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On Thu, Apr 24, 2003 at 10:22:22AM +0530, Suparna Bhattacharya wrote:
> Here is a revised version of the filesystem AIO patches
> for 2.5.68.
>
> 02aiord.patch : Filesystem aio read
Changes to generic_file_aio_read code to use the aio
retry infrastructure. The main blocking points addressed
are lock_page and wait_on_page_locked.
Regards
Suparna
--
Suparna Bhattacharya (suparna@in.ibm.com)
Linux Technology Center
IBM Software Labs, India
02aiord.patch
.............
include/linux/pagemap.h | 19 ++++++++++++++
mm/filemap.c | 63 ++++++++++++++++++++++++++++++++++++++++--------
2 files changed, 72 insertions(+), 10 deletions(-)
diff -ur -X /home/kiran/dontdiff linux-2.5.68/include/linux/pagemap.h linux-aio-2568/include/linux/pagemap.h
--- linux-2.5.68/include/linux/pagemap.h Mon Apr 21 23:30:40 2003
+++ linux-aio-2568/include/linux/pagemap.h Mon Apr 21 17:26:58 2003
@@ -135,6 +135,16 @@
if (TestSetPageLocked(page))
__lock_page(page);
}
+
+extern int FASTCALL(__lock_page_wq(struct page *page, wait_queue_t *wait));
+static inline int lock_page_wq(struct page *page, wait_queue_t *wait)
+{
+ if (TestSetPageLocked(page))
+ return __lock_page_wq(page, wait);
+ else
+ return 0;
+}
+
/*
* This is exported only for wait_on_page_locked/wait_on_page_writeback.
@@ -155,6 +165,15 @@
wait_on_page_bit(page, PG_locked);
}
+extern int FASTCALL(wait_on_page_bit_wq(struct page *page, int bit_nr,
+ wait_queue_t *wait));
+static inline int wait_on_page_locked_wq(struct page *page, wait_queue_t *wait)
+{
+ if (PageLocked(page))
+ return wait_on_page_bit_wq(page, PG_locked, wait);
+ return 0;
+}
+
/*
* Wait for a page to complete writeback
*/
diff -ur -X /home/kiran/dontdiff linux-2.5.68/mm/filemap.c linux-aio-2568/mm/filemap.c
--- linux-2.5.68/mm/filemap.c Mon Apr 21 23:30:40 2003
+++ linux-aio-2568/mm/filemap.c Tue Apr 22 00:28:55 2003
@@ -268,19 +268,32 @@
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_wq(struct page *page, int bit_nr, wait_queue_t *wait)
{
wait_queue_head_t *waitqueue = page_waitqueue(page);
- DEFINE_WAIT(wait);
+ DEFINE_WAIT(local_wait);
+ if (!wait)
+ wait = &local_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 -EIOCBRETRY;
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_wq);
+
+void wait_on_page_bit(struct page *page, int bit_nr)
+{
+ wait_on_page_bit_wq(page, bit_nr, NULL);
}
EXPORT_SYMBOL(wait_on_page_bit);
@@ -336,19 +349,31 @@
* chances are that on the second loop, the block layer's plug list is empty,
* so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
*/
-void __lock_page(struct page *page)
+int __lock_page_wq(struct page *page, wait_queue_t *wait)
{
wait_queue_head_t *wqh = page_waitqueue(page);
- DEFINE_WAIT(wait);
+ DEFINE_WAIT(local_wait);
+ if (!wait)
+ wait = &local_wait;
+
while (TestSetPageLocked(page)) {
- prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
+ prepare_to_wait(wqh, wait, TASK_UNINTERRUPTIBLE);
if (PageLocked(page)) {
sync_page(page);
+ if (!is_sync_wait(wait))
+ return -EIOCBRETRY;
io_schedule();
}
}
- finish_wait(wqh, &wait);
+ finish_wait(wqh, wait);
+ return 0;
+}
+EXPORT_SYMBOL(__lock_page_wq);
+
+void __lock_page(struct page *page)
+{
+ __lock_page_wq(page, NULL);
}
EXPORT_SYMBOL(__lock_page);
@@ -621,7 +655,13 @@
goto page_ok;
/* Get exclusive access to the page ... */
- lock_page(page);
+
+ if (lock_page_wq(page, current->io_wait)) {
+ pr_debug("queued lock page \n");
+ error = -EIOCBRETRY;
+ /* TBD: should we hold on to the cached page ? */
+ goto sync_error;
+ }
/* Did it get unhashed before we got the lock? */
if (!page->mapping) {
@@ -643,12 +683,19 @@
if (!error) {
if (PageUptodate(page))
goto page_ok;
- wait_on_page_locked(page);
+ if (wait_on_page_locked_wq(page, current->io_wait)) {
+ pr_debug("queued wait_on_page \n");
+ error = -EIOCBRETRY;
+ /*TBD:should we hold on to the cached page ?*/
+ goto sync_error;
+ }
+
if (PageUptodate(page))
goto page_ok;
error = -EIO;
}
+sync_error:
/* UHHUH! A synchronous read error occurred. Report it */
desc->error = error;
page_cache_release(page);
@@ -819,6 +866,10 @@
struct kiocb kiocb;
ssize_t ret;
+ if (current->io_wait != NULL) {
+ printk("current->io_wait != NULL\n");
+ dump_stack();
+ }
init_sync_kiocb(&kiocb, filp);
ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
if (-EIOCBQUEUED == ret)
@@ -851,6 +902,7 @@
{
read_descriptor_t desc;
+ BUG_ON(current->io_wait != NULL);
if (!count)
return 0;
-
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