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Subject[PATCH 12/20] ceph: monitor client
Date
The monitor cluster is responsible for managing cluster membership
and state. The monitor client handles what minimal interaction
the Ceph client has with it: checking for updated versions of the
MDS and OSD maps, and getting statfs() information.

Signed-off-by: Sage Weil <sage@newdream.net>
---
fs/ceph/mon_client.c | 450 ++++++++++++++++++++++++++++++++++++++++++++++++++
fs/ceph/mon_client.h | 109 ++++++++++++
2 files changed, 559 insertions(+), 0 deletions(-)
create mode 100644 fs/ceph/mon_client.c
create mode 100644 fs/ceph/mon_client.h

diff --git a/fs/ceph/mon_client.c b/fs/ceph/mon_client.c
new file mode 100644
index 0000000..085e8ec
--- /dev/null
+++ b/fs/ceph/mon_client.c
@@ -0,0 +1,450 @@
+
+#include <linux/types.h>
+#include <linux/random.h>
+#include <linux/sched.h>
+#include "mon_client.h"
+
+#include "ceph_debug.h"
+
+int ceph_debug_mon __read_mostly = -1;
+#define DOUT_MASK DOUT_MASK_MON
+#define DOUT_VAR ceph_debug_mon
+#include "super.h"
+#include "decode.h"
+
+/*
+ * Decode a monmap blob (e.g., during mount).
+ */
+struct ceph_monmap *ceph_monmap_decode(void *p, void *end)
+{
+ struct ceph_monmap *m;
+ int i, err = -EINVAL;
+ __le64 major, minor;
+
+ dout(30, "monmap_decode %p %p len %d\n", p, end, (int)(end-p));
+
+ /* The encoded and decoded sizes match. */
+ m = kmalloc(end-p, GFP_NOFS);
+ if (m == NULL)
+ return ERR_PTR(-ENOMEM);
+
+ ceph_decode_need(&p, end, 2*sizeof(u32) + 2*sizeof(u64), bad);
+ ceph_decode_64_le(&p, major);
+ __ceph_fsid_set_major(&m->fsid, major);
+ ceph_decode_64_le(&p, minor);
+ __ceph_fsid_set_minor(&m->fsid, minor);
+ ceph_decode_32(&p, m->epoch);
+ ceph_decode_32(&p, m->num_mon);
+ ceph_decode_need(&p, end, m->num_mon*sizeof(m->mon_inst[0]), bad);
+ ceph_decode_copy(&p, m->mon_inst, m->num_mon*sizeof(m->mon_inst[0]));
+ if (p != end)
+ goto bad;
+
+ dout(30, "monmap_decode epoch %d, num_mon %d\n", m->epoch,
+ m->num_mon);
+ for (i = 0; i < m->num_mon; i++)
+ dout(30, "monmap_decode mon%d is %u.%u.%u.%u:%u\n", i,
+ IPQUADPORT(m->mon_inst[i].addr.ipaddr));
+ return m;
+
+bad:
+ dout(30, "monmap_decode failed with %d\n", err);
+ kfree(m);
+ return ERR_PTR(err);
+}
+
+/*
+ * return true if *addr is included in the monmap.
+ */
+int ceph_monmap_contains(struct ceph_monmap *m, struct ceph_entity_addr *addr)
+{
+ int i;
+
+ for (i = 0; i < m->num_mon; i++)
+ if (ceph_entity_addr_equal(addr, &m->mon_inst[i].addr))
+ return 1;
+ return 0;
+}
+
+/*
+ * Choose a monitor. If @notmon >= 0, choose a different monitor than
+ * last time.
+ */
+static int pick_mon(struct ceph_mon_client *monc, int newmon)
+{
+ char r;
+
+ if (!newmon && monc->last_mon >= 0)
+ return monc->last_mon;
+ get_random_bytes(&r, 1);
+ monc->last_mon = r % monc->monmap->num_mon;
+ return monc->last_mon;
+}
+
+/*
+ * Generic timeout mechanism for monitor requests
+ */
+static void reschedule_timeout(struct ceph_mon_request_type *req)
+{
+ schedule_delayed_work(&req->delayed_work, req->delay);
+ if (req->delay < MAX_DELAY_INTERVAL)
+ req->delay *= 2;
+ else
+ req->delay = MAX_DELAY_INTERVAL;
+}
+
+static void retry_request(struct work_struct *work)
+{
+ struct ceph_mon_request_type *req =
+ container_of(work, struct ceph_mon_request_type,
+ delayed_work.work);
+
+ /*
+ * if lock is contended, reschedule sooner. we can't wait for
+ * mutex because we cancel the timeout sync with lock held.
