linux-kernel - [PATCH 13/14] staging/lustre/llite: do not clear uptodate bit in page delete

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Date:   Wed,  2 Nov 2016 21:25:03 -0400
From:   Oleg Drokin <green@...uxhacker.ru>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org,
        Andreas Dilger <andreas.dilger@...el.com>,
        James Simmons <jsimmons@...radead.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Lustre Development List <lustre-devel@...ts.lustre.org>,
        Jinshan Xiong <jinshan.xiong@...el.com>,
        Oleg Drokin <green@...uxhacker.ru>
Subject: [PATCH 13/14] staging/lustre/llite: do not clear uptodate bit in page delete

From: Jinshan Xiong <jinshan.xiong@...el.com>

Otherwise, if the race between page fault and truncate occurs, it
will cause the page fault routine to return an EIO error.

In filemap_fault() {
    page_not_uptodate:
    ...
        ClearPageError(page);
        error = mapping->a_ops->readpage(file, page);
        if (!error) {
                wait_on_page_locked(page);
                if (!PageUptodate(page))
                        error = -EIO;
    }
    ...
}

However, I tend to think this is a defect in kernel implementation,
because it assumes PageUptodate shouldn't be cleared but file read
routine doesn't make the same assumption.

Signed-off-by: Jinshan Xiong <jinshan.xiong@...el.com>
Reviewed-on: http://review.whamcloud.com/22827
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8633
Reviewed-by: Li Dongyang <dongyang.li@....edu.au>
Reviewed-by: Bobi Jam <bobijam@...mail.com>
Signed-off-by: Oleg Drokin <green@...uxhacker.ru>
---
 drivers/staging/lustre/lustre/llite/vvp_page.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/staging/lustre/lustre/llite/vvp_page.c b/drivers/staging/lustre/lustre/llite/vvp_page.c
index 25490a5..23d6630 100644
--- a/drivers/staging/lustre/lustre/llite/vvp_page.c
+++ b/drivers/staging/lustre/lustre/llite/vvp_page.c
@@ -166,7 +166,6 @@ static void vvp_page_delete(const struct lu_env *env,
 	refc = atomic_dec_return(&page->cp_ref);
 	LASSERTF(refc >= 1, "page = %p, refc = %d\n", page, refc);
 
-	ClearPageUptodate(vmpage);
 	ClearPagePrivate(vmpage);
 	vmpage->private = 0;
 	/*
-- 
2.7.4