linux-ext4 - [PATCH v2 4/9] jbd2: jump to new copy_done tag when b_frozen

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Date: Tue, 14 May 2024 19:24:33 +0800
From: Kemeng Shi <shikemeng@...weicloud.com>
To: tytso@....edu,
	jack@...e.com,
	yi.zhang@...weicloud.com
Cc: linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/9] jbd2: jump to new copy_done tag when b_frozen_data is created concurrently

If b_frozen_data is created concurrently, we can update new_folio and
new_offset with b_frozen_data and then move forward

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 fs/jbd2/journal.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 714e2ef0115a..5fb5062cf7ae 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -351,7 +351,6 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 	atomic_set(&new_bh->b_count, 1);
 
 	spin_lock(&jh_in->b_state_lock);
-repeat:
 	/*
 	 * If a new transaction has already done a buffer copy-out, then
 	 * we use that version of the data for the commit.
@@ -399,22 +398,22 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 		spin_lock(&jh_in->b_state_lock);
 		if (jh_in->b_frozen_data) {
 			jbd2_free(tmp, bh_in->b_size);
-			goto repeat;
+			goto copy_done;
 		}
 
 		jh_in->b_frozen_data = tmp;
 		memcpy_from_folio(tmp, new_folio, new_offset, bh_in->b_size);
-
-		new_folio = virt_to_folio(tmp);
-		new_offset = offset_in_folio(new_folio, tmp);
-		done_copy_out = 1;
-
 		/*
 		 * This isn't strictly necessary, as we're using frozen
 		 * data for the escaping, but it keeps consistency with
 		 * b_frozen_data usage.
 		 */
 		jh_in->b_frozen_triggers = jh_in->b_triggers;
+
+copy_done:
+		new_folio = virt_to_folio(jh_in->b_frozen_data);
+		new_offset = offset_in_folio(new_folio, jh_in->b_frozen_data);
+		done_copy_out = 1;
 	}
 
 	/*
-- 
2.30.0