diff options
Diffstat (limited to 'disk-io.c')
| -rw-r--r-- | disk-io.c | 25 |
1 files changed, 20 insertions, 5 deletions
@@ -454,22 +454,27 @@ insert: return root; } -struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr) +struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes) { int fp; struct btrfs_root *root; + int flags = O_CREAT | O_RDWR; - fp = open(filename, O_CREAT | O_RDWR, 0600); + if (!writes) + flags = O_RDONLY; + + fp = open(filename, flags, 0600); if (fp < 0) { return NULL; } - root = open_ctree_fd(fp, filename, sb_bytenr); + root = open_ctree_fd(fp, filename, sb_bytenr, writes); close(fp); return root; } -struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr) +struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr, + int writes) { u32 sectorsize; u32 nodesize; @@ -510,6 +515,9 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr) fs_info->chunk_root = chunk_root; fs_info->dev_root = dev_root; + if (!writes) + fs_info->readonly = 1; + extent_io_tree_init(&fs_info->extent_cache); extent_io_tree_init(&fs_info->free_space_cache); extent_io_tree_init(&fs_info->block_group_cache); @@ -527,7 +535,10 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr) __setup_root(4096, 4096, 4096, 4096, tree_root, fs_info, BTRFS_ROOT_TREE_OBJECTID); - ret = btrfs_open_devices(fs_devices, O_RDWR); + if (writes) + ret = btrfs_open_devices(fs_devices, O_RDWR); + else + ret = btrfs_open_devices(fs_devices, O_RDONLY); BUG_ON(ret); ret = btrfs_bootstrap_super_map(&fs_info->mapping_tree, fs_devices); @@ -656,6 +667,10 @@ int write_ctree_super(struct btrfs_trans_handle *trans, int ret; struct btrfs_root *tree_root = root->fs_info->tree_root; struct btrfs_root *chunk_root = root->fs_info->chunk_root; + + if (root->fs_info->readonly) + return 0; + btrfs_set_super_generation(&root->fs_info->super_copy, trans->transid); btrfs_set_super_root(&root->fs_info->super_copy, |