Merge branch 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[deliverable/linux.git] / net / ceph / osd_client.c

#include <linux/ceph/ceph_debug.h>

#include <linux/module.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>
#ifdef CONFIG_BLOCK
#include <linux/bio.h>
#endif

#include <linux/ceph/libceph.h>
#include <linux/ceph/osd_client.h>
#include <linux/ceph/messenger.h>
#include <linux/ceph/decode.h>
#include <linux/ceph/auth.h>
#include <linux/ceph/pagelist.h>

#define OSD_OP_FRONT_LEN        4096
#define OSD_OPREPLY_FRONT_LEN   512

static const struct ceph_connection_operations osd_con_ops;

static void send_queued(struct ceph_osd_client *osdc);
static int __reset_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd);
static void __register_request(struct ceph_osd_client *osdc,
                               struct ceph_osd_request *req);
static void __unregister_linger_request(struct ceph_osd_client *osdc,
                                        struct ceph_osd_request *req);
static void __send_request(struct ceph_osd_client *osdc,
                           struct ceph_osd_request *req);

static int op_needs_trail(int op)
{
        switch (op) {
        case CEPH_OSD_OP_GETXATTR:
        case CEPH_OSD_OP_SETXATTR:
        case CEPH_OSD_OP_CMPXATTR:
        case CEPH_OSD_OP_CALL:
        case CEPH_OSD_OP_NOTIFY:
                return 1;
        default:
                return 0;
        }
}

static int op_has_extent(int op)
{
        return (op == CEPH_OSD_OP_READ ||
                op == CEPH_OSD_OP_WRITE);
}

void ceph_calc_raw_layout(struct ceph_osd_client *osdc,
                        struct ceph_file_layout *layout,
                        u64 snapid,
                        u64 off, u64 *plen, u64 *bno,
                        struct ceph_osd_request *req,
                        struct ceph_osd_req_op *op)
{
        struct ceph_osd_request_head *reqhead = req->r_request->front.iov_base;
        u64 orig_len = *plen;
        u64 objoff, objlen;    /* extent in object */

        reqhead->snapid = cpu_to_le64(snapid);

        /* 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);

        if (op_has_extent(op->op)) {
                op->extent.offset = objoff;
                op->extent.length = objlen;
        }
        req->r_num_pages = calc_pages_for(off, *plen);
        req->r_page_alignment = off & ~PAGE_MASK;
        if (op->op == CEPH_OSD_OP_WRITE)
                op->payload_len = *plen;

        dout("calc_layout bno=%llx %llu~%llu (%d pages)\n",
             *bno, objoff, objlen, req->r_num_pages);

}
EXPORT_SYMBOL(ceph_calc_raw_layout);

/*
 * 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_req_op *op)
{
        u64 bno;

        ceph_calc_raw_layout(osdc, layout, vino.snap, off,
                             plen, &bno, req, op);

        snprintf(req->r_oid, sizeof(req->r_oid), "%llx.%08llx", vino.ino, bno);
        req->r_oid_len = strlen(req->r_oid);
}

/*
 * requests
 */
void ceph_osdc_release_request(struct kref *kref)
{
        struct ceph_osd_request *req = container_of(kref,
                                                    struct ceph_osd_request,
                                                    r_kref);

        if (req->r_request)
                ceph_msg_put(req->r_request);
        if (req->r_con_filling_msg) {
                dout("release_request revoking pages %p from con %p\n",
                     req->r_pages, req->r_con_filling_msg);
                ceph_con_revoke_message(req->r_con_filling_msg,
                                      req->r_reply);
                req->r_con_filling_msg->ops->put(req->r_con_filling_msg);
        }
        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);
#ifdef CONFIG_BLOCK
        if (req->r_bio)
                bio_put(req->r_bio);
#endif
        ceph_put_snap_context(req->r_snapc);
        if (req->r_trail) {
                ceph_pagelist_release(req->r_trail);
                kfree(req->r_trail);
        }
        if (req->r_mempool)
                mempool_free(req, req->r_osdc->req_mempool);
        else
                kfree(req);
}
EXPORT_SYMBOL(ceph_osdc_release_request);

static int get_num_ops(struct ceph_osd_req_op *ops, int *needs_trail)
{
        int i = 0;

        if (needs_trail)
                *needs_trail = 0;
        while (ops[i].op) {
                if (needs_trail && op_needs_trail(ops[i].op))
                        *needs_trail = 1;
                i++;
        }

        return i;
}

struct ceph_osd_request *ceph_osdc_alloc_request(struct ceph_osd_client *osdc,
                                               int flags,
                                               struct ceph_snap_context *snapc,
                                               struct ceph_osd_req_op *ops,
                                               bool use_mempool,
                                               gfp_t gfp_flags,
                                               struct page **pages,
                                               struct bio *bio)
{
        struct ceph_osd_request *req;
        struct ceph_msg *msg;
        int needs_trail;
        int num_op = get_num_ops(ops, &needs_trail);
        size_t msg_size = sizeof(struct ceph_osd_request_head);

        msg_size += num_op*sizeof(struct ceph_osd_op);

        if (use_mempool) {
                req = mempool_alloc(osdc->req_mempool, gfp_flags);
                memset(req, 0, sizeof(*req));
        } else {
                req = kzalloc(sizeof(*req), gfp_flags);
        }
        if (req == NULL)
                return NULL;

        req->r_osdc = osdc;
        req->r_mempool = use_mempool;

        kref_init(&req->r_kref);
        init_completion(&req->r_completion);
        init_completion(&req->r_safe_completion);
        INIT_LIST_HEAD(&req->r_unsafe_item);
        INIT_LIST_HEAD(&req->r_linger_item);
        INIT_LIST_HEAD(&req->r_linger_osd);
        INIT_LIST_HEAD(&req->r_req_lru_item);
        req->r_flags = flags;

        WARN_ON((flags & (CEPH_OSD_FLAG_READ|CEPH_OSD_FLAG_WRITE)) == 0);

        /* create reply message */
        if (use_mempool)
                msg = ceph_msgpool_get(&osdc->msgpool_op_reply, 0);
        else
                msg = ceph_msg_new(CEPH_MSG_OSD_OPREPLY,
                                   OSD_OPREPLY_FRONT_LEN, gfp_flags, true);
        if (!msg) {
                ceph_osdc_put_request(req);
                return NULL;
        }
        req->r_reply = msg;

