From d690cb8ae14bd377d422b7905b6959c7e7a45b95 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 13 Feb 2024 08:34:14 +0100 Subject: block: add an API to atomically update queue limits Add a new queue_limits_{start,commit}_update pair of functions that allows taking an atomic snapshot of queue limits, update it, and commit it if it passes validity checking. Also use the low-level validation helper to implement blk_set_default_limits instead of duplicating the initialization. Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Hannes Reinecke Link: https://lore.kernel.org/r/20240213073425.1621680-5-hch@lst.de Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'include/linux') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 251a11d2d2ae..d41d7fe93457 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -474,6 +474,7 @@ struct request_queue { struct mutex sysfs_lock; struct mutex sysfs_dir_lock; + struct mutex limits_lock; /* * for reusing dead hctx instance in case of updating @@ -862,6 +863,28 @@ static inline unsigned int blk_chunk_sectors_left(sector_t offset, return chunk_sectors - (offset & (chunk_sectors - 1)); } +/** + * queue_limits_start_update - start an atomic update of queue limits + * @q: queue to update + * + * This functions starts an atomic update of the queue limits. It takes a lock + * to prevent other updates and returns a snapshot of the current limits that + * the caller can modify. The caller must call queue_limits_commit_update() + * to finish the update. + * + * Context: process context. The caller must have frozen the queue or ensured + * that there is outstanding I/O by other means. + */ +static inline struct queue_limits +queue_limits_start_update(struct request_queue *q) + __acquires(q->limits_lock) +{ + mutex_lock(&q->limits_lock); + return q->limits; +} +int queue_limits_commit_update(struct request_queue *q, + struct queue_limits *lim); + /* * Access functions for manipulating queue properties */ -- cgit v1.2.3