X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fsrc%2Fmon%2FFSCommands.cc;fp=src%2Fceph%2Fsrc%2Fmon%2FFSCommands.cc;h=98f272d4b0fd86cef95285a21d5dee3a43da7b7a;hb=812ff6ca9fcd3e629e49d4328905f33eee8ca3f5;hp=0000000000000000000000000000000000000000;hpb=15280273faafb77777eab341909a3f495cf248d9;p=stor4nfv.git

diff --git a/src/ceph/src/mon/FSCommands.cc b/src/ceph/src/mon/FSCommands.cc
new file mode 100644
index 0000000..98f272d
--- /dev/null
+++ b/src/ceph/src/mon/FSCommands.cc
@@ -0,0 +1,944 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat Ltd
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software 
+ * Foundation.  See file COPYING.
+ * 
+ */
+
+
+#include "OSDMonitor.h"
+#include "PGMonitor.h"
+
+#include "FSCommands.h"
+#include "MDSMonitor.h"
+
+
+
+static const string EXPERIMENTAL_WARNING("Warning! This feature is experimental."
+"It may cause problems up to and including data loss."
+"Consult the documentation at ceph.com, and if unsure, do not proceed."
+"Add --yes-i-really-mean-it if you are certain.");
+
+
+
+class FlagSetHandler : public FileSystemCommandHandler
+{
+  public:
+  FlagSetHandler()
+    : FileSystemCommandHandler("fs flag set")
+  {
+  }
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    string flag_name;
+    cmd_getval(g_ceph_context, cmdmap, "flag_name", flag_name);
+
+    string flag_val;
+    cmd_getval(g_ceph_context, cmdmap, "val", flag_val);
+
+    string confirm;
+    cmd_getval(g_ceph_context, cmdmap, "confirm", confirm);
+
+    if (flag_name == "enable_multiple") {
+      bool flag_bool = false;
+      int r = parse_bool(flag_val, &flag_bool, ss);
+      if (r != 0) {
+        ss << "Invalid boolean value '" << flag_val << "'";
+        return r;
+      }
+
+      bool jewel = mon->get_quorum_con_features() & CEPH_FEATURE_SERVER_JEWEL;
+      if (flag_bool && !jewel) {
+        ss << "Multiple-filesystems are forbidden until all mons are updated";
+        return -EINVAL;
+      }
+      if (confirm != "--yes-i-really-mean-it") {
+	ss << EXPERIMENTAL_WARNING;
+      }
+      fsmap.set_enable_multiple(flag_bool);
+      return 0;
+    } else {
+      ss << "Unknown flag '" << flag_name << "'";
+      return -EINVAL;
+    }
+  }
+};
+
+class FsNewHandler : public FileSystemCommandHandler
+{
+  public:
+  FsNewHandler(Paxos *paxos)
+    : FileSystemCommandHandler("fs new"), m_paxos(paxos)
+  {
+  }
+
+  bool batched_propose() override {
+    return true;
+  }
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    assert(m_paxos->is_plugged());
+
+    string metadata_name;
+    cmd_getval(g_ceph_context, cmdmap, "metadata", metadata_name);
+    int64_t metadata = mon->osdmon()->osdmap.lookup_pg_pool_name(metadata_name);
+    if (metadata < 0) {
+      ss << "pool '" << metadata_name << "' does not exist";
+      return -ENOENT;
+    }
+
+    string force_str;
+    cmd_getval(g_ceph_context,cmdmap, "force", force_str);
+    bool force = (force_str == "--force");
+    const pool_stat_t *stat = mon->pgservice->get_pool_stat(metadata);
+    if (stat) {
+      int64_t metadata_num_objects = stat->stats.sum.num_objects;
+      if (!force && metadata_num_objects > 0) {
+	ss << "pool '" << metadata_name
+	   << "' already contains some objects. Use an empty pool instead.";
+	return -EINVAL;
+      }
+    }
+
+    string data_name;
+    cmd_getval(g_ceph_context, cmdmap, "data", data_name);
+    int64_t data = mon->osdmon()->osdmap.lookup_pg_pool_name(data_name);
+    if (data < 0) {
+      ss << "pool '" << data_name << "' does not exist";
+      return -ENOENT;
+    }
+    if (data == 0) {
+      ss << "pool '" << data_name << "' has id 0, which CephFS does not allow. Use another pool or recreate it to get a non-zero pool id.";
+      return -EINVAL;
+    }
+
+    string fs_name;
+    cmd_getval(g_ceph_context, cmdmap, "fs_name", fs_name);
+    if (fs_name.empty()) {
+        // Ensure fs name is not empty so that we can implement
+        // commmands that refer to FS by name in future.