        /* allocate space for the trailing data */
        if (needs_trail) {
                req->r_trail = kmalloc(sizeof(struct ceph_pagelist), gfp_flags);
                if (!req->r_trail) {
                        ceph_osdc_put_request(req);
                        return NULL;
                }
                ceph_pagelist_init(req->r_trail);
        }
        /* create request message; allow space for oid */
        msg_size += MAX_OBJ_NAME_SIZE;
        if (snapc)
                msg_size += sizeof(u64) * snapc->num_snaps;
        if (use_mempool)
                msg = ceph_msgpool_get(&osdc->msgpool_op, 0);
        else
                msg = ceph_msg_new(CEPH_MSG_OSD_OP, msg_size, gfp_flags, true);
        if (!msg) {
                ceph_osdc_put_request(req);
                return NULL;
        }

        msg->hdr.type = cpu_to_le16(CEPH_MSG_OSD_OP);
        memset(msg->front.iov_base, 0, msg->front.iov_len);

        req->r_request = msg;
        req->r_pages = pages;
#ifdef CONFIG_BLOCK
        if (bio) {
                req->r_bio = bio;
                bio_get(req->r_bio);
        }
#endif

        return req;
}
EXPORT_SYMBOL(ceph_osdc_alloc_request);

static void osd_req_encode_op(struct ceph_osd_request *req,
                              struct ceph_osd_op *dst,
                              struct ceph_osd_req_op *src)
{
        dst->op = cpu_to_le16(src->op);

        switch (src->op) {
        case CEPH_OSD_OP_READ:
        case CEPH_OSD_OP_WRITE:
                dst->extent.offset =
                        cpu_to_le64(src->extent.offset);
                dst->extent.length =
                        cpu_to_le64(src->extent.length);
                dst->extent.truncate_size =
                        cpu_to_le64(src->extent.truncate_size);
                dst->extent.truncate_seq =
                        cpu_to_le32(src->extent.truncate_seq);
                break;

        case CEPH_OSD_OP_GETXATTR:
        case CEPH_OSD_OP_SETXATTR:
        case CEPH_OSD_OP_CMPXATTR:
                BUG_ON(!req->r_trail);

                dst->xattr.name_len = cpu_to_le32(src->xattr.name_len);
                dst->xattr.value_len = cpu_to_le32(src->xattr.value_len);
                dst->xattr.cmp_op = src->xattr.cmp_op;
                dst->xattr.cmp_mode = src->xattr.cmp_mode;
                ceph_pagelist_append(req->r_trail, src->xattr.name,
                                     src->xattr.name_len);
                ceph_pagelist_append(req->r_trail, src->xattr.val,
                                     src->xattr.value_len);
                break;
        case CEPH_OSD_OP_CALL:
                BUG_ON(!req->r_trail);

                dst->cls.class_len = src->cls.class_len;
                dst->cls.method_len = src->cls.method_len;
                dst->cls.indata_len = cpu_to_le32(src->cls.indata_len);

                ceph_pagelist_append(req->r_trail, src->cls.class_name,
                                     src->cls.class_len);
                ceph_pagelist_append(req->r_trail, src->cls.method_name,
                                     src->cls.method_len);
                ceph_pagelist_append(req->r_trail, src->cls.indata,
                                     src->cls.indata_len);
                break;
        case CEPH_OSD_OP_ROLLBACK:
                dst->snap.snapid = cpu_to_le64(src->snap.snapid);
                break;
        case CEPH_OSD_OP_STARTSYNC:
                break;
        case CEPH_OSD_OP_NOTIFY:
                {
                        __le32 prot_ver = cpu_to_le32(src->watch.prot_ver);
                        __le32 timeout = cpu_to_le32(src->watch.timeout);

                        BUG_ON(!req->r_trail);

                        ceph_pagelist_append(req->r_trail,
                                                &prot_ver, sizeof(prot_ver));
                        ceph_pagelist_append(req->r_trail,
                                                &timeout, sizeof(timeout));
                }
        case CEPH_OSD_OP_NOTIFY_ACK:
        case CEPH_OSD_OP_WATCH:
                dst->watch.cookie = cpu_to_le64(src->watch.cookie);
                dst->watch.ver = cpu_to_le64(src->watch.ver);
                dst->watch.flag = src->watch.flag;
                break;
        default:
                pr_err("unrecognized osd opcode %d\n", dst->op);
                WARN_ON(1);
                break;
        }
        dst->payload_len = cpu_to_le32(src->payload_len);
}

/*
 * build new request AND message
 *
 */
void ceph_osdc_build_request(struct ceph_osd_request *req,
                             u64 off, u64 *plen,
                             struct ceph_osd_req_op *src_ops,
                             struct ceph_snap_context *snapc,
                             struct timespec *mtime,
                             const char *oid,
                             int oid_len)
{
        struct ceph_msg *msg = req->r_request;
        struct ceph_osd_request_head *head;
        struct ceph_osd_req_op *src_op;
        struct ceph_osd_op *op;
        void *p;
        int num_op = get_num_ops(src_ops, NULL);
        size_t msg_size = sizeof(*head) + num_op*sizeof(*op);
        int flags = req->r_flags;
        u64 data_len = 0;
        int i;

        head = msg->front.iov_base;
        op = (void *)(head + 1);
        p = (void *)(op + num_op);

        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);


        /* fill in oid */
        head->object_len = cpu_to_le32(oid_len);
        memcpy(p, oid, oid_len);
        p += oid_len;

        src_op = src_ops;
        while (src_op->op) {
                osd_req_encode_op(req, op, src_op);
                src_op++;
                op++;
        }

        if (req->r_trail)
                data_len += req->r_trail->length;

        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);
                }
        }

        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 + data_len);
        } else if (data_len) {
                req->r_request->hdr.data_off = 0;
                req->r_request->hdr.data_len = cpu_to_le32(data_len);
        }

        req->r_request->page_alignment = req->r_page_alignment;

        BUG_ON(p > msg->front.iov_base + msg->front.iov_len);
        msg_size = p - msg->front.iov_base;
        msg->front.iov_len = msg_size;
        msg->hdr.front_len = cpu_to_le32(msg_size);
        return;
}
EXPORT_SYMBOL(ceph_osdc_build_request);

/*
 * 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,
                                               int page_align)
{
        struct ceph_osd_req_op ops[3];
        struct ceph_osd_request *req;

        ops[0].op = opcode;
        ops[0].extent.truncate_seq = truncate_seq;
        ops[0].extent.truncate_size = truncate_size;
        ops[0].payload_len = 0;

        if (do_sync) {
                ops[1].op = CEPH_OSD_OP_STARTSYNC;
                ops[1].payload_len = 0;
                ops[2].op = 0;
        } else
                ops[1].op = 0;

        req = ceph_osdc_alloc_request(osdc, flags,
                                         snapc, ops,
                                         use_mempool,
                                         GFP_NOFS, NULL, NULL);
        if (!req)
                return NULL;

        /* calculate max write size */
        calc_layout(osdc, vino, layout, off, plen, req, ops);
        req->r_file_layout = *layout;  /* keep a copy */

