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Commit 5565a9d8 authored by Maxim Patlasov's avatar Maxim Patlasov Committed by Miklos Szeredi
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fuse: optimize __fuse_direct_io() 



__fuse_direct_io() allocates fuse-requests by calling fuse_get_req(fc, n). The
patch calculates 'n' based on iov[] array. This is useful because allocating
FUSE_MAX_PAGES_PER_REQ page pointers and descriptors for each fuse request
would be waste of memory in case of iov-s of smaller size.

Signed-off-by: default avatarMaxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent 7c190c8b

fs/fuse/file.c

+21 −4
Original line number Diff line number Diff line
@@ -1088,14 +1088,14 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii, 
		return 0;

	}



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

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

		unsigned npages;

		unsigned long user_addr = fuse_get_user_addr(ii);

		unsigned offset = user_addr & ~PAGE_MASK;

		size_t frag_size = fuse_get_frag_size(ii, *nbytesp - nbytes);

		int ret;



		unsigned n = FUSE_MAX_PAGES_PER_REQ - req->num_pages;

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

		frag_size = min_t(size_t, frag_size, n << PAGE_SHIFT);



		npages = (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -1131,6 +1131,23 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii, 
	return 0;

}



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);

}



static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov,

				unsigned long nr_segs, size_t count,

				loff_t *ppos, int write)
@@ -1145,7 +1162,7 @@ static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov, 


	iov_iter_init(&ii, iov, nr_segs, count, 0);



	req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);

	req = fuse_get_req(fc, fuse_iter_npages(&ii));

	if (IS_ERR(req))

		return PTR_ERR(req);
@@ -1180,7 +1197,7 @@ static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov, 
			break;

		if (count) {

			fuse_put_request(fc, req);

			req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);

			req = fuse_get_req(fc, fuse_iter_npages(&ii));

			if (IS_ERR(req))

				break;

		}