[PATCH] splice: be smarter about calling do_page_cache_readahead()

We don't want to call into the read-ahead logic unless we are at the start of a page, _or_ we have multiple pages to read. Signed-off-by: Jens Axboe <axboe@suse.de>

[PATCH] splice: be smarter about calling do_page_cache_readahead()
We don't want to call into the read-ahead logic unless we are at the start of a page, _or_ we have multiple pages to read. Signed-off-by: Jens Axboe <axboe@suse.de>
Jens Axboe
1 parent 49d0b21be2
Showing 1 changed file with 5 additions and 2 deletions Side-by-side Diff
fs/splice.c
@@ -250,9 +250,12 @@
 		nr_pages = PIPE_BUFFERS;
  
 	/*
-	 * initiate read-ahead on this page range
+	 * initiate read-ahead on this page range. however, don't call into
+	 * read-ahead if this is a non-zero offset (we are likely doing small
+	 * chunk splice and the page is already there) for a single page.
 	 */
-	do_page_cache_readahead(mapping, in, index, nr_pages);
+	if (!offset || nr_pages > 1)
+		do_page_cache_readahead(mapping, in, index, nr_pages);
  
 	/*
 	 * now fill in the holes
...	...	@@ -250,9 +250,12 @@
250	250	nr_pages = PIPE_BUFFERS;
251	251
252	252	/*
253		- * initiate read-ahead on this page range
	253	+ * initiate read-ahead on this page range. however, don't call into
	254	+ * read-ahead if this is a non-zero offset (we are likely doing small
	255	+ * chunk splice and the page is already there) for a single page.
254	256	*/
255		- do_page_cache_readahead(mapping, in, index, nr_pages);
	257	+ if (!offset \|\| nr_pages > 1)
	258	+ do_page_cache_readahead(mapping, in, index, nr_pages);
256	259
257	260	/*
258	261	* now fill in the holes