readahead: convert splice invocations
Fengguang Wu [Thu, 19 Jul 2007 08:48:03 +0000 (01:48 -0700)]
Convert splice reads to use on-demand readahead.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Jens Axboe <axboe@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/splice.c

index 53fc208..722449f 100644 (file)
@@ -287,12 +287,6 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                nr_pages = PIPE_BUFFERS;
 
        /*
-        * Don't try to 2nd guess the read-ahead logic, call into
-        * page_cache_readahead() like the page cache reads would do.
-        */
-       page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages);
-
-       /*
         * Lookup the (hopefully) full range of pages we need.
         */
        spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
@@ -310,11 +304,8 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                 */
                page = find_get_page(mapping, index);
                if (!page) {
-                       /*
-                        * Make sure the read-ahead engine is notified
-                        * about this failure.
-                        */
-                       handle_ra_miss(mapping, &in->f_ra, index);
+                       page_cache_readahead_ondemand(mapping, &in->f_ra, in,
+                                       NULL, index, nr_pages - spd.nr_pages);
 
                        /*
                         * page didn't exist, allocate one.
@@ -361,6 +352,10 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
                page = pages[page_nr];
 
+               if (PageReadahead(page))
+                       page_cache_readahead_ondemand(mapping, &in->f_ra, in,
+                                       page, index, nr_pages - page_nr);
+
                /*
                 * If the page isn't uptodate, we may need to start io on it
                 */
@@ -453,6 +448,7 @@ fill_it:
         */
        while (page_nr < nr_pages)
                page_cache_release(pages[page_nr++]);
+       in->f_ra.prev_index = index;
 
        if (spd.nr_pages)
                return splice_to_pipe(pipe, &spd);