Commit Graph

787 Commits

Author SHA1 Message Date
Lorenzo Stoakes c164154f66 mm: replace get_user_pages_unlocked() write/force parameters with gup_flags
This removes the 'write' and 'force' use from get_user_pages_unlocked()
and replaces them with 'gup_flags' to make the use of FOLL_FORCE
explicit in callers as use of this flag can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-18 14:13:37 -07:00
Ilya Dryomov 64f77566e1 crush: remove redundant local variable
Remove extra x1 variable, it's just temporary placeholder that
clutters the code unnecessarily.

Reflects ceph.git commit 0d19408d91dd747340d70287b4ef9efd89e95c6b.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-10-05 23:02:10 +02:00
Ilya Dryomov 74a5293832 crush: don't normalize input of crush_ln iteratively
Use __builtin_clz() supported by GCC and Clang to figure out
how many bits we should shift instead of shifting by a bit
in a loop until the value gets normalized. Improves performance
of this function by up to 3x in worst-case scenario and overall
straw2 performance by ~10%.

Reflects ceph.git commit 110de33ca497d94fc4737e5154d3fe781fa84a0a.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-10-05 23:02:04 +02:00
Ilya Dryomov 464691bd52 libceph: ceph_build_auth() doesn't need ceph_auth_build_hello()
A static bug finder (EBA) on Linux 4.7:

    Double lock in net/ceph/auth.c
    second lock at 108: mutex_lock(& ac->mutex); [ceph_auth_build_hello]
    after calling from 263: ret = ceph_auth_build_hello(ac, msg_buf, msg_len);
    if ! ac->protocol -> true at 262
    first lock at 261: mutex_lock(& ac->mutex); [ceph_build_auth]

ceph_auth_build_hello() is never called, because the protocol is always
initialized, whether we are checking existing tickets (in delayed_work())
or getting new ones after invalidation (in invalidate_authorizer()).

Reported-by: Iago Abal <iari@itu.dk>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-10-03 16:13:50 +02:00
Ilya Dryomov fdc723e77b libceph: use CEPH_AUTH_UNKNOWN in ceph_auth_build_hello()
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-10-03 16:13:50 +02:00
Ilya Dryomov 005a07bf0a rbd: add 'client_addr' sysfs rbd device attribute
Export client addr/nonce, so userspace can check if a image is being
blacklisted.

Signed-off-by: Mike Christie <mchristi@redhat.com>
[idryomov@gmail.com: ceph_client_addr(), endianess fix]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-08-24 23:49:16 +02:00
Ilya Dryomov ed95b21a4b rbd: support for exclusive-lock feature
Add basic support for RBD_FEATURE_EXCLUSIVE_LOCK feature.  Maintenance
operations (resize, snapshot create, etc) are offloaded to librbd via
returning -EOPNOTSUPP - librbd should request the lock and execute the
operation.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Tested-by: Mike Christie <mchristi@redhat.com>
2016-08-24 23:49:16 +02:00
Ilya Dryomov 99d1694310 rbd: retry watch re-registration periodically
Revamp watch code to support retrying watch re-registration:

- add rbd_dev->watch_state for more robust errcb handling
- store watch cookie separately to avoid dereferencing watch_handle
  which is set to NULL on unwatch
- move re-register code into a delayed work and retry re-registration
  every second, unless the client is blacklisted

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Tested-by: Mike Christie <mchristi@redhat.com>
2016-08-24 23:49:16 +02:00
Ilya Dryomov 033268a5f0 libceph: rename ceph_client_id() -> ceph_client_gid()
It's gid / global_id in other places.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
2016-08-24 23:49:16 +02:00
Douglas Fuller 6305a3b415 libceph: support for blacklisting clients
Reuse ceph_mon_generic_request infrastructure for sending monitor
commands.  In particular, add support for 'blacklist add' to prevent
other, non-responsive clients from making further updates.

