Re: [PATCH V4 0/4] Btrfs: batched discard support for btrfs

[Chris Mason <chris.mason@oracle.com>]

Excerpts from Li Dongyang's message of 2011-03-24 06:24:24 -0400:
> Dear list,
> This is V4 of batched discard support, now we will get full mapping of
> the free space on each device for RAID0/1/10/DUP instead of just a single
> stripe length, and tested with xfsstests 251, Thanks.

I've pushed this out into the for-linus branch, along with a full merge
to 2.6.39 current git.

Please take a look and make sure I've merged it correctly.

Thanks!

-chris

> Changelog V4:
>     *make btrfs_map_block() return full mapping.
> Changelog V3:
>     *fix style problems.
>     *rebase to 2.6.38-rc7.
> Changelog V2:
>     *Check if we have devices support trim before trying to trim the fs, also adjust
>       minlen according to the discard_granularity.
>     *Update reserved extent calculations in btrfs_trim_block_group().
>     *Call cond_resched() without checking need_resched()
>     *Use bitmap_clear_bits() and unlink_free_space() instead of btrfs_remove_free_space(),
>       so we won't search the same extent for twice.
>     *Try harder in btrfs_discard_extent(), now we won't report errors
>      if it's not a EOPNOTSUPP.
>     *make sure the block group is cached before trimming it,or we'll see an empty caching
>      tree if the block group is not cached.
>     *Minor return value fix in btrfs_discard_block_group().