From 601c0bc46753007be011b513ba4fc50ed8e30aef Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Fri, 22 Aug 2008 14:23:35 +0300 Subject: UBIFS: allow for racing between GC and TNC The TNC mutex is unlocked prematurely when reading leaf nodes with non-hashed keys. This is unsafe because the node may be moved by garbage collection and the eraseblock unmapped, although that has never actually happened during stress testing. This patch fixes the flaw by detecting the race and retrying with the TNC mutex locked. Signed-off-by: Adrian Hunter --- fs/ubifs/gc.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'fs/ubifs/gc.c') diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c index d0f3dac..13f1019 100644 --- a/fs/ubifs/gc.c +++ b/fs/ubifs/gc.c @@ -344,6 +344,12 @@ int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp) if (err) goto out; + /* Allow for races with TNC */ + c->gced_lnum = lnum; + smp_wmb(); + c->gc_seq += 1; + smp_wmb(); + if (c->gc_lnum == -1) { c->gc_lnum = lnum; err = LEB_RETAINED; -- cgit v1.1