FileStore: add global replay guard for split, collection_rename

In the event of a split or collection rename, we need to ensure that
we don't replay any operations on objects within those collections
prior to that point.  Thus, we mark a global replay guard on the
collection after doing a syncfs and make sure to check that in
_check_replay_guard() for all object operations.

Fixes: #5154
Signed-off-by: Samuel Just <sam.just@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
(cherry picked from commit f3f92fe21061e21c8b259df5ef283a61782a44db)

Conflicts:

	src/os/FileStore.cc

2 files changed, 84 insertions, 0 deletions

diff --git a/src/os/FileStore.cc b/src/os/FileStore.cc
index a91c252e531..82185dc9d7c 100644
--- a/src/os/FileStore.cc
+++ b/src/os/FileStore.cc
@@ -96,6 +96,7 @@ static const __SWORD_TYPE BTRFS_SUPER_MAGIC(0x9123683E);
 #define CLUSTER_SNAP_ITEM "clustersnap_%s"
 
 #define REPLAY_GUARD_XATTR "user.cephos.seq"
+#define GLOBAL_REPLAY_GUARD_XATTR "user.cephos.gseq"
 
 /*
  * long file names will have the following format:
@@ -2158,6 +2159,78 @@ int FileStore::_do_transactions(
   return r;
 }
 
+void FileStore::_set_global_replay_guard(coll_t cid,
+					 const SequencerPosition &spos)
+{
+  if (btrfs_stable_commits)
+    return;
+
+  // sync all previous operations on this sequencer
+  sync_filesystem(basedir_fd);
+
+  char fn[PATH_MAX];
+  get_cdir(cid, fn, sizeof(fn));
+  int fd = ::open(fn, O_RDONLY);
+  if (fd < 0) {
+    int err = errno;
+    derr << __func__ << ": " << cid << " error " << cpp_strerror(err) << dendl;
+    assert(0 == "_set_global_replay_guard failed");
+  }
+
+  _inject_failure();
+
+  // then record that we did it
+  bufferlist v;
+  ::encode(spos, v);
+  int r = chain_fsetxattr(fd, GLOBAL_REPLAY_GUARD_XATTR, v.c_str(), v.length());
+  if (r < 0) {
+    derr << __func__ << ": fsetxattr " << GLOBAL_REPLAY_GUARD_XATTR
+	 << " got " << cpp_strerror(r) << dendl;
+    assert(0 == "fsetxattr failed");
+  }
+
+  // and make sure our xattr is durable.
+  ::fsync(fd);
+
+  _inject_failure();
+
+  TEMP_FAILURE_RETRY(::close(fd));
+  dout(10) << __func__ << ": " << spos << " done" << dendl;
+}
+
+int FileStore::_check_global_replay_guard(coll_t cid,
+					  const SequencerPosition& spos)
+{
+  if (!replaying || btrfs_stable_commits)
+    return 1;
+
+  char fn[PATH_MAX];
+  get_cdir(cid, fn, sizeof(fn));
+  int fd = ::open(fn, O_RDONLY);
+  if (fd < 0) {
+    dout(10) << __func__ << ": " << cid << " dne" << dendl;
+    return 1;  // if collection does not exist, there is no guard, and we can replay.
+  }
+
+  char buf[100];
+  int r = chain_fgetxattr(fd, GLOBAL_REPLAY_GUARD_XATTR, buf, sizeof(buf));
+  if (r < 0) {
+    dout(20) << __func__ << " no xattr" << dendl;
+    assert(!m_filestore_fail_eio || r != -EIO);
+    return 1;  // no xattr
+  }
+  bufferlist bl;
+  bl.append(buf, r);
+
+  SequencerPosition opos;
+  bufferlist::iterator p = bl.begin();
+  ::decode(opos, p);
+
+  TEMP_FAILURE_RETRY(::close(fd));
+  return spos >= opos ? 1 : -1;
+}
+
+
 void FileStore::_set_replay_guard(coll_t cid,
                                   const SequencerPosition &spos,
                                   bool in_progress=false)
@@ -2261,6 +2334,10 @@ int FileStore::_check_replay_guard(coll_t cid, hobject_t oid, const SequencerPos
   if (!replaying || btrfs_stable_commits)
     return 1;
 
+  int r = _check_global_replay_guard(cid, spos);
+  if (r < 0)
+    return r;
+
   int fd = lfn_open(cid, oid, 0);
   if (fd < 0) {
     dout(10) << "_check_replay_guard " << cid << " " << oid << " dne" << dendl;
@@ -4275,6 +4352,9 @@ int FileStore::_collection_rename(const coll_t &cid, const coll_t &ncid,
   get_cdir(cid, old_coll, sizeof(old_coll));
   get_cdir(ncid, new_coll, sizeof(new_coll));
 
+  _set_global_replay_guard(cid, spos);
+  _set_replay_guard(cid, spos);
+
   if (_check_replay_guard(cid, spos) < 0) {
     return 0;
   }
@@ -4782,6 +4862,7 @@ int FileStore::_split_collection(coll_t cid,
     if (srccmp < 0)
       return 0;
 
+    _set_global_replay_guard(cid, spos);
     _set_replay_guard(cid, spos, true);
     _set_replay_guard(dest, spos, true);
 
diff --git a/src/os/FileStore.h b/src/os/FileStore.h
index d5ca2a4c237..e4f7e81a502 100644
--- a/src/os/FileStore.h
+++ b/src/os/FileStore.h
@@ -333,6 +333,8 @@ public:
   void _set_replay_guard(coll_t cid,
                          const SequencerPosition& spos,
                          bool in_progress);
+  void _set_global_replay_guard(coll_t cid,
+				const SequencerPosition &spos);
 
   /// close a replay guard opened with in_progress=true
   void _close_replay_guard(int fd, const SequencerPosition& spos);
@@ -357,6 +359,7 @@ public:
   int _check_replay_guard(int fd, const SequencerPosition& spos);
   int _check_replay_guard(coll_t cid, const SequencerPosition& spos);
   int _check_replay_guard(coll_t cid, hobject_t oid, const SequencerPosition& pos);
+  int _check_global_replay_guard(coll_t cid, const SequencerPosition& spos);
 
   // ------------------
   // objects