+ */
+ if (mutex_trylock(&req->monc->req_mutex)) {
+ req->do_request(req->monc, 1);
+ reschedule_timeout(req);
+ mutex_unlock(&req->monc->req_mutex);
+ } else
+ schedule_delayed_work(&req->delayed_work, BASE_DELAY_INTERVAL);
+}
+
+static void cancel_timeout(struct ceph_mon_request_type *req)
+{
+ cancel_delayed_work_sync(&req->delayed_work);
+ req->delay = BASE_DELAY_INTERVAL;
+}
+
+static void init_request_type(struct ceph_mon_client *monc,
+ struct ceph_mon_request_type *req,
+ ceph_monc_request_func_t func)
+{
+ req->monc = monc;
+ INIT_DELAYED_WORK(&req->delayed_work, retry_request);
+ req->delay = 0;
+ req->do_request = func;
+}
+
+
+/*
+ * mds map
+ */
+static void request_mdsmap(struct ceph_mon_client *monc, int newmon)
+{
+ struct ceph_msg *msg;
+ struct ceph_mds_getmap *h;
+ int mon = pick_mon(monc, newmon);
+
+ dout(5, "request_mdsmap from mon%d want %u\n", mon, monc->want_mdsmap);
+ msg = ceph_msg_new(CEPH_MSG_MDS_GETMAP, sizeof(*h), 0, 0, NULL);
+ if (IS_ERR(msg))
+ return;
+ h = msg->front.iov_base;
+ h->fsid = monc->monmap->fsid;
+ h->want = cpu_to_le32(monc->want_mdsmap);
+ msg->hdr.dst = monc->monmap->mon_inst[mon];
+ ceph_msg_send(monc->client->msgr, msg, 0);
+}
+
+/*
+ * Register our desire for an mdsmap >= epoch @want.
+ */
+void ceph_monc_request_mdsmap(struct ceph_mon_client *monc, u32 want)
+{
+ dout(5, "request_mdsmap want %u\n", want);
+ mutex_lock(&monc->req_mutex);
+ if (want > monc->want_mdsmap) {
+ monc->want_mdsmap = want;
+ monc->mdsreq.delay = BASE_DELAY_INTERVAL;
+ request_mdsmap(monc, 0);
+ reschedule_timeout(&monc->mdsreq);
+ }
+ mutex_unlock(&monc->req_mutex);
+}
+
+/*
+ * Possibly cancel our desire for a new map
+ */
+int ceph_monc_got_mdsmap(struct ceph_mon_client *monc, u32 got)
+{
+ int ret = 0;
+
+ mutex_lock(&monc->req_mutex);
+ if (got < monc->want_mdsmap) {
+ dout(5, "got_mdsmap %u < wanted %u\n", got, monc->want_mdsmap);
+ ret = -EAGAIN;
+ } else {
+ dout(5, "got_mdsmap %u >= wanted %u\n", got, monc->want_mdsmap);
+ monc->want_mdsmap = 0;
+ cancel_timeout(&monc->mdsreq);
+ }
+ mutex_unlock(&monc->req_mutex);
+ return ret;
+}
+
+
+/*
+ * osd map
+ */
+static void request_osdmap(struct ceph_mon_client *monc, int newmon)
+{
+ struct ceph_msg *msg;
+ struct ceph_osd_getmap *h;
+ int mon = pick_mon(monc, newmon);
+
+ dout(5, "request_osdmap from mon%d want %u\n", mon, monc->want_osdmap);
+ msg = ceph_msg_new(CEPH_MSG_OSD_GETMAP, sizeof(*h), 0, 0, NULL);
+ if (IS_ERR(msg))
+ return;
+ h = msg->front.iov_base;
+ h->fsid = monc->monmap->fsid;
+ h->start = cpu_to_le32(monc->want_osdmap);
+ msg->hdr.dst = monc->monmap->mon_inst[mon];
+ ceph_msg_send(monc->client->msgr, msg, 0);
+}
+
+void ceph_monc_request_osdmap(struct ceph_mon_client *monc, u32 want)
+{
+ dout(5, "request_osdmap want %u\n", want);
+ mutex_lock(&monc->req_mutex);
+ monc->osdreq.delay = BASE_DELAY_INTERVAL;
+ monc->want_osdmap = want;
+ request_osdmap(monc, 0);
+ reschedule_timeout(&monc->osdreq);
+ mutex_unlock(&monc->req_mutex);
