Add way to query creation time of file via cifs xattr

Add parsing for new pseudo-xattr user.cifs.creationtime file
attribute to allow backup and test applications to view
birth time of file on cifs/smb3 mounts.

Signed-off-by: Steve French <steve.french@primarydata.com>

1 files changed, 27 insertions, 1 deletions

diff --git a/fs/cifs/xattr.c b/fs/cifs/xattr.c
index c4237b8ad9c6..20af5187ba63 100644
--- a/fs/cifs/xattr.c
+++ b/fs/cifs/xattr.c
@@ -34,7 +34,7 @@
 #define MAX_EA_VALUE_SIZE 65535
 #define CIFS_XATTR_CIFS_ACL "system.cifs_acl"
 #define CIFS_XATTR_ATTRIB "cifs.dosattrib"  /* full name: user.cifs.dosattrib */
-
+#define CIFS_XATTR_CREATETIME "cifs.creationtime"  /* user.cifs.creationtime */
 /* BB need to add server (Samba e.g) support for security and trusted prefix */
 
 enum { XATTR_USER, XATTR_CIFS_ACL, XATTR_ACL_ACCESS, XATTR_ACL_DEFAULT };
@@ -169,6 +169,29 @@ static int cifs_attrib_get(struct dentry *dentry,
         return sizeof(__u32);
 }
 
+static int cifs_creation_time_get(struct dentry *dentry, struct inode *inode,
+                                  void *value, size_t size)
+{
+        ssize_t rc;
+        __u64 * pcreatetime;
+
+        rc = cifs_revalidate_dentry_attr(dentry);
+        if (rc)
+                return rc;
+
+        if ((value == NULL) || (size == 0))
+                return sizeof(__u64);
+        else if (size < sizeof(__u64))
+                return -ERANGE;
+
+        /* return dos attributes as pseudo xattr */
+        pcreatetime = (__u64 *)value;
+        *pcreatetime = CIFS_I(inode)->createtime;
+        return sizeof(__u64);
+
+        return rc;
+}
+
 
 static int cifs_xattr_get(const struct xattr_handler *handler,
                           struct dentry *dentry, struct inode *inode,
@@ -202,6 +225,9 @@ static int cifs_xattr_get(const struct xattr_handler *handler,
                 if (strcmp(name, CIFS_XATTR_ATTRIB) == 0) {
                         rc = cifs_attrib_get(dentry, inode, value, size);
                         break;
+                } else if (strcmp(name, CIFS_XATTR_CREATETIME) == 0) {
+                        rc = cifs_creation_time_get(dentry, inode, value, size);
+                        break;
                 }
 
                 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_XATTR)