On Thu, Apr 03, 2003 at 09:12:21PM +0530, Suparna Bhattacharya wrote:
> On Wed, Apr 02, 2003 at 03:49:01PM +0530, Suparna Bhattacharya wrote:
> > On Tue, Apr 01, 2003 at 03:27:13PM -0500, Benjamin LaHaise wrote:
> > > On Tue, Apr 01, 2003 at 09:59:57PM +0530, Suparna Bhattacharya wrote:
> > > > I would really appreciate comments and review feedback
> > > > from the perspective of fs developers especially on
> > > > the latter 2 patches in terms of whether this seems a
> > > > sound approach or if I'm missing something very crucial
> > > > (which I just well might be)
> > > > Is this easy to do for other filesystems as well ?
> > >
> > > I disagree with putting the iocb pointer in the task_struct: it feels
> > > completely bogus as it modifies semantics behind the scenes without
> > > fixing APIs.
>
> I later remembered one more reason why I'd tried this out -- it
> enabled me to play with async handling of page faults (i.e. an
> async fault_in_pages .. or a retriable copy_xxx_user). I didn't
> want to inclue that code until/unless I saw some real gains, so its
> not an important consideration, but nevertheless it was an
> added flexibility.
>
> BTW, does making this a wait queue entry pointer rather than iocb
> pointer sound any better (i.e tsk->io_wait instead of tsk->iocb) ? The
> code turns out to be cleaner, and the semantics feels a little
> more natural ... (though maybe its just because I've become used
> to it :))
>
OK, here's a sample of what I meant.
Regards
Suparna
diff -pur linux-2.5.66/include/linux/aio.h linux-2.5.66aio/include/linux/aio.h
--- linux-2.5.66/include/linux/aio.h Tue Mar 25 03:29:54 2003
+++ linux-2.5.66aio/include/linux/aio.h Thu Apr 3 17:14:08 2003
@@ -151,6 +161,14 @@ extern void FASTCALL(exit_aio(struct mm_
#define get_ioctx(kioctx) do { if (unlikely(atomic_read(&(kioctx)->users) <= 0)) BUG(); atomic_inc(&(kioctx)->users); } while (0)
#define put_ioctx(kioctx) do { if (unlikely(atomic_dec_and_test(&(kioctx)->users))) __put_ioctx(kioctx); else if (unlikely(atomic_read(&(kioctx)->users) < 0)) BUG(); } while (0)
+#define do_sync_op(op) do { \
+ DEFINE_WAIT(sync_wait); \
+ wait_queue_t *wait = current->io_wait; \
+ current->io_wait = &sync_wait; \
+ op; \
+ current->io_wait = wait; \
+ } while (0);
+
#include <linux/aio_abi.h>
static inline struct kiocb *list_kiocb(struct list_head *h)
diff -pur linux-2.5.66/include/linux/init_task.h linux-2.5.66aio/include/linux/init_task.h
--- linux-2.5.66/include/linux/init_task.h Tue Mar 25 03:30:00 2003
+++ linux-2.5.66aio/include/linux/init_task.h Thu Apr 3 13:36:07 2003
@@ -103,6 +103,7 @@
.alloc_lock = SPIN_LOCK_UNLOCKED, \
.switch_lock = SPIN_LOCK_UNLOCKED, \
.journal_info = NULL, \
+ .io_wait = NULL, \
}
diff -pur linux-2.5.66/include/linux/sched.h linux-2.5.66aio/include/linux/sched.h
--- linux-2.5.66/include/linux/sched.h Tue Mar 25 03:30:00 2003
+++ linux-2.5.66aio/include/linux/sched.h Thu Apr 3 13:18:28 2003
@@ -438,6 +438,8 @@ struct task_struct {
unsigned long ptrace_message;
siginfo_t *last_siginfo; /* For ptrace use. */
+/* current io wait handle */
+ wait_queue_t *io_wait;
};
extern void __put_task_struct(struct task_struct *tsk);
diff -pur linux-2.5.66/include/linux/wait.h linux-2.5.66aio/include/linux/wait.h
--- linux-2.5.66/include/linux/wait.h Tue Mar 25 03:30:44 2003
+++ linux-2.5.66aio/include/linux/wait.h Thu Apr 3 13:51:11 2003
@@ -80,6 +80,8 @@ static inline int waitqueue_active(wait_
return !list_empty(&q->task_list);
}
+#define is_sync_wait(wait) ((wait)->task != NULL)
+
extern void FASTCALL(add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
extern void FASTCALL(add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait));
extern void FASTCALL(remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
diff -pur linux-2.5.66/kernel/fork.c linux-2.5.66aio/kernel/fork.c
--- linux-2.5.66/kernel/fork.c Tue Mar 25 03:30:00 2003
+++ linux-2.5.66aio/kernel/fork.c Thu Apr 3 13:35:21 2003
@@ -139,8 +139,9 @@ void remove_wait_queue(wait_queue_head_t
void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state)
{
unsigned long flags;
-
- __set_current_state(state);
+
+ if (is_sync_wait(wait))
+ __set_current_state(state);
wait->flags &= ~WQ_FLAG_EXCLUSIVE;
spin_lock_irqsave(&q->lock, flags);
if (list_empty(&wait->task_list))
@@ -153,7 +154,8 @@ prepare_to_wait_exclusive(wait_queue_hea
{
unsigned long flags;
- __set_current_state(state);
+ if (is_sync_wait(wait))
+ __set_current_state(state);
wait->flags |= WQ_FLAG_EXCLUSIVE;
spin_lock_irqsave(&q->lock, flags);
if (list_empty(&wait->task_list))
@@ -856,6 +858,7 @@ static struct task_struct *copy_process(
p->lock_depth = -1; /* -1 = no lock */
p->start_time = get_jiffies_64();
p->security = NULL;
+ p->io_wait = NULL;
retval = -ENOMEM;
if (security_task_alloc(p))
diff -pur linux-2.5.66/mm/filemap.c linux-2.5.66aio/mm/filemap.c
--- linux-2.5.66/mm/filemap.c Tue Mar 25 03:30:15 2003
+++ linux-2.5.66aio/mm/filemap.c Thu Apr 3 16:54:33 2003
@@ -254,19 +254,29 @@ static wait_queue_head_t *page_waitqueue
return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
}
-void wait_on_page_bit(struct page *page, int bit_nr)
+int wait_on_page_bit_async(struct page *page, int bit_nr)
{
wait_queue_head_t *waitqueue = page_waitqueue(page);
- DEFINE_WAIT(wait);
-
+ wait_queue_t *wait = current->io_wait;
+
do {
- prepare_to_wait(waitqueue, &wait, TASK_UNINTERRUPTIBLE);
+ prepare_to_wait(waitqueue, wait, TASK_UNINTERRUPTIBLE);
if (test_bit(bit_nr, &page->flags)) {
sync_page(page);
+ if (!is_sync_wait(wait))
+ return -EIOCBQUEUED;
io_schedule();
}
} while (test_bit(bit_nr, &page->flags));
- finish_wait(waitqueue, &wait);
+ finish_wait(waitqueue, wait);
+
+ return 0;
+}
+EXPORT_SYMBOL(wait_on_page_bit_async);
+
+void wait_on_page_bit(struct page *page, int bit_nr)
+{
+ do_sync_op(wait_on_page_bit_async(page, bit_nr));
}
EXPORT_SYMBOL(wait_on_page_bit);
-
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This archive was generated by hypermail 2b29 : Mon Apr 07 2003 - 22:00:30 EST