linux-kernel - Re: Question regarding direntry read error in fat filesystem when a device is removed

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Message-Id: <E1LgJ4U-00021e-1p@be1.7eggert.dyndns.org>
Date:	Sun, 08 Mar 2009 14:29:37 +0100
From:	Bodo Eggert <7eggert@....de>
To:	YS Kim <historic59@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: Question regarding direntry read error in fat filesystem when a  	device is removed

YS Kim <historic59@...il.com> wrote:

> I have a question about too many error messages from FAT when
> unexpected device removal occurs.
> I got the following error messages when I unplugged a USB
> drive(formatted as FAT) during direntry reading.
> 
> sd 0:0:0:0: rejecting I/O to device being removed
> FAT: Directory bread(block 1478192) failed
> sd 0:0:0:0: rejecting I/O to device being removed
> FAT: Directory bread(block 1478193) failed
> sd 0:0:0:0: rejecting I/O to device being removed
> FAT: Directory bread(block 1478194) failed
> sd 0:0:0:0: rejecting I/O to device being removed
> FAT: Directory bread(block 1478195) failed
> ...
> 
> From the code of fat__get_entry in dir.c, I found that it continues to
> read the next device block
> even if the block reading has been failed. Because of this continuous
> read, a lot of error messages
> come up if the device itself is removed during reading fairly many
> files, and it causes the malfunction
> of my embedded system.
[...]
> Thus, if I modify the code to just return error when fat__get_entry
> fails to read blocks, could it be
> cause any side effects? Except the purpose of backup/recovery, is
> there any other reason for
> the continuous block read?

I guess aborting the directory read would work as expected, but what about
suppressing the messages if you're not sure?

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