linux-ext4 - [PATCH 8/9] ext4: only initialize mmp

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Date:   Wed, 13 Jul 2022 07:53:16 +0200
From:   Christoph Hellwig <hch@....de>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Christoph Böhmwalder 
        <christoph.boehmwalder@...bit.com>,
        "Md. Haris Iqbal" <haris.iqbal@...os.com>,
        Jack Wang <jinpu.wang@...os.com>, Song Liu <song@...nel.org>,
        "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.com>, Mark Fasheh <mark@...heh.com>,
        Joel Becker <jlbec@...lplan.org>,
        Joseph Qi <joseph.qi@...ux.alibaba.com>,
        linux-block@...r.kernel.org, drbd-dev@...ts.linbit.com,
        linux-raid@...r.kernel.org, linux-ext4@...r.kernel.org,
        ocfs2-devel@....oracle.com
Subject: [PATCH 8/9] ext4: only initialize mmp_bdevname once

mmp_bdevname is currently both initialized nested inside the kthread_run
call in ext4_multi_mount_protect and in the kmmpd thread started by it.

Lift the initiaization out of the kthread_run call in
ext4_multi_mount_protect, move the BUILD_BUG_ON next to it and remove
the duplicate assignment inside of kmmpd.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/ext4/mmp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 79d05e464c432..b7a850b0070b8 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -150,8 +150,6 @@ static int kmmpd(void *data)
 	mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval,
 				 EXT4_MMP_MIN_CHECK_INTERVAL);
 	mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
-	BUILD_BUG_ON(sizeof(mmp->mmp_bdevname) < BDEVNAME_SIZE);
-	bdevname(bh->b_bdev, mmp->mmp_bdevname);
 
 	memcpy(mmp->mmp_nodename, init_utsname()->nodename,
 	       sizeof(mmp->mmp_nodename));
@@ -372,13 +370,15 @@ int ext4_multi_mount_protect(struct super_block *sb,
 
 	EXT4_SB(sb)->s_mmp_bh = bh;
 
+	BUILD_BUG_ON(sizeof(mmp->mmp_bdevname) < BDEVNAME_SIZE);
+	bdevname(bh->b_bdev, mmp->mmp_bdevname);
+
 	/*
 	 * Start a kernel thread to update the MMP block periodically.
 	 */
 	EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, sb, "kmmpd-%.*s",
 					     (int)sizeof(mmp->mmp_bdevname),
-					     bdevname(bh->b_bdev,
-						      mmp->mmp_bdevname));
+					     mmp->mmp_bdevname);
 	if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
 		EXT4_SB(sb)->s_mmp_tsk = NULL;
 		ext4_warning(sb, "Unable to create kmmpd thread for %s.",
-- 
2.30.2