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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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d9c7d394a8
Currently io_context has an atomic_t(32-bit) as refcount. In the case of cfq, for each device against whcih a task does I/O, a reference to the io_context would be taken. And when there are multiple process sharing io_contexts(CLONE_IO) would also have a reference to the same io_context. Theoretically the possible maximum number of processes sharing the same io_context + the number of disks/cfq_data referring to the same io_context can overflow the 32-bit counter on a very high-end machine. Even though it is an improbable case, let us make it atomic_long_t. Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
121 lines
2.6 KiB
C
121 lines
2.6 KiB
C
#ifndef IOCONTEXT_H
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#define IOCONTEXT_H
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#include <linux/radix-tree.h>
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#include <linux/rcupdate.h>
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/*
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* This is the per-process anticipatory I/O scheduler state.
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*/
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struct as_io_context {
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spinlock_t lock;
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void (*dtor)(struct as_io_context *aic); /* destructor */
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void (*exit)(struct as_io_context *aic); /* called on task exit */
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unsigned long state;
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atomic_t nr_queued; /* queued reads & sync writes */
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atomic_t nr_dispatched; /* number of requests gone to the drivers */
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/* IO History tracking */
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/* Thinktime */
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unsigned long last_end_request;
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unsigned long ttime_total;
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unsigned long ttime_samples;
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unsigned long ttime_mean;
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/* Layout pattern */
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unsigned int seek_samples;
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sector_t last_request_pos;
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u64 seek_total;
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sector_t seek_mean;
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};
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struct cfq_queue;
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struct cfq_io_context {
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void *key;
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unsigned long dead_key;
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struct cfq_queue *cfqq[2];
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struct io_context *ioc;
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unsigned long last_end_request;
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sector_t last_request_pos;
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unsigned long ttime_total;
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unsigned long ttime_samples;
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unsigned long ttime_mean;
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unsigned int seek_samples;
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u64 seek_total;
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sector_t seek_mean;
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struct list_head queue_list;
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struct hlist_node cic_list;
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void (*dtor)(struct io_context *); /* destructor */
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void (*exit)(struct io_context *); /* called on task exit */
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struct rcu_head rcu_head;
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};
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/*
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* I/O subsystem state of the associated processes. It is refcounted
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* and kmalloc'ed. These could be shared between processes.
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*/
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struct io_context {
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atomic_long_t refcount;
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atomic_t nr_tasks;
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/* all the fields below are protected by this lock */
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spinlock_t lock;
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unsigned short ioprio;
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unsigned short ioprio_changed;
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/*
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* For request batching
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*/
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unsigned long last_waited; /* Time last woken after wait for request */
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int nr_batch_requests; /* Number of requests left in the batch */
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struct as_io_context *aic;
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struct radix_tree_root radix_root;
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struct hlist_head cic_list;
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void *ioc_data;
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};
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static inline struct io_context *ioc_task_link(struct io_context *ioc)
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{
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/*
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* if ref count is zero, don't allow sharing (ioc is going away, it's
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* a race).
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*/
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if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
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atomic_long_inc(&ioc->refcount);
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return ioc;
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}
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return NULL;
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}
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#ifdef CONFIG_BLOCK
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int put_io_context(struct io_context *ioc);
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void exit_io_context(void);
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struct io_context *get_io_context(gfp_t gfp_flags, int node);
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struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
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void copy_io_context(struct io_context **pdst, struct io_context **psrc);
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#else
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static inline void exit_io_context(void)
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{
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}
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struct io_context;
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static inline int put_io_context(struct io_context *ioc)
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{
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return 1;
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}
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#endif
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#endif
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