linux-kernel - RE: [PATCH] aio: fix kernel bug when page is temporally busy

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Date:	Sat, 10 Feb 2007 22:36:29 +0300
From:	"Ananiev, Leonid I" <leonid.i.ananiev@...el.com>
To:	"Ken Chen" <kenchen@...gle.com>, <suparna@...ibm.com>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	<linux-kernel@...r.kernel.org>, "linux-aio" <linux-aio@...ck.org>,
	"Zach Brown" <zach.brown@...cle.com>,
	"Chris Mason" <chris.mason@...cle.com>,
	"Badari Pulavarty" <pbadari@...ibm.com>
Subject: RE: [PATCH] aio: fix kernel bug when page is temporally busy

> If invalidate_inode_pages2_range() says it can not invalidate pages,
> while dio to the same file offset range is in flight, something is
> really wrong there.

If invalidate_inode_pages2_range() says it can not invalidate pages
It means that soft_irq does completing IO now on other cpu.
Next retry() call in aio_run_iocb() will see the IO well completed.

The patch is updated: invalidate_inode_pages2() returns EIO as earlier
for
nfs and other.
But  invalidate_inode_pages2_range() returns EIOCBRETRY for aio and dio.

The patch against 2.6.20.

>From Leonid Ananiev

Fix kernel bug when IO page is temporally busy:
 invalidate_inode_pages2_range() returns EIOCBRETRY but not  EIO.

Signed-off-by: Leonid Ananiev <leonid.i.ananiev@...el.com>
---
--- linux-2.6.20/mm/truncate.c	2007-02-04 10:44:54.000000000 -0800
+++ linux-2.6.20p/mm/truncate.c	2007-02-08 22:56:52.000000000 -0800
@@ -366,7 +366,7 @@ static int do_launder_page(struct addres
  * Any pages which are found to be mapped into pagetables are unmapped
prior to
  * invalidation.
  *
- * Returns -EIO if any pages could not be invalidated.
+ * Returns -EIOCBRETRY if any pages could not be invalidated.
  */
 int invalidate_inode_pages2_range(struct address_space *mapping,
 				  pgoff_t start, pgoff_t end)
@@ -423,7 +423,7 @@ int invalidate_inode_pages2_range(struct
 			}
 			ret = do_launder_page(mapping, page);
 			if (ret == 0 &&
!invalidate_complete_page2(mapping, page))
-				ret = -EIO;
+				ret = -EIOCBRETRY;
 			unlock_page(page);
 		}
 		pagevec_release(&pvec);
@@ -444,6 +444,7 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages
  */
 int invalidate_inode_pages2(struct address_space *mapping)
 {
-	return invalidate_inode_pages2_range(mapping, 0, -1);
+	int ret =  invalidate_inode_pages2_range(mapping, 0, -1);
+	return (ret < 0)?-EIO:ret;
 }
 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
-
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