From: Tahsin Erdogan Subject: [PATCH] e2fsck: eliminate bad update link count attempt Date: Mon, 17 Jul 2017 05:50:35 -0700 Message-ID: <20170717125035.12852-1-tahsin@google.com> Cc: Tahsin Erdogan To: Theodore Ts'o , Andreas Dilger , linux-ext4@vger.kernel.org Return-path: Received: from mail-pf0-f175.google.com ([209.85.192.175]:33709 "EHLO mail-pf0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751290AbdGQMuj (ORCPT ); Mon, 17 Jul 2017 08:50:39 -0400 Received: by mail-pf0-f175.google.com with SMTP id e26so8205513pfd.0 for ; Mon, 17 Jul 2017 05:50:39 -0700 (PDT) Sender: linux-ext4-owner@vger.kernel.org List-ID: Extended attribute inodes have a link count of 1 but they are not attached to any directories. When an xattr inode with zero ea references is found, the remedy is to reconnect it to lost+found dir. Since reconnect operation increments the link count, it would normally become 2 but to avoid that, check_ea_inode() sets the link count to zero in anticipation of reconnect operation. And it does it even when e2fsck is invoked with -n option which causes a fatal e2fsck failure as can be demonstrated with the following test script: mke2fs -b 4096 -I 256 -F -O extent,ea_inode /dev/sdb 1G mount /dev/sdb /mnt/sdb touch /mnt/sdb/x setfattr -n user.ie1 -v $(python -c "print 'v'*5000") /mnt/sdb/x umount /dev/sdb debugfs -w -R 'rm x' /dev/sdb e2fsck -f -n /dev/sdb In this case, e2fsck fails with the following error: e2fsck 1.43.5-WIP (17-Feb-2017) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts ext2fs_write_inode: Attempt to write to filesystem opened read-only while writing inode 13 in check_ea_inode e2fsck: aborted Setting link count to zero is not really required because e2fsck will detect the discrepancy in link count and offer to fix it. Signed-off-by: Tahsin Erdogan --- e2fsck/pass4.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/e2fsck/pass4.c b/e2fsck/pass4.c index 663f87ab59c0..b23347cdb6b0 100644 --- a/e2fsck/pass4.c +++ b/e2fsck/pass4.c @@ -122,17 +122,8 @@ static void check_ea_inode(e2fsck_t ctx, ext2_ino_t i, if (ctx->ea_inode_refs) ea_refcount_fetch(ctx->ea_inode_refs, i, &actual_refs); - if (!actual_refs) { - /* - * There are no attribute references to the ea_inode. - * Zero the link count so that when inode is linked to - * lost+found it has correct link count. - */ - inode->i_links_count = 0; - e2fsck_write_inode(ctx, i, EXT2_INODE(inode), "check_ea_inode"); - ext2fs_icount_store(ctx->inode_link_info, i, 0); + if (!actual_refs) return; - } /* * There are some attribute references, link_counted is now considered -- 2.13.2.932.g7449e964c-goog