From: Samuel Just <sjust@redhat.com>
Date: Sat, 10 Apr 2021 01:02:57 +0000 (-0700)
Subject: crimson/os/seastore/transaction_manager: add zero region reservation
X-Git-Tag: v17.1.0~2198^2~3
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=80f7b59942e394ca513d878cd6f945a58520a92e;p=ceph.git

crimson/os/seastore/transaction_manager: add zero region reservation

Add logical mappings for zero regions for use in reserving contiguous
sections of laddr space.

Signed-off-by: Samuel Just <sjust@redhat.com>
---

diff --git a/src/crimson/os/seastore/seastore_types.cc b/src/crimson/os/seastore/seastore_types.cc
index 1c838ef0bd6c..f5a5debbb6c0 100644
--- a/src/crimson/os/seastore/seastore_types.cc
+++ b/src/crimson/os/seastore/seastore_types.cc
@@ -13,6 +13,8 @@ std::ostream &segment_to_stream(std::ostream &out, const segment_id_t &t)
     return out << "BLOCK_REL_SEG";
   else if (t == RECORD_REL_SEG_ID)
     return out << "RECORD_REL_SEG";
+  else if (t == ZERO_SEG_ID)
+    return out << "ZERO_SEG";
   else if (t == FAKE_SEG_ID)
     return out << "FAKE_SEG";
   else
diff --git a/src/crimson/os/seastore/seastore_types.h b/src/crimson/os/seastore/seastore_types.h
index b56b51450e8d..d6c78a400a3f 100644
--- a/src/crimson/os/seastore/seastore_types.h
+++ b/src/crimson/os/seastore/seastore_types.h
@@ -43,11 +43,16 @@ constexpr segment_id_t RECORD_REL_SEG_ID =
   std::numeric_limits<segment_id_t>::max() - 2;
 constexpr segment_id_t BLOCK_REL_SEG_ID =
   std::numeric_limits<segment_id_t>::max() - 3;
-
 // for tests which generate fake paddrs
 constexpr segment_id_t FAKE_SEG_ID =
   std::numeric_limits<segment_id_t>::max() - 4;
 
+/* Used to denote references to notional zero filled segment, mainly
+ * in denoting reserved laddr ranges for unallocated object data.
+ */
+constexpr segment_id_t ZERO_SEG_ID =
+  std::numeric_limits<segment_id_t>::max() - 5;
+
 std::ostream &segment_to_stream(std::ostream &, const segment_id_t &t);
 
 // Offset within a segment on disk, see SegmentManager
@@ -103,6 +108,27 @@ struct paddr_t {
     return segment == BLOCK_REL_SEG_ID;
   }
 
+  /// Denotes special zero segment addr
+  bool is_zero() const {
+    return segment == ZERO_SEG_ID;
+  }
+
+  /// Denotes special null segment addr
+  bool is_null() const {
+    return segment == NULL_SEG_ID;
+  }
+
+  /**
+   * is_real
+   *
+   * indicates whether addr reflects a physical location, absolute
+   * or relative.  FAKE segments also count as real so as to reflect
+   * the way in which unit tests use them.
+   */
+  bool is_real() const {
+    return !is_zero() && !is_null();
+  }
+
   paddr_t add_offset(segment_off_t o) const {
     return paddr_t{segment, offset + o};
   }
@@ -175,6 +201,9 @@ constexpr paddr_t make_block_relative_paddr(segment_off_t off) {
 constexpr paddr_t make_fake_paddr(segment_off_t off) {
   return paddr_t{FAKE_SEG_ID, off};
 }
+constexpr paddr_t zero_paddr() {
+  return paddr_t{ZERO_SEG_ID, 0};
+}
 
 struct __attribute((packed)) paddr_le_t {
   ceph_le32 segment = ceph_le32(NULL_SEG_ID);
diff --git a/src/crimson/os/seastore/transaction_manager.cc b/src/crimson/os/seastore/transaction_manager.cc
index f9689254b916..3b7d74733a79 100644
--- a/src/crimson/os/seastore/transaction_manager.cc
+++ b/src/crimson/os/seastore/transaction_manager.cc
@@ -156,7 +156,7 @@ TransactionManager::ref_ret TransactionManager::dec_ref(
 {
   return lba_manager->decref_extent(t, offset
   ).safe_then([this, offset, &t](auto result) -> ref_ret {
-    if (result.refcount == 0) {
+    if (result.refcount == 0 && !result.addr.is_zero()) {
       logger().debug(
 	"TransactionManager::dec_ref: offset {} refcount 0",
 	offset);
diff --git a/src/crimson/os/seastore/transaction_manager.h b/src/crimson/os/seastore/transaction_manager.h
index d8c31a924d6e..1b260f4f021b 100644
--- a/src/crimson/os/seastore/transaction_manager.h
+++ b/src/crimson/os/seastore/transaction_manager.h
@@ -168,7 +168,7 @@ public:
     return get_pins(
       t, offset, length
     ).safe_then([this, &t, offset, length](auto pins) {
-      if (pins.size() != 1) {
+      if (pins.size() != 1 || !pins.front()->get_paddr().is_real()) {
 	auto &logger = crimson::get_logger(ceph_subsys_filestore);
 	logger.error(
 	  "TransactionManager::read_extent offset {} len {} got {} extents:",
@@ -267,6 +267,19 @@ public:
     });
   }
 
+  using reserve_extent_ertr = alloc_extent_ertr;
+  using reserve_extent_ret = reserve_extent_ertr::future<LBAPinRef>;
+  reserve_extent_ret reserve_region(
+    Transaction &t,
+    laddr_t hint,
+    extent_len_t len) {
+    return lba_manager->alloc_extent(
+      t,
+      hint,
+      len,
+      zero_paddr());
+  }
+
   using find_hole_ertr = LBAManager::find_hole_ertr;
   using find_hole_ret = LBAManager::find_hole_ret;
   find_hole_ret find_hole(