StrategyDirtyBufferList wasn't being careful to honor max_buffers limit.

tglsfdc · tglsfdc · commit bbf0ebadaf3f · 2004-06-11T17:20:39.000Z
Bug is only latent given that sole caller is passing NBuffers, but it
could bite someone in the rear someday.
diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c
@@ -12,7 +12,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.44 2004/06/03 02:08:03 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.45 2004/06/11 17:20:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -709,6 +709,7 @@ StrategyInvalidateBuffer(BufferDesc *buf)
 	 */
 	CLEAR_BUFFERTAG(buf->tag);
 	buf->flags &= ~(BM_VALID | BM_DIRTY);
+	buf->cntxDirty = false;
 	buf->bufNext = StrategyControl->listFreeBuffers;
 	StrategyControl->listFreeBuffers = buf->buf_id;
 }
@@ -757,8 +758,7 @@ StrategyDirtyBufferList(BufferDesc **buffers, BufferTag *buftags,
 	cdb_id_t1 = StrategyControl->listHead[STRAT_LIST_T1];
 	cdb_id_t2 = StrategyControl->listHead[STRAT_LIST_T2];
 
-	while ((cdb_id_t1 >= 0 || cdb_id_t2 >= 0) && 
-		   num_buffer_dirty < max_buffers)
+	while (cdb_id_t1 >= 0 || cdb_id_t2 >= 0)
 	{
 		if (cdb_id_t1 >= 0)
 		{
@@ -772,6 +772,8 @@ StrategyDirtyBufferList(BufferDesc **buffers, BufferTag *buftags,
 					buffers[num_buffer_dirty] = buf;
 					buftags[num_buffer_dirty] = buf->tag;
 					num_buffer_dirty++;
+					if (num_buffer_dirty >= max_buffers)
+						break;
 				}
 			}
 
@@ -790,6 +792,8 @@ StrategyDirtyBufferList(BufferDesc **buffers, BufferTag *buftags,
 					buffers[num_buffer_dirty] = buf;
 					buftags[num_buffer_dirty] = buf->tag;
 					num_buffer_dirty++;
+					if (num_buffer_dirty >= max_buffers)
+						break;
 				}
 			}
 

Original file line number	Diff line number	Diff line change
`@@ -12,7 +12,7 @@`
`12`	`12`	`*`
`13`	`13`	`*`
`14`	`14`	`* IDENTIFICATION`
`15`		`- * $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.44 2004/06/03 02:08:03 tgl Exp $`
	`15`	`+ * $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.45 2004/06/11 17:20:39 tgl Exp $`
`16`	`16`	`*`
`17`	`17`	`*-------------------------------------------------------------------------`
`18`	`18`	`*/`
`@@ -709,6 +709,7 @@ StrategyInvalidateBuffer(BufferDesc *buf)`
`709`	`709`	`*/`
`710`	`710`	`CLEAR_BUFFERTAG(buf->tag);`
`711`	`711`	`buf->flags &= ~(BM_VALID \| BM_DIRTY);`
	`712`	`+ buf->cntxDirty = false;`
`712`	`713`	`buf->bufNext = StrategyControl->listFreeBuffers;`
`713`	`714`	`StrategyControl->listFreeBuffers = buf->buf_id;`
`714`	`715`	`}`
`@@ -757,8 +758,7 @@ StrategyDirtyBufferList(BufferDesc *buffers, BufferTag buftags,`
`757`	`758`	`cdb_id_t1 = StrategyControl->listHead[STRAT_LIST_T1];`
`758`	`759`	`cdb_id_t2 = StrategyControl->listHead[STRAT_LIST_T2];`
`759`	`760`
`760`		`- while ((cdb_id_t1 >= 0 \|\| cdb_id_t2 >= 0) &&`
`761`		`- num_buffer_dirty < max_buffers)`
	`761`	`+ while (cdb_id_t1 >= 0 \|\| cdb_id_t2 >= 0)`
`762`	`762`	`{`
`763`	`763`	`if (cdb_id_t1 >= 0)`
`764`	`764`	`{`
`@@ -772,6 +772,8 @@ StrategyDirtyBufferList(BufferDesc *buffers, BufferTag buftags,`
`772`	`772`	`buffers[num_buffer_dirty] = buf;`
`773`	`773`	`buftags[num_buffer_dirty] = buf->tag;`
`774`	`774`	`num_buffer_dirty++;`
	`775`	`+ if (num_buffer_dirty >= max_buffers)`
	`776`	`+ break;`
`775`	`777`	`}`
`776`	`778`	`}`
`777`	`779`
`@@ -790,6 +792,8 @@ StrategyDirtyBufferList(BufferDesc *buffers, BufferTag buftags,`
`790`	`792`	`buffers[num_buffer_dirty] = buf;`
`791`	`793`	`buftags[num_buffer_dirty] = buf->tag;`
`792`	`794`	`num_buffer_dirty++;`
	`795`	`+ if (num_buffer_dirty >= max_buffers)`
	`796`	`+ break;`
`793`	`797`	`}`
`794`	`798`	`}`
`795`	`799`