        /* in case it differs from natural (file) alignment that
           calc_layout filled in for us */
        req->r_num_pages = calc_pages_for(page_align, *plen);
        req->r_page_alignment = page_align;

        ceph_osdc_build_request(req, off, plen, ops,
                                snapc,
                                mtime,
                                req->r_oid, req->r_oid_len);

        return req;
}
EXPORT_SYMBOL(ceph_osdc_new_request);

/*
 * 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;
}

/*
 * Resubmit requests pending on the given osd.
 */
static void __kick_osd_requests(struct ceph_osd_client *osdc,
                                struct ceph_osd *osd)
{
        struct ceph_osd_request *req, *nreq;
        int err;

        dout("__kick_osd_requests osd%d\n", osd->o_osd);
        err = __reset_osd(osdc, osd);
        if (err == -EAGAIN)
                return;

        list_for_each_entry(req, &osd->o_requests, r_osd_item) {
                list_move(&req->r_req_lru_item, &osdc->req_unsent);
                dout("requeued %p tid %llu osd%d\n", req, req->r_tid,
                     osd->o_osd);
                if (!req->r_linger)
                        req->r_flags |= CEPH_OSD_FLAG_RETRY;
        }

        list_for_each_entry_safe(req, nreq, &osd->o_linger_requests,
                                 r_linger_osd) {
                /*
                 * reregister request prior to unregistering linger so
                 * that r_osd is preserved.
                 */
                BUG_ON(!list_empty(&req->r_req_lru_item));
                __register_request(osdc, req);
                list_add(&req->r_req_lru_item, &osdc->req_unsent);
                list_add(&req->r_osd_item, &req->r_osd->o_requests);
                __unregister_linger_request(osdc, req);
                dout("requeued lingering %p tid %llu osd%d\n", req, req->r_tid,
                     osd->o_osd);
        }
}

static void kick_osd_requests(struct ceph_osd_client *osdc,
                              struct ceph_osd *kickosd)
{
        mutex_lock(&osdc->request_mutex);
        __kick_osd_requests(osdc, kickosd);
        mutex_unlock(&osdc->request_mutex);
}

/*
 * If the osd connection drops, we need to resubmit all requests.
 */
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;
        down_read(&osdc->map_sem);
        kick_osd_requests(osdc, osd);
        send_queued(osdc);
        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);
        INIT_LIST_HEAD(&osd->o_linger_requests);
        INIT_LIST_HEAD(&osd->o_osd_lru);
        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;

        INIT_LIST_HEAD(&osd->o_keepalive_item);
        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) && osd->o_auth.authorizer) {
                struct ceph_auth_client *ac = osd->o_osdc->client->monc.auth;

                if (ac->ops && ac->ops->destroy_authorizer)
                        ac->ops->destroy_authorizer(ac, osd->o_auth.authorizer);
                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);
        list_del_init(&osd->o_osd_lru);
        ceph_con_close(&osd->o_con);
        put_osd(osd);
}

static void remove_all_osds(struct ceph_osd_client *osdc)
{
        dout("__remove_old_osds %p\n", osdc);
        mutex_lock(&osdc->request_mutex);
        while (!RB_EMPTY_ROOT(&osdc->osds)) {
                struct ceph_osd *osd = rb_entry(rb_first(&osdc->osds),
                                                struct ceph_osd, o_node);
                __remove_osd(osdc, osd);
        }
        mutex_unlock(&osdc->request_mutex);
}

static void __move_osd_to_lru(struct ceph_osd_client *osdc,
                              struct ceph_osd *osd)
{
        dout("__move_osd_to_lru %p\n", osd);
        BUG_ON(!list_empty(&osd->o_osd_lru));
        list_add_tail(&osd->o_osd_lru, &osdc->osd_lru);
        osd->lru_ttl = jiffies + osdc->client->options->osd_idle_ttl * HZ;
}

static void __remove_osd_from_lru(struct ceph_osd *osd)
{
        dout("__remove_osd_from_lru %p\n", osd);
        if (!list_empty(&osd->o_osd_lru))
                list_del_init(&osd->o_osd_lru);
}

static void remove_old_osds(struct ceph_osd_client *osdc)
{
        struct ceph_osd *osd, *nosd;

        dout("__remove_old_osds %p\n", osdc);
        mutex_lock(&osdc->request_mutex);
        list_for_each_entry_safe(osd, nosd, &osdc->osd_lru, o_osd_lru) {
                if (time_before(jiffies, osd->lru_ttl))
                        break;
                __remove_osd(osdc, osd);
        }
        mutex_unlock(&osdc->request_mutex);
}

/*
 * reset osd connect
 */
static int __reset_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd)
{
        struct ceph_osd_request *req;
        int ret = 0;

        dout("__reset_osd %p osd%d\n", osd, osd->o_osd);
        if (list_empty(&osd->o_requests) &&
            list_empty(&osd->o_linger_requests)) {
                __remove_osd(osdc, osd);
        } else if (memcmp(&osdc->osdmap->osd_addr[osd->o_osd],
                          &osd->o_con.peer_addr,
                          sizeof(osd->o_con.peer_addr)) == 0 &&
                   !ceph_con_opened(&osd->o_con)) {
                dout(" osd addr hasn't changed and connection never opened,"
                     " letting msgr retry");
                /* touch each r_stamp for handle_timeout()'s benfit */
                list_for_each_entry(req, &osd->o_requests, r_osd_item)
                        req->r_stamp = jiffies;
                ret = -EAGAIN;
        } 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;

        dout("__insert_osd %p osd%d\n", new, new->o_osd);
        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;
}

static void __schedule_osd_timeout(struct ceph_osd_client *osdc)
{
        schedule_delayed_work(&osdc->timeout_work,
                        osdc->client->options->osd_keepalive_timeout * HZ);
}

static void __cancel_osd_timeout(struct ceph_osd_client *osdc)
{
        cancel_delayed_work(&osdc->timeout_work);
}

/*
 * 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)
{
        req->r_tid = ++osdc->last_tid;
        req->r_request->hdr.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++;
        if (osdc->num_requests == 1) {
                dout(" first request, scheduling timeout\n");
                __schedule_osd_timeout(osdc);
        }
}

static void register_request(struct ceph_osd_client *osdc,
                             struct ceph_osd_request *req)
{
        mutex_lock(&osdc->request_mutex);
        __register_request(osdc, req);
        mutex_unlock(&osdc->request_mutex);
}

