librbd/cache/pwl: make pool size a multiple of 1M

In ssd mode, we need it to be a multiple of bdev block size.
Instead of munging it after opening the bdev in ssd/WriteLog.cc, let's
impose a common restriction and round rbd_persistent_cache_size down to
a 1M boundary.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
(cherry picked from commit 1fc722bc218acfe8a52ad7be2c06347bddb42bbe)

diff --git a/src/librbd/cache/pwl/AbstractWriteLog.cc b/src/librbd/cache/pwl/AbstractWriteLog.cc
index 62fadc3331cf690a1b1d377f62df753300c2f099..518628b952852bd2139fbd90a2b0cfc7b32770b0 100644 (file)
--- a/src/librbd/cache/pwl/AbstractWriteLog.cc
+++ b/src/librbd/cache/pwl/AbstractWriteLog.cc
@@ -511,6 +511,9 @@ void AbstractWriteLog<I>::pwl_init(Context *on_finish, DeferredContexts &later)
 
   m_log_pool_name = m_cache_state->path;
   m_log_pool_size = max(m_cache_state->size, MIN_POOL_SIZE);
+  m_log_pool_size = p2align(m_log_pool_size, POOL_SIZE_ALIGN);
+  ldout(cct, 5) << "pool " << m_log_pool_name << " size " << m_log_pool_size
+                << " (adjusted from " << m_cache_state->size << ")" << dendl;
 
   if ((!m_cache_state->present) &&
       (access(m_log_pool_name.c_str(), F_OK) == 0)) {

diff --git a/src/librbd/cache/pwl/Types.h b/src/librbd/cache/pwl/Types.h
index 5d438b2f11d0631e4eac219306b65ce525c9d822..a646e971acbe19ac4c8f935dc49637c2cf14c407 100644 (file)
--- a/src/librbd/cache/pwl/Types.h
+++ b/src/librbd/cache/pwl/Types.h
@@ -173,6 +173,7 @@ const unsigned int MAX_CONCURRENT_WRITES = (1024 * 1024);
 
 const uint64_t DEFAULT_POOL_SIZE = 1u<<30;
 const uint64_t MIN_POOL_SIZE = DEFAULT_POOL_SIZE;
+const uint64_t POOL_SIZE_ALIGN = 1 << 20;
 constexpr double USABLE_SIZE = (7.0 / 10);
 const uint64_t BLOCK_ALLOC_OVERHEAD_BYTES = 16;
 const uint8_t RWL_POOL_VERSION = 1;