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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139/* SPDX-License-Identifier: GPL-2.0 */#ifndef IOCONTEXT_H#define IOCONTEXT_H
#include <linux/radix-tree.h>#include <linux/rcupdate.h>#include <linux/workqueue.h>
enum { ICQ_EXITED = 1 << 2, ICQ_DESTROYED = 1 << 3,};
/* * An io_cq (icq) is association between an io_context (ioc) and a * request_queue (q). This is used by elevators which need to track * information per ioc - q pair. * * Elevator can request use of icq by setting elevator_type->icq_size and * ->icq_align. Both size and align must be larger than that of struct * io_cq and elevator can use the tail area for private information. The * recommended way to do this is defining a struct which contains io_cq as * the first member followed by private members and using its size and * align. For example, * * struct snail_io_cq { * struct io_cq icq; * int poke_snail; * int feed_snail; * }; * * struct elevator_type snail_elv_type { * .ops = { ... }, * .icq_size = sizeof(struct snail_io_cq), * .icq_align = __alignof__(struct snail_io_cq), * ... * }; * * If icq_size is set, block core will manage icq's. All requests will * have its ->elv.icq field set before elevator_ops->elevator_set_req_fn() * is called and be holding a reference to the associated io_context. * * Whenever a new icq is created, elevator_ops->elevator_init_icq_fn() is * called and, on destruction, ->elevator_exit_icq_fn(). Both functions * are called with both the associated io_context and queue locks held. * * Elevator is allowed to lookup icq using ioc_lookup_icq() while holding * queue lock but the returned icq is valid only until the queue lock is * released. Elevators can not and should not try to create or destroy * icq's. * * As icq's are linked from both ioc and q, the locking rules are a bit * complex. * * - ioc lock nests inside q lock. * * - ioc->icq_list and icq->ioc_node are protected by ioc lock. * q->icq_list and icq->q_node by q lock. * * - ioc->icq_tree and ioc->icq_hint are protected by ioc lock, while icq * itself is protected by q lock. However, both the indexes and icq * itself are also RCU managed and lookup can be performed holding only * the q lock. * * - icq's are not reference counted. They are destroyed when either the * ioc or q goes away. Each request with icq set holds an extra * reference to ioc to ensure it stays until the request is completed. * * - Linking and unlinking icq's are performed while holding both ioc and q * locks. Due to the lock ordering, q exit is simple but ioc exit * requires reverse-order double lock dance. */struct io_cq { struct request_queue *q; struct io_context *ioc;
/* * q_node and ioc_node link io_cq through icq_list of q and ioc * respectively. Both fields are unused once ioc_exit_icq() is * called and shared with __rcu_icq_cache and __rcu_head which are * used for RCU free of io_cq. */ union { struct list_head q_node; struct kmem_cache *__rcu_icq_cache; }; union { struct hlist_node ioc_node; struct rcu_head __rcu_head; };
unsigned int flags;};
/* * I/O subsystem state of the associated processes. It is refcounted * and kmalloc'ed. These could be shared between processes. */struct io_context { atomic_long_t refcount; atomic_t active_ref;
unsigned short ioprio;
#ifdef CONFIG_BLK_ICQ /* all the fields below are protected by this lock */ spinlock_t lock;
struct radix_tree_root icq_tree; struct io_cq __rcu *icq_hint; struct hlist_head icq_list;
struct work_struct release_work;#endif /* CONFIG_BLK_ICQ */};
struct task_struct;#ifdef CONFIG_BLOCKvoid put_io_context(struct io_context *ioc);void exit_io_context(struct task_struct *task);int __copy_io(u64 clone_flags, struct task_struct *tsk);static inline int copy_io(u64 clone_flags, struct task_struct *tsk){ if (!current->io_context) return 0; return __copy_io(clone_flags, tsk);}#elsestruct io_context;static inline void put_io_context(struct io_context *ioc) { }static inline void exit_io_context(struct task_struct *task) { }static inline int copy_io(u64 clone_flags, struct task_struct *tsk){ return 0;}#endif /* CONFIG_BLOCK */
#endif /* IOCONTEXT_H */