linux-kernel - [PATCH 5.2 033/131] ceph: fix dir_lease_is

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Message-Id: <20190805124953.649120015@linuxfoundation.org>
Date:   Mon,  5 Aug 2019 15:02:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, "Yan, Zheng" <zyan@...hat.com>,
        Jeff Layton <jlayton@...hat.com>,
        Ilya Dryomov <idryomov@...il.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.2 033/131] ceph: fix dir_lease_is_valid()

[ Upstream commit feab6ac25dbfe3ab96299cb741925dc8d2da0caf ]

It should call __ceph_dentry_dir_lease_touch() under dentry->d_lock.
Besides, ceph_dentry(dentry) can be NULL when called by LOOKUP_RCU
d_revalidate()

Signed-off-by: "Yan, Zheng" <zyan@...hat.com>
Reviewed-by: Jeff Layton <jlayton@...hat.com>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ceph/dir.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 0637149fb9f9a..1271024a3797a 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1512,18 +1512,26 @@ static int __dir_lease_try_check(const struct dentry *dentry)
 static int dir_lease_is_valid(struct inode *dir, struct dentry *dentry)
 {
 	struct ceph_inode_info *ci = ceph_inode(dir);
-	struct ceph_dentry_info *di = ceph_dentry(dentry);
-	int valid = 0;
+	int valid;
+	int shared_gen;
 
 	spin_lock(&ci->i_ceph_lock);
-	if (atomic_read(&ci->i_shared_gen) == di->lease_shared_gen)
-		valid = __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1);
+	valid = __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1);
+	shared_gen = atomic_read(&ci->i_shared_gen);
 	spin_unlock(&ci->i_ceph_lock);
-	if (valid)
-		__ceph_dentry_dir_lease_touch(di);
-	dout("dir_lease_is_valid dir %p v%u dentry %p v%u = %d\n",
-	     dir, (unsigned)atomic_read(&ci->i_shared_gen),
-	     dentry, (unsigned)di->lease_shared_gen, valid);
+	if (valid) {
+		struct ceph_dentry_info *di;
+		spin_lock(&dentry->d_lock);
+		di = ceph_dentry(dentry);
+		if (dir == d_inode(dentry->d_parent) &&
+		    di && di->lease_shared_gen == shared_gen)
+			__ceph_dentry_dir_lease_touch(di);
+		else
+			valid = 0;
+		spin_unlock(&dentry->d_lock);
+	}
+	dout("dir_lease_is_valid dir %p v%u dentry %p = %d\n",
+	     dir, (unsigned)atomic_read(&ci->i_shared_gen), dentry, valid);
 	return valid;
 }
 
-- 
2.20.1