Merge pull request #41968 from CongMinYin/fix-ssd-bug

librbd/cache/pwl/ssd: fix m_bytes_allocated exceeding m_bytes_allocated_cap

Reviewed-by: Ilya Dryomov <idryomov@gmail.com>

diff --cc src/librbd/cache/pwl/AbstractWriteLog.cc
Simple merge

diff --cc src/librbd/cache/pwl/Types.h
Simple merge

diff --cc src/librbd/cache/pwl/ssd/WriteLog.cc
Simple merge

diff --cc src/librbd/cache/pwl/ssd/WriteLog.h
Simple merge