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From: Jeff Layton <jlayton@kernel.org>
To: "Theodore Y. Ts'o" <tytso@mit.edu>, Matthew Wilcox <willy@infradead.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-fsdevel@vger.kernel.org, fstests@vger.kernel.org,
	xfs <linux-xfs@vger.kernel.org>,
	linux-block <linux-block@vger.kernel.org>
Subject: Re: [PATCH] fs: clear writeback errors in inode_init_always
Date: Mon, 21 May 2018 07:20:05 -0400	[thread overview]
Message-ID: <a11668bbe2050c8b5fb8f27b8b301ba8a78e6a97.camel@kernel.org> (raw)
In-Reply-To: <20180520194124.GB5072@thunk.org>

On Sun, 2018-05-20 at 15:41 -0400, Theodore Y. Ts'o wrote:
> On Sun, May 20, 2018 at 12:20:09PM -0700, Matthew Wilcox wrote:
> > Oh!  I misunderstood.  I thought that bd_inode->i_mapping pointed to
> > lo_backing_file->f_mapping.
> > 
> > So how about this to preserve the error _in the file with the error_?
> > 
> > 	if (bdev) {
> > 		bdput(bdev);
> > 		invalidate_bdev(bdev);
> > +		filp->f_mapping->wb_err = bdev->bd_inode->i_mapping->wb_err;
> > +		bdev->bd_inode->i_mapping->wb_err = 0;
> > 	}
> > 	set_capacity(lo->lo_disk, 0);
> > 	loop_sysfs_exit(lo);
> 
> I don't think it's necessary.  wb_err on the underlying file would
> have already been set when the error was set.  So if someone tried
> calling fsync(2) on the underlying file, it would have collected the
> error already.  Re-setting the error when we detach the loop device
> doesn't seem to make any sense.
> 

(cc'ing linux-block)

Yes, the error would have been set on the original file already. As long
as lo_req_flush or __loop_update_dio weren't called before we detach the
device, it should still be possible to call fsync on the original fd and
get back the error.

As a side note, it looks like __loop_update_dio will discard an error
from vfs_fsync, so certain ioctls against a loop device can cause errors
to be lost. It seems like those ought to get propagated to userland or
to the blockdev's mapping somehow.
-- 
Jeff Layton <jlayton@kernel.org>

  reply	other threads:[~2018-05-21 11:20 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-18 22:50 commit b4678df184b causing xfstests regressions Theodore Y. Ts'o
2018-05-19  2:17 ` Matthew Wilcox
2018-05-19 13:09 ` Jeff Layton
2018-05-19 15:25   ` Darrick J. Wong
2018-05-19 15:27   ` [PATCH] fs: clear writeback errors in inode_init_always Darrick J. Wong
2018-05-19 15:36     ` Matthew Wilcox
2018-05-21 17:54       ` Darrick J. Wong
2018-05-22 10:30         ` Jeff Layton
2018-05-22 22:09           ` Dave Chinner
2018-05-23 10:56             ` Jeff Layton
2018-05-24  3:59               ` Dave Chinner
2018-05-19 23:19     ` Theodore Y. Ts'o
2018-05-20 11:45       ` Jeff Layton
2018-05-20 12:58         ` Matthew Wilcox
2018-05-20 13:18           ` Jeff Layton
2018-05-20 16:29           ` Theodore Y. Ts'o
2018-05-20 19:20             ` Matthew Wilcox
2018-05-20 19:41               ` Theodore Y. Ts'o
2018-05-21 11:20                 ` Jeff Layton [this message]
2018-05-21 14:43                   ` Theodore Y. Ts'o
2018-05-20 17:57         ` Theodore Y. Ts'o
2018-05-22  4:06     ` [PATCH v2] " Darrick J. Wong
2018-05-22 10:14       ` Jeff Layton
2018-05-22 12:14       ` Brian Foster
2018-05-22 14:37         ` Darrick J. Wong
2018-05-22 16:43     ` [PATCH v3] " Darrick J. Wong
2018-05-22 18:40       ` Brian Foster
2018-05-22 18:47         ` Darrick J. Wong
2018-05-22 22:05       ` Dave Chinner
2018-05-23  3:00         ` Darrick J. Wong

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