Commit 7d41870d authored by Xiubo Li's avatar Xiubo Li Committed by Ilya Dryomov
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ceph: implement writeback livelock avoidance using page tagging 



While the mapped IOs continue if we try to flush a file's buffer
we can see that the fsync() won't complete until the IOs finish.

This is analogous to Jan Kara's commit (f446daae mm: implement
writeback livelock avoidance using page tagging), we will try to
avoid livelocks of writeback when some steadily creates dirty pages
in a mapping we are writing out.

Signed-off-by: default avatarXiubo Li <xiubli@redhat.com>
Reviewed-by: default avatarIlya Dryomov <idryomov@gmail.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 7a6c3a03

fs/ceph/addr.c

+10 −1
Original line number Diff line number Diff line
@@ -808,6 +808,7 @@ static int ceph_writepages_start(struct address_space *mapping, 
	bool should_loop, range_whole = false;

	bool done = false;

	bool caching = ceph_is_cache_enabled(inode);

	xa_mark_t tag;



	if (wbc->sync_mode == WB_SYNC_NONE &&

	    fsc->write_congested)
@@ -834,6 +835,11 @@ static int ceph_writepages_start(struct address_space *mapping, 
	start_index = wbc->range_cyclic ? mapping->writeback_index : 0;

	index = start_index;



	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) {

		tag = PAGECACHE_TAG_TOWRITE;

	} else {

		tag = PAGECACHE_TAG_DIRTY;

	}

retry:

	/* find oldest snap context with dirty data */

	snapc = get_oldest_context(inode, &ceph_wbc, NULL);
@@ -872,6 +878,9 @@ static int ceph_writepages_start(struct address_space *mapping, 
		dout(" non-head snapc, range whole\n");

	}



	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)

		tag_pages_for_writeback(mapping, index, end);



	ceph_put_snap_context(last_snapc);

	last_snapc = snapc;
@@ -888,7 +897,7 @@ static int ceph_writepages_start(struct address_space *mapping, 


get_more_pages:

		nr_folios = filemap_get_folios_tag(mapping, &index,

				end, PAGECACHE_TAG_DIRTY, &fbatch);

						   end, tag, &fbatch);

		dout("pagevec_lookup_range_tag got %d\n", nr_folios);

		if (!nr_folios && !locked_pages)

			break;