GFS2: Fix non-recursive truncate bug
Before this patch if you truncated a file to a smaller size it
wasn't freeing all the blocks properly. There are two reasons.
First, the metapath comparison was not comparing previous heights.
I added a function, mp_eq_to_hgt, which checks the metapath at
all heights prior to the target height.
Second, in function find_nonnull_ptr, it needed to zero out all
pointers for heights following the target height. Translated into
decimal integer terms, this way a number like 299, when incremented,
becomes 300, not 399. The 2 gets incremented to 3, and the following
digits need to be reset.
These two things allow the truncate state machine to properly find
the blocks it needs to delete.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index fa3ea29..3dd0cce 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -1104,8 +1104,15 @@ static bool find_nonnull_ptr(struct gfs2_sbd *sdp, struct metapath *mp,
while (true) {
ptr = metapointer(h, mp);
- if (*ptr) /* if we have a non-null pointer */
+ if (*ptr) { /* if we have a non-null pointer */
+ /* Now zero the metapath after the current height. */
+ h++;
+ if (h < GFS2_MAX_META_HEIGHT)
+ memset(&mp->mp_list[h], 0,
+ (GFS2_MAX_META_HEIGHT - h) *
+ sizeof(mp->mp_list[0]));
return true;
+ }
if (mp->mp_list[h] < ptrs)
mp->mp_list[h]++;
@@ -1121,6 +1128,13 @@ enum dealloc_states {
DEALLOC_DONE = 3, /* process complete */
};
+static bool mp_eq_to_hgt(struct metapath *mp, __u16 *nbof, unsigned int h)
+{
+ if (memcmp(mp->mp_list, nbof, h * sizeof(mp->mp_list[0])))
+ return false;
+ return true;
+}
+
/**
* trunc_dealloc - truncate a file down to a desired size
* @ip: inode to truncate
@@ -1198,8 +1212,7 @@ static int trunc_dealloc(struct gfs2_inode *ip, u64 newsize)
/* If we're truncating to a non-zero size and the mp is
at the beginning of file for the strip height, we
need to preserve the first metadata pointer. */
- preserve1 = (newsize &&
- (mp.mp_list[mp_h] == nbof[mp_h]));
+ preserve1 = (newsize && mp_eq_to_hgt(&mp, nbof, mp_h));
bh = mp.mp_bh[mp_h];
gfs2_assert_withdraw(sdp, bh);
if (gfs2_assert_withdraw(sdp,
