Add way to query file attributes via cifs xattr

Add parsing for new pseudo-xattr user.cifs.dosattrib file attribute
so tools can recognize what kind of file it is, and verify if common
SMB3 attributes (system, hidden, archive, sparse, indexed etc.) are
set.

Signed-off-by: Steve French <steve.french@primarydata.com>
Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>

diff --git a/fs/cifs/xattr.c b/fs/cifs/xattr.c
index 5e23f64..c4237b8 100644 (file)
--- a/fs/cifs/xattr.c
+++ b/fs/cifs/xattr.c
@@ -33,6 +33,7 @@
 
 #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 */
 
 /* BB need to add server (Samba e.g) support for security and trusted prefix */
 
@@ -144,6 +145,31 @@ out:
        return rc;
 }
 
+static int cifs_attrib_get(struct dentry *dentry,
+                          struct inode *inode, void *value,
+                          size_t size)
+{
+       ssize_t rc;
+       __u32 *pattribute;
+
+       rc = cifs_revalidate_dentry_attr(dentry);
+
+       if (rc)
+               return rc;
+
+       if ((value == NULL) || (size == 0))
+               return sizeof(__u32);
+       else if (size < sizeof(__u32))
+               return -ERANGE;
+
+       /* return dos attributes as pseudo xattr */
+       pattribute = (__u32 *)value;
+       *pattribute = CIFS_I(inode)->cifsAttrs;
+
+       return sizeof(__u32);
+}
+
+
 static int cifs_xattr_get(const struct xattr_handler *handler,
                          struct dentry *dentry, struct inode *inode,
                          const char *name, void *value, size_t size)
@@ -168,10 +194,16 @@ static int cifs_xattr_get(const struct xattr_handler *handler,
                rc = -ENOMEM;
                goto out;
        }
-       /* return dos attributes as pseudo xattr */
+
        /* return alt name if available as pseudo attr */
        switch (handler->flags) {
        case XATTR_USER:
+               cifs_dbg(FYI, "%s:querying user xattr %s\n", __func__, name);
+               if (strcmp(name, CIFS_XATTR_ATTRIB) == 0) {
+                       rc = cifs_attrib_get(dentry, inode, value, size);
+                       break;
+               }
+
                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_XATTR)
                        goto out;