/*
 * called under osdc->request_mutex
 */
static void __unregister_request(struct ceph_osd_client *osdc,
                                 struct ceph_osd_request *req)
{
        if (RB_EMPTY_NODE(&req->r_node)) {
                dout("__unregister_request %p tid %lld not registered\n",
                        req, req->r_tid);
                return;
        }

        dout("__unregister_request %p tid %lld\n", req, req->r_tid);
        rb_erase(&req->r_node, &osdc->requests);
        osdc->num_requests--;

        if (req->r_osd) {
                /* make sure the original request isn't in flight. */
                ceph_con_revoke(&req->r_osd->o_con, req->r_request);

                list_del_init(&req->r_osd_item);
                if (list_empty(&req->r_osd->o_requests) &&
                    list_empty(&req->r_osd->o_linger_requests)) {
                        dout("moving osd to %p lru\n", req->r_osd);
                        __move_osd_to_lru(osdc, req->r_osd);
                }
                if (list_empty(&req->r_linger_item))
                        req->r_osd = NULL;
        }

        ceph_osdc_put_request(req);

        list_del_init(&req->r_req_lru_item);
        if (osdc->num_requests == 0) {
                dout(" no requests, canceling timeout\n");
                __cancel_osd_timeout(osdc);
        }
}

/*
 * Cancel a previously queued request message
 */
static void __cancel_request(struct ceph_osd_request *req)
{
        if (req->r_sent && req->r_osd) {
                ceph_con_revoke(&req->r_osd->o_con, req->r_request);
                req->r_sent = 0;
        }
}

static void __register_linger_request(struct ceph_osd_client *osdc,
                                    struct ceph_osd_request *req)
{
        dout("__register_linger_request %p\n", req);
        list_add_tail(&req->r_linger_item, &osdc->req_linger);
        list_add_tail(&req->r_linger_osd, &req->r_osd->o_linger_requests);
}

static void __unregister_linger_request(struct ceph_osd_client *osdc,
                                        struct ceph_osd_request *req)
{
        dout("__unregister_linger_request %p\n", req);
        if (req->r_osd) {
                list_del_init(&req->r_linger_item);
                list_del_init(&req->r_linger_osd);

                if (list_empty(&req->r_osd->o_requests) &&
                    list_empty(&req->r_osd->o_linger_requests)) {
                        dout("moving osd to %p lru\n", req->r_osd);
                        __move_osd_to_lru(osdc, req->r_osd);
                }
                if (list_empty(&req->r_osd_item))
                        req->r_osd = NULL;
        }
}

void ceph_osdc_unregister_linger_request(struct ceph_osd_client *osdc,
                                         struct ceph_osd_request *req)
{
        mutex_lock(&osdc->request_mutex);
        if (req->r_linger) {
                __unregister_linger_request(osdc, req);
                ceph_osdc_put_request(req);
        }
        mutex_unlock(&osdc->request_mutex);
}
EXPORT_SYMBOL(ceph_osdc_unregister_linger_request);

void ceph_osdc_set_request_linger(struct ceph_osd_client *osdc,
                                  struct ceph_osd_request *req)
{
        if (!req->r_linger) {
                dout("set_request_linger %p\n", req);
                req->r_linger = 1;
                /*
                 * caller is now responsible for calling
                 * unregister_linger_request
                 */
                ceph_osdc_get_request(req);
        }
}
EXPORT_SYMBOL(ceph_osdc_set_request_linger);

/*
 * 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.  Move the request to the appropriate list
 * (unsent, homeless) or leave on in-flight lru.
 *
 * Return 0 if unchanged, 1 if changed, or negative on error.
 *
 * Caller should hold map_sem for read and request_mutex.
 */
static int __map_request(struct ceph_osd_client *osdc,
                         struct ceph_osd_request *req, int force_resend)
{
        struct ceph_osd_request_head *reqhead = req->r_request->front.iov_base;
        struct ceph_pg pgid;
        int acting[CEPH_PG_MAX_SIZE];
        int o = -1, num = 0;
        int err;

        dout("map_request %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) {
                list_move(&req->r_req_lru_item, &osdc->req_notarget);
                return err;
        }
        pgid = reqhead->layout.ol_pgid;
        req->r_pgid = pgid;

        err = ceph_calc_pg_acting(osdc->osdmap, pgid, acting);
        if (err > 0) {
                o = acting[0];
                num = err;
        }

        if ((!force_resend &&
             req->r_osd && req->r_osd->o_osd == o &&
             req->r_sent >= req->r_osd->o_incarnation &&
             req->r_num_pg_osds == num &&
             memcmp(req->r_pg_osds, acting, sizeof(acting[0])*num) == 0) ||
            (req->r_osd == NULL && o == -1))
                return 0;  /* no change */

        dout("map_request tid %llu pgid %d.%x osd%d (was osd%d)\n",
             req->r_tid, le32_to_cpu(pgid.pool), le16_to_cpu(pgid.ps), o,
             req->r_osd ? req->r_osd->o_osd : -1);

        /* record full pg acting set */
        memcpy(req->r_pg_osds, acting, sizeof(acting[0]) * num);
        req->r_num_pg_osds = num;

        if (req->r_osd) {
                __cancel_request(req);
                list_del_init(&req->r_osd_item);
                req->r_osd = NULL;
        }

        req->r_osd = __lookup_osd(osdc, o);
        if (!req->r_osd && o >= 0) {
                err = -ENOMEM;
                req->r_osd = create_osd(osdc);
                if (!req->r_osd) {
                        list_move(&req->r_req_lru_item, &osdc->req_notarget);
                        goto out;
                }

                dout("map_request 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) {
                __remove_osd_from_lru(req->r_osd);
                list_add(&req->r_osd_item, &req->r_osd->o_requests);
                list_move(&req->r_req_lru_item, &osdc->req_unsent);
        } else {
                list_move(&req->r_req_lru_item, &osdc->req_notarget);
        }
        err = 1;   /* osd or pg changed */

out:
        return err;
}

/*
 * caller should hold map_sem (for read) and request_mutex
 */
static void __send_request(struct ceph_osd_client *osdc,
                           struct ceph_osd_request *req)
{
        struct ceph_osd_request_head *reqhead;

        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_stamp = jiffies;
        list_move_tail(&req->r_req_lru_item, &osdc->req_lru);

        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;
}

/*
 * Send any requests in the queue (req_unsent).
 */
static void send_queued(struct ceph_osd_client *osdc)
{
        struct ceph_osd_request *req, *tmp;

        dout("send_queued\n");
        mutex_lock(&osdc->request_mutex);
        list_for_each_entry_safe(req, tmp, &osdc->req_unsent, r_req_lru_item) {
                __send_request(osdc, req);
        }
        mutex_unlock(&osdc->request_mutex);
}

/*
 * 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, *last_req = NULL;
        struct ceph_osd *osd;
        unsigned long timeout = osdc->client->options->osd_timeout * HZ;
        unsigned long keepalive =
                osdc->client->options->osd_keepalive_timeout * HZ;
        unsigned long last_stamp = 0;
        struct list_head slow_osds;
        dout("timeout\n");
        down_read(&osdc->map_sem);

        ceph_monc_request_next_osdmap(&osdc->client->monc);

        mutex_lock(&osdc->request_mutex);

