[PATCH 08/15] ubifs: Convert ubifs_write_begin() to use a folio

Matthew Wilcox (Oracle)
2024-01-20T23:08:50Z

Save eight calls to compound_head() by using the new folio API.
Remove a few assumptions that would break with large folios.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/ubifs/file.c | 36 +++++++++++++++++-------------------
1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 6302ce65e0b3..ef262499f228 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -428,7 +428,7 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
pgoff_t index = pos >> PAGE_SHIFT;
int err, appending = !!(pos + len > inode->i_size);
int skipped_read = 0;
- struct page *page;
+ struct folio *folio;

ubifs_assert(c, ubifs_inode(inode)->ui_size == inode->i_size);
ubifs_assert(c, !c->ro_media && !c->ro_mount);
@@ -437,13 +437,14 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
return -EROFS;

/* Try out the fast-path part first */
- page = grab_cache_page_write_begin(mapping, index);
- if (unlikely(!page))
- return -ENOMEM;
+ folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
+ mapping_gfp_mask(mapping));
+ if (IS_ERR(folio))
+ return PTR_ERR(folio);

- if (!PageUptodate(page)) {
+ if (!folio_test_uptodate(folio)) {
/* The page is not loaded from the flash */
- if (!(pos & ~PAGE_MASK) && len == PAGE_SIZE) {
+ if (pos == folio_pos(folio) && len >= folio_size(folio)) {
/*
* We change whole page so no need to load it. But we
* do not know whether this page exists on the media or
@@ -453,29 +454,27 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
* media. Thus, we are setting the @PG_checked flag
* here.
*/
- SetPageChecked(page);
+ folio_set_checked(folio);
skipped_read = 1;
} else {
- err = do_readpage(page);
+ err = do_readpage(&folio->page);
if (err) {
- unlock_page(page);
- put_page(page);
+ folio_unlock(folio);
+ folio_put(folio);
return err;
}
}
}

- err = allocate_budget(c, page, ui, appending);
+ err = allocate_budget(c, &folio->page, ui, appending);
if (unlikely(err)) {
ubifs_assert(c, err == -ENOSPC);
/*
* If we skipped reading the page because we were going to
* write all of it, then it is not up to date.
*/
- if (skipped_read) {
- ClearPageChecked(page);
- ClearPageUptodate(page);
- }
+ if (skipped_read)
+ folio_clear_checked(folio);
/*
* Budgeting failed which means it would have to force
* write-back but didn't, because we set the @fast flag in the
@@ -487,8 +486,8 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
ubifs_assert(c, mutex_is_locked(&ui->ui_mutex));
mutex_unlock(&ui->ui_mutex);
}
- unlock_page(page);
- put_page(page);
+ folio_unlock(folio);
+ folio_put(folio);

return write_begin_slow(mapping, pos, len, pagep);
}
@@ -499,9 +498,8 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
* with @ui->ui_mutex locked if we are appending pages, and unlocked
* otherwise. This is an optimization (slightly hacky though).
*/
- *pagep = page;
+ *pagep = &folio->page;
return 0;
-
}

/**
--
2.43.0