X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fsrc%2Ftest%2Flibrados_test_stub%2FTestMemIoCtxImpl.cc;fp=src%2Fceph%2Fsrc%2Ftest%2Flibrados_test_stub%2FTestMemIoCtxImpl.cc;h=cccbe820596317ec2c1aa139e1494b9d9fd60c5b;hb=812ff6ca9fcd3e629e49d4328905f33eee8ca3f5;hp=0000000000000000000000000000000000000000;hpb=15280273faafb77777eab341909a3f495cf248d9;p=stor4nfv.git

diff --git a/src/ceph/src/test/librados_test_stub/TestMemIoCtxImpl.cc b/src/ceph/src/test/librados_test_stub/TestMemIoCtxImpl.cc
new file mode 100644
index 0000000..cccbe82
--- /dev/null
+++ b/src/ceph/src/test/librados_test_stub/TestMemIoCtxImpl.cc
@@ -0,0 +1,788 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "test/librados_test_stub/TestMemIoCtxImpl.h"
+#include "test/librados_test_stub/TestMemRadosClient.h"
+#include "common/Clock.h"
+#include "common/RWLock.h"
+#include "include/err.h"
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/bind.hpp>
+#include <errno.h>
+#include <include/compat.h>
+
+static void to_vector(const interval_set<uint64_t> &set,
+                      std::vector<std::pair<uint64_t, uint64_t> > *vec) {
+  vec->clear();
+  for (interval_set<uint64_t>::const_iterator it = set.begin();
+      it != set.end(); ++it) {
+    vec->push_back(*it);
+  }
+}
+
+namespace librados {
+
+TestMemIoCtxImpl::TestMemIoCtxImpl() {
+}
+
+TestMemIoCtxImpl::TestMemIoCtxImpl(const TestMemIoCtxImpl& rhs)
+    : TestIoCtxImpl(rhs), m_client(rhs.m_client), m_pool(rhs.m_pool) {
+  m_pool->get();
+}
+
+TestMemIoCtxImpl::TestMemIoCtxImpl(TestMemRadosClient *client, int64_t pool_id,
+                                   const std::string& pool_name,
+                                   TestMemCluster::Pool *pool)
+    : TestIoCtxImpl(client, pool_id, pool_name), m_client(client),
+      m_pool(pool) {
+  m_pool->get();
+}
+
+TestMemIoCtxImpl::~TestMemIoCtxImpl() {
+  m_pool->put();
+}
+
+TestIoCtxImpl *TestMemIoCtxImpl::clone() {
+  return new TestMemIoCtxImpl(*this);
+}
+
+int TestMemIoCtxImpl::aio_remove(const std::string& oid, AioCompletionImpl *c) {
+  m_client->add_aio_operation(oid, true,
+                              boost::bind(&TestMemIoCtxImpl::remove, this, oid,
+                                          get_snap_context()),
+                              c);
+  return 0;
+}
+
+int TestMemIoCtxImpl::append(const std::string& oid, const bufferlist &bl,
+                             const SnapContext &snapc) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, true, snapc);
+  }
+
+  RWLock::WLocker l(file->lock);
+  file->data.append(bl);
+  return 0;
+}
+
+int TestMemIoCtxImpl::assert_exists(const std::string &oid) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  RWLock::RLocker l(m_pool->file_lock);
+  TestMemCluster::SharedFile file = get_file(oid, false, get_snap_context());
+  if (file == NULL) {
+    return -ENOENT;
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::create(const std::string& oid, bool exclusive) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  RWLock::WLocker l(m_pool->file_lock);
+  get_file(oid, true, get_snap_context());
+  return 0;
+}
+
+int TestMemIoCtxImpl::list_snaps(const std::string& oid, snap_set_t *out_snaps) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  out_snaps->seq = 0;
+  out_snaps->clones.clear();
+
+  RWLock::RLocker l(m_pool->file_lock);
+  TestMemCluster::Files::iterator it = m_pool->files.find(oid);
+  if (it == m_pool->files.end()) {
+    return -ENOENT;
+  }
+
+  bool include_head = false;
+  TestMemCluster::FileSnapshots &file_snaps = it->second;
+  for (TestMemCluster::FileSnapshots::iterator s_it = file_snaps.begin();
+       s_it != file_snaps.end(); ++s_it) {
+    TestMemCluster::File &file = *s_it->get();
+
+    if (file_snaps.size() > 1) {
+      out_snaps->seq = file.snap_id;
+      TestMemCluster::FileSnapshots::iterator next_it(s_it);
+      ++next_it;
+      if (next_it == file_snaps.end()) {
+        include_head = true;
+        break;
+      }
+
+      ++out_snaps->seq;
+      if (!file.exists) {
+        continue;
+      }
+
