From: Steve French <stfrench@microsoft.com>
Date: Sat, 22 Sep 2018 12:07:06 -0500
Subject: [PATCH] cifs: do not return atime less than mtime
Git-commit: 9b9c5bea0b960616d638711d0ecc270c3a074e7f
Patch-mainline: v4.20-rc1
References: bsc#1144333

In network file system it is fairly easy for server and client
atime vs. mtime to get confused (and atime updated less frequently)
which we noticed broke some apps which expect atime >= mtime

Also ignore relatime mount option (rather than error on it) since
relatime is basically what some network server fs are doing
(relatime).

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/connect.c |    1 +
 fs/cifs/file.c    |    8 ++++++--
 fs/cifs/inode.c   |    6 +++++-
 3 files changed, 12 insertions(+), 3 deletions(-)

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -250,6 +250,7 @@ static const match_table_t cifs_mount_op
 	{ Opt_ignore, "dev" },
 	{ Opt_ignore, "mand" },
 	{ Opt_ignore, "nomand" },
+	{ Opt_ignore, "relatime" },
 	{ Opt_ignore, "_netdev" },
 
 	{ Opt_err, NULL }
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3907,8 +3907,12 @@ static int cifs_readpage_worker(struct f
 	else
 		cifs_dbg(FYI, "Bytes read %d\n", rc);
 
-	file_inode(file)->i_atime =
-		current_time(file_inode(file));
+	/* we do not want atime to be less than mtime, it broke some apps */
+	file_inode(file)->i_atime = current_time(file_inode(file));
+	if (timespec_compare(&(file_inode(file)->i_atime), &(file_inode(file)->i_mtime)))
+		file_inode(file)->i_atime = file_inode(file)->i_mtime;
+	else
+		file_inode(file)->i_atime = current_time(file_inode(file));
 
 	if (PAGE_SIZE > rc)
 		memset(read_data + rc, 0, PAGE_SIZE - rc);
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -162,7 +162,11 @@ cifs_fattr_to_inode(struct inode *inode,
 	cifs_revalidate_cache(inode, fattr);
 
 	spin_lock(&inode->i_lock);
-	inode->i_atime = fattr->cf_atime;
+	/* we do not want atime to be less than mtime, it broke some apps */
+	if (timespec_compare(&fattr->cf_atime, &fattr->cf_mtime))
+		inode->i_atime = fattr->cf_mtime;
+	else
+		inode->i_atime = fattr->cf_atime;
 	inode->i_mtime = fattr->cf_mtime;
 	inode->i_ctime = fattr->cf_ctime;
 	inode->i_rdev = fattr->cf_rdev;