Before updating the super block's flags, which is a non-atomic operation, grab the super_lock in the fs_info structure. At the moment only 2 different code paths can update these flags in parallel:
1) when adding a new device 2) writing all super block copies to disk Signed-off-by: Filipe David Borba Manana <[email protected]> --- fs/btrfs/ctree.h | 4 ++-- fs/btrfs/disk-io.c | 2 ++ fs/btrfs/volumes.c | 2 ++ 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index cbb1263..fd47c02 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1375,8 +1375,8 @@ struct btrfs_fs_info { wait_queue_head_t async_submit_wait; /* - * Used to protect the incompat_flags, compat_flags, compat_ro_flags - * when they are updated. + * Used to protect the incompat_flags, compat_flags, compat_ro_flags, + * flags and label when they are updated. * * Because we do not clear the flags for ever, so we needn't use * the lock on the read side. diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index b71e882..3900c36 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3357,8 +3357,10 @@ static int write_all_supers(struct btrfs_root *root, int max_mirrors) memcpy(dev_item->uuid, dev->uuid, BTRFS_UUID_SIZE); memcpy(dev_item->fsid, dev->fs_devices->fsid, BTRFS_UUID_SIZE); + spin_lock(&root->fs_info->super_lock); flags = btrfs_super_flags(sb); btrfs_set_super_flags(sb, flags | BTRFS_HEADER_FLAG_WRITTEN); + spin_unlock(&root->fs_info->super_lock); ret = write_dev_supers(dev, sb, do_barriers, 0, max_mirrors); if (ret) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 090f57c..8c67bd7 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1862,9 +1862,11 @@ static int btrfs_prepare_sprout(struct btrfs_root *root) generate_random_uuid(fs_devices->fsid); memcpy(root->fs_info->fsid, fs_devices->fsid, BTRFS_FSID_SIZE); memcpy(disk_super->fsid, fs_devices->fsid, BTRFS_FSID_SIZE); + spin_lock(&root->fs_info->super_lock); super_flags = btrfs_super_flags(disk_super) & ~BTRFS_SUPER_FLAG_SEEDING; btrfs_set_super_flags(disk_super, super_flags); + spin_unlock(&root->fs_info->super_lock); return 0; } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
