linux-toradex.git/drivers/md/bcache/btree.c, branch v6.3-rc5

mm: shrinkers: provide shrinkers with names

2022-07-04T01:08:40+00:00

Currently shrinkers are anonymous objects.  For debugging purposes they
can be identified by count/scan function names, but it's not always
useful: e.g.  for superblock's shrinkers it's nice to have at least an
idea of to which superblock the shrinker belongs.

This commit adds names to shrinkers.  register_shrinker() and
prealloc_shrinker() functions are extended to take a format and arguments
to master a name.

In some cases it's not possible to determine a good name at the time when
a shrinker is allocated.  For such cases shrinker_debugfs_rename() is
provided.

The expected format is:
    -[:]-
For some shrinkers an instance can be encoded as (MAJOR:MINOR) pair.

After this change the shrinker debugfs directory looks like:
  $ cd /sys/kernel/debug/shrinker/
  $ ls
    dquota-cache-16     sb-devpts-28     sb-proc-47       sb-tmpfs-42
    mm-shadow-18        sb-devtmpfs-5    sb-proc-48       sb-tmpfs-43
    mm-zspool:zram0-34  sb-hugetlbfs-17  sb-pstore-31     sb-tmpfs-44
    rcu-kfree-0         sb-hugetlbfs-33  sb-rootfs-2      sb-tmpfs-49
    sb-aio-20           sb-iomem-12      sb-securityfs-6  sb-tracefs-13
    sb-anon_inodefs-15  sb-mqueue-21     sb-selinuxfs-22  sb-xfs:vda1-36
    sb-bdev-3           sb-nsfs-4        sb-sockfs-8      sb-zsmalloc-19
    sb-bpf-32           sb-pipefs-14     sb-sysfs-26      thp-deferred_split-10
    sb-btrfs:vda2-24    sb-proc-25       sb-tmpfs-1       thp-zero-9
    sb-cgroup2-30       sb-proc-39       sb-tmpfs-27      xfs-buf:vda1-37
    sb-configfs-23      sb-proc-41       sb-tmpfs-29      xfs-inodegc:vda1-38
    sb-dax-11           sb-proc-45       sb-tmpfs-35
    sb-debugfs-7        sb-proc-46       sb-tmpfs-40

[roman.gushchin@linux.dev: fix build warnings]
  Link: https://lkml.kernel.org/r/Yr+ZTnLb9lJk6fJO@castle
  Reported-by: kernel test robot 
Link: https://lkml.kernel.org/r/20220601032227.4076670-4-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin 
Cc: Christophe JAILLET 
Cc: Dave Chinner 
Cc: Hillf Danton 
Cc: Kent Overstreet 
Cc: Muchun Song 
Signed-off-by: Andrew Morton

bcache: memset on stack variables in bch_btree_check() and bch_sectors_dirty_init()

2022-05-27T15:49:48+00:00

The local variables check_state (in bch_btree_check()) and state (in
bch_sectors_dirty_init()) should be fully filled by 0, because before
allocating them on stack, they were dynamically allocated by kzalloc().

Signed-off-by: Coly Li 
Link: https://lore.kernel.org/r/20220527152818.27545-2-colyli@suse.de
Signed-off-by: Jens Axboe

bcache: improve multithreaded bch_btree_check()

2022-05-24T12:19:33+00:00

Commit 8e7102273f59 ("bcache: make bch_btree_check() to be
multithreaded") makes bch_btree_check() to be much faster when checking
all btree nodes during cache device registration. But it isn't in ideal
shap yet, still can be improved.

This patch does the following thing to improve current parallel btree
nodes check by multiple threads in bch_btree_check(),
- Add read lock to root node while checking all the btree nodes with
  multiple threads. Although currently it is not mandatory but it is
  good to have a read lock in code logic.
- Remove local variable 'char name[32]', and generate kernel thread name
  string directly when calling kthread_run().
- Allocate local variable "struct btree_check_state check_state" on the
  stack and avoid unnecessary dynamic memory allocation for it.
- Reduce BCH_BTR_CHKTHREAD_MAX from 64 to 12 which is enough indeed.
- Increase check_state->started to count created kernel thread after it
  succeeds to create.
- When wait for all checking kernel threads to finish, use wait_event()
  to replace wait_event_interruptible().

With this change, the code is more clear, and some potential error
conditions are avoided.

