linux-kernel - [PATCH V2 4/5] erofs: remove duplicated unregister

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Date:   Fri,  2 Sep 2022 18:53:04 +0800
From:   Jia Zhu <zhujia.zj@...edance.com>
To:     linux-erofs@...ts.ozlabs.org, xiang@...nel.org, chao@...nel.org
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        yinxin.x@...edance.com, jefflexu@...ux.alibaba.com,
        huyue2@...lpad.com, Jia Zhu <zhujia.zj@...edance.com>
Subject: [PATCH V2 4/5] erofs: remove duplicated unregister_cookie

In erofs umount scenario, erofs_fscache_unregister_cookie() is called
twice in kill_sb() and put_super().

It works for original semantics, cause 'ctx' will be set to NULL in
put_super() and will not be unregister again in kill_sb().
However, in shared domain scenario, we use refcount to maintain the
lifecycle of cookie. Unregister the cookie twice will cause it to be
released early.

For the above reasons, this patch removes duplicate unregister_cookie
and move fscache_unregister_* before shotdown_super() to prevent busy
inode(ctx->inode) when umount.

Signed-off-by: Jia Zhu <zhujia.zj@...edance.com>
---
 fs/erofs/super.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 69de1731f454..667a78f0ee70 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -919,19 +919,20 @@ static void erofs_kill_sb(struct super_block *sb)
 		kill_litter_super(sb);
 		return;
 	}
-	if (erofs_is_fscache_mode(sb))
-		generic_shutdown_super(sb);
-	else
-		kill_block_super(sb);
-
 	sbi = EROFS_SB(sb);
 	if (!sbi)
 		return;
 
+	if (erofs_is_fscache_mode(sb)) {
+		erofs_fscache_unregister_cookie(&sbi->s_fscache);
+		erofs_fscache_unregister_fs(sb);
+		generic_shutdown_super(sb);
+	} else {
+		kill_block_super(sb);
+	}
+
 	erofs_free_dev_context(sbi->devs);
 	fs_put_dax(sbi->dax_dev, NULL);
-	erofs_fscache_unregister_cookie(&sbi->s_fscache);
-	erofs_fscache_unregister_fs(sb);
 	kfree(sbi->opt.fsid);
 	kfree(sbi->opt.domain_id);
 	kfree(sbi);
@@ -951,7 +952,6 @@ static void erofs_put_super(struct super_block *sb)
 	iput(sbi->managed_cache);
 	sbi->managed_cache = NULL;
 #endif
-	erofs_fscache_unregister_cookie(&sbi->s_fscache);
 }
 
 struct file_system_type erofs_fs_type = {
-- 
2.20.1