linux-ext4 - Re: [PATCH 01/31] tune2fs: Don't convert block # to cluster # when clearing uninit

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Message-ID: <20131003190444.GA14971@birch.djwong.org>
Date:	Thu, 3 Oct 2013 12:04:44 -0700
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	Lukáš Czerner <lczerner@...hat.com>
Cc:	tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 01/31] tune2fs: Don't convert block # to cluster # when
 clearing uninit_bg

On Thu, Oct 03, 2013 at 06:53:38PM +0200, Lukáš Czerner wrote:
> On Mon, 30 Sep 2013, Darrick J. Wong wrote:
> 
> > Date: Mon, 30 Sep 2013 18:26:49 -0700
> > From: Darrick J. Wong <darrick.wong@...cle.com>
> > To: tytso@....edu, darrick.wong@...cle.com
> > Cc: linux-ext4@...r.kernel.org
> > Subject: [PATCH 01/31] tune2fs: Don't convert block # to cluster # when
> >     clearing uninit_bg
> > 
> > When we're constructing the initial block bitmap as part of removing the
> > gdt_csum (i.e. uninit_bg) feature, we mustn't convert the block numbers to
> > cluster numbers because ext2fs_mark_block_bitmap2() does this for us.
> 
> I wonder if it's possible to use the old-style bitmap interface (the
> one which does not understand 64-bit bitmaps). If so, then you also
> need to fix ext2fs_mark_generic_bmap() (and others) so that we
> convert blocks to clusters if needed.

It's possible to do this (bad thing) by not specifying EXT2_FLAG_64BITS when
calling ext2fs_openfs(); see patch 26 for a quick fix.

(I'm imagining that most bigalloc users probably want 64bit anyway?)

(No idea, bigalloc isn't (currently) my use case.)

--D
> 
> Thanks!
> -Lukas
> 
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
> > ---
> >  misc/tune2fs.c |   13 +++++--------
> >  1 file changed, 5 insertions(+), 8 deletions(-)
> > 
> > 
> > diff --git a/misc/tune2fs.c b/misc/tune2fs.c
> > index ddf3259..52247e0 100644
> > --- a/misc/tune2fs.c
> > +++ b/misc/tune2fs.c
> > @@ -820,20 +820,17 @@ static void disable_uninit_bg(ext2_filsys fs, __u32 csum_feature_flag)
> >  	/* The bbitmap is zeroed; we must mark group metadata blocks in use */
> >  	for (i = 0; i < fs->group_desc_count; i++) {
> >  		b = ext2fs_block_bitmap_loc(fs, i);
> > -		ext2fs_mark_block_bitmap2(fs->block_map, EXT2FS_B2C(fs, b));
> > +		ext2fs_mark_block_bitmap2(fs->block_map, b);
> >  		b = ext2fs_inode_bitmap_loc(fs, i);
> > -		ext2fs_mark_block_bitmap2(fs->block_map, EXT2FS_B2C(fs, b));
> > +		ext2fs_mark_block_bitmap2(fs->block_map, b);
> >  
> >  		retval = ext2fs_super_and_bgd_loc2(fs, i, &b, &c, &d, NULL);
> >  		if (retval == 0 && b)
> > -			ext2fs_mark_block_bitmap2(fs->block_map,
> > -						  EXT2FS_B2C(fs, b));
> > +			ext2fs_mark_block_bitmap2(fs->block_map, b);
> >  		if (retval == 0 && c)
> > -			ext2fs_mark_block_bitmap2(fs->block_map,
> > -						  EXT2FS_B2C(fs, c));
> > +			ext2fs_mark_block_bitmap2(fs->block_map, c);
> >  		if (retval == 0 && d)
> > -			ext2fs_mark_block_bitmap2(fs->block_map,
> > -						  EXT2FS_B2C(fs, d));
> > +			ext2fs_mark_block_bitmap2(fs->block_map, d);
> >  		if (retval) {
> >  			com_err("disable_uninit_bg", retval,
> >  				"while initializing block bitmaps");
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
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> > 
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