linux-ext4 - Re: [PATCH 0/2] Add some msg for io error

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Message-ID: <20230326143128.GA436186@mit.edu>
Date:   Sun, 26 Mar 2023 10:31:28 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     zhanchengbin <zhanchengbin1@...wei.com>
Cc:     linux-ext4@...r.kernel.org, linfeilong@...wei.com,
        louhongxiang@...wei.com, liuzhiqiang26@...wei.com
Subject: Re: [PATCH 0/2] Add some msg for io error

On Sat, Mar 25, 2023 at 02:56:50PM +0800, zhanchengbin wrote:
> If there is an EIO during the process of fsck, the user can be notified of it.

Can you identify a code path where the user is *not* getting notified
while e2fsck is running without this patch series?

The unix_io.c module calls fsync() through unix_flush() only.  When
unix_write_byte() calls flush_cached blocks(), if the read or write
system call fails, the error will be returned to the caller of
flush_cached_byte(), and the unix_write_byte() will return the error
back to the caller (in this case, e2fsck).

So in both cases, e2fsck checks the error return from ext2fs_flush()
(which is the only place where write_byte gets called) and
io_channel->flush(), and so the user will get some kind of error
report already.

The error message might not identify exactly what I/O failed, but the
"Error sync" message that this commit series provides is not going to
be much better.

						- Ted