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From:   Hao Li <lihao2018.fnst@cn.fujitsu.com>
To:     <viro@zeniv.linux.org.uk>
CC:     <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <lihao2018.fnst@cn.fujitsu.com>, <y-goto@fujitsu.com>
Subject: [PATCH] fs: Kill DCACHE_DONTCACHE dentry even if DCACHE_REFERENCED is set
Date:   Fri, 21 Aug 2020 09:59:53 +0800
Message-ID: <20200821015953.22956-1-lihao2018.fnst@cn.fujitsu.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Currently, DCACHE_REFERENCED prevents the dentry with DCACHE_DONTCACHE
set from being killed, so the corresponding inode can't be evicted. If
the DAX policy of an inode is changed, we can't make policy changing
take effects unless dropping caches manually.

This patch fixes this problem and flushes the inode to disk to prepare
for evicting it.

Signed-off-by: Hao Li <lihao2018.fnst@cn.fujitsu.com>
---
 fs/dcache.c | 3 ++-
 fs/inode.c  | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index ea0485861d93..486c7409dc82 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -796,7 +796,8 @@ static inline bool fast_dput(struct dentry *dentry)
 	 */
 	smp_rmb();
 	d_flags = READ_ONCE(dentry->d_flags);
-	d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED;
+	d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED
+			| DCACHE_DONTCACHE;
 
 	/* Nothing to do? Dropping the reference was all we needed? */
 	if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry))
diff --git a/fs/inode.c b/fs/inode.c
index 72c4c347afb7..5218a8aebd7f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1632,7 +1632,7 @@ static void iput_final(struct inode *inode)
 	}
 
 	state = inode->i_state;
-	if (!drop) {
+	if (!drop || (drop && (inode->i_state & I_DONTCACHE))) {
 		WRITE_ONCE(inode->i_state, state | I_WILL_FREE);
 		spin_unlock(&inode->i_lock);
 
-- 
2.28.0