On Sep 5, 2017, at 3:06 PM, Jaegeuk Kim <jaegeuk@xxxxxxxxxx> wrote:
>
> This patch fixes bavail and bfree finally.
>
> long f_bfree; /* free blocks in fs */
> long f_bavail; /* free blocks avail to non-superuser */
>
> So, bfree represents all the reserved blocks, while bavail does the space only
> visible to normal user.
>
> Fix: 3e6d0b4d9c1c ("f2fs: fix incorrect f_bfree calculation in ->statfs")
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.8+
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> fs/f2fs/super.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 7e29db227910..17cca4cb93af 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -955,8 +955,8 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
> buf->f_bsize = sbi->blocksize;
>
> 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) -
> + buf->f_bfree = user_block_count - valid_user_blocks(sbi);
> + buf->f_bavail = user_block_count - valid_user_blocks(sbi) - ovp_count -
> sbi->reserved_blocks;
To keep the statfs data more consistent, you could use:
buf->f_bavail = buf->f_bfree - ovp_count - sbi->reserved_blocks;
That avoids the extra subtraction, and avoids (minor) issues if these values
change while this syscall is running.
Cheers, Andreas
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