+      // update the overlap with the next version's overlap metadata
+      TestMemCluster::File &next_file = *next_it->get();
+      interval_set<uint64_t> overlap;
+      if (next_file.exists) {
+        overlap = next_file.snap_overlap;
+      }
+
+      clone_info_t clone;
+      clone.cloneid = file.snap_id;
+      clone.snaps = file.snaps;
+      to_vector(overlap, &clone.overlap);
+      clone.size = file.data.length();
+      out_snaps->clones.push_back(clone);
+    }
+  }
+
+  if ((file_snaps.size() == 1 && file_snaps.back()->data.length() > 0) ||
+      include_head)
+  {
+    // Include the SNAP_HEAD
+    TestMemCluster::File &file = *file_snaps.back();
+    if (file.exists) {
+      RWLock::RLocker l2(file.lock);
+      if (out_snaps->seq == 0 && !include_head) {
+        out_snaps->seq = file.snap_id;
+      }
+      clone_info_t head_clone;
+      head_clone.cloneid = librados::SNAP_HEAD;
+      head_clone.size = file.data.length();
+      out_snaps->clones.push_back(head_clone);
+    }
+  }
+  return 0;
+
+}
+
+int TestMemIoCtxImpl::omap_get_vals2(const std::string& oid,
+                                    const std::string& start_after,
+                                    const std::string &filter_prefix,
+                                    uint64_t max_return,
+                                    std::map<std::string, bufferlist> *out_vals,
+                                    bool *pmore) {
+  if (out_vals == NULL) {
+    return -EINVAL;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::RLocker l(m_pool->file_lock);
+    file = get_file(oid, false, get_snap_context());
+    if (file == NULL) {
+      return -ENOENT;
+    }
+  }
+
+  out_vals->clear();
+
+  RWLock::RLocker l(file->lock);
+  TestMemCluster::FileOMaps::iterator o_it = m_pool->file_omaps.find(oid);
+  if (o_it == m_pool->file_omaps.end()) {
+    if (pmore) {
+      *pmore = false;
+    }
+    return 0;
+  }
+
+  TestMemCluster::OMap &omap = o_it->second;
+  TestMemCluster::OMap::iterator it = omap.begin();
+  if (!start_after.empty()) {
+    it = omap.upper_bound(start_after);
+  }
+
+  while (it != omap.end() && max_return > 0) {
+    if (filter_prefix.empty() ||
+        boost::algorithm::starts_with(it->first, filter_prefix)) {
+      (*out_vals)[it->first] = it->second;
+      --max_return;
+    }
+    ++it;
+  }
+  if (pmore) {
+    *pmore = (it != omap.end());
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::omap_get_vals(const std::string& oid,
+                                    const std::string& start_after,
+                                    const std::string &filter_prefix,
+                                    uint64_t max_return,
+                                    std::map<std::string, bufferlist> *out_vals) {
+  return omap_get_vals2(oid, start_after, filter_prefix, max_return, out_vals, nullptr);
+}
+
+int TestMemIoCtxImpl::omap_rm_keys(const std::string& oid,
+                                   const std::set<std::string>& keys) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, true, get_snap_context());
+    if (file == NULL) {
+      return -ENOENT;
+    }
+  }
+
+  RWLock::WLocker l(file->lock);
+  for (std::set<std::string>::iterator it = keys.begin();
+       it != keys.end(); ++it) {
+    m_pool->file_omaps[oid].erase(*it);
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::omap_set(const std::string& oid,
+                               const std::map<std::string, bufferlist> &map) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, true, get_snap_context());
+    if (file == NULL) {
+      return -ENOENT;
+    }
+  }
+
+  RWLock::WLocker l(file->lock);
+  for (std::map<std::string, bufferlist>::const_iterator it = map.begin();
+      it != map.end(); ++it) {
+    bufferlist bl;
+    bl.append(it->second);
+    m_pool->file_omaps[oid][it->first] = bl;
+  }
+
+  return 0;
+}
+
+int TestMemIoCtxImpl::read(const std::string& oid, size_t len, uint64_t off,
+                           bufferlist *bl) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::RLocker l(m_pool->file_lock);
