ceph: OSD client

The OSD client is responsible for reading and writing data from/to the
object storage pool.  This includes determining where objects are
stored in the cluster, and ensuring that requests are retried or
redirected in the event of a node failure or data migration.

If an OSD does not respond before a timeout expires, keepalive
messages are sent across the lossless, ordered communications channel
to ensure that any break in the TCP is discovered.  If the session
does reset, a reconnection is attempted and affected requests are
resent (by the message transport layer).

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 1294 insertions, 0 deletions

diff --git a/fs/ceph/osd_client.c b/fs/ceph/osd_client.c
new file mode 100644
index 00000000000..978593a4f46
--- /dev/null
+++ b/fs/ceph/osd_client.c
@@ -0,0 +1,1294 @@
+#include "ceph_debug.h"
+
+#include <linux/err.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#include "super.h"
+#include "osd_client.h"
+#include "messenger.h"
+#include "decode.h"
+
+const static struct ceph_connection_operations osd_con_ops;
+
+static void kick_requests(struct ceph_osd_client *osdc, struct ceph_osd *osd);
+
+/*
+ * Implement client access to distributed object storage cluster.
+ *
+ * All data objects are stored within a cluster/cloud of OSDs, or
+ * "object storage devices."  (Note that Ceph OSDs have _nothing_ to
+ * do with the T10 OSD extensions to SCSI.)  Ceph OSDs are simply
+ * remote daemons serving up and coordinating consistent and safe
+ * access to storage.
+ *
+ * Cluster membership and the mapping of data objects onto storage devices
+ * are described by the osd map.
+ *
+ * We keep track of pending OSD requests (read, write), resubmit
+ * requests to different OSDs when the cluster topology/data layout
+ * change, or retry the affected requests when the communications
+ * channel with an OSD is reset.
+ */
+
+/*
+ * calculate the mapping of a file extent onto an object, and fill out the
+ * request accordingly.  shorten extent as necessary if it crosses an
+ * object boundary.
+ *
+ * fill osd op in request message.
+ */
+static void calc_layout(struct ceph_osd_client *osdc,
+                        struct ceph_vino vino, struct ceph_file_layout *layout,
+                        u64 off, u64 *plen,
+                        struct ceph_osd_request *req)
+{
+        struct ceph_osd_request_head *reqhead = req->r_request->front.iov_base;
+        struct ceph_osd_op *op = (void *)(reqhead + 1);
+        u64 orig_len = *plen;
+        u64 objoff, objlen;    /* extent in object */
+        u64 bno;
+
+        reqhead->snapid = cpu_to_le64(vino.snap);
+
+        /* object extent? */
+        ceph_calc_file_object_mapping(layout, off, plen, &bno,
+                                      &objoff, &objlen);
+        if (*plen < orig_len)
+                dout(" skipping last %llu, final file extent %llu~%llu\n",
+                     orig_len - *plen, off, *plen);
+
+        sprintf(req->r_oid, "%llx.%08llx", vino.ino, bno);
+        req->r_oid_len = strlen(req->r_oid);
+
+        op->extent.offset = cpu_to_le64(objoff);
+        op->extent.length = cpu_to_le64(objlen);
+        req->r_num_pages = calc_pages_for(off, *plen);
+
+        dout("calc_layout %s (%d) %llu~%llu (%d pages)\n",
+             req->r_oid, req->r_oid_len, objoff, objlen, req->r_num_pages);
+}
+
+
+/*
+ * requests
+ */
+void ceph_osdc_put_request(struct ceph_osd_request *req)
+{
+        dout("osdc put_request %p %d -> %d\n", req, atomic_read(&req->r_ref),
+             atomic_read(&req->r_ref)-1);
+        BUG_ON(atomic_read(&req->r_ref) <= 0);
+        if (atomic_dec_and_test(&req->r_ref)) {
+                if (req->r_request)
+                        ceph_msg_put(req->r_request);
+                if (req->r_reply)
+                        ceph_msg_put(req->r_reply);
+                if (req->r_own_pages)
+                        ceph_release_page_vector(req->r_pages,
+                                                 req->r_num_pages);
+                ceph_put_snap_context(req->r_snapc);
+                if (req->r_mempool)
+                        mempool_free(req, req->r_osdc->req_mempool);
+                else
+                        kfree(req);
+        }
+}
+
+/*
+ * build new request AND message, calculate layout, and adjust file
+ * extent as needed.
+ *
+ * if the file was recently truncated, we include information about its
+ * old and new size so that the object can be updated appropriately.  (we
+ * avoid synchronously deleting truncated objects because it's slow.)
+ *
+ * if @do_sync, include a 'startsync' command so that the osd will flush
+ * data quickly.