Fixes: 8e7102273f59 ("bcache: make bch_btree_check() to be multithreaded")
Signed-off-by: Coly Li 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220524102336.10684-2-colyli@suse.de
Signed-off-by: Jens Axboe

bcache: fixup multiple threads crash

2022-03-06T14:33:45+00:00

When multiple threads to check btree nodes in parallel, the main
thread wait for all threads to stop or CACHE_SET_IO_DISABLE flag:

wait_event_interruptible(check_state->wait,
                         atomic_read(&check_state->started) == 0 ||
                         test_bit(CACHE_SET_IO_DISABLE, &c->flags));

However, the bch_btree_node_read and bch_btree_node_read_done
maybe call bch_cache_set_error, then the CACHE_SET_IO_DISABLE
will be set. If the flag already set, the main thread return
error. At the same time, maybe some threads still running and
read NULL pointer, the kernel will crash.

This patch change the event wait condition, the main thread must
wait for all threads to stop.

Fixes: 8e7102273f597 ("bcache: make bch_btree_check() to be multithreaded")
Signed-off-by: Mingzhe Zou 
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Coly Li

bcache: Revert "bcache: use bvec_virt"

2021-11-08T13:23:17+00:00

This reverts commit 2fd3e5efe791946be0957c8e1eed9560b541fe46.

The above commit replaces page_address(bv->bv_page) by bvec_virt(bv) to
avoid directly access to bv->bv_page, but in situation bv->bv_offset is
not zero and page_address(bv->bv_page) is not equal to bvec_virt(bv). In
such case a memory corruption may happen because memory in next page is
tainted by following line in do_btree_node_write(),
	memcpy(bvec_virt(bv), addr, PAGE_SIZE);

This patch reverts the mentioned commit to avoid the memory corruption.

Fixes: 2fd3e5efe791 ("bcache: use bvec_virt")
Signed-off-by: Coly Li 
Cc: Christoph Hellwig 
Cc: stable@vger.kernel.org # 5.15
Signed-off-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20211103151041.70516-1-colyli@suse.de
Signed-off-by: Jens Axboe

bcache: remove bch_crc64_update

2021-10-20T14:40:54+00:00

bch_crc64_update is an entirely pointless wrapper around crc64_be.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Coly Li 
Link: https://lore.kernel.org/r/20211020143812.6403-9-colyli@suse.de
Signed-off-by: Jens Axboe

bcache: use bvec_virt

2021-08-16T16:50:33+00:00

Use bvec_virt instead of open coding it.  Note that the existing code is
fine despite ignoring bv_offset as the bio is known to contain exactly
one page from the page allocator per bio_vec.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Coly Li 
Link: https://lore.kernel.org/r/20210804095634.460779-10-hch@lst.de
Signed-off-by: Jens Axboe

bcache: remove PTR_CACHE

2021-04-11T14:37:55+00:00

Remove the PTR_CACHE inline and replace it with a direct dereference
of c->cache.

(Coly Li: fix the typo from PTR_BUCKET to PTR_CACHE in commit log)

Signed-off-by: Christoph Hellwig 
Signed-off-by: Coly Li 
Link: https://lore.kernel.org/r/20210411134316.80274-3-colyli@suse.de
Signed-off-by: Jens Axboe

bcache: Give btree_io_wq correct semantics again

2021-02-10T15:06:00+00:00

Before killing `btree_io_wq`, the queue was allocated using
`create_singlethread_workqueue()` which has `WQ_MEM_RECLAIM`. After
killing it, it no longer had this property but `system_wq` is not
single threaded.

Let's combine both worlds and make it multi threaded but able to
reclaim memory.

Cc: Coly Li 
Cc: stable@vger.kernel.org # 5.4+
Signed-off-by: Kai Krakow 
Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

Revert "bcache: Kill btree_io_wq"

2021-02-10T15:06:00+00:00

This reverts commit 56b30770b27d54d68ad51eccc6d888282b568cee.

With the btree using the `system_wq`, I seem to see a lot more desktop
latency than I should.

After some more investigation, it looks like the original assumption
of 56b3077 no longer is true, and bcache has a very high potential of
congesting the `system_wq`. In turn, this introduces laggy desktop
performance, IO stalls (at least with btrfs), and input events may be
delayed.

So let's revert this. It's important to note that the semantics of
using `system_wq` previously mean that `btree_io_wq` should be created
before and destroyed after other bcache wqs to keep the same
assumptions.

Cc: Coly Li 
Cc: stable@vger.kernel.org # 5.4+
Signed-off-by: Kai Krakow 
Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe