Re: [PATCH 3/3] btrfs: Ensure btrfs_trim_fs can trim the whole filesystem

[Greg KH <greg@kroah.com>]

On Tue, Nov 20, 2018 at 09:25:56AM +0200, Nikolay Borisov wrote:
> From: Qu Wenruo <wqu@suse.com>
> 
> [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> # v4.4+
> 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>
> ---
> 
> Hello Greg, 
> 
> Please apply upstream commit 6ba9fc8e628becf0e3ec94083450d089b0dec5f5 to 
> 4.4.y and 4.9.y. This backport should apply cleanly to both trees. 

This is already in 4.9.141, so I only applied it to 4.4.y

thanks,

greg k-h