btrfs: use non-RCU list traversal in write_all_supers callees

We take the fs_devices::device_list_mutex mutex in write_all_supers
which will prevent any add/del changes to the device list. Therefore we
don't need to use the RCU variant list_for_each_entry_rcu in any of the
called functions.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index ec9aa34..06c5937 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3395,9 +3395,10 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
        int errors_wait = 0;
        blk_status_t ret;
 
+       lockdep_assert_held(&info->fs_devices->device_list_mutex);
        /* send down all the barriers */
        head = &info->fs_devices->devices;
-       list_for_each_entry_rcu(dev, head, dev_list) {
+       list_for_each_entry(dev, head, dev_list) {
                if (dev->missing)
                        continue;
                if (!dev->bdev)
@@ -3410,7 +3411,7 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
        }
 
        /* wait for all the barriers */
-       list_for_each_entry_rcu(dev, head, dev_list) {
+       list_for_each_entry(dev, head, dev_list) {
                if (dev->missing)
                        continue;
                if (!dev->bdev) {
@@ -3509,7 +3510,7 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
                }
        }
 
-       list_for_each_entry_rcu(dev, head, dev_list) {
+       list_for_each_entry(dev, head, dev_list) {
                if (!dev->bdev) {
                        total_errors++;
                        continue;
@@ -3550,7 +3551,7 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
        }
 
        total_errors = 0;
-       list_for_each_entry_rcu(dev, head, dev_list) {
+       list_for_each_entry(dev, head, dev_list) {
                if (!dev->bdev)
                        continue;
                if (!dev->in_fs_metadata || !dev->writeable)