+    file = get_file(oid, false, get_snap_context());
+    if (file == NULL) {
+      return -ENOENT;
+    }
+  }
+
+  RWLock::RLocker l(file->lock);
+  if (len == 0) {
+    len = file->data.length();
+  }
+  len = clip_io(off, len, file->data.length());
+  if (bl != NULL && len > 0) {
+    bufferlist bit;
+    bit.substr_of(file->data, off, len);
+    append_clone(bit, bl);
+  }
+  return len;
+}
+
+int TestMemIoCtxImpl::remove(const std::string& oid, const SnapContext &snapc) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  RWLock::WLocker l(m_pool->file_lock);
+  TestMemCluster::SharedFile file = get_file(oid, false, snapc);
+  if (file == NULL) {
+    return -ENOENT;
+  }
+  file = get_file(oid, true, snapc);
+
+  RWLock::WLocker l2(file->lock);
+  file->exists = false;
+
+  TestMemCluster::Files::iterator it = m_pool->files.find(oid);
+  assert(it != m_pool->files.end());
+  if (it->second.size() == 1) {
+    m_pool->files.erase(it);
+    m_pool->file_omaps.erase(oid);
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::selfmanaged_snap_create(uint64_t *snapid) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  RWLock::WLocker l(m_pool->file_lock);
+  *snapid = ++m_pool->snap_id;
+  m_pool->snap_seqs.insert(*snapid);
+  return 0;
+}
+
+int TestMemIoCtxImpl::selfmanaged_snap_remove(uint64_t snapid) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  RWLock::WLocker l(m_pool->file_lock);
+  TestMemCluster::SnapSeqs::iterator it =
+    m_pool->snap_seqs.find(snapid);
+  if (it == m_pool->snap_seqs.end()) {
+    return -ENOENT;
+  }
+
+  // TODO clean up all file snapshots
+  m_pool->snap_seqs.erase(it);
+  return 0;
+}
+
+int TestMemIoCtxImpl::selfmanaged_snap_rollback(const std::string& oid,
+                                                uint64_t snapid) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  RWLock::WLocker l(m_pool->file_lock);
+
+  TestMemCluster::SharedFile file;
+  TestMemCluster::Files::iterator f_it = m_pool->files.find(oid);
+  if (f_it == m_pool->files.end()) {
+    return 0;
+  }
+
+  TestMemCluster::FileSnapshots &snaps = f_it->second;
+  file = snaps.back();
+
+  size_t versions = 0;
+  for (TestMemCluster::FileSnapshots::reverse_iterator it = snaps.rbegin();
+      it != snaps.rend(); ++it) {
+    TestMemCluster::SharedFile file = *it;
+    if (file->snap_id < get_snap_read()) {
+      if (versions == 0) {
+        // already at the snapshot version
+        return 0;
+      } else if (file->snap_id == CEPH_NOSNAP) {
+        if (versions == 1) {
+          // delete it current HEAD, next one is correct version
+          snaps.erase(it.base());
+        } else {
+          // overwrite contents of current HEAD
+          file = TestMemCluster::SharedFile (new TestMemCluster::File(**it));
+          file->snap_id = CEPH_NOSNAP;
+          *it = file;
+        }
+      } else {
+        // create new head version
+        file = TestMemCluster::SharedFile (new TestMemCluster::File(**it));
+        file->snap_id = m_pool->snap_id;
+        snaps.push_back(file);
+      }
+      return 0;
+    }
+    ++versions;
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::sparse_read(const std::string& oid, uint64_t off,
+                                  uint64_t len,
+                                  std::map<uint64_t,uint64_t> *m,
+                                  bufferlist *data_bl) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  // TODO verify correctness
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::RLocker l(m_pool->file_lock);
+    file = get_file(oid, false, get_snap_context());
+    if (file == NULL) {
+      return -ENOENT;
+    }
+  }
+
+  RWLock::RLocker l(file->lock);
+  len = clip_io(off, len, file->data.length());
+  if (m != NULL) {
+    m->clear();
+    if (len > 0) {
+      (*m)[off] = len;
+    }
+  }
+  if (data_bl != NULL && len > 0) {
+    bufferlist bit;
+    bit.substr_of(file->data, off, len);
+    append_clone(bit, data_bl);
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::stat(const std::string& oid, uint64_t *psize,
+                           time_t *pmtime) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::RLocker l(m_pool->file_lock);
+    file = get_file(oid, false, get_snap_context());
+    if (file == NULL) {
+      return -ENOENT;
+    }
+  }
+
+  RWLock::RLocker l(file->lock);
+  if (psize != NULL) {
+    *psize = file->data.length();
+  }
+  if (pmtime != NULL) {
+    *pmtime = file->mtime;
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::truncate(const std::string& oid, uint64_t size,
+                               const SnapContext &snapc) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, true, snapc);
+  }
+
+  RWLock::WLocker l(file->lock);
+  bufferlist bl(size);
+
+  interval_set<uint64_t> is;
+  if (file->data.length() > size) {
+    is.insert(size, file->data.length() - size);
+
+    bl.substr_of(file->data, 0, size);
+    file->data.swap(bl);
+  } else if (file->data.length() != size) {
+    if (size == 0) {
+      bl.clear();
+    } else {
+      is.insert(0, size);
+
+      bl.append_zero(size - file->data.length());
+      file->data.append(bl);
+    }
+  }
+  is.intersection_of(file->snap_overlap);
+  file->snap_overlap.subtract(is);
+  return 0;
+}
+
+int TestMemIoCtxImpl::write(const std::string& oid, bufferlist& bl, size_t len,
+                            uint64_t off, const SnapContext &snapc) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, true, snapc);
+  }
+
+  RWLock::WLocker l(file->lock);
+  if (len > 0) {
+    interval_set<uint64_t> is;
+    is.insert(off, len);
+    is.intersection_of(file->snap_overlap);
+    file->snap_overlap.subtract(is);
+  }
+
+  ensure_minimum_length(off + len, &file->data);
+  file->data.copy_in(off, len, bl);
+  return 0;
+}
+
+int TestMemIoCtxImpl::write_full(const std::string& oid, bufferlist& bl,
+                                 const SnapContext &snapc) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, true, snapc);
+    if (file == NULL) {
+      return -ENOENT;
+    }
+  }
+
+  RWLock::WLocker l(file->lock);
+  if (bl.length() > 0) {
+    interval_set<uint64_t> is;
+    is.insert(0, bl.length());
+    is.intersection_of(file->snap_overlap);
+    file->snap_overlap.subtract(is);
+  }
+
+  file->data.clear();
+  file->data.append(bl);
+  return 0;
+}
+
+int TestMemIoCtxImpl::writesame(const std::string& oid, bufferlist& bl, size_t len,
+                                uint64_t off, const SnapContext &snapc) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  if (len == 0 || (len % bl.length())) {
+    return -EINVAL;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, true, snapc);
+  }
+
+  RWLock::WLocker l(file->lock);
+  if (len > 0) {
+    interval_set<uint64_t> is;
+    is.insert(off, len);
+    is.intersection_of(file->snap_overlap);
+    file->snap_overlap.subtract(is);
+  }
+
+  ensure_minimum_length(off + len, &file->data);
+  while (len > 0) {
+    file->data.copy_in(off, bl.length(), bl);
+    off += bl.length();
+    len -= bl.length();
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::cmpext(const std::string& oid, uint64_t off,
+                             bufferlist& cmp_bl) {
+  if (get_snap_read() != CEPH_NOSNAP) {
+    return -EROFS;
+  } else if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  if (cmp_bl.length() == 0) {
+    return -EINVAL;
+  }
+
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, true, get_snap_context());
+  }
+
+  RWLock::RLocker l(file->lock);
+  size_t len = cmp_bl.length();
+  ensure_minimum_length(off + len, &file->data);
+  if (len > 0 && off <= len) {
+    for (uint64_t p = off; p < len; p++)  {
+      if (file->data[p] != cmp_bl[p])
+        return -MAX_ERRNO - p;
+    }
+  }
+  return 0;
+}
+
+int TestMemIoCtxImpl::xattr_get(const std::string& oid,
+                                std::map<std::string, bufferlist>* attrset) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  TestMemCluster::SharedFile file;
+  RWLock::RLocker l(m_pool->file_lock);
+  TestMemCluster::FileXAttrs::iterator it = m_pool->file_xattrs.find(oid);
+  if (it == m_pool->file_xattrs.end()) {
+    return -ENODATA;
+  }
+  *attrset = it->second;
+  return 0;
+}
+
+int TestMemIoCtxImpl::xattr_set(const std::string& oid, const std::string &name,
+                                bufferlist& bl) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  RWLock::WLocker l(m_pool->file_lock);
+  m_pool->file_xattrs[oid][name] = bl;
+  return 0;
+}
+
+int TestMemIoCtxImpl::zero(const std::string& oid, uint64_t off, uint64_t len) {
+  if (m_client->is_blacklisted()) {
+    return -EBLACKLISTED;
+  }
+
+  bool truncate_redirect = false;
+  TestMemCluster::SharedFile file;
+  {
+    RWLock::WLocker l(m_pool->file_lock);
+    file = get_file(oid, false, get_snap_context());
+    if (!file) {
+      return 0;
+    }
+    file = get_file(oid, true, get_snap_context());
+
+    RWLock::RLocker l2(file->lock);
+    if (len > 0 && off + len >= file->data.length()) {
+      // Zero -> Truncate logic embedded in OSD
+      truncate_redirect = true;
+    }
+  }
+  if (truncate_redirect) {
+    return truncate(oid, off, get_snap_context());
+  }
+
+  bufferlist bl;
+  bl.append_zero(len);
+  return write(oid, bl, len, off, get_snap_context());
+}
+
+void TestMemIoCtxImpl::append_clone(bufferlist& src, bufferlist* dest) {
+  // deep-copy the src to ensure our memory-based mock RADOS data cannot
+  // be modified by callers
+  if (src.length() > 0) {
+    bufferlist::iterator iter = src.begin();
+    buffer::ptr ptr;
+    iter.copy_deep(src.length(), ptr);
+    dest->append(ptr);
+  }
+}
+
+size_t TestMemIoCtxImpl::clip_io(size_t off, size_t len, size_t bl_len) {
+  if (off >= bl_len) {
+    len = 0;
+  } else if (off + len > bl_len) {
+    len = bl_len - off;
+  }
+  return len;
+}
+
+void TestMemIoCtxImpl::ensure_minimum_length(size_t len, bufferlist *bl) {
+  if (len > bl->length()) {
+    bufferptr ptr(buffer::create(len - bl->length()));
+    ptr.zero();
+    bl->append(ptr);
+  }
+}
+
+TestMemCluster::SharedFile TestMemIoCtxImpl::get_file(
+    const std::string &oid, bool write, const SnapContext &snapc) {
+  assert(m_pool->file_lock.is_locked() || m_pool->file_lock.is_wlocked());
+  assert(!write || m_pool->file_lock.is_wlocked());
+
+  TestMemCluster::SharedFile file;
+  TestMemCluster::Files::iterator it = m_pool->files.find(oid);
+  if (it != m_pool->files.end()) {
+    file = it->second.back();
+  } else if (!write) {
+    return TestMemCluster::SharedFile();
+  }
+
+  if (write) {
+    bool new_version = false;
+    if (!file || !file->exists) {
+      file = TestMemCluster::SharedFile(new TestMemCluster::File());
+      new_version = true;
+    } else {
+      if (!snapc.snaps.empty() && file->snap_id < snapc.seq) {
+        for (std::vector<snapid_t>::const_reverse_iterator seq_it =
+            snapc.snaps.rbegin();
+            seq_it != snapc.snaps.rend(); ++seq_it) {
+          if (*seq_it > file->snap_id && *seq_it <= snapc.seq) {
+            file->snaps.push_back(*seq_it);
+          }
+        }
+
+        bufferlist prev_data = file->data;
+        file = TestMemCluster::SharedFile(
+          new TestMemCluster::File(*file));
+        file->data.clear();
+        append_clone(prev_data, &file->data);
+        if (prev_data.length() > 0) {
+          file->snap_overlap.insert(0, prev_data.length());
+        }
+        new_version = true;
+      }
+    }
+
+    if (new_version) {
+      file->snap_id = snapc.seq;
+      file->mtime = ceph_clock_now().sec();
+      m_pool->files[oid].push_back(file);
+    }
+    return file;
+  }
+
+  if (get_snap_read() == CEPH_NOSNAP) {
+    if (!file->exists) {
+      assert(it->second.size() > 1);
+      return TestMemCluster::SharedFile();
+    }
+    return file;
+  }
+
+  TestMemCluster::FileSnapshots &snaps = it->second;
+  for (TestMemCluster::FileSnapshots::reverse_iterator it = snaps.rbegin();
+      it != snaps.rend(); ++it) {
+    TestMemCluster::SharedFile file = *it;
+    if (file->snap_id < get_snap_read()) {
+      if (!file->exists) {
+        return TestMemCluster::SharedFile();
+      }
+      return file;
+    }
+  }
+  return TestMemCluster::SharedFile();
+}
+
+} // namespace librados