[PATCHv2 15/41] filemap: handle huge pages in do_generic_file_read()
flat view
From: Kirill A. Shutemov <hidden>
Date: 2016-08-12 18:37:58
Also in:
linux-ext4, linux-fsdevel, linux-mm, lkml
Subsystem:
memory management, page cache, the rest · Maintainers:
Andrew Morton, Matthew Wilcox, Jan Kara, Linus Torvalds
Most of work happans on head page. Only when we need to do copy data to userspace we find relevant subpage. We are still limited by PAGE_SIZE per iteration. Lifting this limitation would require some more work. Signed-off-by: Kirill A. Shutemov <redacted> --- mm/filemap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index ae1d996fa089..9d7d70b265d4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -1860,6 +1860,7 @@ find_page: if (unlikely(page == NULL)) goto no_cached_page; } + page = compound_head(page); if (PageReadahead(page)) { page_cache_async_readahead(mapping, ra, filp, page,
@@ -1936,7 +1937,8 @@ page_ok: * now we can copy it to user space... */ - ret = copy_page_to_iter(page, offset, nr, iter); + ret = copy_page_to_iter(page + index - page->index, offset, + nr, iter); offset += ret; index += offset >> PAGE_SHIFT; offset &= ~PAGE_MASK;
@@ -2356,6 +2358,7 @@ page_not_uptodate: * because there really aren't any performance issues here * and we need to check for errors. */ + page = compound_head(page); ClearPageError(page); error = mapping->a_ops->readpage(file, page); if (!error) {
--
2.8.1