Signed-off-by: Douglas Fuller <dfuller@redhat.com>
[idryomov@gmail.com: refactor, misc fixes throughout]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
2016-08-24 23:49:15 +02:00
Douglas Fuller d4ed4a5305 libceph: support for lock.lock_info
Add an interface for the Ceph OSD lock.lock_info method and associated
data structures.

Based heavily on code by Mike Christie <michaelc@cs.wisc.edu>.

Signed-off-by: Douglas Fuller <dfuller@redhat.com>
[idryomov@gmail.com: refactor, misc fixes throughout]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
2016-08-24 23:49:15 +02:00
Douglas Fuller f66241cb99 libceph: support for advisory locking on RADOS objects
This patch adds support for rados lock, unlock and break lock.

Based heavily on code by Mike Christie <michaelc@cs.wisc.edu>.

Signed-off-by: Douglas Fuller <dfuller@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
2016-08-24 23:49:15 +02:00
Douglas Fuller 428a715811 libceph: add ceph_osdc_call() single-page helper
Add a convenience function to osd_client to send Ceph OSD
'class' ops. The interface assumes that the request and
reply data each consist of single pages.

Signed-off-by: Douglas Fuller <dfuller@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
2016-08-24 23:49:15 +02:00
Douglas Fuller a4ed38d7a1 libceph: support for CEPH_OSD_OP_LIST_WATCHERS
Add support for this Ceph OSD op, needed to support the RBD exclusive
lock feature.

Signed-off-by: Douglas Fuller <dfuller@redhat.com>
[idryomov@gmail.com: refactor, misc fixes throughout]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
2016-08-24 23:49:15 +02:00
Ilya Dryomov f01d5cb24e libceph: rename ceph_entity_name_encode() -> ceph_auth_entity_name_encode()
Clear up EntityName vs entity_name_t confusion.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
2016-08-24 23:49:15 +02:00
Wei Yongjun 864364a29c libceph: using kfree_rcu() to simplify the code
The callback function of call_rcu() just calls a kfree(), so we
can use kfree_rcu() instead of call_rcu() + callback function.

Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-08-08 21:41:42 +02:00
Wei Yongjun f52ec33cbd libceph: make cancel_generic_request() static
Fixes the following sparse warning:

net/ceph/mon_client.c:577:6: warning:
 symbol 'cancel_generic_request' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-08-08 21:41:42 +02:00
Wei Yongjun c22e853a2e libceph: fix return value check in alloc_msg_with_page_vector()
In case of error, the function ceph_alloc_page_vector() returns
ERR_PTR() and never returns NULL. The NULL test in the return value
check should be replaced with IS_ERR().

Fixes: 1907920324 ('libceph: support for sending notifies')
Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-08-08 21:41:41 +02:00
Yan, Zheng 0cabbd94ff libceph: fsmap.user subscription support
Signed-off-by: Yan, Zheng <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-07-28 03:00:40 +02:00
Yan, Zheng cd08e0a274 libceph: make sure redirect does not change namespace
Signed-off-by: Yan, Zheng <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-07-28 02:55:37 +02:00
Yan, Zheng 30c156d995 libceph: rados pool namespace support
Add pool namesapce pointer to struct ceph_file_layout and struct
ceph_object_locator. Pool namespace is used by when mapping object
to PG, it's also used when composing OSD request.

The namespace pointer in struct ceph_file_layout is RCU protected.
So libceph can read namespace without taking lock.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
[idryomov@gmail.com: ceph_oloc_destroy(), misc minor changes]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-07-28 02:55:37 +02:00
Yan, Zheng 51e9273796 libceph: introduce reference counted string
The data structure is for storing namesapce string. It allows namespace
string to be shared between cephfs inodes with same layout. This data
structure can also be referenced by OSD request.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-07-28 02:55:37 +02:00
Yan, Zheng 7627151ea3 libceph: define new ceph_file_layout structure
Define new ceph_file_layout structure and rename old ceph_file_layout
to ceph_file_layout_legacy. This is preparation for adding namespace
to ceph_file_layout structure.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-07-28 02:55:36 +02:00
Ilya Dryomov b2aa5d0bc8 libceph: fix some missing includes
- decode.h needs slab.h for kmalloc()
- osd_client.h needs msgpool.h for struct ceph_msgpool
- msgpool.h doesn't need messenger.h