+ */
+struct ceph_osd_request *ceph_osdc_new_request(struct ceph_osd_client *osdc,
+                                               struct ceph_file_layout *layout,
+                                               struct ceph_vino vino,
+                                               u64 off, u64 *plen,
+                                               int opcode, int flags,
+                                               struct ceph_snap_context *snapc,
+                                               int do_sync,
+                                               u32 truncate_seq,
+                                               u64 truncate_size,
+                                               struct timespec *mtime,
+                                               bool use_mempool, int num_reply)
+{
+        struct ceph_osd_request *req;
+        struct ceph_msg *msg;
+        struct ceph_osd_request_head *head;
+        struct ceph_osd_op *op;
+        void *p;
+        int do_trunc = truncate_seq && (off + *plen > truncate_size);
+        int num_op = 1 + do_sync + do_trunc;
+        size_t msg_size = sizeof(*head) + num_op*sizeof(*op);
+        int err, i;
+        u64 prevofs;
+
+        if (use_mempool) {
+                req = mempool_alloc(osdc->req_mempool, GFP_NOFS);
+                memset(req, 0, sizeof(*req));
+        } else {
+                req = kzalloc(sizeof(*req), GFP_NOFS);
+        }
+        if (req == NULL)
+                return ERR_PTR(-ENOMEM);
+
+        err = ceph_msgpool_resv(&osdc->msgpool_op_reply, num_reply);
+        if (err) {
+                ceph_osdc_put_request(req);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        req->r_osdc = osdc;
+        req->r_mempool = use_mempool;
+        atomic_set(&req->r_ref, 1);
+        init_completion(&req->r_completion);
+        init_completion(&req->r_safe_completion);
+        INIT_LIST_HEAD(&req->r_unsafe_item);
+        req->r_flags = flags;
+
+        WARN_ON((flags & (CEPH_OSD_FLAG_READ|CEPH_OSD_FLAG_WRITE)) == 0);
+
+        /* create message; allow space for oid */
+        msg_size += 40;
+        if (snapc)
+                msg_size += sizeof(u64) * snapc->num_snaps;
+        if (use_mempool)
+                msg = ceph_msgpool_get(&osdc->msgpool_op);
+        else
+                msg = ceph_msg_new(CEPH_MSG_OSD_OP, msg_size, 0, 0, NULL);
+        if (IS_ERR(msg)) {
+                ceph_msgpool_resv(&osdc->msgpool_op_reply, num_reply);
+                ceph_osdc_put_request(req);
+                return ERR_PTR(PTR_ERR(msg));
+        }
+        msg->hdr.type = cpu_to_le16(CEPH_MSG_OSD_OP);
+        memset(msg->front.iov_base, 0, msg->front.iov_len);
+        head = msg->front.iov_base;
+        op = (void *)(head + 1);
+        p = (void *)(op + num_op);
+
+        req->r_request = msg;
+        req->r_snapc = ceph_get_snap_context(snapc);
+
+        head->client_inc = cpu_to_le32(1); /* always, for now. */
+        head->flags = cpu_to_le32(flags);
+        if (flags & CEPH_OSD_FLAG_WRITE)
+                ceph_encode_timespec(&head->mtime, mtime);
+        head->num_ops = cpu_to_le16(num_op);
+        op->op = cpu_to_le16(opcode);
+
+        /* calculate max write size */
+        calc_layout(osdc, vino, layout, off, plen, req);
+        req->r_file_layout = *layout;  /* keep a copy */
+
+        if (flags & CEPH_OSD_FLAG_WRITE) {
+                req->r_request->hdr.data_off = cpu_to_le16(off);
+                req->r_request->hdr.data_len = cpu_to_le32(*plen);
+                op->payload_len = cpu_to_le32(*plen);
+        }
+
+        /* fill in oid */
+        head->object_len = cpu_to_le32(req->r_oid_len);
+        memcpy(p, req->r_oid, req->r_oid_len);
+        p += req->r_oid_len;
+
+        /* additional ops */
+        if (do_trunc) {
+                op++;
+                op->op = cpu_to_le16(opcode == CEPH_OSD_OP_READ ?
+                             CEPH_OSD_OP_MASKTRUNC : CEPH_OSD_OP_SETTRUNC);
+                op->trunc.truncate_seq = cpu_to_le32(truncate_seq);
+                prevofs = le64_to_cpu((op-1)->extent.offset);
+                op->trunc.truncate_size = cpu_to_le64(truncate_size -
+                                                      (off-prevofs));
+        }
+        if (do_sync) {
+                op++;
+                op->op = cpu_to_le16(CEPH_OSD_OP_STARTSYNC);
+        }
+        if (snapc) {
+                head->snap_seq = cpu_to_le64(snapc->seq);
+                head->num_snaps = cpu_to_le32(snapc->num_snaps);
+                for (i = 0; i < snapc->num_snaps; i++) {
+                        put_unaligned_le64(snapc->snaps[i], p);
+                        p += sizeof(u64);
+                }
+        }
+
+        BUG_ON(p > msg->front.iov_base + msg->front.iov_len);
+        return req;
+}
+
+/*
+ * We keep osd requests in an rbtree, sorted by ->r_tid.
+ */
+static void __insert_request(struct ceph_osd_client *osdc,
+                             struct ceph_osd_request *new)
+{
+        struct rb_node **p = &osdc->requests.rb_node;
+        struct rb_node *parent = NULL;
+        struct ceph_osd_request *req = NULL;
+
+        while (*p) {
+                parent = *p;
+                req = rb_entry(parent, struct ceph_osd_request, r_node);
+                if (new->r_tid < req->r_tid)
+                        p = &(*p)->rb_left;
+                else if (new->r_tid > req->r_tid)
+                        p = &(*p)->rb_right;
+                else
+                        BUG();
+        }
+
+        rb_link_node(&new->r_node, parent, p);
+        rb_insert_color(&new->r_node, &osdc->requests);
+}
+
+static struct ceph_osd_request *__lookup_request(struct ceph_osd_client *osdc,
+                                                 u64 tid)
+{
+        struct ceph_osd_request *req;
+        struct rb_node *n = osdc->requests.rb_node;
+
+        while (n) {
+                req = rb_entry(n, struct ceph_osd_request, r_node);
+                if (tid < req->r_tid)
+                        n = n->rb_left;
+                else if (tid > req->r_tid)
+                        n = n->rb_right;
+                else
+                        return req;
+        }
+        return NULL;
+}
+
+static struct ceph_osd_request *
+__lookup_request_ge(struct ceph_osd_client *osdc,
+                    u64 tid)
+{
+        struct ceph_osd_request *req;
+        struct rb_node *n = osdc->requests.rb_node;
+
+        while (n) {
+                req = rb_entry(n, struct ceph_osd_request, r_node);
+                if (tid < req->r_tid) {
+                        if (!n->rb_left)
+                                return req;
+                        n = n->rb_left;
+                } else if (tid > req->r_tid) {
+                        n = n->rb_right;
+                } else {
+                        return req;
+                }
+        }
+        return NULL;
+}
+
+
+/*
+ * The messaging layer will reconnect to the osd as needed.  If the
+ * session has dropped, the OSD will have dropped the session state,
+ * and we'll get notified by the messaging layer.  If that happens, we
+ * need to resubmit all requests for that osd.
