Commit 419234d5 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

fuse: only reuse auxiliary request in fuse_writepage_in_flight() 



Don't reuse the queued request, even if it only contains a single page.
This is needed because previous locking changes (spliting out
fiq->waitq.lock from fc->lock) broke the assumption that request will
remain in FR_PENDING at least until the new page contents are copied.

This fix removes a slight optimization for a rare corner case, so we really
shoudln't care.

Reported-by: default avatarKirill Tkhai <ktkhai@virtuozzo.com>
Fixes: fd22d62e ("fuse: no fc->lock for iqueue parts")
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 7f305ca1

fs/fuse/file.c

+7 −6
Original line number Diff line number Diff line
@@ -1746,9 +1746,9 @@ static void fuse_writepages_send(struct fuse_fill_wb_data *data) 


/*

 * First recheck under fi->lock if the offending offset is still under

 * writeback.  If yes, then iterate write requests, to see if there's one

 * already added for a page at this offset.  If there's none, then insert this

 * new request onto the auxiliary list, otherwise reuse the existing one by

 * writeback.  If yes, then iterate auxiliary write requests, to see if there's

 * one already added for a page at this offset.  If there's none, then insert

 * this new request onto the auxiliary list, otherwise reuse the existing one by

 * copying the new page contents over to the old temporary page.

 */

static bool fuse_writepage_in_flight(struct fuse_req *new_req,
@@ -1771,13 +1771,14 @@ static bool fuse_writepage_in_flight(struct fuse_req *new_req, 
	}



	new_req->num_pages = 1;

	for (tmp = old_req; tmp != NULL; tmp = tmp->misc.write.next) {

	for (tmp = old_req->misc.write.next; tmp; tmp = tmp->misc.write.next) {

		pgoff_t curr_index;



		WARN_ON(tmp->inode != new_req->inode);

		curr_index = tmp->misc.write.in.offset >> PAGE_SHIFT;

		if (tmp->num_pages == 1 && curr_index == page->index &&

		    test_bit(FR_PENDING, &tmp->flags)) {

		if (curr_index == page->index) {

			WARN_ON(tmp->num_pages != 1);

			WARN_ON(!test_bit(FR_PENDING, &tmp->flags));

			copy_highpage(tmp->pages[0], page);

			break;

		}

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