linux-kernel - [PATCH 4.19 149/190] cifs: Properly handle auto disabling of serverino option

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Message-Id: <20190913130611.864977851@linuxfoundation.org>
Date:   Fri, 13 Sep 2019 14:06:44 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, "Paulo Alcantara (SUSE)" <paulo@...lo.ac>,
        Steve French <stfrench@...rosoft.com>,
        Pavel Shilovsky <pshilove@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 149/190] cifs: Properly handle auto disabling of serverino option

[ Upstream commit 29fbeb7a908a60a5ae8c50fbe171cb8fdcef1980 ]

Fix mount options comparison when serverino option is turned off later
in cifs_autodisable_serverino() and thus avoiding mismatch of new cifs
mounts.

Cc: stable@...r.kernel.org
Signed-off-by: Paulo Alcantara (SUSE) <paulo@...lo.ac>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Reviewed-by: Pavel Shilovsky <pshilove@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/cifs/cifs_fs_sb.h | 5 +++++
 fs/cifs/connect.c    | 8 ++++++--
 fs/cifs/misc.c       | 1 +
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index 9731d0d891e7e..aba2b48d4da1a 100644
--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -72,5 +72,10 @@ struct cifs_sb_info {
 	struct delayed_work prune_tlinks;
 	struct rcu_head rcu;
 	char *prepath;
+	/*
+	 * Indicate whether serverino option was turned off later
+	 * (cifs_autodisable_serverino) in order to match new mounts.
+	 */
+	bool mnt_cifs_serverino_autodisabled;
 };
 #endif				/* _CIFS_FS_SB_H */
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index c53a2e86ed544..208430bb66fc6 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3247,12 +3247,16 @@ compare_mount_options(struct super_block *sb, struct cifs_mnt_data *mnt_data)
 {
 	struct cifs_sb_info *old = CIFS_SB(sb);
 	struct cifs_sb_info *new = mnt_data->cifs_sb;
+	unsigned int oldflags = old->mnt_cifs_flags & CIFS_MOUNT_MASK;
+	unsigned int newflags = new->mnt_cifs_flags & CIFS_MOUNT_MASK;
 
 	if ((sb->s_flags & CIFS_MS_MASK) != (mnt_data->flags & CIFS_MS_MASK))
 		return 0;
 
-	if ((old->mnt_cifs_flags & CIFS_MOUNT_MASK) !=
-	    (new->mnt_cifs_flags & CIFS_MOUNT_MASK))
+	if (old->mnt_cifs_serverino_autodisabled)
+		newflags &= ~CIFS_MOUNT_SERVER_INUM;
+
+	if (oldflags != newflags)
 		return 0;
 
 	/*
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index facc94e159a16..e45f8e321371c 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -523,6 +523,7 @@ cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 {
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 		cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
+		cifs_sb->mnt_cifs_serverino_autodisabled = true;
 		cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s. This server doesn't seem to support them properly. Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n",
 			 cifs_sb_master_tcon(cifs_sb)->treeName);
 	}
-- 
2.20.1