wireguard-linux/drivers/md/bcache/bcache.h, branch jd/unified-crypt-queue

bcache: add readahead cache policy options via sysfs interface

2020-02-01T14:55:39Z

In year 2007 high performance SSD was still expensive, in order to save more space for real workload or meta data, the readahead I/Os for non-meta data was bypassed and not cached on SSD. In now days, SSD price drops a lot and people can find larger size SSD with more comfortable price. It is unncessary to alway bypass normal readahead I/Os to save SSD space for now. This patch adds options for readahead data cache policies via sysfs file /sys/block/bcache/readahead_cache_policy, the options are, - "all": cache all readahead data I/Os. - "meta-only": only cache meta data, and bypass other regular I/Os. If users want to make bcache continue to only cache readahead request for metadata and bypass regular data readahead, please set "meta-only" to this sysfs file. By default, bcache will back to cache all read- ahead requests now. Cc: stable@vger.kernel.org Signed-off-by: Coly Li Acked-by: Eric Wheeler Cc: Michael Lyle Signed-off-by: Jens Axboe

bcache: store a pointer to the on-disk sb in the cache and cached_dev structures

2020-01-23T18:40:01Z

This allows to properly build the superblock bio including the offset in the page using the normal bio helpers. This fixes writing the superblock for page sizes larger than 4k where the sb write bio would need an offset in the bio_vec. Signed-off-by: Christoph Hellwig Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: add idle_max_writeback_rate sysfs interface

2019-11-13T22:42:50Z

For writeback mode, if there is no regular I/O request for a while, the writeback rate will be set to the maximum value (1TB/s for now). This is good for most of the storage workload, but there are still people don't what the maximum writeback rate in I/O idle time. This patch adds a sysfs interface file idle_max_writeback_rate to permit people to disable maximum writeback rate. Then the minimum writeback rate can be advised by writeback_rate_minimum in the bcache device's sysfs interface. Reported-by: Christian Balzer Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: fix deadlock in bcache_allocator

2019-11-13T22:42:50Z

bcache_allocator can call the following: bch_allocator_thread() -> bch_prio_write() -> bch_bucket_alloc() -> wait on &ca->set->bucket_wait But the wake up event on bucket_wait is supposed to come from bch_allocator_thread() itself => deadlock: [ 1158.490744] INFO: task bcache_allocato:15861 blocked for more than 10 seconds. [ 1158.495929] Not tainted 5.3.0-050300rc3-generic #201908042232 [ 1158.500653] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1158.504413] bcache_allocato D 0 15861 2 0x80004000 [ 1158.504419] Call Trace: [ 1158.504429] __schedule+0x2a8/0x670 [ 1158.504432] schedule+0x2d/0x90 [ 1158.504448] bch_bucket_alloc+0xe5/0x370 [bcache] [ 1158.504453] ? wait_woken+0x80/0x80 [ 1158.504466] bch_prio_write+0x1dc/0x390 [bcache] [ 1158.504476] bch_allocator_thread+0x233/0x490 [bcache] [ 1158.504491] kthread+0x121/0x140 [ 1158.504503] ? invalidate_buckets+0x890/0x890 [bcache] [ 1158.504506] ? kthread_park+0xb0/0xb0 [ 1158.504510] ret_from_fork+0x35/0x40 Fix by making the call to bch_prio_write() non-blocking, so that bch_allocator_thread() never waits on itself. Moreover, make sure to wake up the garbage collector thread when bch_prio_write() is failing to allocate buckets. BugLink: https://bugs.launchpad.net/bugs/1784665 BugLink: https://bugs.launchpad.net/bugs/1796292 Signed-off-by: Andrea Righi Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: fix a lost wake-up problem caused by mca_cannibalize_lock

2019-11-13T22:42:50Z

This patch fix a lost wake-up problem caused by the race between mca_cannibalize_lock and bch_cannibalize_unlock. Consider two processes, A and B. Process A is executing mca_cannibalize_lock, while process B takes c->btree_cache_alloc_lock and is executing bch_cannibalize_unlock. The problem happens that after process A executes cmpxchg and will execute prepare_to_wait. In this timeslice process B executes wake_up, but after that process A executes prepare_to_wait and set the state to TASK_INTERRUPTIBLE. Then process A goes to sleep but no one will wake up it. This problem may cause bcache device to dead. Signed-off-by: Guoju Fang Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: add reclaimed_journal_buckets to struct cache_set

2019-06-28T13:39:18Z

Now we have counters for how many times jouranl is reclaimed, how many times cached dirty btree nodes are flushed, but we don't know how many jouranl buckets are really reclaimed. This patch adds reclaimed_journal_buckets into struct cache_set, this is an increasing only counter, to tell how many journal buckets are reclaimed since cache set runs. From all these three counters (reclaim, reclaimed_journal_buckets, flush_write), we can have idea how well current journal space reclaim code works. Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: remove retry_flush_write from struct cache_set

2019-06-28T13:39:18Z

In struct cache_set, retry_flush_write is added for commit c4dc2497d50d ("bcache: fix high CPU occupancy during journal") which is reverted in previous patch. Now it is useless anymore, and this patch removes it from bcache code. Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: Revert "bcache: fix high CPU occupancy during journal"

2019-06-28T13:39:17Z

This reverts commit c4dc2497d50d9c6fb16aa0d07b6a14f3b2adb1e0. This patch enlarges a race between normal btree flush code path and flush_btree_write(), which causes deadlock when journal space is exhausted. Reverts this patch makes the race window from 128 btree nodes to only 1 btree nodes. Fixes: c4dc2497d50d ("bcache: fix high CPU occupancy during journal") Signed-off-by: Coly Li Cc: stable@vger.kernel.org Cc: Tang Junhui Signed-off-by: Jens Axboe

bcache: add return value check to bch_cached_dev_run()

2019-06-28T13:39:14Z

This patch adds return value check to bch_cached_dev_run(), now if there is error happens inside bch_cached_dev_run(), it can be catched. Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: option to automatically run gc thread after writeback

2018-12-13T15:15:54Z

The option gc_after_writeback is disabled by default, because garbage collection will discard SSD data which drops cached data. Echo 1 into /sys/fs/bcache//internal/gc_after_writeback will enable this option, which wakes up gc thread when writeback accomplished and all cached data is clean. This option is helpful for people who cares writing performance more. In heavy writing workload, all cached data can be clean only happens when writeback thread cleans all cached data in I/O idle time. In such situation a following gc running may help to shrink bcache B+ tree and discard more clean data, which may be helpful for future writing requests. If you are not sure whether this is helpful for your own workload, please leave it as disabled by default. Signed-off-by: Coly Li Signed-off-by: Jens Axboe