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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Pavel Shilovsky <pshilov@microsoft.com>,
        Steve French <stfrench@microsoft.com>
Subject: [PATCH 4.9 80/92] CIFS: Force revalidate inode when dentry is stale
Date:   Wed, 16 Oct 2019 14:50:53 -0700
Message-Id: <20191016214846.918626643@linuxfoundation.org>
In-Reply-To: <20191016214759.600329427@linuxfoundation.org>
References: <20191016214759.600329427@linuxfoundation.org>
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From: Pavel Shilovsky <piastryyy@gmail.com>

commit c82e5ac7fe3570a269c0929bf7899f62048e7dbc upstream.

Currently the client indicates that a dentry is stale when inode
numbers or type types between a local inode and a remote file
don't match. If this is the case attributes is not being copied
from remote to local, so, it is already known that the local copy
has stale metadata. That's why the inode needs to be marked for
revalidation in order to tell the VFS to lookup the dentry again
before openning a file. This prevents unexpected stale errors
to be returned to the user space when openning a file.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/cifs/inode.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -405,6 +405,7 @@ int cifs_get_inode_info_unix(struct inod
 		/* if uniqueid is different, return error */
 		if (unlikely(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM &&
 		    CIFS_I(*pinode)->uniqueid != fattr.cf_uniqueid)) {
+			CIFS_I(*pinode)->time = 0; /* force reval */
 			rc = -ESTALE;
 			goto cgiiu_exit;
 		}
@@ -412,6 +413,7 @@ int cifs_get_inode_info_unix(struct inod
 		/* if filetype is different, return error */
 		if (unlikely(((*pinode)->i_mode & S_IFMT) !=
 		    (fattr.cf_mode & S_IFMT))) {
+			CIFS_I(*pinode)->time = 0; /* force reval */
 			rc = -ESTALE;
 			goto cgiiu_exit;
 		}
@@ -917,6 +919,7 @@ cifs_get_inode_info(struct inode **inode
 		/* if uniqueid is different, return error */
 		if (unlikely(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM &&
 		    CIFS_I(*inode)->uniqueid != fattr.cf_uniqueid)) {
+			CIFS_I(*inode)->time = 0; /* force reval */
 			rc = -ESTALE;
 			goto cgii_exit;
 		}
@@ -924,6 +927,7 @@ cifs_get_inode_info(struct inode **inode
 		/* if filetype is different, return error */
 		if (unlikely(((*inode)->i_mode & S_IFMT) !=
 		    (fattr.cf_mode & S_IFMT))) {
+			CIFS_I(*inode)->time = 0; /* force reval */
 			rc = -ESTALE;
 			goto cgii_exit;
 		}