio_submit_t submit_io,	int flags)

{

	int seg;

	unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);

	unsigned blkbits = i_blkbits;

	unsigned blocksize_mask = (1 << blkbits) - 1;
@@ -1108,7 +1107,6 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 
	loff_t end = offset + iov_iter_count(iter);

	struct dio *dio;

	struct dio_submit sdio = { 0, };

	unsigned long user_addr;

	struct buffer_head map_bh = { 0, };

	struct blk_plug plug;

	unsigned long align = offset | iov_iter_alignment(iter);
@@ -1231,12 +1229,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 
	if (unlikely(sdio.blkfactor))

		sdio.pages_in_io = 2;



	for (seg = 0; seg < iter->nr_segs; seg++) {

		user_addr = (unsigned long)iter->iov[seg].iov_base;

		sdio.pages_in_io +=

			((user_addr + iter->iov[seg].iov_len + PAGE_SIZE-1) /

				PAGE_SIZE - user_addr / PAGE_SIZE);

	}

	sdio.pages_in_io += iov_iter_npages(iter, INT_MAX);



	blk_start_plug(&plug);

fs/fuse/file.c

+2 −14
Original line number Diff line number Diff line
@@ -1310,7 +1310,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii, 


	while (nbytes < *nbytesp && req->num_pages < req->max_pages) {

		unsigned npages;

		size_t start, end, frag_size;

		size_t start;

		unsigned n = req->max_pages - req->num_pages;

		ssize_t ret = iov_iter_get_pages(ii,

					&req->pages[req->num_pages],
@@ -1344,19 +1344,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii, 


static inline int fuse_iter_npages(const struct iov_iter *ii_p)

{

	struct iov_iter ii = *ii_p;

	int npages = 0;



	while (iov_iter_count(&ii) && npages < FUSE_MAX_PAGES_PER_REQ) {

		unsigned long user_addr = fuse_get_user_addr(&ii);

		unsigned offset = user_addr & ~PAGE_MASK;

		size_t frag_size = iov_iter_single_seg_count(&ii);



		npages += (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;

		iov_iter_advance(&ii, frag_size);

	}



	return min(npages, FUSE_MAX_PAGES_PER_REQ);

	return iov_iter_npages(ii_p, FUSE_MAX_PAGES_PER_REQ);

}



ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,

include/linux/uio.h

+1 −0
Original line number Diff line number Diff line
@@ -73,6 +73,7 @@ void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, 
			unsigned long nr_segs, size_t count);

ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,

			size_t maxsize, size_t *start);

int iov_iter_npages(const struct iov_iter *i, int maxpages);



static inline size_t iov_iter_count(struct iov_iter *i)

{

mm/iov_iter.c

+27 −0
Original line number Diff line number Diff line
@@ -262,3 +262,30 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, 
	return (res == n ? len : res * PAGE_SIZE) - *start;

}

EXPORT_SYMBOL(iov_iter_get_pages);



int iov_iter_npages(const struct iov_iter *i, int maxpages)

{

	size_t offset = i->iov_offset;

	size_t size = i->count;

	const struct iovec *iov = i->iov;

	int npages = 0;

	int n;



	for (n = 0; size && n < i->nr_segs; n++, iov++) {

		unsigned long addr = (unsigned long)iov->iov_base + offset;

		size_t len = iov->iov_len - offset;

		offset = 0;

		if (unlikely(!len))	/* empty segment */

			continue;

		if (len > size)

			len = size;

		npages += (addr + len + PAGE_SIZE - 1) / PAGE_SIZE

			  - addr / PAGE_SIZE;

		if (npages >= maxpages)	/* don't bother going further */

			return maxpages;

		size -= len;

		offset = 0;

	}

	return min(npages, maxpages);

}

EXPORT_SYMBOL(iov_iter_npages);