+ */
+static void osd_reset(struct ceph_connection *con)
+{
+        struct ceph_osd *osd = con->private;
+        struct ceph_osd_client *osdc;
+
+        if (!osd)
+                return;
+        dout("osd_reset osd%d\n", osd->o_osd);
+        osdc = osd->o_osdc;
+        osd->o_incarnation++;
+        down_read(&osdc->map_sem);
+        kick_requests(osdc, osd);
+        up_read(&osdc->map_sem);
+}
+
+/*
+ * Track open sessions with osds.
+ */
+static struct ceph_osd *create_osd(struct ceph_osd_client *osdc)
+{
+        struct ceph_osd *osd;
+
+        osd = kzalloc(sizeof(*osd), GFP_NOFS);
+        if (!osd)
+                return NULL;
+
+        atomic_set(&osd->o_ref, 1);
+        osd->o_osdc = osdc;
+        INIT_LIST_HEAD(&osd->o_requests);
+        osd->o_incarnation = 1;
+
+        ceph_con_init(osdc->client->msgr, &osd->o_con);
+        osd->o_con.private = osd;
+        osd->o_con.ops = &osd_con_ops;
+        osd->o_con.peer_name.type = CEPH_ENTITY_TYPE_OSD;
+        return osd;
+}
+
+static struct ceph_osd *get_osd(struct ceph_osd *osd)
+{
+        if (atomic_inc_not_zero(&osd->o_ref)) {
+                dout("get_osd %p %d -> %d\n", osd, atomic_read(&osd->o_ref)-1,
+                     atomic_read(&osd->o_ref));
+                return osd;
+        } else {
+                dout("get_osd %p FAIL\n", osd);
+                return NULL;
+        }
+}
+
+static void put_osd(struct ceph_osd *osd)
+{
+        dout("put_osd %p %d -> %d\n", osd, atomic_read(&osd->o_ref),
+             atomic_read(&osd->o_ref) - 1);
+        if (atomic_dec_and_test(&osd->o_ref)) {
+                ceph_con_shutdown(&osd->o_con);
+                kfree(osd);
+        }
+}
+
+/*
+ * remove an osd from our map
+ */
+static void remove_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd)
+{
+        dout("remove_osd %p\n", osd);
+        BUG_ON(!list_empty(&osd->o_requests));
+        rb_erase(&osd->o_node, &osdc->osds);
+        ceph_con_close(&osd->o_con);
+        put_osd(osd);
+}
+
+/*
+ * reset osd connect
+ */
+static int reset_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd)
+{
+        int ret = 0;
+
+        dout("reset_osd %p osd%d\n", osd, osd->o_osd);
+        if (list_empty(&osd->o_requests)) {
+                remove_osd(osdc, osd);
+        } else {
+                ceph_con_close(&osd->o_con);
+                ceph_con_open(&osd->o_con, &osdc->osdmap->osd_addr[osd->o_osd]);
+                osd->o_incarnation++;
+        }
+        return ret;
+}
+
+static void __insert_osd(struct ceph_osd_client *osdc, struct ceph_osd *new)
+{
+        struct rb_node **p = &osdc->osds.rb_node;
+        struct rb_node *parent = NULL;
+        struct ceph_osd *osd = NULL;
+
+        while (*p) {
+                parent = *p;
+                osd = rb_entry(parent, struct ceph_osd, o_node);
+                if (new->o_osd < osd->o_osd)
+                        p = &(*p)->rb_left;
+                else if (new->o_osd > osd->o_osd)
+                        p = &(*p)->rb_right;
+                else
+                        BUG();
+        }
+
+        rb_link_node(&new->o_node, parent, p);
+        rb_insert_color(&new->o_node, &osdc->osds);
+}
+
+static struct ceph_osd *__lookup_osd(struct ceph_osd_client *osdc, int o)
+{
+        struct ceph_osd *osd;
+        struct rb_node *n = osdc->osds.rb_node;
+
+        while (n) {
+                osd = rb_entry(n, struct ceph_osd, o_node);
+                if (o < osd->o_osd)
+                        n = n->rb_left;
+                else if (o > osd->o_osd)
+                        n = n->rb_right;
+                else
+                        return osd;
+        }
+        return NULL;
+}
+
+
+/*
+ * Register request, assign tid.  If this is the first request, set up
+ * the timeout event.
+ */
+static void register_request(struct ceph_osd_client *osdc,
+                             struct ceph_osd_request *req)
+{
+        struct ceph_osd_request_head *head = req->r_request->front.iov_base;
+
+        mutex_lock(&osdc->request_mutex);
+        req->r_tid = ++osdc->last_tid;
+        head->tid = cpu_to_le64(req->r_tid);
+
+        dout("register_request %p tid %lld\n", req, req->r_tid);
+        __insert_request(osdc, req);
+        ceph_osdc_get_request(req);
+        osdc->num_requests++;
+
+        req->r_timeout_stamp =
+                jiffies + osdc->client->mount_args.osd_timeout*HZ;
+
+        if (osdc->num_requests == 1) {
+                osdc->timeout_tid = req->r_tid;
+                dout("  timeout on tid %llu at %lu\n", req->r_tid,
+                     req->r_timeout_stamp);
+                schedule_delayed_work(&osdc->timeout_work,
+                      round_jiffies_relative(req->r_timeout_stamp - jiffies));
+        }
+        mutex_unlock(&osdc->request_mutex);
+}
+
+/*
+ * called under osdc->request_mutex
+ */
+static void __unregister_request(struct ceph_osd_client *osdc,
+                                 struct ceph_osd_request *req)
+{
+        dout("__unregister_request %p tid %lld\n", req, req->r_tid);
+        rb_erase(&req->r_node, &osdc->requests);
+        osdc->num_requests--;
+
+        list_del_init(&req->r_osd_item);
+        if (list_empty(&req->r_osd->o_requests))
+                remove_osd(osdc, req->r_osd);
+        req->r_osd = NULL;
+
+        ceph_osdc_put_request(req);
+
+        if (req->r_tid == osdc->timeout_tid) {
+                if (osdc->num_requests == 0) {
+                        dout("no requests, canceling timeout\n");
+                        osdc->timeout_tid = 0;
+                        cancel_delayed_work(&osdc->timeout_work);
+                } else {
+                        req = rb_entry(rb_first(&osdc->requests),
+                                       struct ceph_osd_request, r_node);
+                        osdc->timeout_tid = req->r_tid;
+                        dout("rescheduled timeout on tid %llu at %lu\n",
+                             req->r_tid, req->r_timeout_stamp);
+                        schedule_delayed_work(&osdc->timeout_work,
+                              round_jiffies_relative(req->r_timeout_stamp -
+                                                     jiffies));
+                }
+        }
+}
+
+/*
+ * Cancel a previously queued request message
+ */
+static void __cancel_request(struct ceph_osd_request *req)
+{
+        if (req->r_sent) {
+                ceph_con_revoke(&req->r_osd->o_con, req->r_request);
+                req->r_sent = 0;
+        }
+}
+
+/*
+ * Pick an osd (the first 'up' osd in the pg), allocate the osd struct
+ * (as needed), and set the request r_osd appropriately.  If there is
+ * no up osd, set r_osd to NULL.
