From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751234AbcGGEYY (ORCPT ); Thu, 7 Jul 2016 00:24:24 -0400 Received: from mail.kernel.org ([198.145.29.136]:45798 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750720AbcGGEYX (ORCPT ); Thu, 7 Jul 2016 00:24:23 -0400 From: Chao Yu To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu Subject: [PATCH] f2fs: fix to avoid redundant discard during fstrim Date: Thu, 7 Jul 2016 12:22:12 +0800 Message-Id: <1467865332-9662-1-git-send-email-chao@kernel.org> X-Mailer: git-send-email 2.7.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chao Yu With below test steps, f2fs will issue redundant discard when doing fstrim, the reason is that we issue discards for both prefree segments and consecutive freed region user wants to trim, part regions they covered are overlapped, here, we change to do not to issue any discard for prefree segments no matter in trimmed range or not. 1. mount -t f2fs -o discard /dev/zram0 /mnt/f2fs 2. fstrim -o 0 -l 3221225472 -m 2097152 -v /mnt/f2fs/ 3. dd if=/dev/zero of=/mnt/f2fs/a bs=2M count=1 4. dd if=/dev/zero of=/mnt/f2fs/b bs=1M count=1 5. sync 6. rm /mnt/f2fs/a /mnt/f2fs/b 7. fstrim -o 0 -l 3221225472 -m 2097152 -v /mnt/f2fs/ Before: <...>-5428 [001] ...1 9511.052125: f2fs_issue_discard: dev = (251,0), blkstart = 0x2200, blklen = 0x200 <...>-5428 [001] ...1 9511.052787: f2fs_issue_discard: dev = (251,0), blkstart = 0x2200, blklen = 0x300 After: <...>-6764 [000] ...1 9720.382504: f2fs_issue_discard: dev = (251,0), blkstart = 0x2200, blklen = 0x300 Signed-off-by: Chao Yu --- fs/f2fs/segment.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 6d16ecf..5dafc56 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -710,21 +710,33 @@ void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc) unsigned long *prefree_map = dirty_i->dirty_segmap[PRE]; unsigned int start = 0, end = -1; unsigned int secno, start_segno; + unsigned int trim_start = cpc->trim_start; + unsigned int trim_end = cpc->trim_end; + bool force = (cpc->reason == CP_DISCARD); mutex_lock(&dirty_i->seglist_lock); while (1) { int i; + unsigned int trimmed = 0; + start = find_next_bit(prefree_map, MAIN_SEGS(sbi), end + 1); if (start >= MAIN_SEGS(sbi)) break; end = find_next_zero_bit(prefree_map, MAIN_SEGS(sbi), start + 1); - for (i = start; i < end; i++) - clear_bit(i, prefree_map); + for (i = start; i < end; i++) { + if (!force || (i >= trim_start && i <= trim_end)) { + clear_bit(i, prefree_map); + trimmed++; + } + } + + dirty_i->nr_dirty[PRE] -= trimmed; - dirty_i->nr_dirty[PRE] -= end - start; + if (force) + continue; if (!test_opt(sbi, DISCARD)) continue; @@ -750,7 +762,7 @@ next: /* send small discards */ list_for_each_entry_safe(entry, this, head, list) { - if (cpc->reason == CP_DISCARD && entry->len < cpc->trim_minlen) + if (force && entry->len < cpc->trim_minlen) goto skip; f2fs_issue_discard(sbi, entry->blkaddr, entry->len); cpc->trimmed += entry->len; -- 2.7.2