From 9ad42cd32c3dd98c1d90f1001ce8ffce6ba96616 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Mon, 30 Jun 2025 14:30:38 -0400 Subject: [PATCH v3 6/6] bufmgr: Introduce FlushUnlockedBuffer There were several copies of code locking a buffer, flushing its contents, and unlocking the buffer. It seems worth centralizing that into a helper function. Author: Reviewed-by: Discussion: https://postgr.es/m/ Backpatch: --- src/backend/storage/buffer/bufmgr.c | 36 ++++++++++++++++------------- 1 file changed, 20 insertions(+), 16 deletions(-) diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index ba6c9bbf7c2..4f70cf62a9f 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -533,6 +533,8 @@ static inline BufferDesc *BufferAlloc(SMgrRelation smgr, static bool AsyncReadBuffers(ReadBuffersOperation *operation, int *nblocks_progress); static void CheckReadBuffersOperation(ReadBuffersOperation *operation, bool is_complete); static Buffer GetVictimBuffer(BufferAccessStrategy strategy, IOContext io_context); +static void FlushUnlockedBuffer(BufferDesc *buf, SMgrRelation reln, + IOObject io_object, IOContext io_context); static void FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object, IOContext io_context); static void FindAndDropRelationBuffers(RelFileLocator rlocator, @@ -3948,11 +3950,8 @@ SyncOneBuffer(int buf_id, bool skip_recently_used, WritebackContext *wb_context) * buffer is clean by the time we've locked it.) */ PinBuffer_Locked(bufHdr); - LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED); - FlushBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL); - - LWLockRelease(BufferDescriptorGetContentLock(bufHdr)); + FlushUnlockedBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL); tag = bufHdr->tag; @@ -4400,6 +4399,19 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object, error_context_stack = errcallback.previous; } +/* + * Convenience wrapper around FlushBuffer() that locks/unlocks the buffer + * before/after calling FlushBuffer(). + */ +static void +FlushUnlockedBuffer(BufferDesc *buf, SMgrRelation reln, + IOObject io_object, IOContext io_context) +{ + LWLockAcquire(BufferDescriptorGetContentLock(buf), LW_SHARED); + FlushBuffer(buf, reln, IOOBJECT_RELATION, IOCONTEXT_NORMAL); + LWLockRelease(BufferDescriptorGetContentLock(buf)); +} + /* * RelationGetNumberOfBlocksInFork * Determines the current number of pages in the specified relation fork. @@ -4984,9 +4996,7 @@ FlushRelationBuffers(Relation rel) (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY)) { PinBuffer_Locked(bufHdr); - LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED); - FlushBuffer(bufHdr, srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL); - LWLockRelease(BufferDescriptorGetContentLock(bufHdr)); + FlushUnlockedBuffer(bufHdr, srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL); UnpinBuffer(bufHdr); } else @@ -5081,9 +5091,7 @@ FlushRelationsAllBuffers(SMgrRelation *smgrs, int nrels) (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY)) { PinBuffer_Locked(bufHdr); - LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED); - FlushBuffer(bufHdr, srelent->srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL); - LWLockRelease(BufferDescriptorGetContentLock(bufHdr)); + FlushUnlockedBuffer(bufHdr, srelent->srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL); UnpinBuffer(bufHdr); } else @@ -5309,9 +5317,7 @@ FlushDatabaseBuffers(Oid dbid) (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY)) { PinBuffer_Locked(bufHdr); - LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED); - FlushBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL); - LWLockRelease(BufferDescriptorGetContentLock(bufHdr)); + FlushUnlockedBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL); UnpinBuffer(bufHdr); } else @@ -6601,10 +6607,8 @@ EvictUnpinnedBufferInternal(BufferDesc *desc, bool *buffer_flushed) /* If it was dirty, try to clean it once. */ if (buf_state & BM_DIRTY) { - LWLockAcquire(BufferDescriptorGetContentLock(desc), LW_SHARED); - FlushBuffer(desc, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL); + FlushUnlockedBuffer(desc, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL); *buffer_flushed = true; - LWLockRelease(BufferDescriptorGetContentLock(desc)); } /* This will return false if it becomes dirty or someone else pins it. */ -- 2.48.1.76.g4e746b1a31.dirty