Re: [PATCH 03/15] ubifs: Convert ubifs_writepage to use a folio

Zhihao Cheng
2024-01-22T09:27:53Z

在 2024/1/21 7:08, Matthew Wilcox (Oracle) 写道:
> We still pass the page down to do_writepage(), but ubifs_writepage()
> itself is now large folio safe. It also contains far fewer hidden calls
> to compound_head().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
> fs/ubifs/file.c | 39 +++++++++++++++++----------------------
> 1 file changed, 17 insertions(+), 22 deletions(-)
>

Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>

> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index 007a73052561..7d0967daded3 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -1009,21 +1009,18 @@ static int do_writepage(struct page *page, int len)
> static int ubifs_writepage(struct folio *folio, struct writeback_control *wbc,
> void *data)
> {
> - struct page *page = &folio->page;
> - struct inode *inode = page->mapping->host;
> + struct inode *inode = folio->mapping->host;
> struct ubifs_info *c = inode->i_sb->s_fs_info;
> struct ubifs_inode *ui = ubifs_inode(inode);
> loff_t i_size = i_size_read(inode), synced_i_size;
> - pgoff_t end_index = i_size >> PAGE_SHIFT;
> - int err, len = i_size & (PAGE_SIZE - 1);
> - void *kaddr;
> + int err, len = folio_size(folio);
>
> dbg_gen("ino %lu, pg %lu, pg flags %#lx",
> - inode->i_ino, page->index, page->flags);
> - ubifs_assert(c, PagePrivate(page));
> + inode->i_ino, folio->index, folio->flags);
> + ubifs_assert(c, folio->private != NULL);
>
> - /* Is the page fully outside @i_size? (truncate in progress) */
> - if (page->index > end_index || (page->index == end_index && !len)) {
> + /* Is the folio fully outside @i_size? (truncate in progress) */
> + if (folio_pos(folio) >= i_size) {
> err = 0;
> goto out_unlock;
> }
> @@ -1032,9 +1029,9 @@ static int ubifs_writepage(struct folio *folio, struct writeback_control *wbc,
> synced_i_size = ui->synced_i_size;
> spin_unlock(&ui->ui_lock);
>
> - /* Is the page fully inside @i_size? */
> - if (page->index < end_index) {
> - if (page->index >= synced_i_size >> PAGE_SHIFT) {
> + /* Is the folio fully inside i_size? */
> + if (folio_pos(folio) + len <= i_size) {
> + if (folio_pos(folio) >= synced_i_size) {
> err = inode->i_sb->s_op->write_inode(inode, NULL);
> if (err)
> goto out_redirty;
> @@ -1047,20 +1044,18 @@ static int ubifs_writepage(struct folio *folio, struct writeback_control *wbc,
> * with this.
> */
> }
> - return do_writepage(page, PAGE_SIZE);
> + return do_writepage(&folio->page, len);
> }
>
> /*
> - * The page straddles @i_size. It must be zeroed out on each and every
> + * The folio straddles @i_size. It must be zeroed out on each and every
> * writepage invocation because it may be mmapped. "A file is mapped
> * in multiples of the page size. For a file that is not a multiple of
> * the page size, the remaining memory is zeroed when mapped, and
> * writes to that region are not written out to the file."
> */
> - kaddr = kmap_atomic(page);
> - memset(kaddr + len, 0, PAGE_SIZE - len);
> - flush_dcache_page(page);
> - kunmap_atomic(kaddr);
> + len = i_size - folio_pos(folio);
> + folio_zero_segment(folio, len, folio_size(folio));
>
> if (i_size > synced_i_size) {
> err = inode->i_sb->s_op->write_inode(inode, NULL);
> @@ -1068,16 +1063,16 @@ static int ubifs_writepage(struct folio *folio, struct writeback_control *wbc,
> goto out_redirty;
> }
>
> - return do_writepage(page, len);
> + return do_writepage(&folio->page, len);
> out_redirty:
> /*
> - * redirty_page_for_writepage() won't call ubifs_dirty_inode() because
> + * folio_redirty_for_writepage() won't call ubifs_dirty_inode() because
> * it passes I_DIRTY_PAGES flag while calling __mark_inode_dirty(), so
> * there is no need to do space budget for dirty inode.
> */
> - redirty_page_for_writepage(wbc, page);
> + folio_redirty_for_writepage(wbc, folio);
> out_unlock:
> - unlock_page(page);
> + folio_unlock(folio);
> return err;
> }