From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 836E37EEED for ; Tue, 21 May 2024 13:59:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716299945; cv=none; b=agdYFpcJIkD5iuwMAws9jZo4Z5wRGZUjFP6GwhOyeJK570pYGj3fgJKqK/N8S0iilOFdvQRTLibDoVQZN00AJhhV5XNTTGeTWpOBQU3T4a7dCczw4ORt+705e+h5OrMjtRSHmbocoh85QTFEC8ZS/Bz/uwOMZeoRQ1FmLezPvLg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716299945; c=relaxed/simple; bh=UEZ0WMZ4XArP6KLLkJ6qgnUPdgmhbpCZWin5M8esxRY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VmHoN9d61+9WPm8i+JeNrCPco942wtvuCVg3eM62MVBHyd3VXdC1yE4HV697qDNAo2ZtVAx+IXNJqKazbBMcJVrG/APwj+VP41UNNWEju0w2J9nWO5GGn9Ax+HETwbrMILH19O3EHgwBC+P0jrU22FYSGDXRxP04DWsiwNpPXgU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=m3avxQXa; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="m3avxQXa" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=APnWJvM6F7iuTj7cj3iFBMrZlAdC5FbnyIBf45t3ZyA=; b=m3avxQXaP0tgoNY8FCZdOfu2b9 5pVJ++Eybowa+Ujms+GJ4v4wGCkZdx9boBZY6RKVavWgXpo0bzbhSlAVB4UiE7zgviT5Yd0v5D0NM uGY6d7g0CZpWh5tuNJmR3VepWmMCBlpnnfiA2ML94H6/pEI89OkCVKXndblOuHtiUe1PE9CrzQKIn I6l8VxSJAyu1LBa1ArSuPFWin817TkbXuonXXTtU4dLtSDNKX+1oaPvL+j5M5ut1FXN3yRpAu7qUd jCgJQrjR7tCCJNlzZVIz5GYalSCTwnMBasbdxNdwTFmDvYealChs5j7xCRmfCNkCRroHcMgN3wdiW Ziq3QS2Q==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s9Q19-000000004vd-0GE9; Tue, 21 May 2024 13:59:03 +0000 Date: Tue, 21 May 2024 06:59:03 -0700 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Chandan Babu R , Christoph Hellwig , xfs Subject: Re: [PATCH] xfs: allow symlinks with short remote targets Message-ID: References: <20240521010447.GM25518@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240521010447.GM25518@frogsfrogsfrogs> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, May 20, 2024 at 06:04:47PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > An internal user complained about log recovery failing on a symlink > ("Bad dinode after recovery") with the following (excerpted) format: > > core.magic = 0x494e > core.mode = 0120777 > core.version = 3 > core.format = 2 (extents) > core.nlinkv2 = 1 > core.nextents = 1 > core.size = 297 > core.nblocks = 1 > core.naextents = 0 > core.forkoff = 0 > core.aformat = 2 (extents) > u3.bmx[0] = [startoff,startblock,blockcount,extentflag] > 0:[0,12,1,0] > > This is a symbolic link with a 297-byte target stored in a disk block, > which is to say this is a symlink with a remote target. The forkoff is > 0, which is to say that there's 512 - 176 == 336 bytes in the inode core > to store the data fork. > > Eventually, testing of generic/388 failed with the same inode corruption > message during inode recovery. In writing a debugging patch to call > xfs_dinode_verify on dirty inode log items when we're committing > transactions, I observed that xfs/298 can reproduce the problem quite > quickly. > > xfs/298 creates a symbolic link, adds some extended attributes, then > deletes them all. The test failure occurs when the final removexattr > also deletes the attr fork because that does not convert the remote > symlink back into a shortform symlink. That is how we trip this test. > The only reason why xfs/298 only triggers with the debug patch added is > that it deletes the symlink, so the final iflush shows the inode as > free. > > I wrote a quick fstest to emulate the behavior of xfs/298, except that > it leaves the symlinks on the filesystem after inducing the "corrupt" > state. Kernels going back at least as far as 4.18 have written out > symlink inodes in this manner and prior to 1eb70f54c445f they did not > object to reading them back in. > > Because we've been writing out inodes this way for quite some time, the > only way to fix this is to relax the check for symbolic links. > Directories don't have this problem because di_size is bumped to > blocksize during the sf->data conversion. > > Fixes: 1eb70f54c445f ("xfs: validate inode fork size against fork format") > Signed-off-by: Darrick J. Wong > --- > fs/xfs/libxfs/xfs_inode_buf.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c > index 2305e64a4d5a9..88f4f2a1855ae 100644 > --- a/fs/xfs/libxfs/xfs_inode_buf.c > +++ b/fs/xfs/libxfs/xfs_inode_buf.c > @@ -375,16 +375,27 @@ xfs_dinode_verify_fork( > * For fork types that can contain local data, check that the fork > * format matches the size of local data contained within the fork. > * > + * A symlink with a small target can have a data fork can be in extents This doesn't parse. Do you mean something like: * Even a symlink with a target small enough to fit into the inode can * be stored in extent format if ... ? The existing parts of the comment could also use a bit of an overhaul and be moved closer to the code they are documenting while you are at it. Otherwise looks good: Reviewed-by: Christoph Hellwig