linux-ext4 - Re: [PATCH] [RESEND] ext3: set i_extra

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Date:	Wed, 25 Aug 2010 09:05:52 +0900
From:	Masayoshi MIZUMA <m.mizuma@...fujitsu.com>
To:	Jan Kara <jack@...e.cz>
Cc:	Andreas Dilger <adilger.kernel@...ger.ca>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-ext4 <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] [RESEND] ext3: set i_extra_isize of 11th inode

On Tue, 24 Aug 2010 15:17:36 +0200
Jan Kara <jack@...e.cz> wrote:

> On Mon 23-08-10 09:50:56, Masayoshi MIZUMA wrote:
> > In ext3 filesystem, if following conditions 1., 2., 3. and 4. is satisfied,
> > getfattr can't search the extended attribute (EA) after remount.
> > 
> > Condition:
> >     1. the inode size is over 128 byte
> >     2. "lost+found" whose inode number is 11 was removed
> >     3. the 11th inode is used for a file.
> >     4. the EA locates in-inode
> > 
> > This happens because of following logic:
> >     i_extra_isize is set to over 0 by ext3_new_inode() when we create
> >     a file whose inode number is 11 after removing "lost+found".
> >     Therefore setfattr creates the EA in-inode.
> >     After remount, i_extra_isize of 11th inode is set to 0 by ext3_iget()
> >     when we lookup the file, so getfattr tries to search the EA out-inode.
> >     However, the EA locates in-inode, so getfattr can't search the EA.
> > 
> > How to reproduce:
> >     1. mkfs.ext3 -I 256 /dev/sdXX
> >     2. mount -o acl,user_xattr  /dev/sdXX /TEST
> >     3. rm -rf /TEST/*
> >     4. touch /TEST/file (whose inode number is 11)
> >     5. cd /TEST; setfattr -n user.foo0 -v bar0 file
> >     6. cd /TEST; getfattr -d file
> >        -> can see foo0/bar0
> >     7. umount  /dev/sdXX
> >     8. mount -o acl,user_xattr /dev/sdXX /TEST
> >     9. cd /TEST; getfattr -d file
> >        -> can't see foo0/bar0
> > 
> > Though the 11th inode is used for "lost+found" normally, the other
> > file can also use it. Therefore, i_extra_isize of 11th inode should be set
> > to the suitable value by ext3_iget().
>   Hmm, with which kernel have you tested that? Because my 2.6.32 kernel
> works just fine (and looking into the code, all should be handled well).
I tested at 2.6.35.

> Look:
> mount -o loop,user_xattr ~jack/fs-images/ext3-image /mnt/
> quack:/crypted/home/jack # cd /mnt/
> quack:/mnt # touch file
> quack:/mnt # ls -i file
> 11 file
> quack:/mnt # setfattr -n user.foo0 -v bar0 file
> quack:/mnt # getfattr -d file
> # file: file
> user.foo0="bar0"
> 
> quack:/mnt # cd
> quack:~ # umount /mnt
> quack:~ # mount -o loop,user_xattr ~jack/fs-images/ext3-image /mnt/
> quack:~ # getfattr -d /mnt/file
> getfattr: Removing leading '/' from absolute path names
> # file: mnt/file
> user.foo0="bar0"
What size is the inode ? This problem happens if the size is larger than 128 byte.
(I tested at 256 byte inode.)

Thanks,
Masayoshi

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