PendingReleaseNotes: add rbd compare-and-write notes

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
(cherry picked from commit 4ddcb7ff92a51a6fa17887e54fd357bd5dea5f4e)

Conflicts:
	PendingReleaseNotes [ moved to >=17.2.5 section ]

diff --git a/PendingReleaseNotes b/PendingReleaseNotes
index 53447bf4c2153aebf524c3780c54f538b50de479..f4d85bb6f07f0db9905de7c57fdcf2b5f926e046 100644 (file)
--- a/PendingReleaseNotes
+++ b/PendingReleaseNotes
@@ -1,3 +1,16 @@
+>=17.2.5
+--------
+
+* RBD: The semantics of compare-and-write C++ API (`Image::compare_and_write`
+  and `Image::aio_compare_and_write` methods) now match those of C API.  Both
+  compare and write steps operate only on `len` bytes even if the respective
+  buffers are larger. The previous behavior of comparing up to the size of
+  the compare buffer was prone to subtle breakage upon straddling a stripe
+  unit boundary.
+* RBD: compare-and-write operation is no longer limited to 512-byte sectors.
+  Assuming proper alignment, it now allows operating on stripe units (4M by
+  default).
+
 >=17.2.4
 --------