Implement high-level snapshot flatten and remove commands

src/cmd.cpp

@@ -13,6 +13,7 @@
 #include "epoll_manager.h"
 #include "cluster_client.h"
 #include "pg_states.h"
+#include "base64.h"
 
 #define RM_LISTING 1
 #define RM_REMOVING 2
@@ -33,6 +34,8 @@ struct rm_pg_t
 
 struct rm_inode_t;
 struct snap_merger_t;
+struct snap_flattener_t;
+struct snap_remover_t;
 
 class cli_tool_t
 {
@@ -48,9 +51,12 @@ protected:
     cluster_client_t *cli = NULL;
     ring_consumer_t consumer;
     bool started = false;
+    int waiting = 0;
 
     rm_inode_t *remover = NULL;
     snap_merger_t *merger = NULL;
+    snap_flattener_t *flattener = NULL;
+    snap_remover_t *snap_remover = NULL;
 
 public:
     static json11::Json::object parse_args(int narg, const char *args[])
@@ -107,6 +113,69 @@ public:
 
     friend struct rm_inode_t;
     friend struct snap_merger_t;
+    friend struct snap_flattener_t;
+    friend struct snap_remover_t;
+
+    void change_parent(inode_t cur, inode_t new_parent)
+    {
+        auto cur_cfg_it = cli->st_cli.inode_config.find(cur);
+        if (cur_cfg_it == cli->st_cli.inode_config.end())
+        {
+            fprintf(stderr, "Inode 0x%lx disappeared\n", cur);
+            exit(1);
+        }
+        inode_config_t *cur_cfg = &cur_cfg_it->second;
+        std::string cur_cfg_key = base64_encode(cli->st_cli.etcd_prefix+
+            "/config/inode/"+std::to_string(INODE_POOL(cur))+
+            "/"+std::to_string(INODE_NO_POOL(cur)));
+        json11::Json::object cur_cfg_json = json11::Json::object {
+            { "name", cur_cfg->name },
+            { "size", cur_cfg->size },
+        };
+        if (new_parent)
+        {
+            if (INODE_POOL(cur) != INODE_POOL(new_parent))
+                cur_cfg_json["parent_pool"] = (uint64_t)INODE_POOL(new_parent);
+            cur_cfg_json["parent_id"] = (uint64_t)INODE_NO_POOL(new_parent);
+        }
+        if (cur_cfg->readonly)
+        {
+            cur_cfg_json["readonly"] = true;
+        }
+        waiting++;
+        cli->st_cli.etcd_txn(json11::Json::object {
+            { "compare", json11::Json::array {
+                json11::Json::object {
+                    { "target", "MOD" },
+                    { "key", cur_cfg_key },
+                    { "result", "LESS" },
+                    { "mod_revision", cur_cfg->mod_revision },
+                },
+            } },
+            { "success", json11::Json::array {
+                json11::Json::object {
+                    { "request_put", json11::Json::object {
+                        { "key", cur_cfg_key },
+                        { "value", base64_encode(json11::Json(cur_cfg_json).dump()) },
+                    } }
+                },
+            } },
+        }, ETCD_SLOW_TIMEOUT, [this, cur_cfg](std::string err, json11::Json res)
+        {
+            if (err != "")
+            {
+                fprintf(stderr, "Error changing parent of %s: %s\n", cur_cfg->name.c_str(), err.c_str());
+                exit(1);
+            }
+            if (!res["succeeded"].bool_value())
+            {
+                fprintf(stderr, "Inode %s was modified during snapshot deletion\n", cur_cfg->name.c_str());
+                exit(1);
+            }
+            waiting--;
+            ringloop->wakeup();
+        });
+    }
 };
 
 struct rm_inode_t
@@ -120,6 +189,7 @@ struct rm_inode_t
     uint64_t total_count = 0, total_done = 0, total_prev_pct = 0;
     uint64_t pgs_to_list = 0;
     bool lists_done = false;
+    bool finished = false;
 
     void start_delete()
     {
@@ -203,6 +273,10 @@ struct rm_inode_t
 
     void continue_delete()
     {
+        if (finished)
+        {
+            return;
+        }
         if (parent->list_first && !lists_done)
         {
             return;
@@ -232,9 +306,14 @@ struct rm_inode_t
         if (lists_done && !lists.size())
         {
             printf("Done, inode %lu in pool %u removed\n", (inode & ((1l << (64-POOL_ID_BITS)) - 1)), pool_id);
-            exit(0);
+            finished = true;
         }
     }
+
+    bool is_done()
+    {
+        return finished;
+    }
 };
 
 struct snap_rw_op_t
@@ -246,6 +325,19 @@ struct snap_rw_op_t
     uint32_t start = 0, end = 0;
 };
 