        /*
         * reset osds that appear to be _really_ unresponsive.  this
         * is a failsafe measure.. we really shouldn't be getting to
         * this point if the system is working properly.  the monitors
         * should mark the osd as failed and we should find out about
         * it from an updated osd map.
         */
        while (timeout && !list_empty(&osdc->req_lru)) {
                req = list_entry(osdc->req_lru.next, struct ceph_osd_request,
                                 r_req_lru_item);

                /* hasn't been long enough since we sent it? */
                if (time_before(jiffies, req->r_stamp + timeout))
                        break;

                /* hasn't been long enough since it was acked? */
                if (req->r_request->ack_stamp == 0 ||
                    time_before(jiffies, req->r_request->ack_stamp + timeout))
                        break;

                BUG_ON(req == last_req && req->r_stamp == last_stamp);
                last_req = req;
                last_stamp = req->r_stamp;

                osd = req->r_osd;
                BUG_ON(!osd);
                pr_warning(" tid %llu timed out on osd%d, will reset osd\n",
                           req->r_tid, osd->o_osd);
                __kick_osd_requests(osdc, osd);
        }

        /*
         * ping osds that are a bit slow.  this ensures that if there
         * is a break in the TCP connection we will notice, and reopen
         * a connection with that osd (from the fault callback).
         */
        INIT_LIST_HEAD(&slow_osds);
        list_for_each_entry(req, &osdc->req_lru, r_req_lru_item) {
                if (time_before(jiffies, req->r_stamp + keepalive))
                        break;

                osd = req->r_osd;
                BUG_ON(!osd);
                dout(" tid %llu is slow, will send keepalive on osd%d\n",
                     req->r_tid, osd->o_osd);
                list_move_tail(&osd->o_keepalive_item, &slow_osds);
        }
        while (!list_empty(&slow_osds)) {
                osd = list_entry(slow_osds.next, struct ceph_osd,
                                 o_keepalive_item);
                list_del_init(&osd->o_keepalive_item);
                ceph_con_keepalive(&osd->o_con);
        }

        __schedule_osd_timeout(osdc);
        mutex_unlock(&osdc->request_mutex);
        send_queued(osdc);
        up_read(&osdc->map_sem);
}

static void handle_osds_timeout(struct work_struct *work)
{
        struct ceph_osd_client *osdc =
                container_of(work, struct ceph_osd_client,
                             osds_timeout_work.work);
        unsigned long delay =
                osdc->client->options->osd_idle_ttl * HZ >> 2;

        dout("osds timeout\n");
        down_read(&osdc->map_sem);
        remove_old_osds(osdc);
        up_read(&osdc->map_sem);

        schedule_delayed_work(&osdc->osds_timeout_work,
                              round_jiffies_relative(delay));
}

static void complete_request(struct ceph_osd_request *req)
{
        if (req->r_safe_callback)
                req->r_safe_callback(req, NULL);
        complete_all(&req->r_safe_completion);  /* fsync waiter */
}

/*
 * 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_connection *con)
{
        struct ceph_osd_reply_head *rhead = msg->front.iov_base;
        struct ceph_osd_request *req;
        u64 tid;
        int numops, object_len, flags;
        s32 result;

        tid = le64_to_cpu(msg->hdr.tid);
        if (msg->front.iov_len < sizeof(*rhead))
                goto bad;
        numops = le32_to_cpu(rhead->num_ops);
        object_len = le32_to_cpu(rhead->object_len);
        result = le32_to_cpu(rhead->result);
        if (msg->front.iov_len != sizeof(*rhead) + object_len +
            numops * sizeof(struct ceph_osd_op))
                goto bad;
        dout("handle_reply %p tid %llu result %d\n", msg, tid, (int)result);
        /* 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 this connection filled our message, drop our reference now, to
         * avoid a (safe but slower) revoke later.
         */
        if (req->r_con_filling_msg == con && req->r_reply == msg) {
                dout(" dropping con_filling_msg ref %p\n", con);
                req->r_con_filling_msg = NULL;
                con->ops->put(con);
        }

        if (!req->r_got_reply) {
                unsigned int 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);
                mutex_unlock(&osdc->request_mutex);
                goto done;
        }

        dout("handle_reply tid %llu flags %d\n", tid, flags);

        if (req->r_linger && (flags & CEPH_OSD_FLAG_ONDISK))
                __register_linger_request(osdc, req);

        /* either this is a read, or we got the safe response */
        if (result < 0 ||
            (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_all(&req->r_completion);

        if (flags & CEPH_OSD_FLAG_ONDISK)
                complete_request(req);

done:
        dout("req=%p req->r_linger=%d\n", req, req->r_linger);
        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));
        ceph_msg_dump(msg);
}

static void reset_changed_osds(struct ceph_osd_client *osdc)
{
        struct rb_node *p, *n;

        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) ||
                    memcmp(&osd->o_con.peer_addr,
                           ceph_osd_addr(osdc->osdmap,
                                         osd->o_osd),
                           sizeof(struct ceph_entity_addr)) != 0)
                        __reset_osd(osdc, osd);
        }
}

/*
 * Requeue requests whose mapping to an OSD has changed.  If requests map to
 * no osd, request a new map.
 *
 * Caller should hold map_sem for read and request_mutex.
 */
static void kick_requests(struct ceph_osd_client *osdc, int force_resend)
{
        struct ceph_osd_request *req, *nreq;
        struct rb_node *p;
        int needmap = 0;
        int err;

        dout("kick_requests %s\n", force_resend ? " (force resend)" : "");
        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);
                err = __map_request(osdc, req, force_resend);
                if (err < 0)
                        continue;  /* error */
                if (req->r_osd == NULL) {
                        dout("%p tid %llu maps to no osd\n", req, req->r_tid);
                        needmap++;  /* request a newer map */
                } else if (err > 0) {
                        dout("%p tid %llu requeued on osd%d\n", req, req->r_tid,
                             req->r_osd ? req->r_osd->o_osd : -1);
                        if (!req->r_linger)
                                req->r_flags |= CEPH_OSD_FLAG_RETRY;
                }
        }

        list_for_each_entry_safe(req, nreq, &osdc->req_linger,
                                 r_linger_item) {
                dout("linger req=%p req->r_osd=%p\n", req, req->r_osd);

                err = __map_request(osdc, req, force_resend);
                if (err == 0)
                        continue;  /* no change and no osd was specified */
                if (err < 0)
                        continue;  /* hrm! */
                if (req->r_osd == NULL) {
                        dout("tid %llu maps to no valid osd\n", req->r_tid);
                        needmap++;  /* request a newer map */
                        continue;
                }

                dout("kicking lingering %p tid %llu osd%d\n", req, req->r_tid,
                     req->r_osd ? req->r_osd->o_osd : -1);
                __unregister_linger_request(osdc, req);
                __register_request(osdc, req);
        }
        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_check_fsid(osdc->client, &fsid) < 0)
                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);
                epoch = ceph_decode_32(&p);
                maplen = ceph_decode_32(&p);
                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;
                        }
                        BUG_ON(!newmap);
                        if (newmap != osdc->osdmap) {
                                ceph_osdmap_destroy(osdc->osdmap);
                                osdc->osdmap = newmap;
                        }
                        kick_requests(osdc, 0);
                        reset_changed_osds(osdc);
                } 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);
                epoch = ceph_decode_32(&p);
                maplen = ceph_decode_32(&p);
                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 {
                        int skipped_map = 0;

