Using CR_BEST_AVAIL_LEN only make sense for regular files, as for
non-regular files we never normalize the allocation request length i.e.
goal len is same as original length (ac_g_ex.fe_len == ac_o_ex.fe_len).
Hence there is no scope of trimming the goal length to make it
satisfy original request len. Thus this patch avoids using
CR_BEST_AVAIL_LEN criteria for non-regular files request.
Fixes: 33122aa930f1 ("ext4: Add allocation criteria 1.5 (CR1_5)")
Reported-by: Eric Whitney <enwlinux@xxxxxxxxx>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---
fs/ext4/mballoc.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 3ab37533349f..bc004f5d3f3c 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -975,7 +975,18 @@ static void ext4_mb_choose_next_group_goal_fast(struct ext4_allocation_context *
*group = grp->bb_group;
ac->ac_flags |= EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED;
} else {
- *new_cr = CR_BEST_AVAIL_LEN;
+ /*
+ * CR_BEST_AVAIL_LEN works based on the concept that we have
+ * a larger normalized goal len request which can be trimmed to
+ * a smaller goal len such that it can still satisfy original
+ * request len. However, allocation request for non-regular
+ * files never gets normalized.
+ * See function ext4_mb_normalize_request() (EXT4_MB_HINT_DATA).
+ */
+ if (ac->ac_flags & EXT4_MB_HINT_DATA)
+ *new_cr = CR_BEST_AVAIL_LEN;
+ else
+ *new_cr = CR_GOAL_LEN_SLOW;
}
}
--
2.40.1
