Re: [PATCH 05/15] ubifs: Convert do_writepage() to take a folio

Zhihao Cheng
2024-01-22T11:31:51Z

在 2024/1/21 7:08, Matthew Wilcox (Oracle) 写道:
> Replace the call to SetPageError() with a call to mapping_set_error().
> Support large folios by using kmap_local_folio() and remapping each time
> we cross a page boundary. Saves a lot of hidden calls to compound_head().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
> fs/ubifs/file.c | 56 ++++++++++++++++++++++++++-----------------------
> 1 file changed, 30 insertions(+), 26 deletions(-)
>

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

> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index b297582c9b75..e755d0a11146 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -903,60 +903,64 @@ static int ubifs_read_folio(struct file *file, struct folio *folio)
> return 0;
> }
>
> -static int do_writepage(struct page *page, int len)
> +static int do_writepage(struct folio *folio, size_t len)
> {
> - int err = 0, i, blen;
> + int err = 0, blen;
> unsigned int block;
> void *addr;
> + size_t offset = 0;
> union ubifs_key key;
> - struct inode *inode = page->mapping->host;
> + struct inode *inode = folio->mapping->host;
> struct ubifs_info *c = inode->i_sb->s_fs_info;
>
> #ifdef UBIFS_DEBUG
> struct ubifs_inode *ui = ubifs_inode(inode);
> spin_lock(&ui->ui_lock);
> - ubifs_assert(c, page->index <= ui->synced_i_size >> PAGE_SHIFT);
> + ubifs_assert(c, folio->index <= ui->synced_i_size >> PAGE_SHIFT);
> spin_unlock(&ui->ui_lock);
> #endif
>
> - /* Update radix tree tags */
> - set_page_writeback(page);
> + folio_start_writeback(folio);
>
> - addr = kmap(page);
> - block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
> - i = 0;
> - while (len) {
> - blen = min_t(int, len, UBIFS_BLOCK_SIZE);
> + addr = kmap_local_folio(folio, offset);
> + block = folio->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
> + for (;;) {
> + blen = min_t(size_t, len, UBIFS_BLOCK_SIZE);
> data_key_init(c, &key, inode->i_ino, block);
> err = ubifs_jnl_write_data(c, inode, &key, addr, blen);
> if (err)
> break;
> - if (++i >= UBIFS_BLOCKS_PER_PAGE)
> + len -= blen;
> + if (!len)
> break;
> block += 1;
> addr += blen;
> - len -= blen;
> + if (folio_test_highmem(folio) && !offset_in_page(addr)) {
> + kunmap_local(addr - blen);
> + offset += PAGE_SIZE;
> + addr = kmap_local_folio(folio, offset);
> + }
> }
> + kunmap_local(addr);
> if (err) {
> - SetPageError(page);
> - ubifs_err(c, "cannot write page %lu of inode %lu, error %d",
> - page->index, inode->i_ino, err);
> + mapping_set_error(folio->mapping, err);
> + ubifs_err(c, "cannot write folio %lu of inode %lu, error %d",
> + folio->index, inode->i_ino, err);
> ubifs_ro_mode(c, err);
> }
>
> - ubifs_assert(c, PagePrivate(page));
> - if (PageChecked(page))
> + ubifs_assert(c, folio->private != NULL);
> + if (folio_test_checked(folio))
> release_new_page_budget(c);
> else
> release_existing_page_budget(c);
>
> atomic_long_dec(&c->dirty_pg_cnt);
> - detach_page_private(page);
> - ClearPageChecked(page);
> + folio_detach_private(folio);
> + folio_clear_checked(folio);
>
> - kunmap(page);
> - unlock_page(page);
> - end_page_writeback(page);
> + folio_unlock(folio);
> + folio_end_writeback(folio);
> return err;
> }
>
> @@ -1044,7 +1048,7 @@ static int ubifs_writepage(struct folio *folio, struct writeback_control *wbc,
> * with this.
> */
> }
> - return do_writepage(&folio->page, len);
> + return do_writepage(folio, len);
> }
>
> /*
> @@ -1063,7 +1067,7 @@ static int ubifs_writepage(struct folio *folio, struct writeback_control *wbc,
> goto out_redirty;
> }
>
> - return do_writepage(&folio->page, len);
> + return do_writepage(folio, len);
> out_redirty:
> /*
> * folio_redirty_for_writepage() won't call ubifs_dirty_inode() because
> @@ -1177,7 +1181,7 @@ static int do_truncation(struct ubifs_info *c, struct inode *inode,
> if (UBIFS_BLOCKS_PER_PAGE_SHIFT)
> offset = offset_in_folio(folio,
> new_size);
> - err = do_writepage(&folio->page, offset);
> + err = do_writepage(folio, offset);
> folio_put(folio);
> if (err)
> goto out_budg;