+ *
+ * Return 0 if unchanged, 1 if changed, or negative on error.
+ *
+ * Caller should hold map_sem for read and request_mutex.
+ */
+static int __map_osds(struct ceph_osd_client *osdc,
+                      struct ceph_osd_request *req)
+{
+        struct ceph_osd_request_head *reqhead = req->r_request->front.iov_base;
+        union ceph_pg pgid;
+        int o = -1;
+        int err;
+        struct ceph_osd *newosd = NULL;
+
+        dout("map_osds %p tid %lld\n", req, req->r_tid);
+        err = ceph_calc_object_layout(&reqhead->layout, req->r_oid,
+                                      &req->r_file_layout, osdc->osdmap);
+        if (err)
+                return err;
+        pgid.pg64 = le64_to_cpu(reqhead->layout.ol_pgid);
+        o = ceph_calc_pg_primary(osdc->osdmap, pgid);
+
+        if ((req->r_osd && req->r_osd->o_osd == o &&
+             req->r_sent >= req->r_osd->o_incarnation) ||
+            (req->r_osd == NULL && o == -1))
+                return 0;  /* no change */
+
+        dout("map_osds tid %llu pgid %llx pool %d osd%d (was osd%d)\n",
+             req->r_tid, pgid.pg64, pgid.pg.pool, o,
+             req->r_osd ? req->r_osd->o_osd : -1);
+
+        if (req->r_osd) {
+                __cancel_request(req);
+                list_del_init(&req->r_osd_item);
+                if (list_empty(&req->r_osd->o_requests)) {
+                        /* try to re-use r_osd if possible */
+                        newosd = get_osd(req->r_osd);
+                        remove_osd(osdc, newosd);
+                }
+                req->r_osd = NULL;
+        }
+
+        req->r_osd = __lookup_osd(osdc, o);
+        if (!req->r_osd && o >= 0) {
+                if (newosd) {
+                        req->r_osd = newosd;
+                        newosd = NULL;
+                } else {
+                        err = -ENOMEM;
+                        req->r_osd = create_osd(osdc);
+                        if (!req->r_osd)
+                                goto out;
+                }
+
+                dout("map_osds osd %p is osd%d\n", req->r_osd, o);
+                req->r_osd->o_osd = o;
+                req->r_osd->o_con.peer_name.num = cpu_to_le64(o);
+                __insert_osd(osdc, req->r_osd);
+
+                ceph_con_open(&req->r_osd->o_con, &osdc->osdmap->osd_addr[o]);
+        }
+
+        if (req->r_osd)
+                list_add(&req->r_osd_item, &req->r_osd->o_requests);
+        err = 1;   /* osd changed */
+
+out:
+        if (newosd)
+                put_osd(newosd);
+        return err;
+}
+
+/*
+ * caller should hold map_sem (for read) and request_mutex
+ */
+static int __send_request(struct ceph_osd_client *osdc,
+                          struct ceph_osd_request *req)
+{
+        struct ceph_osd_request_head *reqhead;
+        int err;
+
+        err = __map_osds(osdc, req);
+        if (err < 0)
+                return err;
+        if (req->r_osd == NULL) {
+                dout("send_request %p no up osds in pg\n", req);
+                ceph_monc_request_next_osdmap(&osdc->client->monc);
+                return 0;
+        }
+
+        dout("send_request %p tid %llu to osd%d flags %d\n",
+             req, req->r_tid, req->r_osd->o_osd, req->r_flags);
+
+        reqhead = req->r_request->front.iov_base;
+        reqhead->osdmap_epoch = cpu_to_le32(osdc->osdmap->epoch);
+        reqhead->flags |= cpu_to_le32(req->r_flags);  /* e.g., RETRY */
+        reqhead->reassert_version = req->r_reassert_version;
+
+        req->r_timeout_stamp = jiffies+osdc->client->mount_args.osd_timeout*HZ;
+
+        ceph_msg_get(req->r_request); /* send consumes a ref */
+        ceph_con_send(&req->r_osd->o_con, req->r_request);
+        req->r_sent = req->r_osd->o_incarnation;
+        return 0;
+}
+
+/*
+ * Timeout callback, called every N seconds when 1 or more osd
+ * requests has been active for more than N seconds.  When this
+ * happens, we ping all OSDs with requests who have timed out to
+ * ensure any communications channel reset is detected.  Reset the
+ * request timeouts another N seconds in the future as we go.
+ * Reschedule the timeout event another N seconds in future (unless
+ * there are no open requests).
