linux-kernel - [PATCH 4/6] f2fs: reduce cmd_lock coverage in __issue_discard

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20170919153016.4116-4-chao@kernel.org>
Date:   Tue, 19 Sep 2017 23:30:14 +0800
From:   Chao Yu <chao@...nel.org>
To:     jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>
Subject: [PATCH 4/6] f2fs: reduce cmd_lock coverage in __issue_discard_cmd

From: Chao Yu <yuchao0@...wei.com>

__submit_discard_cmd may lead long latency due to exhaustion of I/O
request resource in block layer, so issuing all discard under cmd_lock
may lead to hangtask, in order to avoid that, let's reduce it's coverage.

Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
 fs/f2fs/segment.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index c3eb355b0171..412ac3a68be3 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1130,14 +1130,14 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
 	int i, iter = 0, issued = 0;
 	bool io_interrupted = false;
 
-	mutex_lock(&dcc->cmd_lock);
-	f2fs_bug_on(sbi,
-		!__check_rb_tree_consistence(sbi, &dcc->root));
-	blk_start_plug(&plug);
 	for (i = MAX_PLIST_NUM - 1; i >= 0; i--) {
 		if (i + 1 < dpolicy->granularity)
 			break;
 		pend_list = &dcc->pend_list[i];
+
+		mutex_lock(&dcc->cmd_lock);
+		f2fs_bug_on(sbi, !__check_rb_tree_consistence(sbi, &dcc->root));
+		blk_start_plug(&plug);
 		list_for_each_entry_safe(dc, tmp, pend_list, list) {
 			f2fs_bug_on(sbi, dc->state != D_PREP);
 
@@ -1151,12 +1151,14 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
 			issued++;
 skip:
 			if (++iter >= dpolicy->max_requests)
-				goto out;
+				break;
 		}
+		blk_finish_plug(&plug);
+		mutex_unlock(&dcc->cmd_lock);
+
+		if (iter >= dpolicy->max_requests)
+			break;
 	}
-out:
-	blk_finish_plug(&plug);
-	mutex_unlock(&dcc->cmd_lock);
 
 	if (!issued && io_interrupted)
 		issued = -1;
-- 
2.14.1.145.gb3622a4ee