linux-kernel - [PATCH v2 5/6] ext4/jbd2: reintroduce jbd2_journal_blocks_per

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Message-ID: <20250611111625.1668035-6-yi.zhang@huaweicloud.com>
Date: Wed, 11 Jun 2025 19:16:24 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-ext4@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	ojaswin@...ux.ibm.com,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	libaokun1@...wei.com,
	yukuai3@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH v2 5/6] ext4/jbd2: reintroduce jbd2_journal_blocks_per_page()

From: Zhang Yi <yi.zhang@...wei.com>

This partially reverts commit d6bf294773a4 ("ext4/jbd2: convert
jbd2_journal_blocks_per_page() to support large folio"). This
jbd2_journal_blocks_per_folio() will lead to a significant
overestimation of journal credits. Since we still reserve credits for
one page and attempt to extend and restart handles during large folio
writebacks, so we should convert this helper back to
ext4_journal_blocks_per_page().

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/ext4_jbd2.h  | 7 +++++++
 fs/ext4/inode.c      | 6 +++---
 fs/jbd2/journal.c    | 6 ++++++
 include/linux/jbd2.h | 1 +
 4 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 63d17c5201b5..c0ee756cb34c 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -326,6 +326,13 @@ static inline int ext4_journal_blocks_per_folio(struct inode *inode)
 	return 0;
 }
 
+static inline int ext4_journal_blocks_per_page(struct inode *inode)
+{
+	if (EXT4_JOURNAL(inode) != NULL)
+		return jbd2_journal_blocks_per_page(inode);
+	return 0;
+}
+
 static inline int ext4_journal_force_commit(journal_t *journal)
 {
 	if (journal)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 67e37dd546eb..9835145b1b27 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2556,7 +2556,7 @@ static int mpage_map_and_submit_extent(handle_t *handle,
  */
 static int ext4_da_writepages_trans_blocks(struct inode *inode)
 {
-	int bpp = ext4_journal_blocks_per_folio(inode);
+	int bpp = ext4_journal_blocks_per_page(inode);
 
 	return ext4_meta_trans_blocks(inode,
 				MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
@@ -2634,7 +2634,7 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
 	ext4_lblk_t lblk;
 	struct buffer_head *head;
 	handle_t *handle = NULL;
-	int bpp = ext4_journal_blocks_per_folio(mpd->inode);
+	int bpp = ext4_journal_blocks_per_page(mpd->inode);
 
 	if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
 		tag = PAGECACHE_TAG_TOWRITE;
@@ -6255,7 +6255,7 @@ int ext4_meta_trans_blocks(struct inode *inode, int lblocks, int pextents)
  */
 int ext4_writepage_trans_blocks(struct inode *inode)
 {
-	int bpp = ext4_journal_blocks_per_folio(inode);
+	int bpp = ext4_journal_blocks_per_page(inode);
 	int ret;
 
 	ret = ext4_meta_trans_blocks(inode, bpp, bpp);
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index d480b94117cd..7fccb425907f 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -84,6 +84,7 @@ EXPORT_SYMBOL(jbd2_journal_start_commit);
 EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
 EXPORT_SYMBOL(jbd2_journal_wipe);
 EXPORT_SYMBOL(jbd2_journal_blocks_per_folio);
+EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
 EXPORT_SYMBOL(jbd2_journal_invalidate_folio);
 EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
 EXPORT_SYMBOL(jbd2_journal_force_commit);
@@ -2661,6 +2662,11 @@ int jbd2_journal_blocks_per_folio(struct inode *inode)
 		     inode->i_sb->s_blocksize_bits);
 }
 
+int jbd2_journal_blocks_per_page(struct inode *inode)
+{
+	return 1 << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
+}
+
 /*
  * helper functions to deal with 32 or 64bit block numbers.
  */
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 43b9297fe8a7..f35369c104ba 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1724,6 +1724,7 @@ static inline int tid_geq(tid_t x, tid_t y)
 }
 
 extern int jbd2_journal_blocks_per_folio(struct inode *inode);
+extern int jbd2_journal_blocks_per_page(struct inode *inode);
 extern size_t journal_tag_bytes(journal_t *journal);
 
 static inline int jbd2_journal_has_csum_v2or3(journal_t *journal)
-- 
2.46.1