+        ss << "Filesystem name may not be empty";
+        return -EINVAL;
+    }
+
+    if (fsmap.get_filesystem(fs_name)) {
+      auto fs = fsmap.get_filesystem(fs_name);
+      if (*(fs->mds_map.get_data_pools().begin()) == data
+          && fs->mds_map.get_metadata_pool() == metadata) {
+        // Identical FS created already, this is a no-op
+        ss << "filesystem '" << fs_name << "' already exists";
+        return 0;
+      } else {
+        ss << "filesystem already exists with name '" << fs_name << "'";
+        return -EINVAL;
+      }
+    }
+
+    if (fsmap.filesystem_count() > 0
+        && !fsmap.get_enable_multiple()) {
+      ss << "Creation of multiple filesystems is disabled.  To enable "
+            "this experimental feature, use 'ceph fs flag set enable_multiple "
+            "true'";
+      return -EINVAL;
+    }
+
+    for (auto fs : fsmap.get_filesystems()) {
+      const std::vector<int64_t> &data_pools = fs->mds_map.get_data_pools();
+      string sure;
+      if ((std::find(data_pools.begin(), data_pools.end(), data) != data_pools.end()
+	   || fs->mds_map.get_metadata_pool() == metadata)
+	  && ((!cmd_getval(g_ceph_context, cmdmap, "sure", sure)
+	       || sure != "--allow-dangerous-metadata-overlay"))) {
+	ss << "Filesystem '" << fs_name
+	   << "' is already using one of the specified RADOS pools. This should ONLY be done in emergencies and after careful reading of the documentation. Pass --allow-dangerous-metadata-overlay to permit this.";
+	return -EEXIST;
+      }
+    }
+
+    pg_pool_t const *data_pool = mon->osdmon()->osdmap.get_pg_pool(data);
+    assert(data_pool != NULL);  // Checked it existed above
+    pg_pool_t const *metadata_pool = mon->osdmon()->osdmap.get_pg_pool(metadata);
+    assert(metadata_pool != NULL);  // Checked it existed above
+
+    int r = _check_pool(mon->osdmon()->osdmap, data, false, force, &ss);
+    if (r < 0) {
+      return r;
+    }
+
+    r = _check_pool(mon->osdmon()->osdmap, metadata, true, force, &ss);
+    if (r < 0) {
+      return r;
+    }
+    
+    // if we're running as luminous, we have to set the pool application metadata
+    if (mon->osdmon()->osdmap.require_osd_release >= CEPH_RELEASE_LUMINOUS ||
+	mon->osdmon()->pending_inc.new_require_osd_release >= CEPH_RELEASE_LUMINOUS) {
+      if (!mon->osdmon()->is_writeable()) {
+	// not allowed to write yet, so retry when we can
+	mon->osdmon()->wait_for_writeable(op, new PaxosService::C_RetryMessage(mon->mdsmon(), op));
+	return -EAGAIN;
+      }
+      mon->osdmon()->do_application_enable(data,
+					   pg_pool_t::APPLICATION_NAME_CEPHFS);
+      mon->osdmon()->do_application_enable(metadata,
+					   pg_pool_t::APPLICATION_NAME_CEPHFS);
+      mon->osdmon()->propose_pending();
+    }
+
+    // All checks passed, go ahead and create.