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-07-28 02:55:35 +02:00
Ilya Dryomov 930c532869 libceph: apply new_state before new_up_client on incrementals
Currently, osd_weight and osd_state fields are updated in the encoding
order.  This is wrong, because an incremental map may look like e.g.

    new_up_client: { osd=6, addr=... } # set osd_state and addr
    new_state: { osd=6, xorstate=EXISTS } # clear osd_state

Suppose osd6's current osd_state is EXISTS (i.e. osd6 is down).  After
applying new_up_client, osd_state is changed to EXISTS | UP.  Carrying
on with the new_state update, we flip EXISTS and leave osd6 in a weird
"!EXISTS but UP" state.  A non-existent OSD is considered down by the
mapping code

2087    for (i = 0; i < pg->pg_temp.len; i++) {
2088            if (ceph_osd_is_down(osdmap, pg->pg_temp.osds[i])) {
2089                    if (ceph_can_shift_osds(pi))
2090                            continue;
2091
2092                    temp->osds[temp->size++] = CRUSH_ITEM_NONE;

and so requests get directed to the second OSD in the set instead of
the first, resulting in OSD-side errors like:

[WRN] : client.4239 192.168.122.21:0/2444980242 misdirected client.4239.1:2827 pg 2.5df899f2 to osd.4 not [1,4,6] in e680/680

and hung rbds on the client:

[  493.566367] rbd: rbd0: write 400000 at 11cc00000 (0)
[  493.566805] rbd: rbd0:   result -6 xferred 400000
[  493.567011] blk_update_request: I/O error, dev rbd0, sector 9330688

The fix is to decouple application from the decoding and:
- apply new_weight first
- apply new_state before new_up_client
- twiddle osd_state flags if marking in
- clear out some of the state if osd is destroyed

Fixes: http://tracker.ceph.com/issues/14901

Cc: stable@vger.kernel.org # 3.15+: 6dd74e44dc1d: libceph: set 'exists' flag for newly up osd
Cc: stable@vger.kernel.org # 3.15+
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Josh Durgin <jdurgin@redhat.com>
2016-07-22 15:17:40 +02:00
Ilya Dryomov 4a3262b17c libceph: use %s instead of %pE in dout()s
Commit d30291b985 ("libceph: variable-sized ceph_object_id") changed
dout()s in what is now encode_request() and ceph_object_locator_to_pg()
to use %pE, mostly to document that, although all rbd and cephfs object
names are NULL-terminated strings, ceph_object_id will handle any RADOS
object name, including the one containing NULs, just fine.

However, it turns out that vbin_printf() can't handle anything but ints
and %s - all %p suffixes are ignored.  The buffer %p** points to isn't
recorded, resulting in trash in the messages if the buffer had been
reused by the time bstr_printf() got to it.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-30 23:00:23 +02:00
Ilya Dryomov dc045a9168 libceph: put request only if it's done in handle_reply()
handle_reply() may be called twice on the same request: on ack and then
on commit.  This occurs on btrfs-formatted OSDs or if cephfs sync write
path is triggered - CEPH_OSD_FLAG_ACK | CEPH_OSD_FLAG_ONDISK.

handle_reply() handles this with the help of done_request().

Fixes: 5aea3dcd50 ("libceph: a major OSD client update")
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-30 23:00:23 +02:00
Ilya Dryomov b7ec35b304 libceph: change ceph_osdmap_flag() to take osdc
For the benefit of every single caller, take osdc instead of map.
Also, now that osdc->osdmap can't ever be NULL, drop the check.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-30 23:00:22 +02:00
Yan, Zheng 0e76abf21e libceph: make ceph_osdc_wait_request() uninterruptible
Ceph_osdc_wait_request() is used when cephfs issues sync IO. In most
cases, the sync IO should be uninterruptible. The fix is use killale
wait function in ceph_osdc_wait_request().

Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26 01:15:40 +02:00
Zhang Zhuoyu 3b33f692c8 ceph: make logical calculation functions return bool
This patch makes serverl logical caculation functions return bool to
improve readability due to these particular functions only using 0/1
as their return value.

No functional change.

Signed-off-by: Zhang Zhuoyu <zhangzhuoyu@cmss.chinamobile.com>
2016-05-26 01:15:39 +02:00
Ilya Dryomov 737cc81ead libceph: support for subscribing to "mdsmap.<id>" maps
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:15:30 +02:00
Ilya Dryomov 7cca78c9dc libceph: replace ceph_monc_request_next_osdmap()
... with a wrapper around maybe_request_map() - no need for two
osdmap-specific functions.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:15:30 +02:00
Ilya Dryomov b4f3479569 libceph: take osdc->lock in osdmap_show() and dump flags in hex
There is now about a dozen CEPH_OSDMAP_* flags.  This is a debugging
interface, so just dump in hex instead of spelling each flag out.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:15:29 +02:00
Ilya Dryomov 4609245e26 libceph: pool deletion detection
This adds the "map check" infrastructure for sending osdmap version
checks on CALC_TARGET_POOL_DNE and completing in-flight requests with
-ENOENT if the target pool doesn't exist or has just been deleted.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:15:29 +02:00
Ilya Dryomov d0b19705e9 libceph: async MON client generic requests
For map check, we are going to need to send CEPH_MSG_MON_GET_VERSION
messages asynchronously and get a callback on completion.  Refactor MON
client to allow firing off generic requests asynchronously and add an
async variant of ceph_monc_get_version().  ceph_monc_do_statfs() is
switched over and remains sync.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:15:29 +02:00
Ilya Dryomov b07d3c4bd7 libceph: support for checking on status of watch
Implement ceph_osdc_watch_check() to be able to check on status of
watch.  Note that the time it takes for a watch/notify event to get
delivered through the notify_wq is taken into account.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:15:28 +02:00
Ilya Dryomov 1907920324 libceph: support for sending notifies
Implement ceph_osdc_notify() for sending notifies.

Due to the fact that the current messenger can't do read-in into
pagelists (it can only do write-out from them), I had to go with a page
vector for a NOTIFY_COMPLETE payload, for now.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:15:28 +02:00
Ilya Dryomov 922dab6134 libceph, rbd: ceph_osd_linger_request, watch/notify v2
This adds support and switches rbd to a new, more reliable version of
watch/notify protocol.  As with the OSD client update, this is mostly
about getting the right structures linked into the right places so that
reconnects are properly sent when needed.  watch/notify v2 also
requires sending regular pings to the OSDs - send_linger_ping().

A major change from the old watch/notify implementation is the
introduction of ceph_osd_linger_request - linger requests no longer
piggy back on ceph_osd_request.  ceph_osd_event has been merged into
ceph_osd_linger_request.

All the details are now hidden within libceph, the interface consists
of a simple pair of watch/unwatch functions and ceph_osdc_notify_ack().
ceph_osdc_watch() does return ceph_osd_linger_request, but only to keep
the lifetime management simple.

ceph_osdc_notify_ack() accepts an optional data payload, which is
relayed back to the notifier.

Portions of this patch are loosely based on work by Douglas Fuller
<dfuller@redhat.com> and Mike Christie <michaelc@cs.wisc.edu>.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:15:02 +02:00
Ilya Dryomov 42b0696527 libceph: wait_request_timeout()
The unwatch timeout is currently implemented in rbd.  With
watch/unwatch code moving into libceph, we are going to need
a ceph_osdc_wait_request() variant with a timeout.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:14:06 +02:00
Ilya Dryomov 3540bfdb30 libceph: request_init() and request_release_checks()
These are going to be used by request_reinit() code.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:14:05 +02:00
Ilya Dryomov 5aea3dcd50 libceph: a major OSD client update
This is a major sync up, up to ~Jewel.  The highlights are:

