linux-ext4 - [PATCH 1/9] ext4: Handle redirtying in ext4_bio_write

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Message-Id: <20221130163608.29034-1-jack@suse.cz>
Date:   Wed, 30 Nov 2022 17:35:52 +0100
From:   Jan Kara <jack@...e.cz>
To:     Ted Tso <tytso@....edu>
Cc:     <linux-ext4@...r.kernel.org>,
        Christoph Hellwig <hch@...radead.org>, Jan Kara <jack@...e.cz>
Subject: [PATCH 1/9] ext4: Handle redirtying in ext4_bio_write_page()

Since we want to transition transaction commits to use ext4_writepages()
for writing back ordered, add handling of page redirtying into
ext4_bio_write_page(). Also move buffer dirty bit clearing into the same
place other buffer state handling.

Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/ext4/page-io.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 97fa7b4c645f..4e68ace86f11 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -482,6 +482,13 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 			/* A hole? We can safely clear the dirty bit */
 			if (!buffer_mapped(bh))
 				clear_buffer_dirty(bh);
+			/*
+			 * Keeping dirty some buffer we cannot write? Make
+			 * sure to redirty the page. This happens e.g. when
+			 * doing writeout for transaction commit.
+			 */
+			if (buffer_dirty(bh) && !PageDirty(page))
+				redirty_page_for_writepage(wbc, page);
 			if (io->io_bio)
 				ext4_io_submit(io);
 			continue;
@@ -489,6 +496,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 		if (buffer_new(bh))
 			clear_buffer_new(bh);
 		set_buffer_async_write(bh);
+		clear_buffer_dirty(bh);
 		nr_to_submit++;
 	} while ((bh = bh->b_this_page) != head);
 
@@ -532,7 +540,10 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 			printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
 			redirty_page_for_writepage(wbc, page);
 			do {
-				clear_buffer_async_write(bh);
+				if (buffer_async_write(bh)) {
+					clear_buffer_async_write(bh);
+					set_buffer_dirty(bh);
+				}
 				bh = bh->b_this_page;
 			} while (bh != head);
 			goto unlock;
@@ -546,7 +557,6 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 		io_submit_add_bh(io, inode,
 				 bounce_page ? bounce_page : page, bh);
 		nr_submitted++;
-		clear_buffer_dirty(bh);
 	} while ((bh = bh->b_this_page) != head);
 
 unlock:
-- 
2.35.3