linux-ext4 - Re: [PATCH] ext4: Automatic setting of {INODE,BLOCK}

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Message-ID: <alpine.LFD.2.00.1210251138100.24674@dhcp-1-104.brq.redhat.com>
Date:	Thu, 25 Oct 2012 11:44:44 +0200 (CEST)
From:	Lukáš Czerner <lczerner@...hat.com>
To:	Yongqiang Yang <xiaoqiangnk@...il.com>
cc:	Tomas Racek <tracek@...hat.com>, linux-ext4@...r.kernel.org,
	lczerner@...hat.com
Subject: Re: [PATCH] ext4: Automatic setting of {INODE,BLOCK}_UNINIT flags

On Thu, 25 Oct 2012, Yongqiang Yang wrote:

> Date: Thu, 25 Oct 2012 15:44:48 +0800
> From: Yongqiang Yang <xiaoqiangnk@...il.com>
> To: Tomas Racek <tracek@...hat.com>
> Cc: linux-ext4@...r.kernel.org, lczerner@...hat.com
> Subject: Re: [PATCH] ext4: Automatic setting of {INODE,BLOCK}_UNINIT flags
> 
> Does it make sense in no journal mode?

I am not sure why it would not ? It only makes changes to the block
group descriptors marking block/inode table as unitialized so we can
skip then in fsck.

Originally it has been only marked uninitialized when we create the
file system, but once we use the particular inode table or block
group bitmap it become initialized forever, even though it has been
completely freed since then. This patch fixes it so it can become
uninitialized again (granted that the flag name is not the best).

Advantages are that we can skip that in fsck, but also we might save
read from disk, because uninitialized descriptors are initialized in
memory rather hen read from the disk.

So my question is, why do you think this might not make sense in no
journal mode ? Maybe I am missing something.

Thanks!
-Lukas

> 
> Thanks,
> Yongqiang.
> 
> On Thu, Oct 25, 2012 at 3:25 PM, Tomas Racek <tracek@...hat.com> wrote:
> > When last inode from bg is freed, set the INODE_UNINIT flag, similarly
> > when last block is freed, set BLOCK_UNINIT flag. This can speed up
> > subsequent fsck run.
> >
> > Signed-off-by: Tomas Racek <tracek@...hat.com>
> > ---
> >  fs/ext4/ialloc.c  | 4 ++++
> >  fs/ext4/mballoc.c | 4 ++++
> >  2 files changed, 8 insertions(+)
> >
> > diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
> > index 4facdd2..6e4b982 100644
> > --- a/fs/ext4/ialloc.c
> > +++ b/fs/ext4/ialloc.c
> > @@ -289,6 +289,10 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
> >
> >         count = ext4_free_inodes_count(sb, gdp) + 1;
> >         ext4_free_inodes_set(sb, gdp, count);
> > +
> > +       if (count == EXT4_INODES_PER_GROUP(sb))
> > +               gdp->bg_flags |= cpu_to_le16(EXT4_BG_INODE_UNINIT);
> > +
> >         if (is_directory) {
> >                 count = ext4_used_dirs_count(sb, gdp) - 1;
> >                 ext4_used_dirs_set(sb, gdp, count);
> > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> > index 526e553..28bce35 100644
> > --- a/fs/ext4/mballoc.c
> > +++ b/fs/ext4/mballoc.c
> > @@ -4665,6 +4665,10 @@ do_more:
> >
> >         ret = ext4_free_group_clusters(sb, gdp) + count_clusters;
> >         ext4_free_group_clusters_set(sb, gdp, ret);
> > +
> > +       if(ret == EXT4_BLOCKS_PER_GROUP(sb))
> > +               gdp->bg_flags |= cpu_to_le16(EXT4_BG_BLOCK_UNINIT);
> > +
> >         ext4_block_bitmap_csum_set(sb, block_group, gdp, bitmap_bh);
> >         ext4_group_desc_csum_set(sb, block_group, gdp);
> >         ext4_unlock_group(sb, block_group);
> > --
> > 1.7.11.7
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> > the body of a message to majordomo@...r.kernel.org
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> 
> 
> 
> 
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