linux-kernel - [078/129] pnfsblock: dont spinlock when freeing block

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Date:	Mon, 23 Jan 2012 18:34:58 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Peng Tao <peng_tao@....com>,
	Benny Halevy <bhalevy@...ian.com>,
	Trond Myklebust <Trond.Myklebust@...app.com>
Subject: [078/129] pnfsblock: dont spinlock when freeing block_dev

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
Content-Length: 1276
Lines: 40

From: Peng Tao <bergwolf@...il.com>

commit 93a3844ee0f843b05a1df4b52e1a19ff26b98d24 upstream.

bl_free_block_dev() may sleep. We can not call it with spinlock held.
Besides, there is no need to take bm_lock as we are last user freeing bm_devlist.

Signed-off-by: Peng Tao <peng_tao@....com>
Signed-off-by: Benny Halevy <bhalevy@...ian.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 fs/nfs/blocklayout/blocklayout.c |   11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -779,16 +779,13 @@ bl_cleanup_layoutcommit(struct nfs4_layo
 static void free_blk_mountid(struct block_mount_id *mid)
 {
 	if (mid) {
-		struct pnfs_block_dev *dev;
-		spin_lock(&mid->bm_lock);
-		while (!list_empty(&mid->bm_devlist)) {
-			dev = list_first_entry(&mid->bm_devlist,
-					       struct pnfs_block_dev,
-					       bm_node);
+		struct pnfs_block_dev *dev, *tmp;
+
+		/* No need to take bm_lock as we are last user freeing bm_devlist */
+		list_for_each_entry_safe(dev, tmp, &mid->bm_devlist, bm_node) {
 			list_del(&dev->bm_node);
 			bl_free_block_dev(dev);
 		}
-		spin_unlock(&mid->bm_lock);
 		kfree(mid);
 	}
 }


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