+ */
+static void handle_timeout(struct work_struct *work)
+{
+        struct ceph_osd_client *osdc =
+                container_of(work, struct ceph_osd_client, timeout_work.work);
+        struct ceph_osd_request *req;
+        struct ceph_osd *osd;
+        unsigned long timeout = osdc->client->mount_args.osd_timeout * HZ;
+        unsigned long next_timeout = timeout + jiffies;
+        struct rb_node *p;
+
+        dout("timeout\n");
+        down_read(&osdc->map_sem);
+
+        ceph_monc_request_next_osdmap(&osdc->client->monc);
+
+        mutex_lock(&osdc->request_mutex);
+        for (p = rb_first(&osdc->requests); p; p = rb_next(p)) {
+                req = rb_entry(p, struct ceph_osd_request, r_node);
+
+                if (req->r_resend) {
+                        int err;
+
+                        dout("osdc resending prev failed %lld\n", req->r_tid);
+                        err = __send_request(osdc, req);
+                        if (err)
+                                dout("osdc failed again on %lld\n", req->r_tid);
+                        else
+                                req->r_resend = false;
+                        continue;
+                }
+        }
+        for (p = rb_first(&osdc->osds); p; p = rb_next(p)) {
+                osd = rb_entry(p, struct ceph_osd, o_node);
+                if (list_empty(&osd->o_requests))
+                        continue;
+                req = list_first_entry(&osd->o_requests,
+                                       struct ceph_osd_request, r_osd_item);
+                if (time_before(jiffies, req->r_timeout_stamp))
+                        continue;
+
+                dout(" tid %llu (at least) timed out on osd%d\n",
+                     req->r_tid, osd->o_osd);
+                req->r_timeout_stamp = next_timeout;
+                ceph_con_keepalive(&osd->o_con);
+        }
+
+        if (osdc->timeout_tid)
+                schedule_delayed_work(&osdc->timeout_work,
+                                      round_jiffies_relative(timeout));
+
+        mutex_unlock(&osdc->request_mutex);
+
+        up_read(&osdc->map_sem);
+}
+
+/*
+ * handle osd op reply.  either call the callback if it is specified,
+ * or do the completion to wake up the waiting thread.
+ */
+static void handle_reply(struct ceph_osd_client *osdc, struct ceph_msg *msg)
+{
+        struct ceph_osd_reply_head *rhead = msg->front.iov_base;
+        struct ceph_osd_request *req;
+        u64 tid;
+        int numops, object_len, flags;
+
+        if (msg->front.iov_len < sizeof(*rhead))
+                goto bad;
+        tid = le64_to_cpu(rhead->tid);
+        numops = le32_to_cpu(rhead->num_ops);
+        object_len = le32_to_cpu(rhead->object_len);
+        if (msg->front.iov_len != sizeof(*rhead) + object_len +
+            numops * sizeof(struct ceph_osd_op))
+                goto bad;
+        dout("handle_reply %p tid %llu\n", msg, tid);
+
+        /* lookup */
+        mutex_lock(&osdc->request_mutex);
+        req = __lookup_request(osdc, tid);
+        if (req == NULL) {
+                dout("handle_reply tid %llu dne\n", tid);
+                mutex_unlock(&osdc->request_mutex);
+                return;
+        }
+        ceph_osdc_get_request(req);
+        flags = le32_to_cpu(rhead->flags);
+
+        if (req->r_reply) {
+                /*
+                 * once we see the message has been received, we don't
+                 * need a ref (which is only needed for revoking
+                 * pages)
+                 */
+                ceph_msg_put(req->r_reply);
+                req->r_reply = NULL;
+        }
+
+        if (!req->r_got_reply) {
+                unsigned bytes;
+
+                req->r_result = le32_to_cpu(rhead->result);
+                bytes = le32_to_cpu(msg->hdr.data_len);
+                dout("handle_reply result %d bytes %d\n", req->r_result,
+                     bytes);
+                if (req->r_result == 0)
+                        req->r_result = bytes;
+
+                /* in case this is a write and we need to replay, */
+                req->r_reassert_version = rhead->reassert_version;
+
+                req->r_got_reply = 1;
+        } else if ((flags & CEPH_OSD_FLAG_ONDISK) == 0) {
+                dout("handle_reply tid %llu dup ack\n", tid);
+                goto done;
+        }
+
+        dout("handle_reply tid %llu flags %d\n", tid, flags);
+
+        /* either this is a read, or we got the safe response */
+        if ((flags & CEPH_OSD_FLAG_ONDISK) ||
+            ((flags & CEPH_OSD_FLAG_WRITE) == 0))
+                __unregister_request(osdc, req);
+
+        mutex_unlock(&osdc->request_mutex);
+
+        if (req->r_callback)
+                req->r_callback(req, msg);
+        else
+                complete(&req->r_completion);
+
+        if (flags & CEPH_OSD_FLAG_ONDISK) {
+                if (req->r_safe_callback)
+                        req->r_safe_callback(req, msg);
+                complete(&req->r_safe_completion);  /* fsync waiter */
+        }
+
+done:
+        ceph_osdc_put_request(req);
+        return;
+
+bad:
+        pr_err("corrupt osd_op_reply got %d %d expected %d\n",
+               (int)msg->front.iov_len, le32_to_cpu(msg->hdr.front_len),
+               (int)sizeof(*rhead));
+}
+
+
+/*
+ * Resubmit osd requests whose osd or osd address has changed.  Request
+ * a new osd map if osds are down, or we are otherwise unable to determine
+ * how to direct a request.
+ *
+ * Close connections to down osds.
+ *
+ * If @who is specified, resubmit requests for that specific osd.
+ *
+ * Caller should hold map_sem for read and request_mutex.