+    fsmap.create_filesystem(fs_name, metadata, data,
+                            mon->get_quorum_con_features());
+    ss << "new fs with metadata pool " << metadata << " and data pool " << data;
+    return 0;
+  }
+
+private:
+  Paxos *m_paxos;
+};
+
+class SetHandler : public FileSystemCommandHandler
+{
+public:
+  SetHandler()
+    : FileSystemCommandHandler("fs set")
+  {}
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    std::string fs_name;
+    if (!cmd_getval(g_ceph_context, cmdmap, "fs_name", fs_name) || fs_name.empty()) {
+      ss << "Missing filesystem name";
+      return -EINVAL;
+    }
+
+    auto fs = fsmap.get_filesystem(fs_name);
+    if (fs == nullptr) {
+      ss << "Not found: '" << fs_name << "'";
+      return -ENOENT;
+    }
+
+    string var;
+    if (!cmd_getval(g_ceph_context, cmdmap, "var", var) || var.empty()) {
+      ss << "Invalid variable";
+      return -EINVAL;
+    }
+    string val;
+    string interr;
+    int64_t n = 0;
+    if (!cmd_getval(g_ceph_context, cmdmap, "val", val)) {
+      return -EINVAL;
+    }
+    // we got a string.  see if it contains an int.
+    n = strict_strtoll(val.c_str(), 10, &interr);
+    if (var == "max_mds") {
+      // NOTE: see also "mds set_max_mds", which can modify the same field.
+      if (interr.length()) {
+        ss << interr;
+	return -EINVAL;
+      }
+
+      if (n <= 0) {
+        ss << "You must specify at least one MDS";
+        return -EINVAL;
+      }
+
+      if (!fs->mds_map.allows_multimds() && n > fs->mds_map.get_max_mds() &&
+	  n > 1) {
+	ss << "multi-MDS clusters are not enabled; set 'allow_multimds' to enable";
+	return -EINVAL;
+      }
+      if (n > MAX_MDS) {
+        ss << "may not have more than " << MAX_MDS << " MDS ranks";
+        return -EINVAL;
+      }
+      fsmap.modify_filesystem(
+          fs->fscid,
+          [n](std::shared_ptr<Filesystem> fs)
+      {
+        fs->mds_map.set_max_mds(n);
+      });
+    } else if (var == "inline_data") {
+      bool enable_inline = false;
+      int r = parse_bool(val, &enable_inline, ss);
+      if (r != 0) {
+        return r;
+      }
+
+      if (enable_inline) {
+	string confirm;
+	if (!cmd_getval(g_ceph_context, cmdmap, "confirm", confirm) ||
+	    confirm != "--yes-i-really-mean-it") {
+	  ss << EXPERIMENTAL_WARNING;
+	  return -EPERM;
+	}
+	ss << "inline data enabled";
+
+        fsmap.modify_filesystem(
+            fs->fscid,
+            [](std::shared_ptr<Filesystem> fs)
+        {
+          fs->mds_map.set_inline_data_enabled(true);
+        });
+
+        // Update `compat`
+        CompatSet c = fsmap.get_compat();
+        c.incompat.insert(MDS_FEATURE_INCOMPAT_INLINE);
+        fsmap.update_compat(c);
+      } else {
+	ss << "inline data disabled";
+        fsmap.modify_filesystem(
+            fs->fscid,
+            [](std::shared_ptr<Filesystem> fs)
+        {
+          fs->mds_map.set_inline_data_enabled(false);
+        });
+      }
+    } else if (var == "balancer") {
+      if (val.empty()) {
+        ss << "unsetting the metadata load balancer";
+      } else {
+        ss << "setting the metadata load balancer to " << val;
+      }
+      fsmap.modify_filesystem(
+	fs->fscid,
+	[val](std::shared_ptr<Filesystem> fs)
+        {
+          fs->mds_map.set_balancer(val);
+        });
+      return true;
+    } else if (var == "max_file_size") {
