[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>

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/splice.c b/fs/splice.c
index 50c43a1e0923..9bfd6af0cf45 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -250,9 +250,12 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe,
                 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