From 6bb8ac8af93986c8b6e01a582b1e068e427ccaa6 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Fri, 16 Jun 2017 00:09:21 +0200 Subject: [PATCH] btrfs: switch to RCU for device traversal in btrfs_ioctl_fs_info We don't need to use the mutex as we do not modify the devices nor the list itself and just read information about device counts. Move copying fsid out of the protected section, not applicable to RCU same as the rest of the retrieved information. Signed-off-by: David Sterba --- fs/btrfs/ioctl.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index f1884c075cd36..ab7ff3efcba6e 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2749,16 +2749,16 @@ static long btrfs_ioctl_fs_info(struct btrfs_fs_info *fs_info, if (!fi_args) return -ENOMEM; - mutex_lock(&fs_devices->device_list_mutex); + rcu_read_lock(); fi_args->num_devices = fs_devices->num_devices; - memcpy(&fi_args->fsid, fs_info->fsid, sizeof(fi_args->fsid)); - list_for_each_entry(device, &fs_devices->devices, dev_list) { + list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) { if (device->devid > fi_args->max_id) fi_args->max_id = device->devid; } - mutex_unlock(&fs_devices->device_list_mutex); + rcu_read_unlock(); + memcpy(&fi_args->fsid, fs_info->fsid, sizeof(fi_args->fsid)); fi_args->nodesize = fs_info->nodesize; fi_args->sectorsize = fs_info->sectorsize; fi_args->clone_alignment = fs_info->sectorsize; -- 2.39.5