cifs: do not return atime less than mtime

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>

3 files changed, 12 insertions, 3 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 1605bf250691..d82f0cc71755 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -250,6 +250,7 @@ static const match_table_t cifs_mount_option_tokens = {
         { Opt_ignore, "dev" },
         { Opt_ignore, "mand" },
         { Opt_ignore, "nomand" },
+        { Opt_ignore, "relatime" },
         { Opt_ignore, "_netdev" },
 
         { Opt_err, NULL }
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 8d41ca7bfcf1..fa723e7a08d7 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3889,8 +3889,12 @@ static int cifs_readpage_worker(struct file *file, struct page *page,
         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 (timespec64_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);
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 6e8765f44508..0945d40030eb 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -162,7 +162,11 @@ cifs_fattr_to_inode(struct inode *inode, struct cifs_fattr *fattr)
         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 (timespec64_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;