diff options
author | Jens Axboe <jens.axboe@oracle.com> | 2008-01-24 08:53:35 +0100 |
---|---|---|
committer | Jens Axboe <jens.axboe@oracle.com> | 2008-01-28 10:50:31 +0100 |
commit | d38ecf935fcb10264a6bc190855d9595165e6eeb (patch) | |
tree | 64e3146ef76678ad3ae8f75c32df9f25ea470953 /include/linux/iocontext.h | |
parent | fd0928df98b9578be8a786ac0cb78a47a5e17a20 (diff) | |
download | linux-stable-d38ecf935fcb10264a6bc190855d9595165e6eeb.tar.gz linux-stable-d38ecf935fcb10264a6bc190855d9595165e6eeb.tar.bz2 linux-stable-d38ecf935fcb10264a6bc190855d9595165e6eeb.zip |
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/iocontext.h')
-rw-r--r-- | include/linux/iocontext.h | 22 |
1 files changed, 18 insertions, 4 deletions
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 |