Function FlushDatabaseBuffers

src/backend/storage/buffer/bufmgr.c:3917–3954

--------------------------------------------------------------------- * FlushDatabaseBuffers * * This function writes all dirty pages of a database out to disk * (or more accurately, out to kernel disk buffers), ensuring that the * kernel has an up-to-date view of the database. * * Generally, the caller should be holding an appropriate lock to ensure * no other backend is active in t

 * --------------------------------------------------------------------
 */
void
FlushDatabaseBuffers(Oid dbid)
{
	int			i;
	BufferDesc *bufHdr;

	/* Make sure we can handle the pin inside the loop */
	ResourceOwnerEnlargeBuffers(CurrentResourceOwner);

	for (i = 0; i < NBuffers; i++)
	{
		uint32		buf_state;

		bufHdr = GetBufferDescriptor(i);

		/*
		 * As in DropRelFileNodeBuffers, an unlocked precheck should be safe
		 * and saves some cycles.
		 */
		if (bufHdr->tag.rnode.dbNode != dbid)
			continue;

		ReservePrivateRefCountEntry();

		buf_state = LockBufHdr(bufHdr);
		if (bufHdr->tag.rnode.dbNode == dbid &&
			(buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
		{
			PinBuffer_Locked(bufHdr);
			AcquireContentLock(bufHdr, LW_SHARED);
			FlushBuffer(bufHdr, NULL);
			ReleaseContentLock(bufHdr);
			UnpinBuffer(bufHdr, true);
		}
		else
			UnlockBufHdr(bufHdr, buf_state);
	}
}

/*
 * Flush a previously, shared or exclusively, locked and pinned buffer to the