ext4: fix incorrect tid assumption in __jbd2_log_wait_for_space()

Function __jbd2_log_wait_for_space() 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@linux.dev>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20240724161119.13448-3-luis.henriques@linux.dev
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 7b593591273a1e9457c9e66ff2f7a37a53de848c..bd34083d5fa2fe582d925777f4eefdb60a1055cf 100644 (file)
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -79,9 +79,12 @@ __releases(&journal->j_state_lock)
                if (space_left < nblocks) {
                        int chkpt = journal->j_checkpoint_transactions != NULL;
                        tid_t tid = 0;
+                       bool has_transaction = false;
 
-                       if (journal->j_committing_transaction)
+                       if (journal->j_committing_transaction) {
                                tid = journal->j_committing_transaction->t_tid;
+                               has_transaction = true;
+                       }
                        spin_unlock(&journal->j_list_lock);
                        write_unlock(&journal->j_state_lock);
                        if (chkpt) {
@@ -92,7 +95,7 @@ __releases(&journal->j_state_lock)
                                 * journal was aborted due to an error.
                                 */
                                ;
-                       } else if (tid) {
+                       } else if (has_transaction) {
                                /*
                                 * jbd2_journal_commit_transaction() may want
                                 * to take the checkpoint_mutex if JBD2_FLUSHED