[PATCHv4 14/43] filemap: handle huge pages in do_generic_file_read()
flat view
From: Kirill A. Shutemov <hidden>
Date: 2016-10-25 00:13:13
Also in:
linux-block, 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 f8387488636f..ca4536f2035e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -1906,6 +1906,7 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos, if (unlikely(page == NULL)) goto no_cached_page; } + page = compound_head(page); if (PageReadahead(page)) { page_cache_async_readahead(mapping, ra, filp, page,
@@ -1984,7 +1985,8 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos, * 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;
@@ -2402,6 +2404,7 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) * 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) {
--
2.9.3
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