Hi,
> This won't work if you receive more than one snapshot, each one derived
> from the previous one ("btrfs send -e snap1 snap2 snap3 snap4"). You
> would always use the first one as the parent, not the predecessor.
> That's implemented differently for the -p option in
> git://git.kernel.org/pub/scm/linux/kernel/git/arne/far-progs.git
I'll take another look on the multi-subvolume stream mode.
> This used to be a search for the received_uuid only. Why is this code
> changed like this in the branch that is executed when -p is not
> specified, in a patch that has the goal to add -p with new functionality
> if -p is specified?
Many things have changed since far-progs, take a look in the original
source I used as basis for my patch:
https://github.com/kdave/btrfs-progs/blob/1b7dd327f43777bcdd217a0500e6bda78128a290/cmds-receive.c#L233
I am pretty sure lookup logic isn't affected if -p is not used.
2015-04-27 9:28 GMT+02:00 Stefan Behrens <sbehr...@giantdisaster.de>:
> On Sun, 26 Apr 2015 12:12:45 +0200, Lauri Võsandi wrote:
>> This patch adds command-line flag -p to btrfs receive
>> which makes it possible to disable automatic parent
>> search for incremental snapshots and use explicitly
>> specified path instead.
>>
>> Signed-off-by: Lauri Võsandi <lauri.vosa...@gmail.com>
>> ---
>> cmds-receive.c | 34 ++++++++++++++++++++++++++--------
>> 1 file changed, 26 insertions(+), 8 deletions(-)
>>
>> diff --git a/cmds-receive.c b/cmds-receive.c
>> index b7cf3f9..391d281 100644
>> --- a/cmds-receive.c
>> +++ b/cmds-receive.c
>> @@ -61,6 +61,7 @@ struct btrfs_receive
>> char *root_path;
>> char *dest_dir_path; /* relative to root_path */
>> char *full_subvol_path;
>> + char *explicit_parent_path;
>> int dest_dir_chroot;
>>
>> struct subvol_info *cur_subvol;
>> @@ -220,20 +221,32 @@ static int process_snapshot(const char *path, const u8
>> *uuid, u64 ctransid,
>> fprintf(stderr, "receiving snapshot %s uuid=%s, "
>> "ctransid=%llu ", path, uuid_str,
>> r->cur_subvol->stransid);
>> - uuid_unparse(parent_uuid, uuid_str);
>> - fprintf(stderr, "parent_uuid=%s, parent_ctransid=%llu\n",
>> - uuid_str, parent_ctransid);
>> }
>>
>> memset(&args_v2, 0, sizeof(args_v2));
>> strncpy_null(args_v2.name, path);
>>
>> - parent_subvol = subvol_uuid_search(&r->sus, 0, parent_uuid,
>> - parent_ctransid, NULL, subvol_search_by_received_uuid);
>> - if (!parent_subvol) {
>> + if (r->explicit_parent_path) {
>> + if (g_verbose) {
>> + fprintf(stderr, "using explicit parent %s\n",
>> + r->explicit_parent_path);
>> + }
>> + parent_subvol = subvol_uuid_search(&r->sus, 0, NULL,
>> + 0, r->explicit_parent_path, subvol_search_by_path);
>
> This won't work if you receive more than one snapshot, each one derived
> from the previous one ("btrfs send -e snap1 snap2 snap3 snap4"). You
> would always use the first one as the parent, not the predecessor.
> That's implemented differently for the -p option in
> git://git.kernel.org/pub/scm/linux/kernel/git/arne/far-progs.git
>
>
>> + } else {
>> + if (g_verbose) {
>> + uuid_unparse(parent_uuid, uuid_str);
>> + fprintf(stderr, "parent_uuid=%s,
>> parent_ctransid=%llu\n",
>> + uuid_str, parent_ctransid);
>> + }
>> parent_subvol = subvol_uuid_search(&r->sus, 0, parent_uuid,
>> - parent_ctransid, NULL, subvol_search_by_uuid);
>> + parent_ctransid, NULL, subvol_search_by_received_uuid);
>> + if (!parent_subvol) {
>> + parent_subvol = subvol_uuid_search(&r->sus, 0,
>> parent_uuid,
>> + parent_ctransid, NULL,
>> subvol_search_by_uuid);
>> + }
>
> This used to be a search for the received_uuid only. Why is this code
> changed like this in the branch that is executed when -p is not
> specified, in a patch that has the goal to add -p with new functionality
> if -p is specified?
>
>
>> }
>> +
>> if (!parent_subvol) {
>> ret = -ENOENT;
>> fprintf(stderr, "ERROR: could not find parent subvolume\n");
>> @@ -962,11 +975,14 @@ int cmd_receive(int argc, char **argv)
>> { NULL, 0, NULL, 0 }
>> };
>>
>> - c = getopt_long(argc, argv, "Cevf:", long_opts, NULL);
>> + c = getopt_long(argc, argv, "Cevf:p:", long_opts, NULL);
>> if (c < 0)
>> break;
>>
>> switch (c) {
>> + case 'p':
>> + r.explicit_parent_path = optarg;
>> + break;
>> case 'v':
>> g_verbose++;
>> break;
>> @@ -1028,6 +1044,8 @@ const char * const cmd_receive_usage[] = {
>> " in the data stream. Without this option,",
>> " the receiver terminates only if an error",
>> " is recognized or on EOF.",
>> + "-p <subvol> Disables the automatic searching for parents",
>> + " if incremental streams are received.",
>> "-C|--chroot confine the process to <mount> using chroot",
>> "--max-errors <N> Terminate as soon as N errors happened while",
>> " processing commands from the send stream.",
>>
>
--
Lauri Võsandi
tel: +372 53329412
e-mail: lauri.vosa...@gmail.com
blog: http://lauri.vosandi.com/
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