[PATCH] btrfs: use list_for_each_entry_safe() when delete items

[Azat Khuzhin]

Replace list_for_each_entry() by list_for_each_entry_safe() in
__btrfs_close_devices()

list_for_each_entry() {
        list_replace_rcu();
        call_rcu();             <--    We may free the device, if we get next
                                       device by the current one, the page fault
                                       may happen.
}

Signed-off-by: Azat Khuzhin <a3at.mail@xxxxxxxxx>
Reviewed-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
---
V2: Add some comments from Miao into commit message

 fs/btrfs/volumes.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 78b8717..1d1b595 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -616,13 +616,13 @@ static void free_device(struct rcu_head *head)
 
 static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 {
-	struct btrfs_device *device;
+	struct btrfs_device *device, *next;
 
 	if (--fs_devices->opened > 0)
 		return 0;
 
 	mutex_lock(&fs_devices->device_list_mutex);
-	list_for_each_entry(device, &fs_devices->devices, dev_list) {
+	list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
 		struct btrfs_device *new_device;
 		struct rcu_string *name;
 
-- 
1.7.10.4

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