linux-ext4 - [PATCH] ext4: disable defrag for metadata

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Message-Id: <1366322282-4673-1-git-send-email-tytso@mit.edu>
Date:	Thu, 18 Apr 2013 17:58:02 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	Theodore Ts'o <tytso@....edu>,
	"Darrick J. Wong" <darrick.wong@...cle.com>
Subject: [PATCH] ext4: disable defrag for metadata_csum file systems

It looks like there is absolutely no support for metadata checksums in
fs/ext4/move_extent.c.  So if you try to defrag a file on a
metadata_csum, it leaves the file system corrupted.

We really, really should get this fixed ASAP, but until we do, let's
disable e4defrag on metadata_csum file systems so we avoid corrupting
file systems.

Cc: "Darrick J. Wong" <darrick.wong@...cle.com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
 fs/ext4/ioctl.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 9491ac0..2d043da 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -450,6 +450,15 @@ group_extend_out:
 			goto mext_out;
 		}
 
+		if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
+			EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Online defrag not supported with "
+				 "metadata_csum");
+			err = -EOPNOTSUPP;
+			goto mext_out;
+		}
+
 		err = mnt_want_write_file(filp);
 		if (err)
 			goto mext_out;
-- 
1.7.12.rc0.22.gcdd159b

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