On Fri, Sep 07, 2018 at 02:16:24PM +0800, Qu Wenruo wrote:
> [BUG]
> fstrim on some btrfs only trims the unallocated space, not trimming any
> space in existing block groups.
>
> [CAUSE]
> Before fstrim_range passed to btrfs_trim_fs(), it get truncated to
> range [0, super->total_bytes).
> So later btrfs_trim_fs() will only be able to trim block groups in range
> [0, super->total_bytes).
>
> While for btrfs, any bytenr aligned to sector size is valid, since btrfs use
> its logical address space, there is nothing limiting the location where
> we put block groups.
>
> For btrfs with routine balance, it's quite easy to relocate all
> block groups and bytenr of block groups will start beyond super->total_bytes.
>
> In that case, btrfs will not trim existing block groups.
>
> [FIX]
> Just remove the truncation in btrfs_ioctl_fitrim(), so btrfs_trim_fs()
> can get the unmodified range, which is normally set to [0, U64_MAX].
>
> Reported-by: Chris Murphy <lists@xxxxxxxxxxxxxxxxx>
> Fixes: f4c697e6406d ("btrfs: return EINVAL if start > total_bytes in fitrim ioctl")
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.0+
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