                        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;
                        }
                        BUG_ON(!newmap);
                        oldmap = osdc->osdmap;
                        osdc->osdmap = newmap;
                        if (oldmap) {
                                if (oldmap->epoch + 1 < newmap->epoch)
                                        skipped_map = 1;
                                ceph_osdmap_destroy(oldmap);
                        }
                        kick_requests(osdc, skipped_map);
                }
                p += maplen;
                nr_maps--;
        }

done:
        downgrade_write(&osdc->map_sem);
        ceph_monc_got_osdmap(&osdc->client->monc, osdc->osdmap->epoch);

        /*
         * subscribe to subsequent osdmap updates if full to ensure
         * we find out when we are no longer full and stop returning
         * ENOSPC.
         */
        if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL))
                ceph_monc_request_next_osdmap(&osdc->client->monc);

        send_queued(osdc);
        up_read(&osdc->map_sem);
        wake_up_all(&osdc->client->auth_wq);
        return;

bad:
        pr_err("osdc handle_map corrupt msg\n");
        ceph_msg_dump(msg);
        up_write(&osdc->map_sem);
        return;
}

/*
 * watch/notify callback event infrastructure
 *
 * These callbacks are used both for watch and notify operations.
 */
static void __release_event(struct kref *kref)
{
        struct ceph_osd_event *event =
                container_of(kref, struct ceph_osd_event, kref);

        dout("__release_event %p\n", event);
        kfree(event);
}

static void get_event(struct ceph_osd_event *event)
{
        kref_get(&event->kref);
}

void ceph_osdc_put_event(struct ceph_osd_event *event)
{
        kref_put(&event->kref, __release_event);
}
EXPORT_SYMBOL(ceph_osdc_put_event);

static void __insert_event(struct ceph_osd_client *osdc,
                             struct ceph_osd_event *new)
{
        struct rb_node **p = &osdc->event_tree.rb_node;
        struct rb_node *parent = NULL;
        struct ceph_osd_event *event = NULL;

        while (*p) {
                parent = *p;
                event = rb_entry(parent, struct ceph_osd_event, node);
                if (new->cookie < event->cookie)
                        p = &(*p)->rb_left;
                else if (new->cookie > event->cookie)
                        p = &(*p)->rb_right;
                else
                        BUG();
        }

        rb_link_node(&new->node, parent, p);
        rb_insert_color(&new->node, &osdc->event_tree);
}

static struct ceph_osd_event *__find_event(struct ceph_osd_client *osdc,
                                                u64 cookie)
{
        struct rb_node **p = &osdc->event_tree.rb_node;
        struct rb_node *parent = NULL;
        struct ceph_osd_event *event = NULL;

        while (*p) {
                parent = *p;
                event = rb_entry(parent, struct ceph_osd_event, node);
                if (cookie < event->cookie)
                        p = &(*p)->rb_left;
                else if (cookie > event->cookie)
                        p = &(*p)->rb_right;
                else
                        return event;
        }
        return NULL;
}

static void __remove_event(struct ceph_osd_event *event)
{
        struct ceph_osd_client *osdc = event->osdc;

        if (!RB_EMPTY_NODE(&event->node)) {
                dout("__remove_event removed %p\n", event);
                rb_erase(&event->node, &osdc->event_tree);
                ceph_osdc_put_event(event);
        } else {
                dout("__remove_event didn't remove %p\n", event);
        }
}

int ceph_osdc_create_event(struct ceph_osd_client *osdc,
                           void (*event_cb)(u64, u64, u8, void *),
                           int one_shot, void *data,
                           struct ceph_osd_event **pevent)
{
        struct ceph_osd_event *event;

        event = kmalloc(sizeof(*event), GFP_NOIO);
        if (!event)
                return -ENOMEM;

        dout("create_event %p\n", event);
        event->cb = event_cb;
        event->one_shot = one_shot;
        event->data = data;
        event->osdc = osdc;
        INIT_LIST_HEAD(&event->osd_node);
        kref_init(&event->kref);   /* one ref for us */
        kref_get(&event->kref);    /* one ref for the caller */
        init_completion(&event->completion);

        spin_lock(&osdc->event_lock);
        event->cookie = ++osdc->event_count;
        __insert_event(osdc, event);
        spin_unlock(&osdc->event_lock);

        *pevent = event;
        return 0;
}
EXPORT_SYMBOL(ceph_osdc_create_event);

void ceph_osdc_cancel_event(struct ceph_osd_event *event)
{
        struct ceph_osd_client *osdc = event->osdc;

        dout("cancel_event %p\n", event);
        spin_lock(&osdc->event_lock);
        __remove_event(event);
        spin_unlock(&osdc->event_lock);
        ceph_osdc_put_event(event); /* caller's */
}
EXPORT_SYMBOL(ceph_osdc_cancel_event);


static void do_event_work(struct work_struct *work)
{
        struct ceph_osd_event_work *event_work =
                container_of(work, struct ceph_osd_event_work, work);
        struct ceph_osd_event *event = event_work->event;
        u64 ver = event_work->ver;
        u64 notify_id = event_work->notify_id;
        u8 opcode = event_work->opcode;

        dout("do_event_work completing %p\n", event);
        event->cb(ver, notify_id, opcode, event->data);
        complete(&event->completion);
        dout("do_event_work completed %p\n", event);
        ceph_osdc_put_event(event);
        kfree(event_work);
}


