Re: [PATCH] btrfs: relocation: Output current relocation stage at btrfs_relocate_block_group()

[David Sterba <dsterba@suse.cz>]

On Thu, Nov 28, 2019 at 03:54:36PM +0800, Qu Wenruo wrote:
> There are several reports of hanging relocation, populating the dmesg
> with things like:
>   BTRFS info (device dm-5): found 1 extents
> 
> The investigation is still on going, but will never hurt to output a
> little more info.
> 
> This patch will also output the current relocation stage, making that
> output something like:
> 
>   BTRFS info (device dm-5): balance: start -d -m -s
>   BTRFS info (device dm-5): relocating block group 30408704 flags metadata|dup
>   BTRFS info (device dm-5): found 2 extents at MOVE_DATA_EXTENT stage
>   BTRFS info (device dm-5): relocating block group 22020096 flags system|dup
>   BTRFS info (device dm-5): found 1 extents at MOVE_DATA_EXTENT stage
>   BTRFS info (device dm-5): relocating block group 13631488 flags data
>   BTRFS info (device dm-5): found 1 extents at MOVE_DATA_EXTENT stage
>   BTRFS info (device dm-5): found 1 extents at UPDATE_DATA_PTRS stage
>   BTRFS info (device dm-5): balance: ended with status: 0
> 
> The string "MOVE_DATA_EXTENT" and "UPDATE_DATA_PTRS" is mostly from the
> macro MOVE_DATA_EXTENTS and UPDATE_DATA_PTRS, but the 'S' from
> MOVE_DATA_EXTENTS is removed in the output string to make the alignment
> better.
> 
> This patch will not increase the number of lines, but with extra info
> for us to debug the reported problem.

Nice. I'd suggest to make it more user friendly

	relocation: found 111 extents, stage: move data blocks
	relocation: found 111 extents, stage: update data pointers

The identifier can be understood what it means but it's IMHO not
important to copy it to the message verbatim.