[PATCH 00/14] Convert block layer & drivers to XArray
- To: email@example.com
- Cc: Matthew Wilcox <firstname.lastname@example.org>, Paolo Valente <email@example.com>, Jens Axboe <firstname.lastname@example.org>, FUJITA Tomonori <email@example.com>, Philipp Reisner <firstname.lastname@example.org>, Lars Ellenberg <email@example.com>, Josef Bacik <firstname.lastname@example.org>, Minchan Kim <email@example.com>, Nitin Gupta <firstname.lastname@example.org>, Sergey Senozhatsky <email@example.com>, Dennis Zhou <firstname.lastname@example.org>, Tejun Heo <email@example.com>, Liu Bo <firstname.lastname@example.org>, "Dennis Zhou " <email@example.com>, Bart Van Assche <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org
- Subject: [PATCH 00/14] Convert block layer & drivers to XArray
- From: Matthew Wilcox <email@example.com>
- Date: Mon, 18 Mar 2019 12:48:07 -0700
- Message-id: <[🔎] firstname.lastname@example.org>
I would like to remove the IDR and radix tree APIs from the kernel.
This patch series converts all the IDRs and radix trees in the block
layer and block drivers to use the XArray APIs. Testing of these
patches has been minimal, mostly limited to compilation testing.
I would be grateful if you could take these patches through your tree.
To cut down on wasted electrons, only this cover letter is being
distributed to everyone listed by get-maintainers; the patches can
be found on the linux-block mailing list.
Please check these patches over carefully and test them; there may be
off-by-one errors, locking mistakes, or various other failures on my part.
Substantive interface changes
- The IDR and radix tree required callers to handle their own locking.
The XArray embeds a spinlock which is taken for modifications to
the data structure; plain lookups occur under the RCU read lock or
under the spinlock.
- You can take the spinlock yourself (xa_lock() and friends) to protect
- idr_alloc() returned -ENOSPC, radix_tree_insert() returned -EEXIST.
xa_insert() and xa_alloc() return -EBUSY.
- The search keys which the radix tree calls "tags", the XArray calls
- There is no preloading in the XArray API. Most users of the
preloading APIs only needed to use it because they were trying to
allocate under their own spinlock. If your locking is exceptionally
complicated, you may need to use xa_insert() with a NULL pointer.
- The radix tree provided GFP flags as part of the tree definition;
the XArray (like the IDR) passes GFP flags at the point of allocation.
- radix_tree_insert() of a NULL pointer was not well-specified. The
XArray treats it as reserving the entry (it reads back as NULL but
a subsequent xa_insert() to that slot will fail).
- xa_alloc_cyclic() returns 1 if the allocation wraps, unlike
idr_alloc_cyclic() which provides no indication.
- There is no equivalent to idr_for_each(); the xa_for_each() iterator
is similar to idr_for_each_entry().
- idr_replace() has no exact equivalent. Some users relied on its exact
semantics of only storing if the entry was non-NULL, but all users of
idr_replace() were able to use xa_store() or xa_cmpxchg().
- The family of radix tree gang lookup functions have been replaced with
Matthew Wilcox (14):
blk-cgroup: Convert to XArray
blk-cgroup: Remove blkg_list hlist
blk-cgroup: Reduce scope of blkg_array lock
blk-ioc: Convert to XArray
blk-ioc: Remove ioc's icq_list
genhd: Convert to XArray
bsg: Convert bsg_minor_idr to XArray
brd: Convert to XArray
null_blk: Convert to XArray
loop: Convert loop_index_idr to XArray
nbd: Convert nbd_index_idr to XArray
zram: Convert zram_index_idr to XArray
drbd: Convert drbd devices to XArray
drbd: Convert peer devices to XArray
block/bfq-cgroup.c | 7 +-
block/blk-cgroup.c | 94 +++++++------------
block/blk-ioc.c | 38 ++++----
block/bsg.c | 20 ++--
block/genhd.c | 42 ++++-----
drivers/block/brd.c | 93 ++++++------------
drivers/block/drbd/drbd_debugfs.c | 16 ++--
drivers/block/drbd/drbd_int.h | 10 +-
drivers/block/drbd/drbd_main.c | 77 +++++++--------
drivers/block/drbd/drbd_nl.c | 77 ++++++++-------
drivers/block/drbd/drbd_proc.c | 8 +-
drivers/block/drbd/drbd_receiver.c | 33 +++----
drivers/block/drbd/drbd_state.c | 67 ++++++-------
drivers/block/drbd/drbd_worker.c | 20 ++--
drivers/block/loop.c | 88 ++++++-----------
drivers/block/nbd.c | 145 ++++++++++++-----------------
drivers/block/null_blk.h | 4 +-
drivers/block/null_blk_main.c | 97 ++++++++-----------
drivers/block/zram/zram_drv.c | 40 +++-----
include/linux/blk-cgroup.h | 7 +-
include/linux/iocontext.h | 22 ++---
21 files changed, 419 insertions(+), 586 deletions(-)