Re: [PATCH] btrfs-progs: enclose uuid tree compat code with ifdefs

[Wang Shilong <wangsl.fnst@cn.fujitsu.com>]

Hi David,

On 01/21/2014 11:56 PM, David Sterba wrote:
> Commit "Btrfs-progs: make send/receive compatible with older kernels"
> adds code that will become deprecated, let's clearly mark it in the
> sources.
>
> CC: Stefan Behrens <sbehrens@giantdisaster.de>
> CC: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
> Signed-off-by: David Sterba <dsterba@suse.cz>
> ---
>   send-utils.c |   28 ++++++++++++++++++++++++++++
>   send-utils.h |   10 ++++++++++
>   2 files changed, 38 insertions(+), 0 deletions(-)
>
> diff --git a/send-utils.c b/send-utils.c
> index 1772d2c5c0f3..8d4f46e3dd04 100644
> --- a/send-utils.c
> +++ b/send-utils.c
> @@ -159,6 +159,7 @@ static int btrfs_read_root_item(int mnt_fd, u64 root_id,
>   	return 0;
>   }
>   
> +#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
>   static struct rb_node *tree_insert(struct rb_root *root,
>   				   struct subvol_info *si,
>   				   enum subvol_search_type type)
> @@ -223,6 +224,7 @@ static struct rb_node *tree_insert(struct rb_root *root,
>   	}
>   	return NULL;
>   }
> +#endif
>   
>   int btrfs_subvolid_resolve(int fd, char *path, size_t path_len, u64 subvol_id)
>   {
> @@ -320,6 +322,7 @@ static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
>   	return 0;
>   }
>   
> +#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
>   static int count_bytes(void *buf, int len, char b)
>   {
>   	int cnt = 0;
> @@ -416,6 +419,16 @@ static struct subvol_info *subvol_uuid_search_old(struct subvol_uuid_search *s,
>   		return NULL;
>   	return tree_search(root, root_id, uuid, transid, path, type);
>   }
> +#else
> +void subvol_uuid_search_add(struct subvol_uuid_search *s,
> +			    struct subvol_info *si)
> +{
> +	if (si) {
> +		free(si->path);
> +		free(si);
> +	}
> +}
> +#endif
I noticed subvol_uuid_search_add() function before, anyway
it is not called anywhere before, aslo IMO it is a little strange that 
we free
memory here.

Thanks,
Wang
>   
>   struct subvol_info *subvol_uuid_search(struct subvol_uuid_search *s,
>   				       u64 root_id, const u8 *uuid, u64 transid,
> @@ -426,9 +439,11 @@ struct subvol_info *subvol_uuid_search(struct subvol_uuid_search *s,
>   	struct btrfs_root_item root_item;
>   	struct subvol_info *info = NULL;
>   
> +#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
>   	if (!s->uuid_tree_existed)
>   		return subvol_uuid_search_old(s, root_id, uuid, transid,
>   					     path, type);
> +#endif
>   	switch (type) {
>   	case subvol_search_by_received_uuid:
>   		ret = btrfs_lookup_uuid_received_subvol_item(s->mnt_fd, uuid,
> @@ -481,6 +496,7 @@ out:
>   	return info;
>   }
>   
> +#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
>   static int is_uuid_tree_supported(int fd)
>   {
>   	int ret;
> @@ -679,6 +695,18 @@ void subvol_uuid_search_finit(struct subvol_uuid_search *s)
>   	s->received_subvols = RB_ROOT;
>   	s->path_subvols = RB_ROOT;
>   }
> +#else
> +int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
> +{
> +	s->mnt_fd = mnt_fd;
> +
> +	return 0;
> +}
> +
> +void subvol_uuid_search_finit(struct subvol_uuid_search *s)
> +{
> +}
> +#endif
>   
>   char *path_cat(const char *p1, const char *p2)
>   {
> diff --git a/send-utils.h b/send-utils.h
> index 943b0277cf7e..f451c1cb6071 100644
> --- a/send-utils.h
> +++ b/send-utils.h
> @@ -30,6 +30,12 @@
>   extern "C" {
>   #endif
>   
> +/*
> + * Compatibility code for kernels < 3.12; the UUID tree is not available there
> + * and we have to do the slow search. This should be deprecated someday.
> + */
> +#define BTRFS_COMPAT_SEND_NO_UUID_TREE 1
> +
>   enum subvol_search_type {
>   	subvol_search_by_root_id,
>   	subvol_search_by_uuid,
> @@ -38,10 +44,12 @@ enum subvol_search_type {
>   };
>   
>   struct subvol_info {
> +#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
>   	struct rb_node rb_root_id_node;
>   	struct rb_node rb_local_node;
>   	struct rb_node rb_received_node;
>   	struct rb_node rb_path_node;
> +#endif
>   
>   	u64 root_id;
>   	u8 uuid[BTRFS_UUID_SIZE];
> @@ -57,12 +65,14 @@ struct subvol_info {
>   
>   struct subvol_uuid_search {
>   	int mnt_fd;
> +#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
>   	int uuid_tree_existed;
>   
>   	struct rb_root root_id_subvols;
>   	struct rb_root local_subvols;
>   	struct rb_root received_subvols;
>   	struct rb_root path_subvols;
> +#endif
>   };
>   
>   int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s);