+}
+
+int ceph_monc_got_osdmap(struct ceph_mon_client *monc, u32 got)
+{
+ int ret = 0;
+
+ mutex_lock(&monc->req_mutex);
+ if (got < monc->want_osdmap) {
+ dout(5, "got_osdmap %u < wanted %u\n", got, monc->want_osdmap);
+ ret = -EAGAIN;
+ } else {
+ dout(5, "got_osdmap %u >= wanted %u\n", got, monc->want_osdmap);
+ monc->want_osdmap = 0;
+ cancel_timeout(&monc->osdreq);
+ }
+ mutex_unlock(&monc->req_mutex);
+ return ret;
+}
+
+
+/*
+ * umount
+ */
+static void request_umount(struct ceph_mon_client *monc, int newmon)
+{
+ struct ceph_msg *msg;
+ int mon = pick_mon(monc, newmon);
+
+ dout(5, "request_umount from mon%d\n", mon);
+ msg = ceph_msg_new(CEPH_MSG_CLIENT_UNMOUNT, 0, 0, 0, NULL);
+ if (IS_ERR(msg))
+ return;
+ msg->hdr.dst = monc->monmap->mon_inst[mon];
+ ceph_msg_send(monc->client->msgr, msg, 0);
+}
+
+void ceph_monc_request_umount(struct ceph_mon_client *monc)
+{
+ struct ceph_client *client = monc->client;
+
+ /* don't bother if forced unmount */
+ if (client->mount_state == CEPH_MOUNT_SHUTDOWN)
+ return;
+
+ mutex_lock(&monc->req_mutex);
+ monc->umountreq.delay = BASE_DELAY_INTERVAL;
+ request_umount(monc, 0);
+ reschedule_timeout(&monc->umountreq);
+ mutex_unlock(&monc->req_mutex);
+}
+
+void ceph_monc_handle_umount(struct ceph_mon_client *monc,
+ struct ceph_msg *msg)
+{
+ dout(5, "handle_umount\n");
+ mutex_lock(&monc->req_mutex);
+ cancel_timeout(&monc->umountreq);
+ monc->client->mount_state = CEPH_MOUNT_UNMOUNTED;
+ mutex_unlock(&monc->req_mutex);
+ wake_up(&monc->client->mount_wq);
+}
+
+
+/*
+ * statfs
+ */
+void ceph_monc_handle_statfs_reply(struct ceph_mon_client *monc,
+ struct ceph_msg *msg)
+{
+ struct ceph_mon_statfs_request *req;
+ struct ceph_mon_statfs_reply *reply = msg->front.iov_base;
+ u64 tid;
+
+ if (msg->front.iov_len != sizeof(*reply))
+ goto bad;
+ tid = le64_to_cpu(reply->tid);
+ dout(10, "handle_statfs_reply %p tid %llu\n", msg, tid);
+
+ mutex_lock(&monc->statfs_mutex);
+ req = radix_tree_lookup(&monc->statfs_request_tree, tid);
+ if (req) {
+ req->buf->f_total = reply->st.f_total;
+ req->buf->f_free = reply->st.f_free;
+ req->buf->f_avail = reply->st.f_avail;
+ req->buf->f_objects = reply->st.f_objects;
+ req->result = 0;
+ }
+ mutex_unlock(&monc->statfs_mutex);
+ if (req)
+ complete(&req->completion);
+ return;
+
+bad:
+ derr(10, "corrupt statfs reply, no tid\n");
+}
+
+/*
+ * (re)send a statfs request
+ */
+static int send_statfs(struct ceph_mon_client *monc, u64 tid, int newmon)
+{
+ struct ceph_msg *msg;
+ struct ceph_mon_statfs *h;
+ int mon = pick_mon(monc, newmon ? 1:-1);
+
+ dout(10, "send_statfs to mon%d tid %llu\n", mon, tid);
+ msg = ceph_msg_new(CEPH_MSG_STATFS, sizeof(*h), 0, 0, NULL);
+ if (IS_ERR(msg))
+ return PTR_ERR(msg);
+ h = msg->front.iov_base;
+ h->fsid = monc->monmap->fsid;
+ h->tid = cpu_to_le64(tid);
+ msg->hdr.dst = monc->monmap->mon_inst[mon];
+ ceph_msg_send(monc->client->msgr, msg, 0);
+ return 0;
+}
+
+/*
+ * Do a synchronous statfs().
