Re: [PATCH 2/2] btrfs: Ensure btrfs_trim_fs can trim the whole filesystem

Sasha Levin
2018-11-24T06:16:52Z

On Tue, Nov 20, 2018 at 10:26:37AM +0800, Qu Wenruo wrote:
>Commit 6ba9fc8e628becf0e3ec94083450d089b0dec5f5 upstream.
>
>[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 gets 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 sectorsize is valid, since btrfs
>uses its logical address space, there is nothing limiting the location
>where we put block groups.
>
>For filesystem with frequent 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@colorremedies.com>
>Fixes: f4c697e6406d ("btrfs: return EINVAL if start > total_bytes in fitrim ioctl")
>CC: <stable@vger.kernel.org> # v4.9
>Signed-off-by: Qu Wenruo <wqu@suse.com>
>Reviewed-by: Nikolay Borisov <nborisov@suse.com>
>Reviewed-by: David Sterba <dsterba@suse.com>
>Signed-off-by: David Sterba <dsterba@suse.com>
>[ change parameter from @fs_info to @fs_info->root for older kernel ]

Queued both for 4.9, thank you.

--
Thanks,
Sasha