+      if (interr.length()) {
+	ss << var << " requires an integer value";
+	return -EINVAL;
+      }
+      if (n < CEPH_MIN_STRIPE_UNIT) {
+	ss << var << " must at least " << CEPH_MIN_STRIPE_UNIT;
+	return -ERANGE;
+      }
+      fsmap.modify_filesystem(
+          fs->fscid,
+          [n](std::shared_ptr<Filesystem> fs)
+      {
+        fs->mds_map.set_max_filesize(n);
+      });
+    } else if (var == "allow_new_snaps") {
+      bool enable_snaps = false;
+      int r = parse_bool(val, &enable_snaps, ss);
+      if (r != 0) {
+        return r;
+      }
+
+      if (!enable_snaps) {
+        fsmap.modify_filesystem(
+            fs->fscid,
+            [](std::shared_ptr<Filesystem> fs)
+        {
+          fs->mds_map.clear_snaps_allowed();
+        });
+	ss << "disabled new snapshots";
+      } else {
+	string confirm;
+	if (!cmd_getval(g_ceph_context, cmdmap, "confirm", confirm) ||
+	    confirm != "--yes-i-really-mean-it") {
+	  ss << EXPERIMENTAL_WARNING;
+	  return -EPERM;
+	}
+        fsmap.modify_filesystem(
+            fs->fscid,
+            [](std::shared_ptr<Filesystem> fs)
+        {
+          fs->mds_map.set_snaps_allowed();
+        });
+	ss << "enabled new snapshots";
+      }
+    } else if (var == "allow_multimds") {
+      bool enable_multimds = false;
+      int r = parse_bool(val, &enable_multimds, ss);
+      if (r != 0) {
+	return r;
+      }
+
+      if (!enable_multimds) {
+	fsmap.modify_filesystem(fs->fscid,
+	     [](std::shared_ptr<Filesystem> fs)
+		{
+		  fs->mds_map.clear_multimds_allowed();
+		});
+	ss << "disallowed increasing the cluster size past 1";
+      } else {
+        fsmap.modify_filesystem(
+            fs->fscid,
+            [](std::shared_ptr<Filesystem> fs)
+        {
+          fs->mds_map.set_multimds_allowed();
+        });
+	ss << "enabled creation of more than 1 active MDS";
+      }
+    } else if (var == "allow_dirfrags") {
+      bool enable_dirfrags = false;
+      int r = parse_bool(val, &enable_dirfrags, ss);
+      if (r != 0) {
+	return r;
+      }
+
+      if (!enable_dirfrags) {
+	fsmap.modify_filesystem(fs->fscid,
+	     [](std::shared_ptr<Filesystem> fs)
+		{
+		  fs->mds_map.clear_dirfrags_allowed();
+		});
+	ss << "disallowed new directory fragmentation";
+      } else {
+        fsmap.modify_filesystem(
+            fs->fscid,
+            [](std::shared_ptr<Filesystem> fs)
+        {
+          fs->mds_map.set_dirfrags_allowed();
+        });
+	ss << "enabled directory fragmentation";
+      }
+    } else if (var == "cluster_down") {
+      bool is_down = false;
+      int r = parse_bool(val, &is_down, ss);
+      if (r != 0) {
+        return r;
+      }
+
+      fsmap.modify_filesystem(
+          fs->fscid,
+          [is_down](std::shared_ptr<Filesystem> fs)
+      {
+        if (is_down) {
+          fs->mds_map.set_flag(CEPH_MDSMAP_DOWN);
+        } else {
+          fs->mds_map.clear_flag(CEPH_MDSMAP_DOWN);
+        }
+      });
+
+      ss << "marked " << (is_down ? "down" : "up");
+    } else if (var == "standby_count_wanted") {
+      if (interr.length()) {
+       ss << var << " requires an integer value";
+       return -EINVAL;
+      }
+      if (n < 0) {
+       ss << var << " must be non-negative";
+       return -ERANGE;
+      }
+      fsmap.modify_filesystem(
+          fs->fscid,
+          [n](std::shared_ptr<Filesystem> fs)
+      {
