From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH v7 16/22] block: convert to errseq_t based writeback
 error tracking
Date: Tue, 27 Jun 2017 08:20:00 -0700
Message-ID: <20170627152000.GA29664@infradead.org>
References: <20170616193427.13955-1-jlayton@redhat.com>
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Cc: Christoph Hellwig <hch@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Al Viro <viro@ZenIV.linux.org.uk>, Jan Kara <jack@suse.cz>,
	tytso@mit.edu, axboe@kernel.dk, mawilcox@microsoft.com,
	ross.zwisler@linux.intel.com, corbet@lwn.net,
	Chris Mason <clm@fb.com>, Josef Bacik <jbacik@fb.com>,
	David Sterba <dsterba@suse.com>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	Carlos Maiolino <cmaiolino@redhat.com>,
	Eryu Guan <eguan@redhat.com>, David Howells <dhowells@redhat.com>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
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To: Jeff Layton <jlayton@redhat.com>
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On Mon, Jun 26, 2017 at 10:34:18AM -0400, Jeff Layton wrote:
> The bigger question is -- what about more complex filesystems like
> ext4?  There are a couple of cases where we can return -EIO or -EROFS on
> fsync before filemap_write_and_wait_range is ever called. Like this one
> for instance:
> 
>         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
>                 return -EIO;
> 
> ...and the EXT4_MF_FS_ABORTED case.
> 
> Are those conditions ever recoverable, such that a later fsync could
> succeed? IOW, could I do a remount or something such that the existing
> fds are left open and become usable again? 

This looks copied from the xfs forced shutdown code, and in that
case it's final and permanent - you'll need an unmount to
clear it.

> If so, then we really ought to advance the errseq_t in the file when we
> catch those cases as well. If we have to do that, then it probably makes
> sense to leave the ext4 patch as-is.

I think it can switch to the new file helper.

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