Re: [PATCH 1/2] btrfs: use correct offset for reloc_inode in prealloc_file_extent_cluster()

[Wang Xiaoguang <wangxg.fnst@xxxxxxxxxxxxxx>]

hello,

On 07/07/2016 03:54 AM, Liu Bo wrote:
> On Wed, Jul 06, 2016 at 06:37:52PM +0800, Wang Xiaoguang wrote:
> > In prealloc_file_extent_cluster(), btrfs_check_data_free_space() uses
> > wrong file offset for reloc_inode, it uses cluster->start and cluster->end,
> > which indeed are extent's bytenr. The correct value should be
> > cluster->[start|end] minus block group's start bytenr.
> >
> > start bytenr   cluster->start
> > |              |     extent      |   extent   | ...| extent |
> > |----------------------------------------------------------------|
> > |                block group reloc_inode                         |
> >
> > Signed-off-by: Wang Xiaoguang <wangxg.fnst@xxxxxxxxxxxxxx>
> > ---
> >   fs/btrfs/relocation.c | 27 +++++++++++++++------------
> >   1 file changed, 15 insertions(+), 12 deletions(-)
> >
> > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> > index 0477dca..abc2f69 100644
> > --- a/fs/btrfs/relocation.c
> > +++ b/fs/btrfs/relocation.c
> > @@ -3030,34 +3030,37 @@ int prealloc_file_extent_cluster(struct inode *inode,
> >   	u64 num_bytes;
> >   	int nr = 0;
> >   	int ret = 0;
> > +	u64 prealloc_start, prealloc_end;
> >   
> >   	BUG_ON(cluster->start != cluster->boundary[0]);
> >   	inode_lock(inode);
> >   
> > -	ret = btrfs_check_data_free_space(inode, cluster->start,
> > -					  cluster->end + 1 - cluster->start);
> > +	start = cluster->start - offset;
> > +	end = cluster->end - offset;
> > +	ret = btrfs_check_data_free_space(inode, start, end + 1 - start);
> >   	if (ret)
> >   		goto out;
> >   
> >   	while (nr < cluster->nr) {
> > -		start = cluster->boundary[nr] - offset;
> > +		prealloc_start = cluster->boundary[nr] - offset;
> >   		if (nr + 1 < cluster->nr)
> > -			end = cluster->boundary[nr + 1] - 1 - offset;
> > +			prealloc_end = cluster->boundary[nr + 1] - 1 - offset;
> >   		else
> > -			end = cluster->end - offset;
> > +			prealloc_end = cluster->end - offset;
> >   
> > -		lock_extent(&BTRFS_I(inode)->io_tree, start, end);
> > -		num_bytes = end + 1 - start;
> > -		ret = btrfs_prealloc_file_range(inode, 0, start,
> > +		lock_extent(&BTRFS_I(inode)->io_tree, prealloc_start,
> > +			    prealloc_end);
> > +		num_bytes = prealloc_end + 1 - prealloc_start;
> > +		ret = btrfs_prealloc_file_range(inode, 0, prealloc_start,
> >   						num_bytes, num_bytes,
> > -						end + 1, &alloc_hint);
> > -		unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
> > +						prealloc_end + 1, &alloc_hint);
> > +		unlock_extent(&BTRFS_I(inode)->io_tree, prealloc_start,
> > +			      prealloc_end);
> Changing names is unnecessary, we can pick up other names for btrfs_{check/free}_data_free_space().
OK, then the changes will be small, thanks.

Regards,
Xiaoguang Wang

> Thanks,
>
> -liubo
>
> >   		if (ret)
> >   			break;
> >   		nr++;
> >   	}
> > -	btrfs_free_reserved_data_space(inode, cluster->start,
> > -				       cluster->end + 1 - cluster->start);
> > +	btrfs_free_reserved_data_space(inode, start, end + 1 - start);
> >   out:
> >   	inode_unlock(inode);
> >   	return ret;
> > --
> > 2.9.0
> >
> >
> >
> > --
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