kernel/linux.git/drivers/md/bcache/writeback.c, branch v4.19.16

bcache: release dc->writeback_lock properly in bch_writeback_thread()

2018-08-22T21:06:29+00:00

The writeback thread would exit with a lock held when the cache device is detached via sysfs interface, fix it by releasing the held lock before exiting the while-loop. Fixes: fadd94e05c02 (bcache: quit dc->writeback_thread when BCACHE_DEV_DETACHING is set) Signed-off-by: Shan Hai Signed-off-by: Coly Li Tested-by: Shenghui Wang Cc: stable@vger.kernel.org #4.17+ Signed-off-by: Jens Axboe

bcache: fix code comments style

2018-08-11T21:46:42+00:00

This patch fixes 3 style issues warned by checkpatch.pl, - Comment lines are not aligned - Comments use "/*" on subsequent lines - Comment lines use a trailing "*/" Signed-off-by: Coly Li Reviewed-by: Shenghui Wang Signed-off-by: Jens Axboe

bcache: style fixes for lines over 80 characters

2018-08-11T21:46:41+00:00

This patch fixes the lines over 80 characters into more lines, to minimize warnings by checkpatch.pl. There are still some lines exceed 80 characters, but it is better to be a single line and I don't change them. Signed-off-by: Coly Li Reviewed-by: Shenghui Wang Signed-off-by: Jens Axboe

bcache: style fix to add a blank line after declarations

2018-08-11T21:46:41+00:00

Signed-off-by: Coly Li Reviewed-by: Shenghui Wang Signed-off-by: Jens Axboe

bcache: style fix to replace 'unsigned' by 'unsigned int'

2018-08-11T21:46:41+00:00

This patch fixes warning reported by checkpatch.pl by replacing 'unsigned' with 'unsigned int'. Signed-off-by: Coly Li Reviewed-by: Shenghui Wang Signed-off-by: Jens Axboe

bcache: set max writeback rate when I/O request is idle

2018-08-09T14:21:15+00:00

Commit b1092c9af9ed ("bcache: allow quick writeback when backing idle") allows the writeback rate to be faster if there is no I/O request on a bcache device. It works well if there is only one bcache device attached to the cache set. If there are many bcache devices attached to a cache set, it may introduce performance regression because multiple faster writeback threads of the idle bcache devices will compete the btree level locks with the bcache device who have I/O requests coming. This patch fixes the above issue by only permitting fast writebac when all bcache devices attached on the cache set are idle. And if one of the bcache devices has new I/O request coming, minimized all writeback throughput immediately and let PI controller __update_writeback_rate() to decide the upcoming writeback rate for each bcache device. Also when all bcache devices are idle, limited wrieback rate to a small number is wast of thoughput, especially when backing devices are slower non-rotation devices (e.g. SATA SSD). This patch sets a max writeback rate for each backing device if the whole cache set is idle. A faster writeback rate in idle time means new I/Os may have more available space for dirty data, and people may observe a better write performance then. Please note bcache may change its cache mode in run time, and this patch still works if the cache mode is switched from writeback mode and there is still dirty data on cache. Fixes: Commit b1092c9af9ed ("bcache: allow quick writeback when backing idle") Cc: stable@vger.kernel.org #4.16+ Signed-off-by: Coly Li Tested-by: Kai Krakow Tested-by: Stefan Priebe Cc: Michael Lyle Signed-off-by: Jens Axboe

bcache: fix I/O significant decline while backend devices registering

2018-07-27T15:15:46+00:00

I attached several backend devices in the same cache set, and produced lots of dirty data by running small rand I/O writes in a long time, then I continue run I/O in the others cached devices, and stopped a cached device, after a mean while, I register the stopped device again, I see the running I/O in the others cached devices dropped significantly, sometimes even jumps to zero. In currently code, bcache would traverse each keys and btree node to count the dirty data under read locker, and the writes threads can not get the btree write locker, and when there is a lot of keys and btree node in the registering device, it would last several seconds, so the write I/Os in others cached device are blocked and declined significantly. In this patch, when a device registering to a ache set, which exist others cached devices with running I/Os, we get the amount of dirty data of the device in an incremental way, and do not block other cached devices all the time. Patch v2: Rename some variables and macros name as Coly suggested. Signed-off-by: Tang Junhui Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: simplify the calculation of the total amount of flash dirty data

2018-07-27T15:15:46+00:00

Currently we calculate the total amount of flash only devices dirty data by adding the dirty data of each flash only device under registering locker. It is very inefficient. In this patch, we add a member flash_dev_dirty_sectors in struct cache_set to record the total amount of flash only devices dirty data in real time, so we didn't need to calculate the total amount of dirty data any more. Signed-off-by: Tang Junhui Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: count backing device I/O error for writeback I/O

2018-05-03T14:35:12+00:00

Commit c7b7bd07404c5 ("bcache: add io_disable to struct cached_dev") counts backing device I/O requets and set dc->io_disable to true if error counters exceeds dc->io_error_limit. But it only counts I/O errors for regular I/O request, neglects errors of write back I/Os when backing device is offline. This patch counts the errors of writeback I/Os, in dirty_endio() if bio->bi_status is not 0, it means error happens when writing dirty keys to backing device, then bch_count_backing_io_errors() is called. By this fix, even there is no reqular I/O request coming, if writeback I/O errors exceed dc->io_error_limit, the bcache device may still be stopped for the broken backing device. Fixes: c7b7bd07404c5 ("bcache: add io_disable to struct cached_dev") Signed-off-by: Coly Li Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe

bcache: add backing_request_endio() for bi_end_io

2018-03-19T02:15:20+00:00

In order to catch I/O error of backing device, a separate bi_end_io call back is required. Then a per backing device counter can record I/O errors number and retire the backing device if the counter reaches a per backing device I/O error limit. This patch adds backing_request_endio() to bcache backing device I/O code path, this is a preparation for further complicated backing device failure handling. So far there is no real code logic change, I make this change a separate patch to make sure it is stable and reliable for further work. Changelog: v2: Fix code comments typo, remove a redundant bch_writeback_add() line added in v4 patch set. v1: indeed this is new added in this patch set. [mlyle: truncated commit subject] Signed-off-by: Coly Li Reviewed-by: Hannes Reinecke Reviewed-by: Michael Lyle Cc: Junhui Tang Cc: Michael Lyle Signed-off-by: Jens Axboe