linux-ext4 - Re: [PATCH 1/1] ext4: Remove empty index blocks when punching holes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LFD.2.00.1202290916590.4926@dhcp-27-109.brq.redhat.com>
Date:	Wed, 29 Feb 2012 09:18:54 +0100 (CET)
From:	Lukas Czerner <lczerner@...hat.com>
To:	Allison Henderson <achender@...ux.vnet.ibm.com>
cc:	Lukas Czerner <lczerner@...hat.com>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/1] ext4: Remove empty index blocks when punching
 holes

On Wed, 29 Feb 2012, Allison Henderson wrote:

> On 02/29/2012 12:44 AM, Lukas Czerner wrote:
> > On Wed, 29 Feb 2012, Allison Henderson wrote:
> > 
> > > When punching holes, it is possible that all the entries of an
> > > index block may be removed.  These empty index blocks need to
> > > be removed once punch hole completes.  This patch adds some extra
> > > logic to the punch hole code to remove empty index blocks.
> > 
> > Hi Allison,
> > 
> > I have not looked at the patch, but just to let you know. I am working
> > on a patch to reorganize the punch hole support a bit in order to fix
> > a bug I found but more importantly to make it faster, better
> > understandable and to reuse more of an existing code paths.
> > 
> > I am cleaning up the patches and testing them right now, so hopefully by
> > the end of the week I'll send those out.
> > 
> > Thanks!
> > -Lukas
> > 
> 
> Hi Lukas,
> 
> Alrighty then, sounds good.  This patch seemed to correct the loop discard bug
> we saw earlier for me.  So please make sure you have some similar fix in your
> new patch.  Basically we had some extra index blocks hanging around when the
> depth was greater than one, so the patch just adds some code to free up those
> index blocks in the path if they are empty.  Hope this helps!  Thx!  :)

Thanks Allison,

Actually I started to modifying the punch hole code in order to find
that bug and this problem does go away with my pathes. I'll CC
you on the patches when I send them out.

Thanks!
-Lukas

> 
> Allison Henderson
> 
> > > 
> > > Signed-off-by: Allison Henderson<achender@...ux.vnet.ibm.com>
> > > ---
> > > :100644 100644 ad39627... 6bb2f55... M	fs/ext4/extents.c
> > >   fs/ext4/extents.c |   17 ++++++++++++++++-
> > >   1 files changed, 16 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> > > index ad39627..6bb2f55 100644
> > > --- a/fs/ext4/extents.c
> > > +++ b/fs/ext4/extents.c
> > > @@ -3709,7 +3709,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct
> > > inode *inode,
> > >   	struct ext4_extent newex, *ex, *ex2;
> > >   	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> > >   	ext4_fsblk_t newblock = 0;
> > > -	int free_on_err = 0, err = 0, depth, ret;
> > > +	int free_on_err = 0, err = 0, depth, ret, i;
> > >   	unsigned int allocated = 0, offset = 0;
> > >   	unsigned int allocated_clusters = 0, reserved_clusters = 0;
> > >   	unsigned int punched_out = 0;
> > > @@ -3880,6 +3880,21 @@ int ext4_ext_map_blocks(handle_t *handle, struct
> > > inode *inode,
> > >   			err = ext4_ext_rm_leaf(handle, inode, path,
> > >   					&partial_cluster, map->m_lblk,
> > >   					       map->m_lblk + punched_out);
> > > +			if (err)
> > > +				goto out2;
> > > +
> > > +			/*
> > > +			 * Walk back up the path and remove
> > > +			 * empty index blocks
> > > +			 */
> > > +			for (i = depth - 1; i>  0; i--) {
> > > +				if (path[i].p_hdr->eh_entries == 0) {
> > > +					err = ext4_ext_rm_idx(handle, inode,
> > > +								path + i);
> > > +					if (err)
> > > +						goto out2;
> > > +				}
> > > +			}
> > > 
> > >   			if (!err&&  path->p_hdr->eh_entries == 0) {
> > >   				/*
> > > 
> > 
> 
> 

-- 
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html