+static inode_config_t* get_inode_cfg(cluster_client_t *cli, const std::string & name)
+{
+    for (auto & ic: cli->st_cli.inode_config)
+    {
+        if (ic.second.name == name)
+        {
+            return &ic.second;
+        }
+    }
+    fprintf(stderr, "Layer %s not found\n", name.c_str());
+    exit(1);
+}
+
 // Layer merge is the base for multiple operations:
 // 1) Delete snapshot "up" = merge child layer into the parent layer, remove the child
 //    and rename the parent to the child
@@ -255,15 +347,11 @@ struct snap_merger_t
 {
     cli_tool_t *parent;
 
+    // -- CONFIGURATION --
     // merge from..to into target (target may be one of from..to)
     std::string from_name, to_name, target_name;
-
     // inode=>rank (bigger rank means child layers)
     std::map<inode_t,int> sources;
-    // target to merge data into
-    inode_t target;
-    // rank of the target
-    int target_rank;
     // delete merged source inode data during merge
     bool delete_source = false;
     // use CAS writes (0 = never, 1 = auto, 2 = always)
@@ -273,6 +361,9 @@ struct snap_merger_t
     // interval between fsyncs
     int fsync_interval = 128;
 
+    // -- STATE --
+    inode_t target;
+    int target_rank;
     bool inside_continue = false;
     int state = 0;
     int lists_todo = 0;
@@ -288,25 +379,12 @@ struct snap_merger_t
     int deleted_unsynced = 0;
     uint64_t processed = 0, to_process = 0;
 
-    inode_config_t* get_inode_cfg(const std::string & name)
-    {
-        for (auto & ic: parent->cli->st_cli.inode_config)
-        {
-            if (ic.second.name == name)
-            {
-                return &ic.second;
-            }
-        }
-        fprintf(stderr, "Layer %s not found\n", name.c_str());
-        exit(1);
-    }
-
     void start_merge()
     {
         check_delete_source = delete_source || check_delete_source;
-        inode_config_t *from_cfg = get_inode_cfg(from_name);
-        inode_config_t *to_cfg = get_inode_cfg(to_name);
-        inode_config_t *target_cfg = target_name == "" ? from_cfg : get_inode_cfg(target_name);
+        inode_config_t *from_cfg = get_inode_cfg(parent->cli, from_name);
+        inode_config_t *to_cfg = get_inode_cfg(parent->cli, to_name);
+        inode_config_t *target_cfg = target_name == "" ? from_cfg : get_inode_cfg(parent->cli, target_name);
         if (to_cfg->num == from_cfg->num)
         {
             fprintf(stderr, "Only one layer specified, nothing to merge\n");
@@ -324,7 +402,7 @@ struct snap_merger_t
             auto it = parent->cli->st_cli.inode_config.find(cur->parent_id);
             if (it == parent->cli->st_cli.inode_config.end())
             {
-                fprintf(stderr, "Parent inode of layer %s (%lx) not found\n", cur->name.c_str(), cur->parent_id);
+                fprintf(stderr, "Parent inode of layer %s (id %ld) not found\n", cur->name.c_str(), cur->parent_id);
                 exit(1);
             }
             cur = &it->second;
@@ -424,6 +502,11 @@ struct snap_merger_t
         }
     }
 
+    bool is_done()
+    {
+        return state == 7;
+    }
+
     void continue_merge()
     {
         if (state == 1)
@@ -438,6 +521,8 @@ struct snap_merger_t
             goto resume_5;
         else if (state == 6)
             goto resume_6;
+        else if (state == 7)
+            return;
         // First list lower layers
         list_layers(true);
         state = 1;
@@ -517,7 +602,7 @@ struct snap_merger_t
     resume_6:
         // Done
         printf("Done, layers from %s to %s merged into %s\n", from_name.c_str(), to_name.c_str(), target_name.c_str());
-        exit(0);
+        state = 7;
     }
 
     void list_layers(bool lower)
@@ -789,6 +874,335 @@ struct snap_merger_t
     }
 };
 
