kernel/linux.git/block/blk-iolatency.c, branch v6.6.148

block: fix bad lockdep annotation in blk-iolatency

2023-08-10T23:24:53+00:00

A previous commit added a lockdep annotation, but botched it. Use the right type. Fixes: 4eb44d10766a ("block: remove init_mutex and open-code blk_iolatency_try_init") Signed-off-by: Jens Axboe

block: remove init_mutex and open-code blk_iolatency_try_init

2023-08-10T13:20:31+00:00

Commit a13696b83da4 ("blk-iolatency: Make initialization lazy") adds a mutex named "init_mutex" in blk_iolatency_try_init for the race condition of initializing RQ_QOS_LATENCY. Now a new lock has been add to struct request_queue by commit a13bd91be223 ("block/rq_qos: protect rq_qos apis with a new lock"). And it has been held in blkg_conf_open_bdev before calling blk_iolatency_init. So it's not necessary to keep init_mutex in blk_iolatency_try_init, just remove it. Since init_mutex has been removed, blk_iolatency_try_init can be open-coded back to iolatency_set_limit() like ioc_qos_write(). Signed-off-by: Li Lingfeng Reviewed-by: Michal Koutný Link: https://lore.kernel.org/r/20230810035111.2236335-1-lilingfeng@huaweicloud.com Signed-off-by: Jens Axboe

blk-iolatency: Make initialization lazy

2023-04-13T12:46:49+00:00

Other rq_qos policies such as wbt and iocost are lazy-initialized when they are configured for the first time for the device but iolatency is initialized unconditionally from blkcg_init_disk() during gendisk init. Lazy init is beneficial because rq_qos policies add runtime overhead when initialized as every IO has to walk all registered rq_qos callbacks. This patch switches iolatency to lazy initialization too so that it only registered its rq_qos policy when it is first configured. Note that there is a known race condition between blkcg config file writes and del_gendisk() and this patch makes iolatency susceptible to it by exposing the init path to race against the deletion path. However, that problem already exists in iocost and is being worked on. Signed-off-by: Tejun Heo Reviewed-by: Christoph Hellwig Cc: Josef Bacik Link: https://lore.kernel.org/r/20230413000649.115785-5-tj@kernel.org Signed-off-by: Jens Axboe

blk-iolatency: s/blkcg_rq_qos/iolat_rq_qos/

2023-04-13T12:46:49+00:00

The name was too generic given that there are multiple blkcg rq-qos policies. Signed-off-by: Tejun Heo Reviewed-by: Christoph Hellwig Cc: Josef Bacik Link: https://lore.kernel.org/r/20230413000649.115785-4-tj@kernel.org Signed-off-by: Jens Axboe

blkcg: Restructure blkg_conf_prep() and friends

2023-04-13T12:46:49+00:00

We want to support lazy init of rq-qos policies so that iolatency is enabled lazily on configuration instead of gendisk initialization. The way blkg config helpers are structured now is a bit awkward for that. Let's restructure: * blkcg_conf_open_bdev() is renamed to blkg_conf_open_bdev(). The blkcg_ prefix was used because the bdev opening step is blkg-independent. However, the distinction is too subtle and confuses more than helps. Let's switch to blkg prefix so that it's consistent with the type and other helper names. * struct blkg_conf_ctx now remembers the original input string and is always initialized by the new blkg_conf_init(). * blkg_conf_open_bdev() is updated to take a pointer to blkg_conf_ctx like blkg_conf_prep() and can be called multiple times safely. Instead of modifying the double pointer to input string directly, blkg_conf_open_bdev() now sets blkg_conf_ctx->body. * blkg_conf_finish() is renamed to blkg_conf_exit() for symmetry and now must be called on all blkg_conf_ctx's which were initialized with blkg_conf_init(). Combined, this allows the users to either open the bdev first or do it altogether with blkg_conf_prep() which will help implementing lazy init of rq-qos policies. blkg_conf_init/exit() will also be used implement synchronization against device removal. This is necessary because iolat / iocost are configured through cgroupfs instead of one of the files under /sys/block/DEVICE. As cgroupfs operations aren't synchronized with block layer, the lazy init and other configuration operations may race against device removal. This patch makes blkg_conf_init/exit() used consistently for all cgroup-orginating configurations making them a good place to implement explicit synchronization. Users are updated accordingly. No behavior change is intended by this patch. v2: bfq wasn't updated in v1 causing a build error. Fixed. v3: Update the description to include future use of blkg_conf_init/exit() as synchronization points. Signed-off-by: Tejun Heo Cc: Josef Bacik Cc: Christoph Hellwig Cc: Yu Kuai Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20230413000649.115785-3-tj@kernel.org Signed-off-by: Jens Axboe

Revert "blk-cgroup: pin the gendisk in struct blkcg_gq"

2023-02-14T21:24:09+00:00

This reverts commit 84d7d462b16dd5f0bf7c7ca9254bf81db2c952a2. Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20230214183308.1658775-6-hch@lst.de Signed-off-by: Jens Axboe

Revert "blk-cgroup: move the cgroup information to struct gendisk"

2023-02-14T21:24:09+00:00

This reverts commit 3f13ab7c80fdb0ada86a8e3e818960bc1ccbaa59 as a patch it depends on caused a few problems. Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20230214183308.1658775-2-hch@lst.de Signed-off-by: Jens Axboe

blk-cgroup: move the cgroup information to struct gendisk

2023-02-03T15:20:05+00:00

cgroup information only makes sense on a live gendisk that allows file system I/O (which includes the raw block device). So move over the cgroup related members. Signed-off-by: Christoph Hellwig Reviewed-by: Andreas Herrmann Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20230203150400.3199230-20-hch@lst.de Signed-off-by: Jens Axboe

blk-cgroup: pass a gendisk to pd_alloc_fn

2023-02-03T15:20:05+00:00

No need to the request_queue here, pass a gendisk and extract the node ids from that. Signed-off-by: Christoph Hellwig Reviewed-by: Andreas Herrmann Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20230203150400.3199230-18-hch@lst.de Signed-off-by: Jens Axboe

blk-cgroup: pass a gendisk to blkcg_{de,}activate_policy

2023-02-03T15:20:05+00:00

Prepare for storing the blkcg information in the gendisk instead of the request_queue. Signed-off-by: Christoph Hellwig Reviewed-by: Andreas Herrmann Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20230203150400.3199230-17-hch@lst.de Signed-off-by: Jens Axboe