From 3d48749d93a3dce732dd30a14002ab90ec4355f3 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 5 Mar 2012 13:15:25 -0800 Subject: block: ioc_task_link() can't fail ioc_task_link() is used to share %current's ioc on clone. If %current->io_context is set, %current is guaranteed to have refcount on the ioc and, thus, ioc_task_link() can't fail. Replace error checking in ioc_task_link() with WARN_ON_ONCE() and make it just increment refcount and nr_tasks. -v2: Description typo fix (Vivek). Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- include/linux/iocontext.h | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) (limited to 'include/linux/iocontext.h') diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index 1a3018063034..81a8870ac224 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -120,18 +120,12 @@ struct io_context { struct work_struct release_work; }; -static inline struct io_context *ioc_task_link(struct io_context *ioc) +static inline void 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_long_inc_not_zero(&ioc->refcount)) { - atomic_inc(&ioc->nr_tasks); - return ioc; - } - - return NULL; + WARN_ON_ONCE(atomic_long_read(&ioc->refcount) <= 0); + WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0); + atomic_long_inc(&ioc->refcount); + atomic_inc(&ioc->nr_tasks); } struct task_struct; -- cgit v1.2.2 From f6e8d01bee036460e03bd4f6a79d014f98ba712e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 5 Mar 2012 13:15:26 -0800 Subject: block: add io_context->active_ref Currently ioc->nr_tasks is used to decide two things - whether an ioc is done issuing IOs and whether it's shared by multiple tasks. This patch separate out the first into ioc->active_ref, which is acquired and released using {get|put}_io_context_active() respectively. This will be used to associate bio's with a given task. This patch doesn't introduce any visible behavior change. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- include/linux/iocontext.h | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'include/linux/iocontext.h') diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index 81a8870ac224..6f1a2608e91f 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -100,6 +100,7 @@ struct io_cq { */ struct io_context { atomic_long_t refcount; + atomic_t active_ref; atomic_t nr_tasks; /* all the fields below are protected by this lock */ @@ -120,17 +121,34 @@ struct io_context { struct work_struct release_work; }; -static inline void ioc_task_link(struct io_context *ioc) +/** + * get_io_context_active - get active reference on ioc + * @ioc: ioc of interest + * + * Only iocs with active reference can issue new IOs. This function + * acquires an active reference on @ioc. The caller must already have an + * active reference on @ioc. + */ +static inline void get_io_context_active(struct io_context *ioc) { WARN_ON_ONCE(atomic_long_read(&ioc->refcount) <= 0); - WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0); + WARN_ON_ONCE(atomic_read(&ioc->active_ref) <= 0); atomic_long_inc(&ioc->refcount); + atomic_inc(&ioc->active_ref); +} + +static inline void ioc_task_link(struct io_context *ioc) +{ + get_io_context_active(ioc); + + WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0); atomic_inc(&ioc->nr_tasks); } struct task_struct; #ifdef CONFIG_BLOCK void put_io_context(struct io_context *ioc); +void put_io_context_active(struct io_context *ioc); void exit_io_context(struct task_struct *task); struct io_context *get_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node); -- cgit v1.2.2 From 2b566fa55b9a94b53217c2818e6c5e5756eeb1a1 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 19 Mar 2012 15:10:59 -0700 Subject: block: remove ioc_*_changed() After the previous patch to cfq, there's no ioc_get_changed() user left. This patch yanks out ioc_{ioprio|cgroup|get}_changed() and all related stuff. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- include/linux/iocontext.h | 7 ------- 1 file changed, 7 deletions(-) (limited to 'include/linux/iocontext.h') diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index 6f1a2608e91f..df38db2ef45b 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -6,11 +6,7 @@ #include enum { - ICQ_IOPRIO_CHANGED = 1 << 0, - ICQ_CGROUP_CHANGED = 1 << 1, ICQ_EXITED = 1 << 2, - - ICQ_CHANGED_MASK = ICQ_IOPRIO_CHANGED | ICQ_CGROUP_CHANGED, }; /* @@ -152,9 +148,6 @@ void put_io_context_active(struct io_context *ioc); void exit_io_context(struct task_struct *task); struct io_context *get_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node); -void ioc_ioprio_changed(struct io_context *ioc, int ioprio); -void ioc_cgroup_changed(struct io_context *ioc); -unsigned int icq_get_changed(struct io_cq *icq); #else struct io_context; static inline void put_io_context(struct io_context *ioc) { } -- cgit v1.2.2