NTFS: Enable ATTR_SIZE attribute changes in ntfs_setattr(). This completes

      the initial implementation of file truncation.  Now both open(2)ing
      a file with the O_TRUNC flag and the {,f}truncate(2) system calls
      will resize a file appropriately.  The limitations are that only
      uncompressed and unencrypted files are supported.  Also, there is
      only very limited support for highly fragmented files (the ones whose
      $DATA attribute is split into multiple attribute extents).

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/ChangeLog

@@ -50,6 +50,13 @@ ToDo/Notes:
 	  but not the initialized size can be extended, too.
 	- Implement fs/ntfs/inode.[hc]::ntfs_truncate().  It only supports
 	  uncompressed and unencrypted files.
+	- Enable ATTR_SIZE attribute changes in ntfs_setattr().  This completes
+	  the initial implementation of file truncation.  Now both open(2)ing
+	  a file with the O_TRUNC flag and the {,f}truncate(2) system calls
+	  will resize a file appropriately.  The limitations are that only
+	  uncompressed and unencrypted files are supported.  Also, there is
+	  only very limited support for highly fragmented files (the ones whose
+	  $DATA attribute is split into multiple attribute extents).
 
 2.1.24 - Lots of bug fixes and support more clean journal states.
 

fs/ntfs/inode.c

@@ -2845,8 +2845,7 @@ int ntfs_setattr(struct dentry *dentry, struct iattr *attr)
 
 	err = inode_change_ok(vi, attr);
 	if (err)
-		return err;
-
+		goto out;
 	/* We do not support NTFS ACLs yet. */
 	if (ia_valid & (ATTR_UID | ATTR_GID | ATTR_MODE)) {
 		ntfs_warning(vi->i_sb, "Changes in user/group/mode are not "
@@ -2854,14 +2853,22 @@ int ntfs_setattr(struct dentry *dentry, struct iattr *attr)
 		err = -EOPNOTSUPP;
 		goto out;
 	}
-
 	if (ia_valid & ATTR_SIZE) {
 		if (attr->ia_size != i_size_read(vi)) {
-			ntfs_warning(vi->i_sb, "Changes in inode size are not "
-					"supported yet, ignoring.");
-			err = -EOPNOTSUPP;
-			// TODO: Implement...
-			// err = vmtruncate(vi, attr->ia_size);
+			ntfs_inode *ni = NTFS_I(vi);
+			/*
+			 * FIXME: For now we do not support resizing of
+			 * compressed or encrypted files yet.
+			 */
+			if (NInoCompressed(ni) || NInoEncrypted(ni)) {
+				ntfs_warning(vi->i_sb, "Changes in inode size "
+						"are not supported yet for "
+						"%s files, ignoring.",
+						NInoCompressed(ni) ?
+						"compressed" : "encrypted");
+				err = -EOPNOTSUPP;
+			} else
+				err = vmtruncate(vi, attr->ia_size);
 			if (err || ia_valid == ATTR_SIZE)
 				goto out;
 		} else {