+// Flatten a layer: merge all parents into a layer and break the connection completely
+struct snap_flattener_t
+{
+    cli_tool_t *parent;
+
+    // target to flatten
+    std::string target_name;
+    // writers are stopped, we can safely change writable layers
+    bool writers_stopped = false;
+    // use CAS writes (0 = never, 1 = auto, 2 = always)
+    int use_cas = 1;
+    // interval between fsyncs
+    int fsync_interval = 128;
+
+    std::string top_parent_name;
+    inode_t target_id = 0;
+    int state = 0;
+    snap_merger_t *merger = NULL;
+
+    void get_merge_parents()
+    {
+        // Get all parents of target
+        inode_config_t *target_cfg = get_inode_cfg(parent->cli, target_name);
+        target_id = target_cfg->num;
+        std::vector<inode_t> chain_list;
+        inode_config_t *cur = target_cfg;
+        chain_list.push_back(cur->num);
+        while (cur->parent_id != 0 && cur->parent_id != target_cfg->num)
+        {
+            auto it = parent->cli->st_cli.inode_config.find(cur->parent_id);
+            if (it == parent->cli->st_cli.inode_config.end())
+            {
+                fprintf(stderr, "Parent inode of layer %s (id %ld) not found\n", cur->name.c_str(), cur->parent_id);
+                exit(1);
+            }
+            cur = &it->second;
+            chain_list.push_back(cur->num);
+        }
+        if (cur->parent_id != 0)
+        {
+            fprintf(stderr, "Layer %s has a loop in parents\n", target_name.c_str());
+            exit(1);
+        }
+        top_parent_name = cur->name;
+    }
+
+    bool is_done()
+    {
+        return state == 5;
+    }
+
+    void loop()
+    {
+        if (state == 1)
+            goto resume_1;
+        else if (state == 2)
+            goto resume_2;
+        else if (state == 3)
+            goto resume_3;
+        // Get parent layers
+        get_merge_parents();
+        // Start merger
+        merger = new snap_merger_t();
+        merger->parent = parent;
+        merger->from_name = top_parent_name;
+        merger->to_name = target_name;
+        merger->target_name = target_name;
+        merger->delete_source = false;
+        merger->use_cas = this->use_cas;
+        merger->fsync_interval = this->fsync_interval;
+        merger->start_merge();
+        // Wait for it
+        while (!merger->is_done())
+        {
+            state = 1;
+            return;
+resume_1:
+            merger->continue_merge_reent();
+        }
+        delete merger;
+        // Change parent
+        parent->change_parent(target_id, 0);
+        // Wait for it to complete
+        state = 2;
+resume_2:
+        if (parent->waiting > 0)
+            return;
+        state = 3;
+resume_3:
+        // Done
+        return;
+    }
+};
+
+// Remove layer(s): similar to merge, but alters metadata and processes multiple merge targets
+// If the requested snapshot chain has only 1 child and --writers-stopped is specified
+// then that child can be merged "down" into the snapshot chain.
+// Otherwise we iterate over all children of the chain, merge removed parents into them,
+// and delete children afterwards.
+//
+// Example:
+//
+// <parent> - <from> - <layer 2> - <to> - <child 1>
+//                 \           \       \- <child 2>
+//                  \           \- <child 3>
+//                   \-<child 4>
+//
+// 1) Merge <from>..<to> to <child 2>
+// 2) Set <child 2> parent to <parent>
+// 3) Variant #1, trickier, beneficial when <child 1> has less data than <to>
+//    (not implemented yet):
+//    - Merge <to>..<child 1> to <to>
+//    - Rename <to> to <child 1>
+//      It can be done without extra precautions if <child 1> is a read-only layer itself
+//      Otherwise it should be either done offline or by pausing writers
+//    - <to> is now deleted, repeat deletion with <from>..<layer 2>
+// 4) Variant #2, simple:
+//    - Repeat 1-2 with <child 1>
+//    - Delete <to>
+// 5) Process all other children
+struct snap_remover_t
+{
+    cli_tool_t *parent;
+
+    // remove from..to
+    std::string from_name, to_name;
+    // writers are stopped, we can safely change writable layers
+    bool writers_stopped = false;
+    // use CAS writes (0 = never, 1 = auto, 2 = always)
+    int use_cas = 1;
+    // interval between fsyncs
+    int fsync_interval = 128;
+
+    std::vector<inode_t> merge_children;
+    std::vector<inode_t> chain_list;
+    inode_t new_parent = 0;
+    int state = 0;
+    int current_child = 0;
+    snap_merger_t *merger = NULL;
+    rm_inode_t *remover = NULL;
+
+    void get_merge_children()
+    {
+        // Get all children of from..to
+        inode_config_t *from_cfg = get_inode_cfg(parent->cli, from_name);
