On 14.02.20 г. 23:11 ч., Josef Bacik wrote:
> There are a few different ways to free roots, either you allocated them
> yourself and you just do
>
> free_extent_buffer(root->node);
> free_extent_buffer(root->commit_node);
> btrfs_put_root(root);
>
> Which is the pattern for log roots. Or for snapshots/subvolumes that
> are being dropped you simply call btrfs_free_fs_root() which does all
> the cleanup for you.
>
> Unify this all into btrfs_put_root(), so that we don't free up things
> associated with the root until the last reference is dropped. This
> makes the root freeing code much more significant.
>
> The only caveat is at close_ctree() time we have to free the extent
> buffers for all of our main roots (extent_root, chunk_root, etc) because
> we have to drop the btree_inode and we'll run into issues if we hold
> onto those nodes until ->kill_sb() time. This will be addressed in the
> future when we kill the btree_inode.
>
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Nit: This patch obsoleted the last comment in btrfs_init_fs_root, namely:
/* The caller is responsible to call btrfs_free_fs_root */
> ---
> fs/btrfs/disk-io.c | 64 ++++++++++++++++++------------------
> fs/btrfs/disk-io.h | 16 +--------
> fs/btrfs/extent-tree.c | 7 ++--
> fs/btrfs/extent_io.c | 16 +++++++--
> fs/btrfs/free-space-tree.c | 2 --
> fs/btrfs/qgroup.c | 7 +---
> fs/btrfs/relocation.c | 4 ---
> fs/btrfs/tests/btrfs-tests.c | 5 +--
> fs/btrfs/tree-log.c | 6 ----
> 9 files changed, 50 insertions(+), 77 deletions(-)
>
<snip>
> @@ -4795,7 +4803,6 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
>
> static void __free_extent_buffer(struct extent_buffer *eb)
> {
> - btrfs_leak_debug_del(&eb->fs_info->eb_leak_lock, &eb->leak_list);
> kmem_cache_free(extent_buffer_cache, eb);
> }
This function becomes a trivial wrapper so should be eliminated altogether.
<snip>
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 034f5f151a74..4fb7e3cc2aca 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -2549,10 +2549,6 @@ void free_reloc_roots(struct list_head *list)
> reloc_root = list_entry(list->next, struct btrfs_root,
> root_list);
> __del_reloc_root(reloc_root);
> - free_extent_buffer(reloc_root->node);
> - free_extent_buffer(reloc_root->commit_root);
> - reloc_root->node = NULL;
> - reloc_root->commit_root = NULL;
Shouldn't you do btrfs_put_root(reloc_root) here ?
> }
> }
>
<snip>
