[PATCH] (drop after 2.6.28) ext4: fix header check in ext4_ext_search_right() for deep extent trees

[Tim Gardner]

TJ wrote:
> Bug #337246
> http://launchpad.net/bugs/337246
> "kernel bug corrupts filesystem on heavy parallel I/O"
> 
> Upstream has received a patch that fixes this issue via
> 
> http://bugzilla.kernel.org/show_bug.cgi?id=12821
> 
> I've confirmed it applies cleanly to Jaunty.
> 
> Please cherry-pick commit 395a87bfefbc400011417e9eaae33169f9f036c0
> 
> Author: Eric Sandeen <sandeen at redhat.com>
> Date:   Tue Mar 10 18:18:47 2009 -0400
> 
> ext4: fix header check in ext4_ext_search_right() for deep extent trees.
>     
> The ext4_ext_search_right() function is confusing; it uses a
> "depth" variable which is 0 at the root and maximum at the leaves,
> but the on-disk metadata uses a "depth" (actually eh_depth) which
> is opposite: maximum at the root, and 0 at the leaves.
>     
> The ext4_ext_check_header() function is given a depth and checks
> the header agaisnt that depth; it expects the on-disk semantics,
> but we are giving it the opposite in the while loop in this
> function.  We should be giving it the on-disk notion of "depth"
> which we can get from (p_depth - depth) - and if you look, the last
> (more commonly hit) call to ext4_ext_check_header() does just this.
>     
> Sending in the wrong depth results in (incorrect) messages
> about corruption:
>     
> EXT4-fs error (device sdb1): ext4_ext_search_right: bad header
> in inode #2621457: unexpected eh_depth - magic f30a, entries 340,
> max 340(0), depth 1(2)
>     
> http://bugzilla.kernel.org/show_bug.cgi?id=12821
>     
> Reported-by: David Dindorp <ddi at dubex.dk>
> Signed-off-by: Eric Sandeen <sandeen at redhat.com>
> Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
> 
> 
> 

Applied
https://bugs.edge.launchpad.net/ubuntu/+source/linux/+bug/346194/comments/2

On a side note, clean cherry-picks from Linus' tree don't need to be
marked as '(drop after 2.6.28)'.

rtg
-- 
Tim Gardner tim.gardner at canonical.com