os/bluestore: Add ExtentMap::split_at and ExtentMap::maybe_split_at

Created dedicated mutator of ExtentMap that is useful when
a logical extent must be split.

Signed-off-by: Adam Kupczyk <akupczyk@ibm.com>

diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index 3bcdfa72b4c909a126ee2d70fc95120976014e6e..d646cb56294f2096936c39afea9dd27b1554cf78 100644 (file)
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -4299,6 +4299,42 @@ BlueStore::extent_map_t::const_iterator BlueStore::ExtentMap::seek_lextent(
   return fp;
 }
 
+// Split extent at desired offset.
+// Returns iterator to the right part.
+BlueStore::extent_map_t::iterator BlueStore::ExtentMap::split_at(
+  BlueStore::extent_map_t::iterator p, uint32_t offset)
+{
+  ceph_assert(p != extent_map.end());
+  ceph_assert(p->logical_offset < offset);
+  ceph_assert(offset < p->logical_end());
+  add(offset, p->blob_offset + (offset - p->logical_offset),
+      p->logical_end() - offset, p->blob);
+  p->length = offset - p->logical_offset;
+  ++p;
+  return p;
+}
+
+// If inside extent split it, and return right part.
+// If not inside extent return extent on right.
+BlueStore::extent_map_t::iterator BlueStore::ExtentMap::maybe_split_at(uint32_t offset)
+{
+  auto p = seek_lextent(offset);
+  if (p != extent_map.end()) {
+    if (p->logical_offset < offset && offset < p->logical_end()) {
+      // need to split
+      add(offset, p->blob_offset + (offset - p->logical_offset),
+          p->logical_end() - offset, p->blob);
+      p->length = offset - p->logical_offset;
+      ++p;
+      // check that we moved to proper extent
+      ceph_assert(p->logical_offset == offset);
+    } else {
+      // the extent is either outside offset or exactly at
+    }
+  }
+  return p;
+}
+
 bool BlueStore::ExtentMap::has_any_lextents(uint64_t offset, uint64_t length)
 {
   auto fp = seek_lextent(offset);

diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
index 87fe96ccc988b4f7877732642a7b22190624ae85..2cb7229942d8a93080da3963d0918db6ed6c21fd 100644 (file)
--- a/src/os/bluestore/BlueStore.h
+++ b/src/os/bluestore/BlueStore.h
@@ -1149,6 +1149,10 @@ public:
     extent_map_t::iterator seek_lextent(uint64_t offset);
     extent_map_t::const_iterator seek_lextent(uint64_t offset) const;
 
+    /// split extent
+    extent_map_t::iterator split_at(extent_map_t::iterator p, uint32_t offset);
+    /// if inside extent split it, if not return extent on right
+    extent_map_t::iterator maybe_split_at(uint32_t offset);
     /// add a new Extent
     void add(uint32_t lo, uint32_t o, uint32_t l, BlobRef& b) {
       extent_map.insert(*new Extent(lo, o, l, b));