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Commit 7f305ca1 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

fuse: clean up fuse_writepage_in_flight() 



Restructure the function to better separate the locked and the unlocked
parts.  Use the "old_req" local variable to mean only the queued request,
and not any auxiliary requests added onto its misc.write.next list.  These
changes are in preparation for the following patch.

Also turn BUG_ON instances into WARN_ON and add a header comment explaining
what the function does.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 2fe93bd4

fs/fuse/file.c

+24 −16
Original line number Diff line number Diff line
@@ -1744,6 +1744,13 @@ static void fuse_writepages_send(struct fuse_fill_wb_data *data) 
		end_page_writeback(data->orig_pages[i]);

}



/*

 * 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

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

 */

static bool fuse_writepage_in_flight(struct fuse_req *new_req,

				     struct page *page)

{
@@ -1751,9 +1758,8 @@ static bool fuse_writepage_in_flight(struct fuse_req *new_req, 
	struct fuse_inode *fi = get_fuse_inode(new_req->inode);

	struct fuse_req *tmp;

	struct fuse_req *old_req;

	pgoff_t curr_index;



	BUG_ON(new_req->num_pages != 0);

	WARN_ON(new_req->num_pages != 0);



	spin_lock(&fc->lock);

	list_del(&new_req->writepages_entry);
@@ -1766,32 +1772,34 @@ 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) {

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

		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) {

			old_req = tmp;

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

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

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

			break;

		}

	}



	if (old_req->num_pages == 1 && test_bit(FR_PENDING, &old_req->flags)) {

		struct backing_dev_info *bdi = inode_to_bdi(page->mapping->host);

	if (!tmp) {

		new_req->misc.write.next = old_req->misc.write.next;

		old_req->misc.write.next = new_req;

	}



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

	spin_unlock(&fc->lock);



	if (tmp) {

		struct backing_dev_info *bdi = inode_to_bdi(new_req->inode);



		dec_wb_stat(&bdi->wb, WB_WRITEBACK);

		dec_node_page_state(new_req->pages[0], NR_WRITEBACK_TEMP);

		wb_writeout_inc(&bdi->wb);

		fuse_writepage_free(fc, new_req);

		fuse_request_free(new_req);

		goto out;

	} else {

		new_req->misc.write.next = old_req->misc.write.next;

		old_req->misc.write.next = new_req;

	}

	spin_unlock(&fc->lock);

out:



	return true;

}