+ */
+int ceph_monc_do_statfs(struct ceph_mon_client *monc, struct ceph_statfs *buf)
+{
+ struct ceph_mon_statfs_request req;
+ int err;
+
+ req.buf = buf;
+ init_completion(&req.completion);
+
+ /* register request */
+ mutex_lock(&monc->statfs_mutex);
+ req.tid = ++monc->last_tid;
+ req.last_attempt = jiffies;
+ req.delay = BASE_DELAY_INTERVAL;
+ if (radix_tree_insert(&monc->statfs_request_tree, req.tid, &req) < 0) {
+ mutex_unlock(&monc->statfs_mutex);
+ derr(10, "ENOMEM in do_statfs\n");
+ return -ENOMEM;
+ }
+ if (monc->num_statfs_requests == 0)
+ schedule_delayed_work(&monc->statfs_delayed_work,
+ round_jiffies_relative(1*HZ));
+ monc->num_statfs_requests++;
+ mutex_unlock(&monc->statfs_mutex);
+
+ /* send request and wait */
+ err = send_statfs(monc, req.tid, 0);
+ if (!err)
+ err = wait_for_completion_interruptible(&req.completion);
+
+ mutex_lock(&monc->statfs_mutex);
+ radix_tree_delete(&monc->statfs_request_tree, req.tid);
+ monc->num_statfs_requests--;
+ if (monc->num_statfs_requests == 0)
+ cancel_delayed_work(&monc->statfs_delayed_work);
+ mutex_unlock(&monc->statfs_mutex);
+
+ if (!err)
+ err = req.result;
+ return err;
+}
+
+/*
+ * Resend any statfs requests that have timed out.
+ */
+static void do_statfs_check(struct work_struct *work)
+{
+ struct ceph_mon_client *monc =
+ container_of(work, struct ceph_mon_client,
+ statfs_delayed_work.work);
+ u64 next_tid = 0;
+ int got;
+ int did = 0;
+ int newmon = 1;
+ struct ceph_mon_statfs_request *req;
+
+ dout(10, "do_statfs_check\n");
+ mutex_lock(&monc->statfs_mutex);
+ while (1) {
+ got = radix_tree_gang_lookup(&monc->statfs_request_tree,
+ (void **)&req,
+ next_tid, 1);
+ if (got == 0)
+ break;
+ did++;
+ next_tid = req->tid + 1;
+ if (time_after(jiffies, req->last_attempt + req->delay)) {
+ req->last_attempt = jiffies;
+ if (req->delay < MAX_DELAY_INTERVAL)
+ req->delay *= 2;
+ send_statfs(monc, req->tid, newmon);
+ newmon = 0;
+ }
+ }
+ mutex_unlock(&monc->statfs_mutex);
+
+ if (did)
+ schedule_delayed_work(&monc->statfs_delayed_work,
+ round_jiffies_relative(1*HZ));
+}
+
+
+int ceph_monc_init(struct ceph_mon_client *monc, struct ceph_client *cl)
+{
+ dout(5, "init\n");
+ memset(monc, 0, sizeof(*monc));
+ monc->client = cl;
+ monc->monmap = kzalloc(sizeof(struct ceph_monmap) +
+ sizeof(struct ceph_entity_addr) * MAX_MON_MOUNT_ADDR,
+ GFP_KERNEL);
+ if (monc->monmap == NULL)
+ return -ENOMEM;
+ mutex_init(&monc->statfs_mutex);
+ INIT_RADIX_TREE(&monc->statfs_request_tree, GFP_NOFS);
+ monc->num_statfs_requests = 0;
+ monc->last_tid = 0;
+ INIT_DELAYED_WORK(&monc->statfs_delayed_work, do_statfs_check);
+ init_request_type(monc, &monc->mdsreq, request_mdsmap);
+ init_request_type(monc, &monc->osdreq, request_osdmap);
+ init_request_type(monc, &monc->umountreq, request_umount);
+ mutex_init(&monc->req_mutex);
+ monc->want_mdsmap = 0;
+ monc->want_osdmap = 0;
+ return 0;
+}
+
+void ceph_monc_stop(struct ceph_mon_client *monc)
+{
+ dout(5, "stop\n");
+ cancel_timeout(&monc->mdsreq);
+ cancel_timeout(&monc->osdreq);
+ cancel_timeout(&monc->umountreq);
+ cancel_delayed_work_sync(&monc->statfs_delayed_work);
+ kfree(monc->monmap);
+}
diff --git a/fs/ceph/mon_client.h b/fs/ceph/mon_client.h
new file mode 100644
index 0000000..5b05b24
--- /dev/null
+++ b/fs/ceph/mon_client.h
@@ -0,0 +1,109 @@
+#ifndef _FS_CEPH_MON_CLIENT_H
+#define _FS_CEPH_MON_CLIENT_H
+
+#include "messenger.h"
+#include <linux/completion.h>
+#include <linux/radix-tree.h>
+
+/*
+ * A small cluster of Ceph "monitors" are responsible for managing critical
+ * cluster configuration and state information. An odd number (e.g., 3, 5)
+ * of cmon daemons use a modified version of the Paxos part-time parliament
+ * algorithm to manage the MDS map (mds cluster membership), OSD map, and
+ * list of clients who have mounted the file system.