+ */
+static void kick_requests(struct ceph_osd_client *osdc,
+                          struct ceph_osd *kickosd)
+{
+        struct ceph_osd_request *req;
+        struct rb_node *p, *n;
+        int needmap = 0;
+        int err;
+
+        dout("kick_requests osd%d\n", kickosd ? kickosd->o_osd : -1);
+        mutex_lock(&osdc->request_mutex);
+        if (!kickosd) {
+                for (p = rb_first(&osdc->osds); p; p = n) {
+                        struct ceph_osd *osd =
+                                rb_entry(p, struct ceph_osd, o_node);
+
+                        n = rb_next(p);
+                        if (!ceph_osd_is_up(osdc->osdmap, osd->o_osd) ||
+                            !ceph_entity_addr_equal(&osd->o_con.peer_addr,
+                                            ceph_osd_addr(osdc->osdmap,
+                                                          osd->o_osd)))
+                                reset_osd(osdc, osd);
+                }
+        }
+
+        for (p = rb_first(&osdc->requests); p; p = rb_next(p)) {
+                req = rb_entry(p, struct ceph_osd_request, r_node);
+
+                if (req->r_resend) {
+                        dout(" r_resend set on tid %llu\n", req->r_tid);
+                        goto kick;
+                }
+                if (req->r_osd && kickosd == req->r_osd)
+                        goto kick;
+
+                err = __map_osds(osdc, req);
+                if (err == 0)
+                        continue;  /* no change */
+                if (err < 0) {
+                        /*
+                         * FIXME: really, we should set the request
+                         * error and fail if this isn't a 'nofail'
+                         * request, but that's a fair bit more
+                         * complicated to do.  So retry!
+                         */
+                        dout(" setting r_resend on %llu\n", req->r_tid);
+                        req->r_resend = true;
+                        continue;
+                }
+                if (req->r_osd == NULL) {
+                        dout("tid %llu maps to no valid osd\n", req->r_tid);
+                        needmap++;  /* request a newer map */
+                        continue;
+                }
+
+kick:
+                dout("kicking tid %llu osd%d\n", req->r_tid, req->r_osd->o_osd);
+                req->r_flags |= CEPH_OSD_FLAG_RETRY;
+                err = __send_request(osdc, req);
+                if (err) {
+                        dout(" setting r_resend on %llu\n", req->r_tid);
+                        req->r_resend = true;
+                }
+        }
+        mutex_unlock(&osdc->request_mutex);
+
+        if (needmap) {
+                dout("%d requests for down osds, need new map\n", needmap);
+                ceph_monc_request_next_osdmap(&osdc->client->monc);
+        }
+}
+
+/*
+ * Process updated osd map.
+ *
+ * The message contains any number of incremental and full maps, normally
+ * indicating some sort of topology change in the cluster.  Kick requests
+ * off to different OSDs as needed.
+ */
+void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg)
+{
+        void *p, *end, *next;
+        u32 nr_maps, maplen;
+        u32 epoch;
+        struct ceph_osdmap *newmap = NULL, *oldmap;
+        int err;
+        struct ceph_fsid fsid;
+
+        dout("handle_map have %u\n", osdc->osdmap ? osdc->osdmap->epoch : 0);
+        p = msg->front.iov_base;
+        end = p + msg->front.iov_len;
+
+        /* verify fsid */
+        ceph_decode_need(&p, end, sizeof(fsid), bad);
+        ceph_decode_copy(&p, &fsid, sizeof(fsid));
+        if (ceph_fsid_compare(&fsid, &osdc->client->monc.monmap->fsid)) {
+                pr_err("got osdmap with wrong fsid, ignoring\n");
+                return;
+        }
+
+        down_write(&osdc->map_sem);
+
+        /* incremental maps */
+        ceph_decode_32_safe(&p, end, nr_maps, bad);
+        dout(" %d inc maps\n", nr_maps);
+        while (nr_maps > 0) {
+                ceph_decode_need(&p, end, 2*sizeof(u32), bad);
+                ceph_decode_32(&p, epoch);
+                ceph_decode_32(&p, maplen);
+                ceph_decode_need(&p, end, maplen, bad);
+                next = p + maplen;
+                if (osdc->osdmap && osdc->osdmap->epoch+1 == epoch) {
+                        dout("applying incremental map %u len %d\n",
+                             epoch, maplen);
+                        newmap = osdmap_apply_incremental(&p, next,
+                                                          osdc->osdmap,
+                                                          osdc->client->msgr);
+                        if (IS_ERR(newmap)) {
+                                err = PTR_ERR(newmap);
+                                goto bad;
+                        }
+                        if (newmap != osdc->osdmap) {
+                                ceph_osdmap_destroy(osdc->osdmap);
+                                osdc->osdmap = newmap;
+                        }
+                } else {
+                        dout("ignoring incremental map %u len %d\n",
+                             epoch, maplen);
+                }
+                p = next;
+                nr_maps--;
+        }
+        if (newmap)
+                goto done;
+
+        /* full maps */
+        ceph_decode_32_safe(&p, end, nr_maps, bad);
+        dout(" %d full maps\n", nr_maps);
+        while (nr_maps) {
+                ceph_decode_need(&p, end, 2*sizeof(u32), bad);
+                ceph_decode_32(&p, epoch);
+                ceph_decode_32(&p, maplen);
+                ceph_decode_need(&p, end, maplen, bad);
+                if (nr_maps > 1) {
+                        dout("skipping non-latest full map %u len %d\n",
+                             epoch, maplen);
+                } else if (osdc->osdmap && osdc->osdmap->epoch >= epoch) {
+                        dout("skipping full map %u len %d, "
+                             "older than our %u\n", epoch, maplen,
+                             osdc->osdmap->epoch);
+                } else {
+                        dout("taking full map %u len %d\n", epoch, maplen);
+                        newmap = osdmap_decode(&p, p+maplen);
+                        if (IS_ERR(newmap)) {
+                                err = PTR_ERR(newmap);
+                                goto bad;
+                        }
+                        oldmap = osdc->osdmap;
+                        osdc->osdmap = newmap;
+                        if (oldmap)
+                                ceph_osdmap_destroy(oldmap);
+                }
+                p += maplen;
+                nr_maps--;
+        }
+
+done:
+        downgrade_write(&osdc->map_sem);
+        ceph_monc_got_osdmap(&osdc->client->monc, osdc->osdmap->epoch);
+        if (newmap)
+                kick_requests(osdc, NULL);
+        up_read(&osdc->map_sem);
+        return;
+
+bad:
+        pr_err("osdc handle_map corrupt msg\n");
+        up_write(&osdc->map_sem);
+        return;
+}
+
+
+/*
+ * A read request prepares specific pages that data is to be read into.