+        inode_config_t *to_cfg = get_inode_cfg(parent->cli, to_name);
+        // Check that to_cfg is actually a child of from_cfg
+        // FIXME de-copypaste the following piece of code with snap_merger_t
+        inode_config_t *cur = to_cfg;
+        chain_list.push_back(cur->num);
+        while (cur->num != from_cfg->num && cur->parent_id != 0)
+        {
+            auto it = parent->cli->st_cli.inode_config.find(cur->parent_id);
+            if (it == parent->cli->st_cli.inode_config.end())
+            {
+                fprintf(stderr, "Parent inode of layer %s (id %ld) not found\n", cur->name.c_str(), cur->parent_id);
+                exit(1);
+            }
+            cur = &it->second;
+            chain_list.push_back(cur->num);
+        }
+        if (cur->num != from_cfg->num)
+        {
+            fprintf(stderr, "Layer %s is not a child of %s\n", to_name.c_str(), from_name.c_str());
+            exit(1);
+        }
+        new_parent = from_cfg->parent_id;
+        // Calculate ranks
+        std::map<inode_t,int> sources;
+        int i = chain_list.size()-1;
+        for (inode_t item: chain_list)
+        {
+            sources[item] = i--;
+        }
+        for (auto & ic: parent->cli->st_cli.inode_config)
+        {
+            if (!ic.second.parent_id)
+            {
+                continue;
+            }
+            auto it = sources.find(ic.second.parent_id);
+            if (it != sources.end() && sources.find(ic.second.num) == sources.end())
+            {
+                merge_children.push_back(ic.second.num);
+            }
+        }
+    }
+
+    bool is_done()
+    {
+        return state == 5;
+    }
+
+    void loop()
+    {
+        if (state == 1)
+            goto resume_1;
+        else if (state == 2)
+            goto resume_2;
+        else if (state == 3)
+            goto resume_3;
+        else if (state == 4)
+            goto resume_4;
+        else if (state == 5)
+            goto resume_5;
+        // Get children to merge
+        get_merge_children();
+        // Merge children one by one
+        for (current_child = 0; current_child < merge_children.size(); current_child++)
+        {
+            start_merge_child();
+            while (!merger->is_done())
+            {
+                state = 1;
+                return;
+resume_1:
+                merger->continue_merge_reent();
+            }
+            delete merger;
+            parent->change_parent(merge_children[current_child], new_parent);
+            state = 2;
+resume_2:
+            if (parent->waiting > 0)
+                return;
+        }
+        // Delete sources
+        for (current_child = 0; current_child < chain_list.size(); current_child++)
+        {
+            start_delete_source();
+            while (!remover->is_done())
+            {
+                state = 3;
+                return;
+resume_3:
+                remover->continue_delete();
+            }
+            delete remover;
+            delete_inode_config(chain_list[current_child]);
+            state = 4;
+resume_4:
+            if (parent->waiting > 0)
+                return;
+        }
+resume_5:
+        // Done
+        return;
+    }
+
+    void delete_inode_config(inode_t cur)
+    {
+        auto cur_cfg_it = parent->cli->st_cli.inode_config.find(cur);
+        if (cur_cfg_it == parent->cli->st_cli.inode_config.end())
+        {
+            fprintf(stderr, "Inode 0x%lx disappeared\n", cur);
+            exit(1);
+        }
+        inode_config_t *cur_cfg = &cur_cfg_it->second;
+        std::string cur_cfg_key = base64_encode(parent->cli->st_cli.etcd_prefix+
+            "/config/inode/"+std::to_string(INODE_POOL(cur))+
+            "/"+std::to_string(INODE_NO_POOL(cur)));
+        parent->waiting++;
+        parent->cli->st_cli.etcd_txn(json11::Json::object {
+            { "compare", json11::Json::array {
+                json11::Json::object {
+                    { "target", "MOD" },
+                    { "key", cur_cfg_key },
+                    { "result", "LESS" },
+                    { "mod_revision", cur_cfg->mod_revision },
+                },
+            } },
+            { "success", json11::Json::array {
+                json11::Json::object {
+                    { "request_delete_range", json11::Json::object {
+                        { "key", cur_cfg_key },
+                    } }
+                },
+            } },
+        }, ETCD_SLOW_TIMEOUT, [this, cur_cfg](std::string err, json11::Json res)
+        {
+            if (err != "")
+            {
+                fprintf(stderr, "Error deleting %s: %s\n", cur_cfg->name.c_str(), err.c_str());
+                exit(1);
