linux-ext4 - [PATCH 2/3] ext4: support freezing ext2 (nojournal) file systems

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Date:	Thu, 18 Sep 2014 16:26:28 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	Dexuan Cui <decui@...rosoft.com>, Theodore Ts'o <tytso@....edu>
Subject: [PATCH 2/3] ext4: support freezing ext2 (nojournal) file systems

Through an oversight, when we added nojournal support to ext4, we
didn't add support to allow file system freezing.  This is relatively
easy to add, so let's do it.

Signed-off-by: Theodore Ts'o <tytso@....edu>
Reported-by: Dexuan Cui <decui@...rosoft.com>
---
 fs/ext4/super.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 4770c98..921d5b4 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1131,6 +1131,8 @@ static const struct super_operations ext4_nojournal_sops = {
 	.drop_inode	= ext4_drop_inode,
 	.evict_inode	= ext4_evict_inode,
 	.sync_fs	= ext4_sync_fs,
+	.freeze_fs	= ext4_freeze,
+	.unfreeze_fs	= ext4_unfreeze,
 	.put_super	= ext4_put_super,
 	.statfs		= ext4_statfs,
 	.remount_fs	= ext4_remount,
@@ -4758,23 +4760,26 @@ static int ext4_freeze(struct super_block *sb)
 
 	journal = EXT4_SB(sb)->s_journal;
 
-	/* Now we set up the journal barrier. */
-	jbd2_journal_lock_updates(journal);
+	if (journal) {
+		/* Now we set up the journal barrier. */
+		jbd2_journal_lock_updates(journal);
 
-	/*
-	 * Don't clear the needs_recovery flag if we failed to flush
-	 * the journal.
-	 */
-	error = jbd2_journal_flush(journal);
-	if (error < 0)
-		goto out;
+		/*
+		 * Don't clear the needs_recovery flag if we failed to
+		 * flush the journal.
+		 */
+		error = jbd2_journal_flush(journal);
+		if (error < 0)
+			goto out;
+	}
 
 	/* Journal blocked and flushed, clear needs_recovery flag. */
 	EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
 	error = ext4_commit_super(sb, 1);
 out:
-	/* we rely on upper layer to stop further updates */
-	jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+	if (journal)
+		/* we rely on upper layer to stop further updates */
+		jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
 	return error;
 }
 
-- 
2.1.0

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