From: Kent Overstreet Date: Fri, 25 Oct 2019 22:54:58 +0000 (-0400) Subject: bcachefs: Fix an error path race X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=406d6d5a0733f3eacbcd4c33905bf63c5b2f4c07;p=linux.git bcachefs: Fix an error path race On IO error, bch2_writepages_io_done() will set the page state to indicate nothing's already reserved (since the write didn't happen, we don't know what's already reserved). This can race with the buffered IO path, in between getting a disk reservation and calling bch2_set_page_dirty(). Signed-off-by: Kent Overstreet --- diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c index c539ed3aa48dd..93f6cdbbf7c72 100644 --- a/fs/bcachefs/fs-io.c +++ b/fs/bcachefs/fs-io.c @@ -491,7 +491,12 @@ static void bch2_set_page_dirty(struct bch_fs *c, unsigned sectors = sectors_to_reserve(&s->s[i], res->disk.nr_replicas); - BUG_ON(sectors > res->disk.sectors); + /* + * This can happen if we race with the error path in + * bch2_writepage_io_done(): + */ + sectors = min_t(unsigned, sectors, res->disk.sectors); + s->s[i].replicas_reserved += sectors; res->disk.sectors -= sectors;