+        fs->mds_map.set_standby_count_wanted(n);
+      });
+    } else {
+      ss << "unknown variable " << var;
+      return -EINVAL;
+    }
+
+    return 0;
+  }
+};
+
+class AddDataPoolHandler : public FileSystemCommandHandler
+{
+  public:
+  AddDataPoolHandler(Paxos *paxos)
+    : FileSystemCommandHandler("fs add_data_pool"), m_paxos(paxos)
+  {}
+
+  bool batched_propose() override {
+    return true;
+  }
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    assert(m_paxos->is_plugged());
+
+    string poolname;
+    cmd_getval(g_ceph_context, cmdmap, "pool", poolname);
+
+    std::string fs_name;
+    if (!cmd_getval(g_ceph_context, cmdmap, "fs_name", fs_name)
+        || fs_name.empty()) {
+      ss << "Missing filesystem name";
+      return -EINVAL;
+    }
+
+    auto fs = fsmap.get_filesystem(fs_name);
+    if (fs == nullptr) {
+      ss << "Not found: '" << fs_name << "'";
+      return -ENOENT;
+    }
+
+    int64_t poolid = mon->osdmon()->osdmap.lookup_pg_pool_name(poolname);
+    if (poolid < 0) {
+      string err;
+      poolid = strict_strtol(poolname.c_str(), 10, &err);
+      if (err.length()) {
+	ss << "pool '" << poolname << "' does not exist";
+	return -ENOENT;
+      }
+    }
+
+    int r = _check_pool(mon->osdmon()->osdmap, poolid, false, false, &ss);
+    if (r != 0) {
+      return r;
+    }
+
+    // no-op when the data_pool already on fs
+    if (fs->mds_map.is_data_pool(poolid)) {
+      ss << "data pool " << poolid << " is already on fs " << fs_name;
+      return 0;
+    }
+
+    // if we're running as luminous, we have to set the pool application metadata
+    if (mon->osdmon()->osdmap.require_osd_release >= CEPH_RELEASE_LUMINOUS ||
+	mon->osdmon()->pending_inc.new_require_osd_release >= CEPH_RELEASE_LUMINOUS) {
+      if (!mon->osdmon()->is_writeable()) {
+	// not allowed to write yet, so retry when we can
+	mon->osdmon()->wait_for_writeable(op, new PaxosService::C_RetryMessage(mon->mdsmon(), op));
+	return -EAGAIN;
+      }
+      mon->osdmon()->do_application_enable(poolid, pg_pool_t::APPLICATION_NAME_CEPHFS);
+      mon->osdmon()->propose_pending();
+    }
+
+    fsmap.modify_filesystem(
+        fs->fscid,
+        [poolid](std::shared_ptr<Filesystem> fs)
+    {
+      fs->mds_map.add_data_pool(poolid);
+    });
+
+    ss << "added data pool " << poolid << " to fsmap";
+
+    return 0;
+  }
+
+private:
+  Paxos *m_paxos;
+};
+
+class SetDefaultHandler : public FileSystemCommandHandler
+{
+  public:
+  SetDefaultHandler()
+    : FileSystemCommandHandler("fs set-default")
+  {}
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    std::string fs_name;
+    cmd_getval(g_ceph_context, cmdmap, "fs_name", fs_name);
+    auto fs = fsmap.get_filesystem(fs_name);
+    if (fs == nullptr) {
+        ss << "filesystem '" << fs_name << "' does not exist";
+        return -ENOENT;
+    }
+
+    fsmap.set_legacy_client_fscid(fs->fscid);
+    return 0;
+  }
+};
+
+class RemoveFilesystemHandler : public FileSystemCommandHandler
+{
+  public:
+  RemoveFilesystemHandler()
+    : FileSystemCommandHandler("fs rm")
+  {}
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    // Check caller has correctly named the FS to delete
+    // (redundant while there is only one FS, but command
+    //  syntax should apply to multi-FS future)
+    string fs_name;
+    cmd_getval(g_ceph_context, cmdmap, "fs_name", fs_name);