/*
 * Process osd watch notifications
 */
void handle_watch_notify(struct ceph_osd_client *osdc, struct ceph_msg *msg)
{
        void *p, *end;
        u8 proto_ver;
        u64 cookie, ver, notify_id;
        u8 opcode;
        struct ceph_osd_event *event;
        struct ceph_osd_event_work *event_work;

        p = msg->front.iov_base;
        end = p + msg->front.iov_len;

        ceph_decode_8_safe(&p, end, proto_ver, bad);
        ceph_decode_8_safe(&p, end, opcode, bad);
        ceph_decode_64_safe(&p, end, cookie, bad);
        ceph_decode_64_safe(&p, end, ver, bad);
        ceph_decode_64_safe(&p, end, notify_id, bad);

        spin_lock(&osdc->event_lock);
        event = __find_event(osdc, cookie);
        if (event) {
                get_event(event);
                if (event->one_shot)
                        __remove_event(event);
        }
        spin_unlock(&osdc->event_lock);
        dout("handle_watch_notify cookie %lld ver %lld event %p\n",
             cookie, ver, event);
        if (event) {
                event_work = kmalloc(sizeof(*event_work), GFP_NOIO);
                if (!event_work) {
                        dout("ERROR: could not allocate event_work\n");
                        goto done_err;
                }
                INIT_WORK(&event_work->work, do_event_work);
                event_work->event = event;
                event_work->ver = ver;
                event_work->notify_id = notify_id;
                event_work->opcode = opcode;
                if (!queue_work(osdc->notify_wq, &event_work->work)) {
                        dout("WARNING: failed to queue notify event work\n");
                        goto done_err;
                }
        }

        return;

done_err:
        complete(&event->completion);
        ceph_osdc_put_event(event);
        return;

bad:
        pr_err("osdc handle_watch_notify corrupt msg\n");
        return;
}

int ceph_osdc_wait_event(struct ceph_osd_event *event, unsigned long timeout)
{
        int err;

        dout("wait_event %p\n", event);
        err = wait_for_completion_interruptible_timeout(&event->completion,
                                                        timeout * HZ);
        ceph_osdc_put_event(event);
        if (err > 0)
                err = 0;
        dout("wait_event %p returns %d\n", event, err);
        return err;
}
EXPORT_SYMBOL(ceph_osdc_wait_event);

/*
 * Register request, send initial attempt.
 */
int ceph_osdc_start_request(struct ceph_osd_client *osdc,
                            struct ceph_osd_request *req,
                            bool nofail)
{
        int rc = 0;

        req->r_request->pages = req->r_pages;
        req->r_request->nr_pages = req->r_num_pages;
#ifdef CONFIG_BLOCK
        req->r_request->bio = req->r_bio;
#endif
        req->r_request->trail = req->r_trail;

        register_request(osdc, req);

        down_read(&osdc->map_sem);
        mutex_lock(&osdc->request_mutex);
        /*
         * a racing kick_requests() may have sent the message for us
         * while we dropped request_mutex above, so only send now if
         * the request still han't been touched yet.
         */
        if (req->r_sent == 0) {
                rc = __map_request(osdc, req, 0);
                if (rc < 0) {
                        if (nofail) {
                                dout("osdc_start_request failed map, "
                                     " will retry %lld\n", req->r_tid);
                                rc = 0;
                        }
                        goto out_unlock;
                }
                if (req->r_osd == NULL) {
                        dout("send_request %p no up osds in pg\n", req);
                        ceph_monc_request_next_osdmap(&osdc->client->monc);
                } else {
                        __send_request(osdc, req);
                }
                rc = 0;
        }

out_unlock:
        mutex_unlock(&osdc->request_mutex);
        up_read(&osdc->map_sem);
        return rc;
}
EXPORT_SYMBOL(ceph_osdc_start_request);

/*
 * 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);
                __unregister_request(osdc, req);
                mutex_unlock(&osdc->request_mutex);
                complete_request(req);
                dout("wait_request tid %llu canceled/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;
}
EXPORT_SYMBOL(ceph_osdc_wait_request);

/*
 * 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);
}
EXPORT_SYMBOL(ceph_osdc_sync);

/*
 * 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->last_tid = 0;
        osdc->osds = RB_ROOT;
        INIT_LIST_HEAD(&osdc->osd_lru);
        osdc->requests = RB_ROOT;
        INIT_LIST_HEAD(&osdc->req_lru);
        INIT_LIST_HEAD(&osdc->req_unsent);
        INIT_LIST_HEAD(&osdc->req_notarget);
        INIT_LIST_HEAD(&osdc->req_linger);
        osdc->num_requests = 0;
        INIT_DELAYED_WORK(&osdc->timeout_work, handle_timeout);
        INIT_DELAYED_WORK(&osdc->osds_timeout_work, handle_osds_timeout);
        spin_lock_init(&osdc->event_lock);
        osdc->event_tree = RB_ROOT;
        osdc->event_count = 0;

        schedule_delayed_work(&osdc->osds_timeout_work,
           round_jiffies_relative(osdc->client->options->osd_idle_ttl * HZ));

        err = -ENOMEM;
        osdc->req_mempool = mempool_create_kmalloc_pool(10,
                                        sizeof(struct ceph_osd_request));
        if (!osdc->req_mempool)
                goto out;

        err = ceph_msgpool_init(&osdc->msgpool_op, OSD_OP_FRONT_LEN, 10, true,
                                "osd_op");
        if (err < 0)
                goto out_mempool;
        err = ceph_msgpool_init(&osdc->msgpool_op_reply,
                                OSD_OPREPLY_FRONT_LEN, 10, true,
                                "osd_op_reply");
        if (err < 0)
                goto out_msgpool;

        osdc->notify_wq = create_singlethread_workqueue("ceph-watch-notify");
        if (IS_ERR(osdc->notify_wq)) {
                err = PTR_ERR(osdc->notify_wq);
                osdc->notify_wq = NULL;
                goto out_msgpool;
        }
        return 0;

out_msgpool:
        ceph_msgpool_destroy(&osdc->msgpool_op);
out_mempool:
        mempool_destroy(osdc->req_mempool);
out:
        return err;
}
EXPORT_SYMBOL(ceph_osdc_init);

void ceph_osdc_stop(struct ceph_osd_client *osdc)
{
        flush_workqueue(osdc->notify_wq);
        destroy_workqueue(osdc->notify_wq);
        cancel_delayed_work_sync(&osdc->timeout_work);
        cancel_delayed_work_sync(&osdc->osds_timeout_work);
        if (osdc->osdmap) {
                ceph_osdmap_destroy(osdc->osdmap);
                osdc->osdmap = NULL;
        }
        remove_all_osds(osdc);
        mempool_destroy(osdc->req_mempool);
        ceph_msgpool_destroy(&osdc->msgpool_op);
        ceph_msgpool_destroy(&osdc->msgpool_op_reply);
}
EXPORT_SYMBOL(ceph_osdc_stop);

/*
 * 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, int page_align)
{
        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, page_align);
        if (!req)
                return -ENOMEM;

        /* it may be a short read due to an object boundary */
        req->r_pages = pages;

        dout("readpages  final extent is %llu~%llu (%d pages align %d)\n",
             off, *plen, req->r_num_pages, page_align);

        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;
}
EXPORT_SYMBOL(ceph_osdc_readpages);