+ *
+ * Communication with the monitor cluster is lossy, so requests for
+ * information may have to be resent if we time out waiting for a response.
+ * As long as we do not time out, we continue to send all requests to the
+ * same monitor. If there is a problem, we randomly pick a new monitor from
+ * the cluster to try.
+ */
+
+struct ceph_client;
+struct ceph_mount_args;
+
+/*
+ * The monitor map enumerates the set of all monitors.
+ *
+ * Make sure this structure size matches the encoded map size, or change
+ * ceph_monmap_decode().
+ */
+struct ceph_monmap {
+ ceph_fsid_t fsid;
+ u32 epoch;
+ u32 num_mon;
+ struct ceph_entity_inst mon_inst[0];
+};
+
+struct ceph_mon_client;
+
+/*
+ * Generic mechanism for resending monitor requests.
+ */
+typedef void (*ceph_monc_request_func_t)(struct ceph_mon_client *monc,
+ int newmon);
+struct ceph_mon_request_type {
+ struct ceph_mon_client *monc;
+ struct delayed_work delayed_work;
+ unsigned long delay;
+ ceph_monc_request_func_t do_request;
+};
+
+/* statfs() is done a bit differently */
+struct ceph_mon_statfs_request {
+ u64 tid;
+ int result;
+ struct ceph_statfs *buf;
+ struct completion completion;
+ unsigned long last_attempt, delay; /* jiffies */
+};
+
+struct ceph_mon_client {
+ struct ceph_client *client;
+ int last_mon; /* last monitor i contacted */
+ struct ceph_monmap *monmap;
+
+ /* pending statfs requests */
+ struct mutex statfs_mutex;
+ struct radix_tree_root statfs_request_tree;
+ int num_statfs_requests;
+ u64 last_tid;
+ struct delayed_work statfs_delayed_work;
+
+ /* mds/osd map or umount requests */
+ struct mutex req_mutex;
+ struct ceph_mon_request_type mdsreq, osdreq, umountreq;
+ u32 want_mdsmap;
+ u32 want_osdmap;
+};
+
+extern struct ceph_monmap *ceph_monmap_decode(void *p, void *end);
+extern int ceph_monmap_contains(struct ceph_monmap *m,
+ struct ceph_entity_addr *addr);
+
+extern int ceph_monc_init(struct ceph_mon_client *monc, struct ceph_client *cl);
+extern void ceph_monc_stop(struct ceph_mon_client *monc);
+
+/*
+ * The model here is to indicate that we need a new map of at least epoch
+ * @want, and to indicate which maps receive. Periodically rerequest the map
+ * from the monitor cluster until we get what we want.
+ */
+extern void ceph_monc_request_mdsmap(struct ceph_mon_client *monc, u32 want);
+extern int ceph_monc_got_mdsmap(struct ceph_mon_client *monc, u32 have);
+
+extern void ceph_monc_request_osdmap(struct ceph_mon_client *monc, u32 want);
+extern int ceph_monc_got_osdmap(struct ceph_mon_client *monc, u32 have);
+
+extern void ceph_monc_request_umount(struct ceph_mon_client *monc);
+
+extern int ceph_monc_do_statfs(struct ceph_mon_client *monc,
+ struct ceph_statfs *buf);
+extern void ceph_monc_handle_statfs_reply(struct ceph_mon_client *monc,
+ struct ceph_msg *msg);
+
+extern void ceph_monc_request_umount(struct ceph_mon_client *monc);
+extern void ceph_monc_handle_umount(struct ceph_mon_client *monc,
+ struct ceph_msg *msg);
+
+#endif
--
1.5.6.5


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