linux-kernel - [PATCH 4/4] fsfreeze: avoid to return zero in __get_user

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Message-ID: <515FF3CC.80106@gmail.com>
Date:	Sat, 06 Apr 2013 12:07:08 +0200
From:	Marco Stornelli <marco.stornelli@...il.com>
To:	Linux FS Devel <linux-fsdevel@...r.kernel.org>
CC:	Mike Snitzer <snitzer@...hat.com>,
	Alasdair G Kergon <agk@...hat.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>
Subject: [PATCH 4/4] fsfreeze: avoid to return zero in __get_user_pages

In case of VM_FAULT_RETRY, __get_user_pages returns the number
of pages alredy gotten, but there isn't a check if this number is
zero. Instead, we have to return a proper error code so we can avoid
a possible extra call of __get_user_pages. There are several
places where get_user_pages is called inside a loop until all the
pages requested are gotten or an error code is returned.

Signed-off-by: Marco Stornelli <marco.stornelli@...il.com>
---
 mm/memory.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 494526a..cca14ed 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1858,7 +1858,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 				if (ret & VM_FAULT_RETRY) {
 					if (nonblocking)
 						*nonblocking = 0;
-					return i;
+					return i ? i : -ERESTARTSYS;
 				}
 
 				/*
-- 
1.7.3.4
--
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