]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - block/blk-ioc.c
2 * Functions related to io context handling
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/init.h>
8 #include <linux/blkdev.h>
9 #include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
14 * For io context allocations
16 static struct kmem_cache
*iocontext_cachep
;
18 static void cfq_dtor(struct io_context
*ioc
)
20 if (!hlist_empty(&ioc
->cic_list
)) {
21 struct cfq_io_context
*cic
;
23 cic
= list_entry(ioc
->cic_list
.first
, struct cfq_io_context
,
30 * IO Context helper functions. put_io_context() returns 1 if there are no
31 * more users of this io context, 0 otherwise.
33 int put_io_context(struct io_context
*ioc
)
38 BUG_ON(atomic_long_read(&ioc
->refcount
) == 0);
40 if (atomic_long_dec_and_test(&ioc
->refcount
)) {
45 kmem_cache_free(iocontext_cachep
, ioc
);
50 EXPORT_SYMBOL(put_io_context
);
52 static void cfq_exit(struct io_context
*ioc
)
56 if (!hlist_empty(&ioc
->cic_list
)) {
57 struct cfq_io_context
*cic
;
59 cic
= list_entry(ioc
->cic_list
.first
, struct cfq_io_context
,
66 /* Called by the exitting task */
67 void exit_io_context(struct task_struct
*task
)
69 struct io_context
*ioc
;
72 ioc
= task
->io_context
;
73 task
->io_context
= NULL
;
76 if (atomic_dec_and_test(&ioc
->nr_tasks
)) {
83 struct io_context
*alloc_io_context(gfp_t gfp_flags
, int node
)
85 struct io_context
*ret
;
87 ret
= kmem_cache_alloc_node(iocontext_cachep
, gfp_flags
, node
);
89 atomic_long_set(&ret
->refcount
, 1);
90 atomic_set(&ret
->nr_tasks
, 1);
91 spin_lock_init(&ret
->lock
);
92 ret
->ioprio_changed
= 0;
94 ret
->last_waited
= jiffies
; /* doesn't matter... */
95 ret
->nr_batch_requests
= 0; /* because this is 0 */
96 INIT_RADIX_TREE(&ret
->radix_root
, GFP_ATOMIC
| __GFP_HIGH
);
97 INIT_HLIST_HEAD(&ret
->cic_list
);
105 * If the current task has no IO context then create one and initialise it.
106 * Otherwise, return its existing IO context.
108 * This returned IO context doesn't have a specifically elevated refcount,
109 * but since the current task itself holds a reference, the context can be
110 * used in general code, so long as it stays within `current` context.
112 struct io_context
*current_io_context(gfp_t gfp_flags
, int node
)
114 struct task_struct
*tsk
= current
;
115 struct io_context
*ret
;
117 ret
= tsk
->io_context
;
121 ret
= alloc_io_context(gfp_flags
, node
);
123 /* make sure set_task_ioprio() sees the settings above */
125 tsk
->io_context
= ret
;
132 * If the current task has no IO context then create one and initialise it.
133 * If it does have a context, take a ref on it.
135 * This is always called in the context of the task which submitted the I/O.
137 struct io_context
*get_io_context(gfp_t gfp_flags
, int node
)
139 struct io_context
*ret
= NULL
;
142 * Check for unlikely race with exiting task. ioc ref count is
143 * zero when ioc is being detached.
146 ret
= current_io_context(gfp_flags
, node
);
149 } while (!atomic_long_inc_not_zero(&ret
->refcount
));
153 EXPORT_SYMBOL(get_io_context
);
155 void copy_io_context(struct io_context
**pdst
, struct io_context
**psrc
)
157 struct io_context
*src
= *psrc
;
158 struct io_context
*dst
= *pdst
;
161 BUG_ON(atomic_long_read(&src
->refcount
) == 0);
162 atomic_long_inc(&src
->refcount
);
167 EXPORT_SYMBOL(copy_io_context
);
169 static int __init
blk_ioc_init(void)
171 iocontext_cachep
= kmem_cache_create("blkdev_ioc",
172 sizeof(struct io_context
), 0, SLAB_PANIC
, NULL
);
175 subsys_initcall(blk_ioc_init
);