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Commit 6ad84aca authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Linus Torvalds
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[PATCH] fuse: ensure progress in read and write 



In direct_io mode, send at least one page per reqest.  Previously it was
possible that reqests with zero data were sent, and hence the read/write
didn't make any progress, resulting in an infinite (though interruptible)
loop.

Signed-off-by: default avatarMiklos Szeredi <miklos@szeredi.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 3ec870d5

fs/fuse/file.c

+3 −4
Original line number Diff line number Diff line
@@ -475,7 +475,7 @@ static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf, 


	nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);

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

	npages = min(npages, FUSE_MAX_PAGES_PER_REQ);

	npages = min(max(npages, 1), FUSE_MAX_PAGES_PER_REQ);

	down_read(&current->mm->mmap_sem);

	npages = get_user_pages(current, current->mm, user_addr, npages, write,

				0, req->pages, NULL);
@@ -506,7 +506,6 @@ static ssize_t fuse_direct_io(struct file *file, const char __user *buf, 
		return -EINTR;



	while (count) {

		size_t tmp;

		size_t nres;

		size_t nbytes = min(count, nmax);

		int err = fuse_get_user_pages(req, buf, nbytes, !write);
@@ -514,8 +513,8 @@ static ssize_t fuse_direct_io(struct file *file, const char __user *buf, 
			res = err;

			break;

		}

		tmp = (req->num_pages << PAGE_SHIFT) - req->page_offset;

		nbytes = min(nbytes, tmp);

		nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;

		nbytes = min(count, nbytes);

		if (write)

			nres = fuse_send_write(req, file, inode, pos, nbytes);

		else