linux-kernel - [RFC PATCH V2 2/2] ext4: Replace the __block_write_begin with ext4_block_write

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Message-Id: <20240809064606.3490994-3-zhangshida@kylinos.cn>
Date: Fri,  9 Aug 2024 14:46:06 +0800
From: zhangshida <starzhangzsd@...il.com>
To: tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.com
Cc: linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	zhangshida@...inos.cn,
	starzhangzsd@...il.com,
	Jan Kara <jack@...e.cz>
Subject: [RFC PATCH V2 2/2] ext4: Replace the __block_write_begin with ext4_block_write_begin

From: Shida Zhang <zhangshida@...inos.cn>

Using __block_write_begin() make it inconvenient to journal the
user data dirty process. We can't tell the block layer maintainer,
‘Hey, we want to trace the dirty user data in ext4, can we add some
special code for ext4 in __block_write_begin?’:P

So use ext4_block_write_begin() instead.

The two functions are basically doing the same thing except for the
fscrypt related code. Narrow the scope of CONFIG_FS_ENCRYPTION
so as to allow ext4_block_write_begin() to function like
__block_write_begin when the config is disabled.

Suggested-by: Jan Kara <jack@...e.cz>
Signed-off-by: Shida Zhang <zhangshida@...inos.cn>
---
 fs/ext4/inode.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index de46c0a6842a..31389633086a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1046,7 +1046,6 @@ int do_journal_get_write_access(handle_t *handle, struct inode *inode,
 	return ret;
 }
 
-#ifdef CONFIG_FS_ENCRYPTION
 static int ext4_block_write_begin(handle_t *handle, struct folio *folio,
 				  loff_t pos, unsigned len,
 				  get_block_t *get_block)
@@ -1135,7 +1134,9 @@ static int ext4_block_write_begin(handle_t *handle, struct folio *folio,
 							 from, to);
 		else
 			folio_zero_new_buffers(folio, from, to);
-	} else if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
+	}
+#ifdef CONFIG_FS_ENCRYPTION
+	else if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
 		for (i = 0; i < nr_wait; i++) {
 			int err2;
 
@@ -1147,10 +1148,10 @@ static int ext4_block_write_begin(handle_t *handle, struct folio *folio,
 			}
 		}
 	}
+#endif
 
 	return err;
 }
-#endif
 
 /*
  * To preserve ordering, it is essential that the hole instantiation and
@@ -1232,20 +1233,12 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 	/* In case writeback began while the folio was unlocked */
 	folio_wait_stable(folio);
 
-#ifdef CONFIG_FS_ENCRYPTION
 	if (ext4_should_dioread_nolock(inode))
 		ret = ext4_block_write_begin(handle, folio, pos, len,
 					     ext4_get_block_unwritten);
 	else
 		ret = ext4_block_write_begin(handle, folio, pos, len,
 					     ext4_get_block);
-#else
-	if (ext4_should_dioread_nolock(inode))
-		ret = __block_write_begin(&folio->page, pos, len,
-					  ext4_get_block_unwritten);
-	else
-		ret = __block_write_begin(&folio->page, pos, len, ext4_get_block);
-#endif
 	if (!ret && ext4_should_journal_data(inode)) {
 		ret = ext4_walk_page_buffers(handle, inode,
 					     folio_buffers(folio), from, to,
@@ -2978,12 +2971,8 @@ static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
 	if (IS_ERR(folio))
 		return PTR_ERR(folio);
 
-#ifdef CONFIG_FS_ENCRYPTION
 	ret = ext4_block_write_begin(NULL, folio, pos, len,
 				     ext4_da_get_block_prep);
-#else
-	ret = __block_write_begin(&folio->page, pos, len, ext4_da_get_block_prep);
-#endif
 	if (ret < 0) {
 		folio_unlock(folio);
 		folio_put(folio);
-- 
2.33.0