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btrfs: Factor out tree roots initialization during mount 

The code responsible for reading and initializing tree roots is
scattered in open_ctree among 2 labels, emulating a loop. This is rather
confusing to reason about. Instead, factor the code to a new function,
init_tree_roots which implements the same logical flow.

There are a couple of notable differences, namely:

* Instead of using next_backup_root it's using the newly introduced
  read_backup_root.

* If read_backup_root returns an error init_tree_roots propagates the
  error and there is no special handling of that case e.g. the code jumps
  straight to 'fail_tree_roots' label. The old code, however, was
  (erroneously) jumping to 'fail_block_groups' label if next_backup_root
  did fail, this was unnecessary since the tree roots init logic doesn't
  modify the state of block groups.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Nikolay Borisov 2019-10-15 18:42:20 +03:00 коммит произвёл David Sterba
Родитель bd2336b2ac
Коммит b8522a1e5f
1 изменённых файлов: 85 добавлений и 57 удалений
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142
fs/btrfs/disk-io.c
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@ -2610,6 +2610,89 @@ out:
return ret;
}
int __cold init_tree_roots(struct btrfs_fs_info *fs_info)
{
struct btrfs_super_block *sb = fs_info->super_copy;
struct btrfs_root *tree_root = fs_info->tree_root;
bool handle_error = false;
int ret = 0;
int i;
for (i = 0; i < BTRFS_NUM_BACKUP_ROOTS; i++) {
u64 generation;
int level;
if (handle_error) {
if (!IS_ERR(tree_root->node))
free_extent_buffer(tree_root->node);
tree_root->node = NULL;
if (!btrfs_test_opt(fs_info, USEBACKUPROOT))
break;
free_root_pointers(fs_info, 0);
/*
* Don't use the log in recovery mode, it won't be
* valid
*/
btrfs_set_super_log_root(sb, 0);
/* We can't trust the free space cache either */
btrfs_set_opt(fs_info->mount_opt, CLEAR_CACHE);
ret = read_backup_root(fs_info, i);
if (ret < 0)
return ret;
}
generation = btrfs_super_generation(sb);
level = btrfs_super_root_level(sb);
tree_root->node = read_tree_block(fs_info, btrfs_super_root(sb),
generation, level, NULL);
if (IS_ERR(tree_root->node) ||
!extent_buffer_uptodate(tree_root->node)) {
handle_error = true;
if (IS_ERR(tree_root->node))
ret = PTR_ERR(tree_root->node);
else if (!extent_buffer_uptodate(tree_root->node))
ret = -EUCLEAN;
btrfs_warn(fs_info, "failed to read tree root");
continue;
}
btrfs_set_root_node(&tree_root->root_item, tree_root->node);
tree_root->commit_root = btrfs_root_node(tree_root);
btrfs_set_root_refs(&tree_root->root_item, 1);
mutex_lock(&tree_root->objectid_mutex);
ret = btrfs_find_highest_objectid(tree_root,
&tree_root->highest_objectid);
if (ret < 0) {
mutex_unlock(&tree_root->objectid_mutex);
handle_error = true;
continue;
}
ASSERT(tree_root->highest_objectid <= BTRFS_LAST_FREE_OBJECTID);
mutex_unlock(&tree_root->objectid_mutex);
ret = btrfs_read_roots(fs_info);
if (ret < 0) {
handle_error = true;
continue;
}
/* All successful */
fs_info->generation = generation;
fs_info->last_trans_committed = generation;
break;
}
return ret;
}
int __cold open_ctree(struct super_block *sb,
struct btrfs_fs_devices *fs_devices,
char *options)
@ -2628,8 +2711,6 @@ int __cold open_ctree(struct super_block *sb,
struct btrfs_root *chunk_root;
int ret;
int err = -EINVAL;
int num_backups_tried = 0;
int backup_index = 0;
int clear_free_space_tree = 0;
int level;
@ -3051,44 +3132,9 @@ int __cold open_ctree(struct super_block *sb,
goto fail_tree_roots;
}
retry_root_backup:
generation = btrfs_super_generation(disk_super);
level = btrfs_super_root_level(disk_super);
tree_root->node = read_tree_block(fs_info,
btrfs_super_root(disk_super),
generation, level, NULL);
if (IS_ERR(tree_root->node) ||
!extent_buffer_uptodate(tree_root->node)) {
btrfs_warn(fs_info, "failed to read tree root");
if (!IS_ERR(tree_root->node))
free_extent_buffer(tree_root->node);
tree_root->node = NULL;
goto recovery_tree_root;
}
btrfs_set_root_node(&tree_root->root_item, tree_root->node);
tree_root->commit_root = btrfs_root_node(tree_root);
btrfs_set_root_refs(&tree_root->root_item, 1);
mutex_lock(&tree_root->objectid_mutex);
ret = btrfs_find_highest_objectid(tree_root,
&tree_root->highest_objectid);
if (ret) {
mutex_unlock(&tree_root->objectid_mutex);
goto recovery_tree_root;
}
ASSERT(tree_root->highest_objectid <= BTRFS_LAST_FREE_OBJECTID);
mutex_unlock(&tree_root->objectid_mutex);
ret = btrfs_read_roots(fs_info);
ret = init_tree_roots(fs_info);
if (ret)
goto recovery_tree_root;
fs_info->generation = generation;
fs_info->last_trans_committed = generation;
goto fail_tree_roots;
ret = btrfs_verify_dev_extents(fs_info);
if (ret) {
@ -3383,24 +3429,6 @@ fail:
btrfs_free_stripe_hash_table(fs_info);
btrfs_close_devices(fs_info->fs_devices);
return err;
recovery_tree_root:
if (!btrfs_test_opt(fs_info, USEBACKUPROOT))
goto fail_tree_roots;
free_root_pointers(fs_info, false);
/* don't use the log in recovery mode, it won't be valid */
btrfs_set_super_log_root(disk_super, 0);
/* we can't trust the free space cache either */
btrfs_set_opt(fs_info->mount_opt, CLEAR_CACHE);
ret = next_root_backup(fs_info, fs_info->super_copy,
&num_backups_tried, &backup_index);
if (ret == -1)
goto fail_block_groups;
goto retry_root_backup;
}
ALLOW_ERROR_INJECTION(open_ctree, ERRNO);