+ * When a message is being read off the wire, we call prepare_pages to
+ * find those pages.
+ *  0 = success, -1 failure.
+ */
+static int prepare_pages(struct ceph_connection *con, struct ceph_msg *m,
+                         int want)
+{
+        struct ceph_osd *osd = con->private;
+        struct ceph_osd_client *osdc;
+        struct ceph_osd_reply_head *rhead = m->front.iov_base;
+        struct ceph_osd_request *req;
+        u64 tid;
+        int ret = -1;
+        int type = le16_to_cpu(m->hdr.type);
+
+        if (!osd)
+                return -1;
+        osdc = osd->o_osdc;
+
+        dout("prepare_pages on msg %p want %d\n", m, want);
+        if (unlikely(type != CEPH_MSG_OSD_OPREPLY))
+                return -1;  /* hmm! */
+
+        tid = le64_to_cpu(rhead->tid);
+        mutex_lock(&osdc->request_mutex);
+        req = __lookup_request(osdc, tid);
+        if (!req) {
+                dout("prepare_pages unknown tid %llu\n", tid);
+                goto out;
+        }
+        dout("prepare_pages tid %llu has %d pages, want %d\n",
+             tid, req->r_num_pages, want);
+        if (likely(req->r_num_pages >= want && !req->r_prepared_pages)) {
+                m->pages = req->r_pages;
+                m->nr_pages = req->r_num_pages;
+                req->r_reply = m;  /* only for duration of read over socket */
+                ceph_msg_get(m);
+                req->r_prepared_pages = 1;
+                ret = 0; /* success */
+        }
+out:
+        mutex_unlock(&osdc->request_mutex);
+        return ret;
+}
+
+/*
+ * Register request, send initial attempt.
+ */
+int ceph_osdc_start_request(struct ceph_osd_client *osdc,
+                            struct ceph_osd_request *req,
+                            bool nofail)
+{
+        int rc;
+
+        req->r_request->pages = req->r_pages;
+        req->r_request->nr_pages = req->r_num_pages;
+
+        register_request(osdc, req);
+
+        down_read(&osdc->map_sem);
+        mutex_lock(&osdc->request_mutex);
+        rc = __send_request(osdc, req);
+        if (rc) {
+                if (nofail) {
+                        dout("osdc_start_request failed send, marking %lld\n",
+                             req->r_tid);
+                        req->r_resend = true;
+                        rc = 0;
+                } else {
+                        __unregister_request(osdc, req);
+                }
+        }
+        mutex_unlock(&osdc->request_mutex);
+        up_read(&osdc->map_sem);
+        return rc;
+}
+
+/*
+ * wait for a request to complete
+ */
+int ceph_osdc_wait_request(struct ceph_osd_client *osdc,
+                           struct ceph_osd_request *req)
+{
+        int rc;
+
+        rc = wait_for_completion_interruptible(&req->r_completion);
+        if (rc < 0) {
+                mutex_lock(&osdc->request_mutex);
+                __cancel_request(req);
+                mutex_unlock(&osdc->request_mutex);
+                dout("wait_request tid %llu timed out\n", req->r_tid);
+                return rc;
+        }
+
+        dout("wait_request tid %llu result %d\n", req->r_tid, req->r_result);
+        return req->r_result;
+}
+
+/*
+ * sync - wait for all in-flight requests to flush.  avoid starvation.
+ */
+void ceph_osdc_sync(struct ceph_osd_client *osdc)
+{
+        struct ceph_osd_request *req;
+        u64 last_tid, next_tid = 0;
+
+        mutex_lock(&osdc->request_mutex);
+        last_tid = osdc->last_tid;
+        while (1) {
+                req = __lookup_request_ge(osdc, next_tid);
+                if (!req)
+                        break;
+                if (req->r_tid > last_tid)
+                        break;
+
+                next_tid = req->r_tid + 1;
+                if ((req->r_flags & CEPH_OSD_FLAG_WRITE) == 0)
+                        continue;
+
+                ceph_osdc_get_request(req);
+                mutex_unlock(&osdc->request_mutex);
+                dout("sync waiting on tid %llu (last is %llu)\n",
+                     req->r_tid, last_tid);
+                wait_for_completion(&req->r_safe_completion);
+                mutex_lock(&osdc->request_mutex);
+                ceph_osdc_put_request(req);
+        }
+        mutex_unlock(&osdc->request_mutex);
+        dout("sync done (thru tid %llu)\n", last_tid);
+}
+
+/*
+ * init, shutdown
+ */
+int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
+{
+        int err;
+
+        dout("init\n");
+        osdc->client = client;
+        osdc->osdmap = NULL;
+        init_rwsem(&osdc->map_sem);
+        init_completion(&osdc->map_waiters);
+        osdc->last_requested_map = 0;
+        mutex_init(&osdc->request_mutex);
+        osdc->timeout_tid = 0;
+        osdc->last_tid = 0;
+        osdc->osds = RB_ROOT;
+        osdc->requests = RB_ROOT;
+        osdc->num_requests = 0;
+        INIT_DELAYED_WORK(&osdc->timeout_work, handle_timeout);
+
+        osdc->req_mempool = mempool_create_kmalloc_pool(10,
+                                        sizeof(struct ceph_osd_request));
+        if (!osdc->req_mempool)
+                return -ENOMEM;
+
+        err = ceph_msgpool_init(&osdc->msgpool_op, 4096, 10, true);
+        if (err < 0)
+                return -ENOMEM;
+        err = ceph_msgpool_init(&osdc->msgpool_op_reply, 512, 0, false);
+        if (err < 0)
+                return -ENOMEM;
+
+        return 0;
+}
+
+void ceph_osdc_stop(struct ceph_osd_client *osdc)
+{
+        cancel_delayed_work_sync(&osdc->timeout_work);
+        if (osdc->osdmap) {
+                ceph_osdmap_destroy(osdc->osdmap);
+                osdc->osdmap = NULL;
+        }
+        mempool_destroy(osdc->req_mempool);
+        ceph_msgpool_destroy(&osdc->msgpool_op);
+        ceph_msgpool_destroy(&osdc->msgpool_op_reply);
+}
+
+/*
+ * Read some contiguous pages.  If we cross a stripe boundary, shorten
+ * *plen.  Return number of bytes read, or error.
