linux-ext4 - [PATCH 1/4] ext4: fix incorrect tid assumption in ext4_wait_for_tail_page

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Message-ID: <20240723154402.21125-2-luis.henriques@linux.dev>
Date: Tue, 23 Jul 2024 16:43:59 +0100
From: "Luis Henriques (SUSE)" <luis.henriques@...ux.dev>
To: Theodore Ts'o <tytso@....edu>,
	Andreas Dilger <adilger@...ger.ca>,
	Jan Kara <jack@...e.cz>,
	Harshad Shirwadkar <harshadshirwadkar@...il.com>
Cc: linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Luis Henriques (SUSE)" <luis.henriques@...ux.dev>
Subject: [PATCH 1/4] ext4: fix incorrect tid assumption in ext4_wait_for_tail_page_commit()

Function ext4_wait_for_tail_page_commit() assumes that '0' is not a valid
value for transaction IDs, which is incorrect.  Don't assume that and invoke
jbd2_log_wait_commit() if the journal had a committing transaction instead.

Signed-off-by: Luis Henriques (SUSE) <luis.henriques@...ux.dev>
---
 fs/ext4/inode.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 941c1c0d5c6e..e65fc2086701 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5279,8 +5279,9 @@ static void ext4_wait_for_tail_page_commit(struct inode *inode)
 {
 	unsigned offset;
 	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
-	tid_t commit_tid = 0;
+	tid_t commit_tid;
 	int ret;
+	bool has_transaction = false;
 
 	offset = inode->i_size & (PAGE_SIZE - 1);
 	/*
@@ -5305,12 +5306,13 @@ static void ext4_wait_for_tail_page_commit(struct inode *inode)
 		folio_put(folio);
 		if (ret != -EBUSY)
 			return;
-		commit_tid = 0;
 		read_lock(&journal->j_state_lock);
-		if (journal->j_committing_transaction)
+		if (journal->j_committing_transaction) {
 			commit_tid = journal->j_committing_transaction->t_tid;
+			has_transaction = true;
+		}
 		read_unlock(&journal->j_state_lock);
-		if (commit_tid)
+		if (has_transaction)
 			jbd2_log_wait_commit(journal, commit_tid);
 	}
 }