/*
 * 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;
        int page_align = off & ~PAGE_MASK;

        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, page_align);
        if (!req)
                return -ENOMEM;

        /* it may be a short write due to an object boundary */
        req->r_pages = pages;
        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;
}
EXPORT_SYMBOL(ceph_osdc_writepages);

/*
 * 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;
        int type = le16_to_cpu(msg->hdr.type);

        if (!osd)
                goto out;
        osdc = osd->o_osdc;

        switch (type) {
        case CEPH_MSG_OSD_MAP:
                ceph_osdc_handle_map(osdc, msg);
                break;
        case CEPH_MSG_OSD_OPREPLY:
                handle_reply(osdc, msg, con);
                break;
        case CEPH_MSG_WATCH_NOTIFY:
                handle_watch_notify(osdc, msg);
                break;

        default:
                pr_err("received unknown message type %d %s\n", type,
                       ceph_msg_type_name(type));
        }
out:
        ceph_msg_put(msg);
}

/*
 * lookup and return message for incoming reply.  set up reply message
 * pages.
 */
static struct ceph_msg *get_reply(struct ceph_connection *con,
                                  struct ceph_msg_header *hdr,
                                  int *skip)
{
        struct ceph_osd *osd = con->private;
        struct ceph_osd_client *osdc = osd->o_osdc;
        struct ceph_msg *m;
        struct ceph_osd_request *req;
        int front = le32_to_cpu(hdr->front_len);
        int data_len = le32_to_cpu(hdr->data_len);
        u64 tid;

        tid = le64_to_cpu(hdr->tid);
        mutex_lock(&osdc->request_mutex);
        req = __lookup_request(osdc, tid);
        if (!req) {
                *skip = 1;
                m = NULL;
                pr_info("get_reply unknown tid %llu from osd%d\n", tid,
                        osd->o_osd);
                goto out;
        }

        if (req->r_con_filling_msg) {
                dout("get_reply revoking msg %p from old con %p\n",
                     req->r_reply, req->r_con_filling_msg);
                ceph_con_revoke_message(req->r_con_filling_msg, req->r_reply);
                req->r_con_filling_msg->ops->put(req->r_con_filling_msg);
                req->r_con_filling_msg = NULL;
        }

        if (front > req->r_reply->front.iov_len) {
                pr_warning("get_reply front %d > preallocated %d\n",
                           front, (int)req->r_reply->front.iov_len);
                m = ceph_msg_new(CEPH_MSG_OSD_OPREPLY, front, GFP_NOFS, false);
                if (!m)
                        goto out;
                ceph_msg_put(req->r_reply);
                req->r_reply = m;
        }
        m = ceph_msg_get(req->r_reply);

        if (data_len > 0) {
                int want = calc_pages_for(req->r_page_alignment, data_len);

                if (unlikely(req->r_num_pages < want)) {
                        pr_warning("tid %lld reply has %d bytes %d pages, we"
                                   " had only %d pages ready\n", tid, data_len,
                                   want, req->r_num_pages);
                        *skip = 1;
                        ceph_msg_put(m);
                        m = NULL;
                        goto out;
                }
                m->pages = req->r_pages;
                m->nr_pages = req->r_num_pages;
                m->page_alignment = req->r_page_alignment;
#ifdef CONFIG_BLOCK
                m->bio = req->r_bio;
#endif
        }
        *skip = 0;
        req->r_con_filling_msg = con->ops->get(con);
        dout("get_reply tid %lld %p\n", tid, m);

out:
        mutex_unlock(&osdc->request_mutex);
        return m;

}

static struct ceph_msg *alloc_msg(struct ceph_connection *con,
                                  struct ceph_msg_header *hdr,
                                  int *skip)
{
        struct ceph_osd *osd = con->private;
        int type = le16_to_cpu(hdr->type);
        int front = le32_to_cpu(hdr->front_len);

        switch (type) {
        case CEPH_MSG_OSD_MAP:
        case CEPH_MSG_WATCH_NOTIFY:
                return ceph_msg_new(type, front, GFP_NOFS, false);
        case CEPH_MSG_OSD_OPREPLY:
                return get_reply(con, hdr, skip);
        default:
                pr_info("alloc_msg unexpected msg type %d from osd%d\n", type,
                        osd->o_osd);
                *skip = 1;
                return NULL;
        }
}

/*
 * 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);
}

/*
 * authentication
 */
/*
 * Note: returned pointer is the address of a structure that's
 * managed separately.  Caller must *not* attempt to free it.
 */
static struct ceph_auth_handshake *get_authorizer(struct ceph_connection *con,
                                        int *proto, int force_new)
{
        struct ceph_osd *o = con->private;
        struct ceph_osd_client *osdc = o->o_osdc;
        struct ceph_auth_client *ac = osdc->client->monc.auth;
        struct ceph_auth_handshake *auth = &o->o_auth;

        if (force_new && auth->authorizer) {
                if (ac->ops && ac->ops->destroy_authorizer)
                        ac->ops->destroy_authorizer(ac, auth->authorizer);
                auth->authorizer = NULL;
        }
        if (!auth->authorizer && ac->ops && ac->ops->create_authorizer) {
                int ret = ac->ops->create_authorizer(ac, CEPH_ENTITY_TYPE_OSD,
                                                        auth);
                if (ret)
                        return ERR_PTR(ret);
        }
        *proto = ac->protocol;

        return auth;
}


static int verify_authorizer_reply(struct ceph_connection *con, int len)
{
        struct ceph_osd *o = con->private;
        struct ceph_osd_client *osdc = o->o_osdc;
        struct ceph_auth_client *ac = osdc->client->monc.auth;

        /*
         * XXX If ac->ops or ac->ops->verify_authorizer_reply is null,
         * XXX which do we do:  succeed or fail?
         */
        return ac->ops->verify_authorizer_reply(ac, o->o_auth.authorizer, len);
}

static int invalidate_authorizer(struct ceph_connection *con)
{
        struct ceph_osd *o = con->private;
        struct ceph_osd_client *osdc = o->o_osdc;
        struct ceph_auth_client *ac = osdc->client->monc.auth;

        if (ac->ops && ac->ops->invalidate_authorizer)
                ac->ops->invalidate_authorizer(ac, CEPH_ENTITY_TYPE_OSD);

        return ceph_monc_validate_auth(&osdc->client->monc);
}

static const struct ceph_connection_operations osd_con_ops = {
        .get = get_osd_con,
        .put = put_osd_con,
        .dispatch = dispatch,
        .get_authorizer = get_authorizer,
        .verify_authorizer_reply = verify_authorizer_reply,
        .invalidate_authorizer = invalidate_authorizer,
        .alloc_msg = alloc_msg,
        .fault = osd_reset,
};