+ */
+int ceph_osdc_readpages(struct ceph_osd_client *osdc,
+                        struct ceph_vino vino, struct ceph_file_layout *layout,
+                        u64 off, u64 *plen,
+                        u32 truncate_seq, u64 truncate_size,
+                        struct page **pages, int num_pages)
+{
+        struct ceph_osd_request *req;
+        int rc = 0;
+
+        dout("readpages on ino %llx.%llx on %llu~%llu\n", vino.ino,
+             vino.snap, off, *plen);
+        req = ceph_osdc_new_request(osdc, layout, vino, off, plen,
+                                    CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
+                                    NULL, 0, truncate_seq, truncate_size, NULL,
+                                    false, 1);
+        if (IS_ERR(req))
+                return PTR_ERR(req);
+
+        /* it may be a short read due to an object boundary */
+        req->r_pages = pages;
+        num_pages = calc_pages_for(off, *plen);
+        req->r_num_pages = num_pages;
+
+        dout("readpages  final extent is %llu~%llu (%d pages)\n",
+             off, *plen, req->r_num_pages);
+
+        rc = ceph_osdc_start_request(osdc, req, false);
+        if (!rc)
+                rc = ceph_osdc_wait_request(osdc, req);
+
+        ceph_osdc_put_request(req);
+        dout("readpages result %d\n", rc);
+        return rc;
+}
+
+/*
+ * do a synchronous write on N pages
+ */
+int ceph_osdc_writepages(struct ceph_osd_client *osdc, struct ceph_vino vino,
+                         struct ceph_file_layout *layout,
+                         struct ceph_snap_context *snapc,
+                         u64 off, u64 len,
+                         u32 truncate_seq, u64 truncate_size,
+                         struct timespec *mtime,
+                         struct page **pages, int num_pages,
+                         int flags, int do_sync, bool nofail)
+{
+        struct ceph_osd_request *req;
+        int rc = 0;
+
+        BUG_ON(vino.snap != CEPH_NOSNAP);
+        req = ceph_osdc_new_request(osdc, layout, vino, off, &len,
+                                    CEPH_OSD_OP_WRITE,
+                                    flags | CEPH_OSD_FLAG_ONDISK |
+                                            CEPH_OSD_FLAG_WRITE,
+                                    snapc, do_sync,
+                                    truncate_seq, truncate_size, mtime,
+                                    nofail, 1);
+        if (IS_ERR(req))
+                return PTR_ERR(req);
+
+        /* it may be a short write due to an object boundary */
+        req->r_pages = pages;
+        req->r_num_pages = calc_pages_for(off, len);
+        dout("writepages %llu~%llu (%d pages)\n", off, len,
+             req->r_num_pages);
+
+        rc = ceph_osdc_start_request(osdc, req, nofail);
+        if (!rc)
+                rc = ceph_osdc_wait_request(osdc, req);
+
+        ceph_osdc_put_request(req);
+        if (rc == 0)
+                rc = len;
+        dout("writepages result %d\n", rc);
+        return rc;
+}
+
+/*
+ * handle incoming message
+ */
+static void dispatch(struct ceph_connection *con, struct ceph_msg *msg)
+{
+        struct ceph_osd *osd = con->private;
+        struct ceph_osd_client *osdc = osd->o_osdc;
+        int type = le16_to_cpu(msg->hdr.type);
+
+        if (!osd)
+                return;
+
+        switch (type) {
+        case CEPH_MSG_OSD_MAP:
+                ceph_osdc_handle_map(osdc, msg);
+                break;
+        case CEPH_MSG_OSD_OPREPLY:
+                handle_reply(osdc, msg);
+                break;
+
+        default:
+                pr_err("received unknown message type %d %s\n", type,
+                       ceph_msg_type_name(type));
+        }
+        ceph_msg_put(msg);
+}
+
+static struct ceph_msg *alloc_msg(struct ceph_connection *con,
+                                  struct ceph_msg_header *hdr)
+{
+        struct ceph_osd *osd = con->private;
+        struct ceph_osd_client *osdc = osd->o_osdc;
+        int type = le16_to_cpu(hdr->type);
+
+        switch (type) {
+        case CEPH_MSG_OSD_OPREPLY:
+                return ceph_msgpool_get(&osdc->msgpool_op_reply);
+        }
+        return ceph_alloc_msg(con, hdr);
+}
+
+/*
+ * Wrappers to refcount containing ceph_osd struct
+ */
+static struct ceph_connection *get_osd_con(struct ceph_connection *con)
+{
+        struct ceph_osd *osd = con->private;
+        if (get_osd(osd))
+                return con;
+        return NULL;
+}
+
+static void put_osd_con(struct ceph_connection *con)
+{
+        struct ceph_osd *osd = con->private;
+        put_osd(osd);
+}
+
+const static struct ceph_connection_operations osd_con_ops = {
+        .get = get_osd_con,
+        .put = put_osd_con,
+        .dispatch = dispatch,
+        .alloc_msg = alloc_msg,
+        .peer_reset = osd_reset,
+        .alloc_middle = ceph_alloc_middle,
+        .prepare_pages = prepare_pages,
+};