- per-session request trees (vs a global per-client tree)
- per-session locking (vs a global per-client rwlock)
- homeless OSD session
- no ad-hoc global per-client lists
- support for pool quotas
- foundation for watch/notify v2 support
- foundation for map check (pool deletion detection) support

The switchover is incomplete: lingering requests can be setup and
teared down but aren't ever reestablished.  This functionality is
restored with the introduction of the new lingering infrastructure
(ceph_osd_linger_request, linger_work, etc) in a later commit.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:14:03 +02:00
Ilya Dryomov 9dd2845ccb libceph: protect osdc->osd_lru list with a spinlock
OSD client is getting moved from the big per-client lock to a set of
per-session locks.  The big rwlock would only be held for read most of
the time, so a global osdc->osd_lru needs additional protection.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:12:30 +02:00
Ilya Dryomov 7a28f59bf9 libceph: allocate ceph_osd with GFP_NOFAIL
create_osd() is called way too deep in the stack to be able to error
out in a sane way; a failing create_osd() just messes everything up.
The current req_notarget list solution is broken - the list is never
traversed as it's not entirely clear when to do it, I guess.

If we were to start traversing it at regular intervals and retrying
each request, we wouldn't be far off from what __GFP_NOFAIL is doing,
so allocate OSD sessions with __GFP_NOFAIL, at least until we come up
with a better fix.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:12:29 +02:00
Ilya Dryomov 0247a0cf3e libceph: osd_init() and osd_cleanup()
These are going to be used by homeless OSD sessions code.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:12:29 +02:00
Ilya Dryomov 42c1b12403 libceph: handle_one_map()
Separate osdmap handling from decoding and iterating over a bag of maps
in a fresh MOSDMap message.  This sets up the scene for the updated OSD
client.

Of particular importance here is the addition of pi->was_full, which
can be used to answer "did this pool go full -> not-full in this map?".
This is the key bit for supporting pool quotas.

We won't be able to downgrade map_sem for much longer, so drop
downgrade_write().

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 01:12:27 +02:00
Ilya Dryomov e5253a7bde libceph: allocate dummy osdmap in ceph_osdc_init()
This leads to a simpler osdmap handling code, particularly when dealing
with pi->was_full, which is introduced in a later commit.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 00:36:29 +02:00
Ilya Dryomov fbca963532 libceph: schedule tick from ceph_osdc_init()
Both homeless OSD sessions and watch/notify v2, introduced in later
commits, require periodic ticks which don't depend on ->num_requests.
Schedule the initial tick from ceph_osdc_init() and reschedule from
handle_timeout() unconditionally.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 00:36:28 +02:00
Ilya Dryomov b37ee1b9b8 libceph: move schedule_delayed_work() in ceph_osdc_init()
ceph_osdc_stop() isn't called if ceph_osdc_init() fails, so we end up
with handle_osds_timeout() running on invalid memory if any one of the
allocations fails.  Call schedule_delayed_work() after everything is
setup, just before returning.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 00:36:28 +02:00
Ilya Dryomov fe5da05e97 libceph: redo callbacks and factor out MOSDOpReply decoding
If you specify ACK | ONDISK and set ->r_unsafe_callback, both
->r_callback and ->r_unsafe_callback(true) are called on ack.  This is
very confusing.  Redo this so that only one of them is called:

    ->r_unsafe_callback(true), on ack
    ->r_unsafe_callback(false), on commit

or

    ->r_callback, on ack|commit

Decode everything in decode_MOSDOpReply() to reduce clutter.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 00:36:28 +02:00
Ilya Dryomov 85e084feb4 libceph: drop msg argument from ceph_osdc_callback_t
finish_read(), its only user, uses it to get to hdr.data_len, which is
what ->r_result is set to on success.  This gains us the ability to
safely call callbacks from contexts other than reply, e.g. map check.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26 00:36:27 +02:00