UBIFS: add ubifs_err() to print error reason

This patch adds ubifs_err() output to some error paths to tell the user
what's going on.

Artem: improve the messages, rename too long variable
Signed-off-by: Subodh Nijsure <snijsure@grid-net.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Ben Shelton <ben.shelton@ni.com>
Acked-by: Brad Mouring <brad.mouring@ni.com>
Acked-by: Terry Wilcox <terry.wilcox@ni.com>
Acked-by: Gratian Crisan <gratian.crisan@ni.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

fs/ubifs/xattr.c

@@ -100,24 +100,30 @@ static const struct file_operations empty_fops;
 static int create_xattr(struct ubifs_info *c, struct inode *host,
 			const struct qstr *nm, const void *value, int size)
 {
-	int err;
+	int err, names_len;
 	struct inode *inode;
 	struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
 	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
 				.new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
 				.dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
 
-	if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE)
+	if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) {
+		ubifs_err("inode %lu already has too many xattrs (%d), cannot create more",
+			  host->i_ino, host_ui->xattr_cnt);
 		return -ENOSPC;
+	}
 	/*
 	 * Linux limits the maximum size of the extended attribute names list
 	 * to %XATTR_LIST_MAX. This means we should not allow creating more
 	 * extended attributes if the name list becomes larger. This limitation
 	 * is artificial for UBIFS, though.
 	 */
-	if (host_ui->xattr_names + host_ui->xattr_cnt +
-					nm->len + 1 > XATTR_LIST_MAX)
+	names_len = host_ui->xattr_names + host_ui->xattr_cnt + nm->len + 1;
+	if (names_len > XATTR_LIST_MAX) {
+		ubifs_err("cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
+			  host->i_ino, names_len, XATTR_LIST_MAX);
 		return -ENOSPC;
+	}
 
 	err = ubifs_budget_space(c, &req);
 	if (err)
@@ -651,5 +657,8 @@ int ubifs_init_security(struct inode *dentry, struct inode *inode,
 					   &init_xattrs, 0);
 	mutex_unlock(&inode->i_mutex);
 
+	if (err)
+		ubifs_err("cannot initialize security for inode %lu, error %d",
+			  inode->i_ino, err);
 	return err;
 }