Re: [PATCH v9 06/11] btrfs: implement RST version of scrub

[David Sterba]

On Fri, Sep 15, 2023 at 10:28:50AM +0930, Qu Wenruo wrote:
> 
> 
> On 2023/9/15 01:37, Johannes Thumshirn wrote:
> > A filesystem that uses the RAID stripe tree for logical to physical
> > address translation can't use the regular scrub path, that reads all
> > stripes and then checks if a sector is unused afterwards.
> >
> > When using the RAID stripe tree, this will result in lookup errors, as the
> > stripe tree doesn't know the requested logical addresses.
> >
> > Instead, look up stripes that are backed by the extent bitmap.
> >
> > Signed-off-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
> > ---
> >   fs/btrfs/bio.c              |  2 ++
> >   fs/btrfs/raid-stripe-tree.c |  8 ++++++-
> >   fs/btrfs/scrub.c            | 53 +++++++++++++++++++++++++++++++++++++++++++++
> >   fs/btrfs/volumes.h          |  1 +
> >   4 files changed, 63 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
> > index ddbe6f8d4ea2..bdb6e3effdbb 100644
> > --- a/fs/btrfs/bio.c
> > +++ b/fs/btrfs/bio.c
> > @@ -663,6 +663,8 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
> >   	blk_status_t ret;
> >   	int error;
> >
> > +	smap.is_scrub = !bbio->inode;
> > +
> >   	btrfs_bio_counter_inc_blocked(fs_info);
> >   	error = btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length,
> >   				&bioc, &smap, &mirror_num, 1);
> > diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
> > index 697a6e1fd255..63bf62c33436 100644
> > --- a/fs/btrfs/raid-stripe-tree.c
> > +++ b/fs/btrfs/raid-stripe-tree.c
> > @@ -334,6 +334,11 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
> >   	if (!path)
> >   		return -ENOMEM;
> >
> > +	if (stripe->is_scrub) {
> > +		path->skip_locking = 1;
> > +		path->search_commit_root = 1;
> > +	}
> > +
> >   	ret = btrfs_search_slot(NULL, stripe_root, &stripe_key, path, 0, 0);
> >   	if (ret < 0)
> >   		goto free_path;
> > @@ -420,7 +425,8 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
> >   out:
> >   	if (ret > 0)
> >   		ret = -ENOENT;
> > -	if (ret && ret != -EIO) {
> > +	if (ret && ret != -EIO && !stripe->is_scrub) {
> > +
> 
> One extra newline.

There were way more stray newlines, you don't have to point that out
in reviews, I fix them once we have version that would not change too
much.