+            }
+            if (!res["succeeded"].bool_value())
+            {
+                fprintf(stderr, "Inode %s was modified during deletion\n", cur_cfg->name.c_str());
+                exit(1);
+            }
+            parent->waiting--;
+            parent->ringloop->wakeup();
+        });
+    }
+
+    void start_merge_child()
+    {
+        auto target = parent->cli->st_cli.inode_config.find(merge_children[current_child]);
+        if (target == parent->cli->st_cli.inode_config.end())
+        {
+            fprintf(stderr, "Inode %ld disappeared\n", merge_children[current_child]);
+            exit(1);
+        }
+        merger = new snap_merger_t();
+        merger->parent = parent;
+        merger->from_name = from_name;
+        merger->to_name = target->second.name;
+        merger->target_name = target->second.name;
+        merger->delete_source = false;
+        merger->use_cas = this->use_cas;
+        merger->fsync_interval = this->fsync_interval;
+        merger->start_merge();
+    }
+
+    void start_delete_source()
+    {
+        auto source = parent->cli->st_cli.inode_config.find(chain_list[current_child]);
+        if (source == parent->cli->st_cli.inode_config.end())
+        {
+            fprintf(stderr, "Inode %ld disappeared\n", chain_list[current_child]);
+            exit(1);
+        }
+        remover = new rm_inode_t();
+        remover->parent = parent;
+        remover->inode = chain_list[current_child];
+        remover->pool_id = INODE_POOL(remover->inode);
+        remover->start_delete();
+    }
+};
+
 void cli_tool_t::run(json11::Json cfg)
 {
     json11::Json::array cmd = cfg["command"].array_items();
@@ -833,6 +1247,45 @@ void cli_tool_t::run(json11::Json cfg)
         if (!cfg["cas"].is_null())
             merger->use_cas = cfg["cas"].uint64_value() ? 2 : 0;
     }
+    else if (cmd[0] == "flatten")
+    {
+        // Merge layer data without affecting metadata
+        flattener = new snap_flattener_t();
+        flattener->parent = this;
+        flattener->target_name = cmd[1].string_value();
+        if (flattener->target_name == "")
+        {
+            fprintf(stderr, "Layer to flatten argument is missing\n");
+            exit(1);
+        }
+        flattener->fsync_interval = cfg["fsync-interval"].uint64_value();
+        if (!flattener->fsync_interval)
+            flattener->fsync_interval = 128;
+        if (!cfg["cas"].is_null())
+            flattener->use_cas = cfg["cas"].uint64_value() ? 2 : 0;
+    }
+    else if (cmd[0] == "snap-rm")
+    {
+        // Remove multiple snapshots and rebase their children
+        snap_remover = new snap_remover_t();
+        snap_remover->parent = this;
+        snap_remover->from_name = cmd[1].string_value();
+        snap_remover->to_name = cmd[2].string_value();
+        if (snap_remover->from_name == "")
+        {
+            fprintf(stderr, "Layer to remove argument is missing\n");
+            exit(1);
+        }
+        if (snap_remover->to_name == "")
+        {
+            snap_remover->to_name = snap_remover->from_name;
+        }
+        snap_remover->fsync_interval = cfg["fsync-interval"].uint64_value();
+        if (!snap_remover->fsync_interval)
+            snap_remover->fsync_interval = 128;
+        if (!cfg["cas"].is_null())
+            snap_remover->use_cas = cfg["cas"].uint64_value() ? 2 : 0;
+    }
     else
     {
         fprintf(stderr, "unknown command: %s\n", cmd[0].string_value().c_str());
@@ -878,6 +1331,14 @@ void cli_tool_t::start_work()
     {
         merger->start_merge();
     }
+    else if (flattener)
+    {
+        flattener->loop();
+    }
+    else if (snap_remover)
+    {
+        snap_remover->loop();
+    }
     started = true;
 }
 
@@ -886,10 +1347,34 @@ void cli_tool_t::continue_work()
     if (remover)
     {
         remover->continue_delete();
+        if (remover->is_done())
+        {
+            exit(0);
+        }
     }
     else if (merger)
     {
         merger->continue_merge_reent();
+        if (merger->is_done())
+        {
+            exit(0);
+        }
+    }
+    else if (flattener)
+    {
+        flattener->loop();
+        if (flattener->is_done())
+        {
+            exit(0);
+        }
+    }
+    else if (snap_remover)
+    {
+        snap_remover->loop();
+        if (snap_remover->is_done())
+        {
+            exit(0);
+        }
     }
 }
 

src/osd_id.h

@@ -9,6 +9,7 @@
 #define POOL_ID_MAX 0x10000
 #define POOL_ID_BITS 16
 #define INODE_POOL(inode) (pool_id_t)((inode) >> (64 - POOL_ID_BITS))
+#define INODE_NO_POOL(inode) (inode_t)(inode & ((1l << (64-POOL_ID_BITS)) - 1))
 
 // Pool ID is 16 bits long
 typedef uint32_t pool_id_t;