From: Bean Huo <beanhuo@xxxxxxxxxx>
Current generic_file_buffered_read() will break up the larger batches of pages
and read data in single page length in case of ra->ra_pages == 0. This patch is
to allow it to pass the batches of pages down to the device if the supported
maximum IO size >= the requested size.
Signed-off-by: Bean Huo <beanhuo@xxxxxxxxxx>
---
mm/filemap.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 1aaea26556cc..0deec1897817 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2062,6 +2062,7 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
struct file *filp = iocb->ki_filp;
struct address_space *mapping = filp->f_mapping;
struct inode *inode = mapping->host;
+ struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
struct file_ra_state *ra = &filp->f_ra;
loff_t *ppos = &iocb->ki_pos;
pgoff_t index;
@@ -2098,9 +2099,14 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
if (!page) {
if (iocb->ki_flags & IOCB_NOIO)
goto would_block;
- page_cache_sync_readahead(mapping,
- ra, filp,
- index, last_index - index);
+
+ if (!ra->ra_pages && bdi->io_pages >= last_index - index)
+ __do_page_cache_readahead(mapping, filp, index,
+ last_index - index, 0);
+ else
+ page_cache_sync_readahead(mapping, ra, filp,
+ index,
+ last_index - index);
page = find_get_page(mapping, index);
if (unlikely(page == NULL))
goto no_cached_page;
--
2.17.1
