UBIFS: fix clean znode counter corruption in error cases
UBIFS maintains per-filesystem and global clean znode counters
('c->clean_zn_cnt' and 'ubifs_clean_zn_cnt'). It is important to maintain
correct values there since the shrinker relies on 'ubifs_clean_zn_cnt'.
However, in case of failures during commit the counters were corrupted. E.g.,
if a failure happens in the middle of 'write_index()', then some nodes in the
commit list ('c->cnext') are marked as clean, and some are marked as dirty. And
the 'ubifs_destroy_tnc_subtree()' frees does not retrun correct count, and we
end up with non-zero 'c->clean_zn_cnt' when unmounting. This means that if we
have 2 file-sytem and one of them fails, and we unmount it,
'ubifs_clean_zn_cnt' stays incorrect and confuses the shrinker.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 8119b1f..91b4213 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -2876,12 +2876,13 @@
*/
void ubifs_tnc_close(struct ubifs_info *c)
{
- long clean_freed;
-
tnc_destroy_cnext(c);
if (c->zroot.znode) {
- clean_freed = ubifs_destroy_tnc_subtree(c->zroot.znode);
- atomic_long_sub(clean_freed, &ubifs_clean_zn_cnt);
+ long n;
+
+ ubifs_destroy_tnc_subtree(c->zroot.znode);
+ n = atomic_long_read(&c->clean_zn_cnt);
+ atomic_long_sub(n, &ubifs_clean_zn_cnt);
}
kfree(c->gap_lebs);
kfree(c->ilebs);