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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) {
> > > /*
> > >
> >
>
>
--
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