From 6a09084cd4e67ab2e454cf6da6737383a7c6d41c Mon Sep 17 00:00:00 2001
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: Thu, 11 Jul 2024 11:42:46 -0400
Subject: ecryptfs: Use a folio in ecryptfs_write_begin()

Use __filemap_get_folio() instead of grab_cache_page_write_begin()
and use the folio throughout.  No attempt is made here to support
large folios, simply converting this function to use folio APIs is
the goal.  Saves many hidden calls to compound_head().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 fs/ecryptfs/mmap.c | 53 +++++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index 9b86fad2b9d1..75ce28d757b7 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -268,35 +268,36 @@ static int ecryptfs_write_begin(struct file *file,
 			struct page **pagep, void **fsdata)
 {
 	pgoff_t index = pos >> PAGE_SHIFT;
-	struct page *page;
+	struct folio *folio;
 	loff_t prev_page_end_size;
 	int rc = 0;
 
-	page = grab_cache_page_write_begin(mapping, index);
-	if (!page)
-		return -ENOMEM;
-	*pagep = page;
+	folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
+			mapping_gfp_mask(mapping));
+	if (IS_ERR(folio))
+		return PTR_ERR(folio);
+	*pagep = &folio->page;
 
 	prev_page_end_size = ((loff_t)index << PAGE_SHIFT);
-	if (!PageUptodate(page)) {
+	if (!folio_test_uptodate(folio)) {
 		struct ecryptfs_crypt_stat *crypt_stat =
 			&ecryptfs_inode_to_private(mapping->host)->crypt_stat;
 
 		if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 			rc = ecryptfs_read_lower_page_segment(
-				page, index, 0, PAGE_SIZE, mapping->host);
+				&folio->page, index, 0, PAGE_SIZE, mapping->host);
 			if (rc) {
 				printk(KERN_ERR "%s: Error attempting to read "
 				       "lower page segment; rc = [%d]\n",
 				       __func__, rc);
-				ClearPageUptodate(page);
+				folio_clear_uptodate(folio);
 				goto out;
 			} else
-				SetPageUptodate(page);
+				folio_mark_uptodate(folio);
 		} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
 			if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
 				rc = ecryptfs_copy_up_encrypted_with_header(
-					page, crypt_stat);
+					&folio->page, crypt_stat);
 				if (rc) {
 					printk(KERN_ERR "%s: Error attempting "
 					       "to copy the encrypted content "
@@ -304,46 +305,46 @@ static int ecryptfs_write_begin(struct file *file,
 					       "inserting the metadata from "
 					       "the xattr into the header; rc "
 					       "= [%d]\n", __func__, rc);
-					ClearPageUptodate(page);
+					folio_clear_uptodate(folio);
 					goto out;
 				}
-				SetPageUptodate(page);
+				folio_mark_uptodate(folio);
 			} else {
 				rc = ecryptfs_read_lower_page_segment(
-					page, index, 0, PAGE_SIZE,
+					&folio->page, index, 0, PAGE_SIZE,
 					mapping->host);
 				if (rc) {
 					printk(KERN_ERR "%s: Error reading "
 					       "page; rc = [%d]\n",
 					       __func__, rc);
-					ClearPageUptodate(page);
+					folio_clear_uptodate(folio);
 					goto out;
 				}
-				SetPageUptodate(page);
+				folio_mark_uptodate(folio);
 			}
 		} else {
 			if (prev_page_end_size
-			    >= i_size_read(page->mapping->host)) {
-				zero_user(page, 0, PAGE_SIZE);
-				SetPageUptodate(page);
+			    >= i_size_read(mapping->host)) {
+				folio_zero_range(folio, 0, PAGE_SIZE);
+				folio_mark_uptodate(folio);
 			} else if (len < PAGE_SIZE) {
-				rc = ecryptfs_decrypt_page(page);
+				rc = ecryptfs_decrypt_page(&folio->page);
 				if (rc) {
 					printk(KERN_ERR "%s: Error decrypting "
 					       "page at index [%ld]; "
 					       "rc = [%d]\n",
-					       __func__, page->index, rc);
-					ClearPageUptodate(page);
+					       __func__, folio->index, rc);
+					folio_clear_uptodate(folio);
 					goto out;
 				}
-				SetPageUptodate(page);
+				folio_mark_uptodate(folio);
 			}
 		}
 	}
 	/* If creating a page or more of holes, zero them out via truncate.
 	 * Note, this will increase i_size. */
 	if (index != 0) {
-		if (prev_page_end_size > i_size_read(page->mapping->host)) {
+		if (prev_page_end_size > i_size_read(mapping->host)) {
 			rc = ecryptfs_truncate(file->f_path.dentry,
 					       prev_page_end_size);
 			if (rc) {
@@ -359,11 +360,11 @@ static int ecryptfs_write_begin(struct file *file,
 	 * of page?  Zero it out. */
 	if ((i_size_read(mapping->host) == prev_page_end_size)
 	    && (pos != 0))
-		zero_user(page, 0, PAGE_SIZE);
+		folio_zero_range(folio, 0, PAGE_SIZE);
 out:
 	if (unlikely(rc)) {
-		unlock_page(page);
-		put_page(page);
+		folio_unlock(folio);
+		folio_put(folio);
 		*pagep = NULL;
 	}
 	return rc;
-- 
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