From e2ba58ccc9099514380c3300cbc0750b5055fc1c Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Wed, 30 Jul 2025 21:49:53 -0700 Subject: block: Fix default IO priority if there is no IO context Upstream commit 53889bcaf536 ("block: make __get_task_ioprio() easier to read") changes the IO priority returned to the caller if no IO context is defined for the task. Prior to this commit, the returned IO priority was determined by task_nice_ioclass() and task_nice_ioprio(). Now it is always IOPRIO_DEFAULT, which translates to IOPRIO_CLASS_NONE with priority 0. However, task_nice_ioclass() returns IOPRIO_CLASS_IDLE, IOPRIO_CLASS_RT, or IOPRIO_CLASS_BE depending on the task scheduling policy, and task_nice_ioprio() returns a value determined by task_nice(). This causes regressions in test code checking the IO priority and class of IO operations on tasks with no IO context. Fix the problem by returning the IO priority calculated from task_nice_ioclass() and task_nice_ioprio() if no IO context is defined to match earlier behavior. Fixes: 53889bcaf536 ("block: make __get_task_ioprio() easier to read") Cc: Jens Axboe Cc: Bart Van Assche Signed-off-by: Guenter Roeck Reviewed-by: Yu Kuai Reviewed-by: Damien Le Moal Link: https://lore.kernel.org/r/20250731044953.1852690-1-linux@roeck-us.net Signed-off-by: Jens Axboe --- include/linux/ioprio.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h index b25377b6ea98..5210e8371238 100644 --- a/include/linux/ioprio.h +++ b/include/linux/ioprio.h @@ -60,7 +60,8 @@ static inline int __get_task_ioprio(struct task_struct *p) int prio; if (!ioc) - return IOPRIO_DEFAULT; + return IOPRIO_PRIO_VALUE(task_nice_ioclass(p), + task_nice_ioprio(p)); if (p != current) lockdep_assert_held(&p->alloc_lock); -- cgit v1.2.3 From 42e6c6ce03fd3e41e39a0f93f9b1a1d9fa664338 Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Thu, 7 Aug 2025 11:24:12 +0800 Subject: lib/sbitmap: convert shallow_depth from one word to the whole sbitmap Currently elevators will record internal 'async_depth' to throttle asynchronous requests, and they both calculate shallow_dpeth based on sb->shift, with the respect that sb->shift is the available tags in one word. However, sb->shift is not the availbale tags in the last word, see __map_depth: if (index == sb->map_nr - 1) return sb->depth - (index << sb->shift); For consequence, if the last word is used, more tags can be get than expected, for example, assume nr_requests=256 and there are four words, in the worst case if user set nr_requests=32, then the first word is the last word, and still use bits per word, which is 64, to calculate async_depth is wrong. One the ohter hand, due to cgroup qos, bfq can allow only one request to be allocated, and set shallow_dpeth=1 will still allow the number of words request to be allocated. Fix this problems by using shallow_depth to the whole sbitmap instead of per word, also change kyber, mq-deadline and bfq to follow this, a new helper __map_depth_with_shallow() is introduced to calculate available bits in each word. Signed-off-by: Yu Kuai Link: https://lore.kernel.org/r/20250807032413.1469456-2-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe --- include/linux/sbitmap.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h index 189140bf11fc..4adf4b364fcd 100644 --- a/include/linux/sbitmap.h +++ b/include/linux/sbitmap.h @@ -213,12 +213,12 @@ int sbitmap_get(struct sbitmap *sb); * sbitmap_get_shallow() - Try to allocate a free bit from a &struct sbitmap, * limiting the depth used from each word. * @sb: Bitmap to allocate from. - * @shallow_depth: The maximum number of bits to allocate from a single word. + * @shallow_depth: The maximum number of bits to allocate from the bitmap. * * This rather specific operation allows for having multiple users with * different allocation limits. E.g., there can be a high-priority class that * uses sbitmap_get() and a low-priority class that uses sbitmap_get_shallow() - * with a @shallow_depth of (1 << (@sb->shift - 1)). Then, the low-priority + * with a @shallow_depth of (sb->depth >> 1). Then, the low-priority * class can only allocate half of the total bits in the bitmap, preventing it * from starving out the high-priority class. * @@ -478,7 +478,7 @@ unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags, * sbitmap_queue, limiting the depth used from each word, with preemption * already disabled. * @sbq: Bitmap queue to allocate from. - * @shallow_depth: The maximum number of bits to allocate from a single word. + * @shallow_depth: The maximum number of bits to allocate from the queue. * See sbitmap_get_shallow(). * * If you call this, make sure to call sbitmap_queue_min_shallow_depth() after -- cgit v1.2.3 From 45fa9f97e65231a9fd4f9429489cb74c10ccd0fd Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Thu, 7 Aug 2025 11:24:13 +0800 Subject: lib/sbitmap: make sbitmap_get_shallow() internal Because it's only used in sbitmap.c Signed-off-by: Yu Kuai Reviewed-by: Damien Le Moal Reviewed-by: Jan Kara Reviewed-by: Bart Van Assche Link: https://lore.kernel.org/r/20250807032413.1469456-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe --- include/linux/sbitmap.h | 17 ----------------- 1 file changed, 17 deletions(-) (limited to 'include/linux') diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h index 4adf4b364fcd..ffb9907c7070 100644 --- a/include/linux/sbitmap.h +++ b/include/linux/sbitmap.h @@ -209,23 +209,6 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int depth); */ int sbitmap_get(struct sbitmap *sb); -/** - * sbitmap_get_shallow() - Try to allocate a free bit from a &struct sbitmap, - * limiting the depth used from each word. - * @sb: Bitmap to allocate from. - * @shallow_depth: The maximum number of bits to allocate from the bitmap. - * - * This rather specific operation allows for having multiple users with - * different allocation limits. E.g., there can be a high-priority class that - * uses sbitmap_get() and a low-priority class that uses sbitmap_get_shallow() - * with a @shallow_depth of (sb->depth >> 1). Then, the low-priority - * class can only allocate half of the total bits in the bitmap, preventing it - * from starving out the high-priority class. - * - * Return: Non-negative allocated bit number if successful, -1 otherwise. - */ -int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth); - /** * sbitmap_any_bit_set() - Check for a set bit in a &struct sbitmap. * @sb: Bitmap to check. -- cgit v1.2.3