[PATCHv5 25/36] ext4: make ext4_writepage() work on huge pages

Kirill A. Shutemov
2016-11-29T11:23:42Z

Change ext4_writepage() and underlying ext4_bio_write_page().

It basically removes assumption on page size, infer it from struct page
instead.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
fs/ext4/inode.c | 10 +++++-----
fs/ext4/page-io.c | 11 +++++++++--
2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ebccc535b15e..fa4467e4b129 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2037,10 +2037,10 @@ static int ext4_writepage(struct page *page,

trace_ext4_writepage(page);
size = i_size_read(inode);
- if (page->index == size >> PAGE_SHIFT)
- len = size & ~PAGE_MASK;
- else
- len = PAGE_SIZE;
+
+ len = hpage_size(page);
+ if (page->index + hpage_nr_pages(page) - 1 == size >> PAGE_SHIFT)
+ len = size & ~hpage_mask(page);

page_bufs = page_buffers(page);
/*
@@ -2064,7 +2064,7 @@ static int ext4_writepage(struct page *page,
ext4_bh_delay_or_unwritten)) {
redirty_page_for_writepage(wbc, page);
if ((current->flags & PF_MEMALLOC) ||
- (inode->i_sb->s_blocksize == PAGE_SIZE)) {
+ (inode->i_sb->s_blocksize == hpage_size(page))) {
/*
* For memory cleaning there's no point in writing only
* some buffers. So just bail out. Warn if we came here
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index d83b0f3c5fe9..360c74daec5c 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -413,6 +413,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,

BUG_ON(!PageLocked(page));
BUG_ON(PageWriteback(page));
+ BUG_ON(PageTail(page));

if (keep_towrite)
set_page_writeback_keepwrite(page);
@@ -429,8 +430,14 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
- if (len < PAGE_SIZE)
- zero_user_segment(page, len, PAGE_SIZE);
+ if (len < hpage_size(page)) {
+ page += len / PAGE_SIZE;
+ if (len % PAGE_SIZE)
+ zero_user_segment(page, len % PAGE_SIZE, PAGE_SIZE);
+ while (page + 1 == compound_head(page))
+ clear_highpage(++page);
+ page = compound_head(page);
+ }
/*
* In the first loop we prepare and mark buffers to submit. We have to
* mark all buffers in the page before submitting so that
--
2.10.2