linux-ext4 - [PATCH 1/2] ext4: hoist ext4_block_write_begin and replace the __block_write

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Message-Id: <20240823013329.1996741-2-zhangshida@kylinos.cn>
Date: Fri, 23 Aug 2024 09:33:28 +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: [PATCH 1/2] ext4: hoist ext4_block_write_begin and replace the __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.
And hoist the ext4_block_write_begin so that it can be used in other
files.

Suggested-by: Jan Kara <jack@...e.cz>
Signed-off-by: Shida Zhang <zhangshida@...inos.cn>
---
 fs/ext4/ext4.h   |  2 ++
 fs/ext4/inline.c | 10 +++++-----
 fs/ext4/inode.c  | 23 ++++++-----------------
 3 files changed, 13 insertions(+), 22 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 08acd152261e..5f8257b68190 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3851,6 +3851,8 @@ static inline int ext4_buffer_uptodate(struct buffer_head *bh)
 	return buffer_uptodate(bh);
 }
 
+extern int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
+				  get_block_t *get_block);
 #endif	/* __KERNEL__ */
 
 #define EFSBADCRC	EBADMSG		/* Bad CRC detected */
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index e7a09a99837b..0a1a8431e281 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -601,10 +601,10 @@ static int ext4_convert_inline_data_to_extent(struct address_space *mapping,
 		goto out;
 
 	if (ext4_should_dioread_nolock(inode)) {
-		ret = __block_write_begin(&folio->page, from, to,
-					  ext4_get_block_unwritten);
+		ret = ext4_block_write_begin(folio, from, to,
+					     ext4_get_block_unwritten);
 	} else
-		ret = __block_write_begin(&folio->page, from, to, ext4_get_block);
+		ret = ext4_block_write_begin(folio, from, to, ext4_get_block);
 
 	if (!ret && ext4_should_journal_data(inode)) {
 		ret = ext4_walk_page_buffers(handle, inode,
@@ -856,8 +856,8 @@ static int ext4_da_convert_inline_data_to_extent(struct address_space *mapping,
 			goto out;
 	}
 
-	ret = __block_write_begin(&folio->page, 0, inline_size,
-				  ext4_da_get_block_prep);
+	ret = ext4_block_write_begin(folio, 0, inline_size,
+				     ext4_da_get_block_prep);
 	if (ret) {
 		up_read(&EXT4_I(inode)->xattr_sem);
 		folio_unlock(folio);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 941c1c0d5c6e..6b15805ca88b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1041,9 +1041,8 @@ int do_journal_get_write_access(handle_t *handle, struct inode *inode,
 	return ret;
 }
 
-#ifdef CONFIG_FS_ENCRYPTION
-static int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
-				  get_block_t *get_block)
+int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
+			   get_block_t *get_block)
 {
 	unsigned from = pos & (PAGE_SIZE - 1);
 	unsigned to = from + len;
@@ -1119,7 +1118,9 @@ static int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
 	}
 	if (unlikely(err)) {
 		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;
 
@@ -1131,10 +1132,10 @@ static int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
 			}
 		}
 	}
+#endif
 
 	return err;
 }
-#endif
 
 /*
  * To preserve ordering, it is essential that the hole instantiation and
@@ -1216,19 +1217,11 @@ 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(folio, pos, len,
 					     ext4_get_block_unwritten);
 	else
 		ret = ext4_block_write_begin(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,
@@ -2961,11 +2954,7 @@ 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(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