+    auto fs = fsmap.get_filesystem(fs_name);
+    if (fs == nullptr) {
+        // Consider absence success to make deletes idempotent
+        ss << "filesystem '" << fs_name << "' does not exist";
+        return 0;
+    }
+
+    // Check that no MDS daemons are active
+    if (fs->mds_map.get_num_up_mds() > 0) {
+      ss << "all MDS daemons must be inactive before removing filesystem";
+      return -EINVAL;
+    }
+
+    // Check for confirmation flag
+    string sure;
+    cmd_getval(g_ceph_context, cmdmap, "sure", sure);
+    if (sure != "--yes-i-really-mean-it") {
+      ss << "this is a DESTRUCTIVE operation and will make data in your filesystem permanently" \
+            " inaccessible.  Add --yes-i-really-mean-it if you are sure you wish to continue.";
+      return -EPERM;
+    }
+
+    if (fsmap.get_legacy_client_fscid() == fs->fscid) {
+      fsmap.set_legacy_client_fscid(FS_CLUSTER_ID_NONE);
+    }
+
+    std::vector<mds_gid_t> to_fail;
+    // There may be standby_replay daemons left here
+    for (const auto &i : fs->mds_map.get_mds_info()) {
+      assert(i.second.state == MDSMap::STATE_STANDBY_REPLAY);
+      to_fail.push_back(i.first);
+    }
+
+    for (const auto &gid : to_fail) {
+      // Standby replays don't write, so it isn't important to
+      // wait for an osdmap propose here: ignore return value.
+      mon->mdsmon()->fail_mds_gid(gid);
+    }
+
+    fsmap.erase_filesystem(fs->fscid);
+
+    return 0;
+  }
+};
+
+class ResetFilesystemHandler : public FileSystemCommandHandler
+{
+  public:
+  ResetFilesystemHandler()
+    : FileSystemCommandHandler("fs reset")
+  {}
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    string fs_name;
+    cmd_getval(g_ceph_context, cmdmap, "fs_name", fs_name);
+    auto fs = fsmap.get_filesystem(fs_name);
+    if (fs == nullptr) {
+        ss << "filesystem '" << fs_name << "' does not exist";
+        // Unlike fs rm, we consider this case an error
+        return -ENOENT;
+    }
+
+    // Check that no MDS daemons are active
+    if (fs->mds_map.get_num_up_mds() > 0) {
+      ss << "all MDS daemons must be inactive before resetting filesystem: set the cluster_down flag"
+            " and use `ceph mds fail` to make this so";
+      return -EINVAL;
+    }
+
+    // Check for confirmation flag
+    string sure;
+    cmd_getval(g_ceph_context, cmdmap, "sure", sure);
+    if (sure != "--yes-i-really-mean-it") {
+      ss << "this is a potentially destructive operation, only for use by experts in disaster recovery.  "
+        "Add --yes-i-really-mean-it if you are sure you wish to continue.";
+      return -EPERM;
+    }
+
+    fsmap.reset_filesystem(fs->fscid);
+
+    return 0;
+  }
+};
+
+class RemoveDataPoolHandler : public FileSystemCommandHandler
+{
+  public:
+  RemoveDataPoolHandler()
+    : FileSystemCommandHandler("fs rm_data_pool")
+  {}
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    string poolname;
+    cmd_getval(g_ceph_context, cmdmap, "pool", poolname);
+
+    std::string fs_name;
+    if (!cmd_getval(g_ceph_context, cmdmap, "fs_name", fs_name)
+        || fs_name.empty()) {
+      ss << "Missing filesystem name";
+      return -EINVAL;
+    }
+
+    auto fs = fsmap.get_filesystem(fs_name);
+    if (fs == nullptr) {
+      ss << "Not found: '" << fs_name << "'";
+      return -ENOENT;
+    }
+
