Re: [PATCH] f2fs: fix some cases with reserved_blocks

[Yunlong Song]

Does this means the reserved_blocks cannot be used by users by can be 
used by filesystem?
If it can be used by filesystem, then this cannot ensure the flash 
device really reserve the
reserved_blocks space, right? The reserved_blocks is just for users?

On 2017/8/8 14:08, Chao Yu wrote:
> On 2017/8/8 12:12, Yunlong Song wrote:
> > Signed-off-by: Yunlong Song <yunlong.song@xxxxxxxxxx>
> > ---
> >   fs/f2fs/recovery.c | 3 ++-
> >   fs/f2fs/super.c    | 9 +++++----
> >   2 files changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> > index a3d0261..e288319 100644
> > --- a/fs/f2fs/recovery.c
> > +++ b/fs/f2fs/recovery.c
> > @@ -51,7 +51,8 @@ bool space_for_roll_forward(struct f2fs_sb_info *sbi)
> >   {
> >   	s64 nalloc = percpu_counter_sum_positive(&sbi->alloc_valid_block_count);
> >   
> > -	if (sbi->last_valid_block_count + nalloc > sbi->user_block_count)
> > +	if (sbi->last_valid_block_count + nalloc +
> > +			sbi->reserved_blocks > sbi->user_block_count)
> I think we can treat reserved blocks as over-provision space in f2fs, so it
> would be safe to store invalid data (may become valid during recovery) there.
> Anyway, it OK to remain old condition judgment.
>
> >   		return false;
> >   	return true;
> >   }
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > index 4c1bdcb..c644bf5 100644
> > --- a/fs/f2fs/super.c
> > +++ b/fs/f2fs/super.c
> > @@ -946,6 +946,7 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
> >   	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
> >   	block_t total_count, user_block_count, start_count, ovp_count;
> >   	u64 avail_node_count;
> > +	block_t avail_user_block_count;
> >   
> >   	total_count = le64_to_cpu(sbi->raw_super->block_count);
> >   	user_block_count = sbi->user_block_count;
> > @@ -953,16 +954,16 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
> >   	ovp_count = SM_I(sbi)->ovp_segments << sbi->log_blocks_per_seg;
> >   	buf->f_type = F2FS_SUPER_MAGIC;
> >   	buf->f_bsize = sbi->blocksize;
> > +	avail_user_block_count = user_block_count - sbi->reserved_blocks;
> >   
> >   	buf->f_blocks = total_count - start_count;
> >   	buf->f_bfree = user_block_count - valid_user_blocks(sbi) + ovp_count;
> > -	buf->f_bavail = user_block_count - valid_user_blocks(sbi) -
> > -						sbi->reserved_blocks;
> > +	buf->f_bavail = avail_user_block_count - valid_user_blocks(sbi);
> >   
> >   	avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
> >   
> > -	if (avail_node_count > user_block_count) {
> > -		buf->f_files = user_block_count;
> > +	if (avail_node_count > avail_user_block_count) {
> Likewise f_blocks calculation, the f_files one doesn't need to consider
> reserved_blocks.
>
> Thanks,
>
> > +		buf->f_files = avail_user_block_count;
> >   		buf->f_ffree = buf->f_bavail;
> >   	} else {
> >   		buf->f_files = avail_node_count;
>
> .

--
Thanks,
Yunlong Song