linux-kernel - [PATCH] jffs2: Make handling of erase_completion_lock consistent in jffs2_do_reserve

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Date:	Mon,  5 Nov 2012 22:40:14 +0400
From:	Alexey Khoroshilov <khoroshilov@...ras.ru>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	Artem Bityutskiy <Artem.Bityutskiy@...ux.intel.com>,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	ldv-project@...uxtesting.org
Subject: [PATCH] jffs2: Make handling of erase_completion_lock consistent in jffs2_do_reserve_space()

Users of jffs2_do_reserve_space() expect they still held
erase_completion_lock after call to it. But there is a path
where jffs2_do_reserve_space() leaves erase_completion_lock unlocked.
The patch fixes it.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
---
 fs/jffs2/nodemgmt.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/jffs2/nodemgmt.c b/fs/jffs2/nodemgmt.c
index 0c96eb5..0331072 100644
--- a/fs/jffs2/nodemgmt.c
+++ b/fs/jffs2/nodemgmt.c
@@ -417,14 +417,16 @@ static int jffs2_do_reserve_space(struct jffs2_sb_info *c, uint32_t minsize,
 			spin_unlock(&c->erase_completion_lock);
 
 			ret = jffs2_prealloc_raw_node_refs(c, jeb, 1);
-			if (ret)
-				return ret;
+
 			/* Just lock it again and continue. Nothing much can change because
 			   we hold c->alloc_sem anyway. In fact, it's not entirely clear why
 			   we hold c->erase_completion_lock in the majority of this function...
 			   but that's a question for another (more caffeine-rich) day. */
 			spin_lock(&c->erase_completion_lock);
 
+			if (ret)
+				return ret;
+
 			waste = jeb->free_size;
 			jffs2_link_node_ref(c, jeb,
 					    (jeb->offset + c->sector_size - waste) | REF_OBSOLETE,
-- 
1.7.9.5

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