Hi, Andreas Gruenbacher found a thinko in the previous version of this patch. Here is the revised version 2 patch.
Bob Peterson --- 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 <[email protected]> --- diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index fa3ea29f39cf..2def66d81c86 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[0], &nbof[0], 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,