+    int64_t poolid = mon->osdmon()->osdmap.lookup_pg_pool_name(poolname);
+    if (poolid < 0) {
+      string err;
+      poolid = strict_strtol(poolname.c_str(), 10, &err);
+      if (err.length()) {
+	ss << "pool '" << poolname << "' does not exist";
+        return -ENOENT;
+      } else if (poolid < 0) {
+        ss << "invalid pool id '" << poolid << "'";
+        return -EINVAL;
+      }
+    }
+
+    assert(poolid >= 0);  // Checked by parsing code above
+
+    if (fs->mds_map.get_first_data_pool() == poolid) {
+      ss << "cannot remove default data pool";
+      return -EINVAL;
+    }
+
+
+    int r = 0;
+    fsmap.modify_filesystem(fs->fscid,
+        [&r, poolid](std::shared_ptr<Filesystem> fs)
+    {
+      r = fs->mds_map.remove_data_pool(poolid);
+    });
+    if (r == -ENOENT) {
+      // It was already removed, succeed in silence
+      return 0;
+    } else if (r == 0) {
+      // We removed it, succeed
+      ss << "removed data pool " << poolid << " from fsmap";
+      return 0;
+    } else {
+      // Unexpected error, bubble up
+      return r;
+    }
+  }
+};
+
+
+/**
+ * For commands that refer to a particular filesystem,
+ * enable wrapping to implement the legacy version of
+ * the command (like "mds add_data_pool" vs "fs add_data_pool")
+ *
+ * The wrapped handler must expect a fs_name argument in
+ * its command map.
+ */
+template<typename T>
+class LegacyHandler : public T
+{
+  std::string legacy_prefix;
+
+  public:
+  template <typename... Args>
+  LegacyHandler(const std::string &new_prefix, Args&&... args)
+    : T(std::forward<Args>(args)...)
+  {
+    legacy_prefix = new_prefix;
+  }
+
+  std::string const &get_prefix() override {return legacy_prefix;}
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    auto fs = fsmap.get_legacy_filesystem();
+    if (fs == nullptr) {
+      ss << "No filesystem configured";
+      return -ENOENT;
+    }
+    std::map<string, cmd_vartype> modified = cmdmap;
+    modified["fs_name"] = fs->mds_map.get_fs_name();
+    return T::handle(mon, fsmap, op, modified, ss);
+  }
+};
+
+/**
+ * For commands with an alternative prefix
+ */
+template<typename T>
+class AliasHandler : public T
+{
+  std::string alias_prefix;
+
+  public:
+  AliasHandler(const std::string &new_prefix)
+    : T()
+  {
+    alias_prefix = new_prefix;
+  }
+
+  std::string const &get_prefix() override {return alias_prefix;}
+
+  int handle(
+      Monitor *mon,
+      FSMap &fsmap,
+      MonOpRequestRef op,
+      map<string, cmd_vartype> &cmdmap,
+      std::stringstream &ss) override
+  {
+    return T::handle(mon, fsmap, op, cmdmap, ss);
+  }
+};
+
+
+std::list<std::shared_ptr<FileSystemCommandHandler> >
+FileSystemCommandHandler::load(Paxos *paxos)
+{
+  std::list<std::shared_ptr<FileSystemCommandHandler> > handlers;
+
+  handlers.push_back(std::make_shared<SetHandler>());
+  handlers.push_back(std::make_shared<LegacyHandler<SetHandler> >("mds set"));
+  handlers.push_back(std::make_shared<FlagSetHandler>());
+  handlers.push_back(std::make_shared<AddDataPoolHandler>(paxos));
+  handlers.push_back(std::make_shared<LegacyHandler<AddDataPoolHandler> >(
+        "mds add_data_pool", paxos));
+  handlers.push_back(std::make_shared<RemoveDataPoolHandler>());
+  handlers.push_back(std::make_shared<LegacyHandler<RemoveDataPoolHandler> >(
+        "mds remove_data_pool"));
+  handlers.push_back(std::make_shared<LegacyHandler<RemoveDataPoolHandler> >(
