Merge: ext4: avoid journaling sb update on error if journal is destroying

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/7087

JIRA: https://issues.redhat.com/browse/RHEL-93593
CVE: CVE-2025-22113

Fix BUG_ON due to transaction start on an unmounting journal.

Signed-off-by: Brian Foster <bfoster@redhat.com>

Approved-by: Xiubo Li <xiubli@redhat.com>
Approved-by: Jay Shin <jaeshin@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

fs/ext4/ext4.h

@@ -1834,7 +1834,8 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
 enum {
 	EXT4_MF_MNTDIR_SAMPLED,
 	EXT4_MF_FS_ABORTED,	/* Fatal error detected */
-	EXT4_MF_FC_INELIGIBLE	/* Fast commit ineligible */
+	EXT4_MF_FC_INELIGIBLE,	/* Fast commit ineligible */
+	EXT4_MF_JOURNAL_DESTROY	/* Journal is in process of destroying */
 };
 
 static inline void ext4_set_mount_flag(struct super_block *sb, int bit)

fs/ext4/ext4_jbd2.h

@@ -513,4 +513,33 @@ static inline int ext4_should_dioread_nolock(struct inode *inode)
 	return 1;
 }
 
+/*
+ * Pass journal explicitly as it may not be cached in the sbi->s_journal in some
+ * cases
+ */
+static inline int ext4_journal_destroy(struct ext4_sb_info *sbi, journal_t *journal)
+{
+	int err = 0;
+
+	/*
+	 * At this point only two things can be operating on the journal.
+	 * JBD2 thread performing transaction commit and s_sb_upd_work
+	 * issuing sb update through the journal. Once we set
+	 * EXT4_JOURNAL_DESTROY, new ext4_handle_error() calls will not
+	 * queue s_sb_upd_work and ext4_force_commit() makes sure any
+	 * ext4_handle_error() calls from the running transaction commit are
+	 * finished. Hence no new s_sb_upd_work can be queued after we
+	 * flush it here.
+	 */
+	ext4_set_mount_flag(sbi->s_sb, EXT4_MF_JOURNAL_DESTROY);
+
+	ext4_force_commit(sbi->s_sb);
+	flush_work(&sbi->s_sb_upd_work);
+
+	err = jbd2_journal_destroy(journal);
+	sbi->s_journal = NULL;
+
+	return err;
+}
+
 #endif	/* _EXT4_JBD2_H */

fs/ext4/super.c

@@ -704,9 +704,13 @@ static void ext4_handle_error(struct super_block *sb, bool force_ro, int error,
 		 * In case the fs should keep running, we need to writeout
 		 * superblock through the journal. Due to lock ordering
 		 * constraints, it may not be safe to do it right here so we
-		 * defer superblock flushing to a workqueue.
+		 * defer superblock flushing to a workqueue. We just need to be
+		 * careful when the journal is already shutting down. If we get
+		 * here in that case, just update the sb directly as the last
+		 * transaction won't commit anyway.
 		 */
-		if (continue_fs && journal)
+		if (continue_fs && journal &&
+		    !ext4_test_mount_flag(sb, EXT4_MF_JOURNAL_DESTROY))
 			schedule_work(&EXT4_SB(sb)->s_sb_upd_work);
 		else
 			ext4_commit_super(sb);
@@ -1236,18 +1240,17 @@ static void ext4_put_super(struct super_block *sb)
 	ext4_unregister_li_request(sb);
 	ext4_quota_off_umount(sb);
 
-	flush_work(&sbi->s_sb_upd_work);
 	destroy_workqueue(sbi->rsv_conversion_wq);
 	ext4_release_orphan_info(sb);
 
 	if (sbi->s_journal) {
 		aborted = is_journal_aborted(sbi->s_journal);
-		err = jbd2_journal_destroy(sbi->s_journal);
-		sbi->s_journal = NULL;
+		err = ext4_journal_destroy(sbi, sbi->s_journal);
 		if ((err < 0) && !aborted) {
 			ext4_abort(sb, -err, "Couldn't clean up the journal");
 		}
-	}
+	} else
+		flush_work(&sbi->s_sb_upd_work);
 
 	ext4_es_unregister_shrinker(sbi);
 	timer_shutdown_sync(&sbi->s_err_report);
@@ -4907,10 +4910,7 @@ static int ext4_load_and_init_journal(struct super_block *sb,
 	return 0;
 
 out:
-	/* flush s_sb_upd_work before destroying the journal. */
-	flush_work(&sbi->s_sb_upd_work);
-	jbd2_journal_destroy(sbi->s_journal);
-	sbi->s_journal = NULL;
+	ext4_journal_destroy(sbi, sbi->s_journal);
 	return -EINVAL;
 }
 
@@ -5672,10 +5672,7 @@ failed_mount8: __maybe_unused
 	sbi->s_ea_block_cache = NULL;
 
 	if (sbi->s_journal) {
-		/* flush s_sb_upd_work before journal destroy. */
-		flush_work(&sbi->s_sb_upd_work);
-		jbd2_journal_destroy(sbi->s_journal);
-		sbi->s_journal = NULL;
+		ext4_journal_destroy(sbi, sbi->s_journal);
 	}
 failed_mount3a:
 	ext4_es_unregister_shrinker(sbi);
@@ -5962,7 +5959,7 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb,
 	return journal;
 
 out_journal:
-	jbd2_journal_destroy(journal);
+	ext4_journal_destroy(EXT4_SB(sb), journal);
 out_bdev:
 	bdev_fput(bdev_file);
 	return NULL;
@@ -6079,8 +6076,7 @@ static int ext4_load_journal(struct super_block *sb,
 	EXT4_SB(sb)->s_journal = journal;
 	err = ext4_clear_journal_err(sb, es);
 	if (err) {
-		EXT4_SB(sb)->s_journal = NULL;
-		jbd2_journal_destroy(journal);
+		ext4_journal_destroy(EXT4_SB(sb), journal);
 		return err;
 	}
 
@@ -6098,7 +6094,7 @@ static int ext4_load_journal(struct super_block *sb,
 	return 0;
 
 err_out:
-	jbd2_journal_destroy(journal);
+	ext4_journal_destroy(EXT4_SB(sb), journal);
 	return err;
 }