From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Linux Kernel List <linux-kernel@vger.kernel.org>,
linux-mtd@lists.infradead.org
Subject: [BUG] 2.6.8-rc3 jffs2 unable to read filesystems
Date: Sat, 7 Aug 2004 14:18:29 +0100 [thread overview]
Message-ID: <20040807141829.D2805@flint.arm.linux.org.uk> (raw)
The following two messages sum up the problem:
JFFS2 compression type 0x5a06 not avaiable.
Error: jffs2_decompress returned -5
It appears that a jffs2 change committed on July 15th has caused recent
2.6.8-rc kernels to be incompatible with jffs2 filesystems modified by
previous kernel versions.
The "new format" jffs2 filesystem uses both "compr" and "usercompr"
of the jffs2_raw_inode structure, whereas previous implementations
left "usercompr" uninitialised and thus contains random data.
This can be seen by tracing through the code from jffs2_alloc_raw_inode()
and noticing that previous implementations do not initialise this field -
AFAICS kmem_cache_alloc() does not guarantee that memory returned by
this function will be initialised.
Therefore, recent 2.6.8-rc kernels must _NOT_ use this field if they
wish to remain compatible with existing jffs2 filesystems.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
WARNING: multiple messages have this Message-ID (diff)
From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Linux Kernel List <linux-kernel@vger.kernel.org>,
linux-mtd@lists.infradead.org
Subject: [BUG] 2.6.8-rc3 jffs2 unable to read filesystems
Date: Sat, 7 Aug 2004 14:18:29 +0100 [thread overview]
Message-ID: <20040807141829.D2805@flint.arm.linux.org.uk> (raw)
The following two messages sum up the problem:
JFFS2 compression type 0x5a06 not avaiable.
Error: jffs2_decompress returned -5
It appears that a jffs2 change committed on July 15th has caused recent
2.6.8-rc kernels to be incompatible with jffs2 filesystems modified by
previous kernel versions.
The "new format" jffs2 filesystem uses both "compr" and "usercompr"
of the jffs2_raw_inode structure, whereas previous implementations
left "usercompr" uninitialised and thus contains random data.
This can be seen by tracing through the code from jffs2_alloc_raw_inode()
and noticing that previous implementations do not initialise this field -
AFAICS kmem_cache_alloc() does not guarantee that memory returned by
this function will be initialised.
Therefore, recent 2.6.8-rc kernels must _NOT_ use this field if they
wish to remain compatible with existing jffs2 filesystems.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
next reply other threads:[~2004-08-07 13:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-07 13:18 Russell King [this message]
2004-08-07 13:18 ` [BUG] 2.6.8-rc3 jffs2 unable to read filesystems Russell King
2004-08-07 21:58 ` David Woodhouse
2004-08-07 21:58 ` David Woodhouse
2004-08-07 22:45 ` Russell King
2004-08-07 22:45 ` Russell King
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