[v2,00/21] btrfs: refactor and generalize chunk/dev_extent/extent allocation
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Message ID 20200212072048.629856-1-naohiro.aota@wdc.com
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  • btrfs: refactor and generalize chunk/dev_extent/extent allocation
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Naohiro Aota Feb. 12, 2020, 7:20 a.m. UTC
This series refactors chunk allocation, device_extent allocation and
extent allocation functions and make them generalized to be able to
implement other allocation policy easily.

On top of this series, we can simplify some part of the "btrfs: zoned
block device support" series as adding a new type of chunk allocator
and extent allocator for zoned block devices. Furthermore, we will be
able to implement and test some other allocator in the idea page of
the wiki e.g. SSD caching, dedicated metadata drive, chunk allocation
groups, and so on.

This series has no functional changes except introducing "enum
btrfs_chunk_allocation_policy" and "enum
btrfs_extent_allocation_policy".

* Refactoring chunk/dev_extent allocator

Two functions are separated from find_free_dev_extent_start().
dev_extent_search_start() decides the starting position of the search.
dev_extent_hole_check() checks if a hole found is suitable for device
extent allocation.

__btrfs_alloc_chunk() is split into four functions. set_parameters()
initializes the parameters of an allocation. gather_device_info()
loops over devices and gather information of
them. decide_stripe_size() decides the size of chunk and
device_extent. And, create_chunk() creates a chunk and device extents.

* Refactoring extent allocator

Three functions are introduced in
find_free_extent(). prepare_allocation() initializes the parameters
and gives a hint byte to start the allocation with. do_allocation()
handles the actual allocation in a given block group.
release_block_group() is called when it gives up an allocation from a
block group, so the allocation context should be reset.

Two functions are introduced in find_free_extent_update_loop().
found_extent() is called when the allocator finally find a proper
extent. chunk_allocation_failed() is called when it failed to allocate
a new chunk. An allocator implementation can use this hook to set the
next stage to try e.g. LOOP_NO_EMPTY_SIZE.

Furthermore, LOOP_NO_EMPTY_SIZE stage is tweaked so that other
allocator than the current clustered allocator skips this stage.

* Patch organization

Patch 1 is a trivial patch to fix the type of an argument of
find_free_extent_update_loop().

Patch 2 removes a BUG_ON from __btrfs_alloc_chunk().

Patches 3-10 refactors chunk and device_extent allocation functions:
find_free_dev_extent_start() and __btrfs_alloc_chunk().

Patches 11-21 refactors extent allocation function: find_free_extent()
and find_free_extent_update_loop().

* Changelog

 - v2
   - Stop separating "clustered_alloc_info" from find_free_extent_ctl
   - Change return type of dev_extent_hole_check() to bool
   - Rename set_parameters() to init_alloc_chunk_ctl()
   - Add a patch to remove BUG_ON from __btrfs_alloc_chunk()

Naohiro Aota (21):
  btrfs: change type of full_search to bool
  btrfs: do not BUG_ON with invalid profile
  btrfs: introduce chunk allocation policy
  btrfs: refactor find_free_dev_extent_start()
  btrfs: introduce alloc_chunk_ctl
  btrfs: factor out init_alloc_chunk_ctl
  btrfs: factor out gather_device_info()
  btrfs: factor out decide_stripe_size()
  btrfs: factor out create_chunk()
  btrfs: parameterize dev_extent_min
  btrfs: introduce extent allocation policy
  btrfs: move hint_byte into find_free_extent_ctl
  btrfs: move vairalbes for clustered allocation into
    find_free_extent_ctl
  btrfs: factor out do_allocation()
  btrfs: drop unnecessary arguments from clustered allocation functions
  btrfs: factor out release_block_group()
  btrfs: factor out found_extent()
  btrfs: drop unnecessary arguments from find_free_extent_update_loop()
  btrfs: factor out chunk_allocation_failed()
  btrfs: skip LOOP_NO_EMPTY_SIZE if not clustered allocation
  btrfs: factor out prepare_allocation()

 fs/btrfs/extent-tree.c | 313 +++++++++++++++++++++-----------
 fs/btrfs/volumes.c     | 398 +++++++++++++++++++++++++++--------------
 fs/btrfs/volumes.h     |   6 +
 3 files changed, 481 insertions(+), 236 deletions(-)