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

Matthew Wilcox (Oracle)
2024-01-20T23:08:45Z

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(-)

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;
}

--
2.43.0