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| author | Jens Axboe <jens.axboe@oracle.com> | 2008-01-24 10:53:35 +0300 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-01-28 12:50:31 +0300 |
| commit | d38ecf935fcb10264a6bc190855d9595165e6eeb (patch) | |
| tree | 64e3146ef76678ad3ae8f75c32df9f25ea470953 /include/linux | |
| parent | fd0928df98b9578be8a786ac0cb78a47a5e17a20 (diff) | |
| download | linux-d38ecf935fcb10264a6bc190855d9595165e6eeb.tar.xz | |
io context sharing: preliminary support
Detach task state from ioc, instead keep track of how many processes
are accessing the ioc.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/blkdev.h | 2 | ||||
| -rw-r--r-- | include/linux/iocontext.h | 22 |
2 files changed, 19 insertions, 5 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 510a18ba1ec5..2483a05231c7 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -34,7 +34,7 @@ struct sg_io_hdr; #define BLKDEV_MIN_RQ 4 #define BLKDEV_MAX_RQ 128 /* Default maximum */ -void put_io_context(struct io_context *ioc); +int put_io_context(struct io_context *ioc); void exit_io_context(void); struct io_context *get_io_context(gfp_t gfp_flags, int node); struct io_context *alloc_io_context(gfp_t gfp_flags, int node); diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index 186807ea62e2..cd44d458124a 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -54,13 +54,15 @@ struct cfq_io_context { }; /* - * This is the per-process I/O subsystem state. It is refcounted and - * kmalloc'ed. Currently all fields are modified in process io context - * (apart from the atomic refcount), so require no locking. + * I/O subsystem state of the associated processes. It is refcounted + * and kmalloc'ed. These could be shared between processes. */ struct io_context { atomic_t refcount; - struct task_struct *task; + atomic_t nr_tasks; + + /* all the fields below are protected by this lock */ + spinlock_t lock; unsigned short ioprio; unsigned short ioprio_changed; @@ -76,4 +78,16 @@ struct io_context { void *ioc_data; }; +static inline struct io_context *ioc_task_link(struct io_context *ioc) +{ + /* + * if ref count is zero, don't allow sharing (ioc is going away, it's + * a race). + */ + if (ioc && atomic_inc_not_zero(&ioc->refcount)) + return ioc; + + return NULL; +} + #endif |