+        "mds rm_data_pool"));
+  handlers.push_back(std::make_shared<FsNewHandler>(paxos));
+  handlers.push_back(std::make_shared<RemoveFilesystemHandler>());
+  handlers.push_back(std::make_shared<ResetFilesystemHandler>());
+
+  handlers.push_back(std::make_shared<SetDefaultHandler>());
+  handlers.push_back(std::make_shared<AliasHandler<SetDefaultHandler> >(
+        "fs set_default"));
+
+  return handlers;
+}
+
+int FileSystemCommandHandler::parse_bool(
+      const std::string &bool_str,
+      bool *result,
+      std::ostream &ss)
+{
+  assert(result != nullptr);
+
+  string interr;
+  int64_t n = strict_strtoll(bool_str.c_str(), 10, &interr);
+
+  if (bool_str == "false" || bool_str == "no"
+      || (interr.length() == 0 && n == 0)) {
+    *result = false;
+    return 0;
+  } else if (bool_str == "true" || bool_str == "yes"
+      || (interr.length() == 0 && n == 1)) {
+    *result = true;
+    return 0;
+  } else {
+    ss << "value must be false|no|0 or true|yes|1";
+    return -EINVAL;
+  }
+}
+
+int FileSystemCommandHandler::_check_pool(
+    OSDMap &osd_map,
+    const int64_t pool_id,
+    bool metadata,
+    bool force,
+    std::stringstream *ss) const
+{
+  assert(ss != NULL);
+
+  const pg_pool_t *pool = osd_map.get_pg_pool(pool_id);
+  if (!pool) {
+    *ss << "pool id '" << pool_id << "' does not exist";
+    return -ENOENT;
+  }
+
+  const string& pool_name = osd_map.get_pool_name(pool_id);
+
+  if (pool->is_erasure() && metadata) {
+      *ss << "pool '" << pool_name << "' (id '" << pool_id << "')"
+         << " is an erasure-coded pool.  Use of erasure-coded pools"
+         << " for CephFS metadata is not permitted";
+    return -EINVAL;
+  } else if (pool->is_erasure() && !pool->allows_ecoverwrites()) {
+    // non-overwriteable EC pools are only acceptable with a cache tier overlay
+    if (!pool->has_tiers() || !pool->has_read_tier() || !pool->has_write_tier()) {
+      *ss << "pool '" << pool_name << "' (id '" << pool_id << "')"
+         << " is an erasure-coded pool, with no overwrite support";
+      return -EINVAL;
+    }
+
+    // That cache tier overlay must be writeback, not readonly (it's the
+    // write operations like modify+truncate we care about support for)
+    const pg_pool_t *write_tier = osd_map.get_pg_pool(
+        pool->write_tier);
+    assert(write_tier != NULL);  // OSDMonitor shouldn't allow DNE tier
+    if (write_tier->cache_mode == pg_pool_t::CACHEMODE_FORWARD
+        || write_tier->cache_mode == pg_pool_t::CACHEMODE_READONLY) {
+      *ss << "EC pool '" << pool_name << "' has a write tier ("
+          << osd_map.get_pool_name(pool->write_tier)
+          << ") that is configured "
+             "to forward writes.  Use a cache mode such as 'writeback' for "
+             "CephFS";
+      return -EINVAL;
+    }
+  }
+
+  if (pool->is_tier()) {
+    *ss << " pool '" << pool_name << "' (id '" << pool_id
+      << "') is already in use as a cache tier.";
+    return -EINVAL;
+  }
+
+  if (!force && !pool->application_metadata.empty() &&
+      pool->application_metadata.count(
+        pg_pool_t::APPLICATION_NAME_CEPHFS) == 0) {
+    *ss << " pool '" << pool_name << "' (id '" << pool_id
+        << "') has a non-CephFS application enabled.";
+    return -EINVAL;
+  }
+
+  // Nothing special about this pool, so it is permissible
+  return 0;
+}
+