[3.11.y.z extended stable] Patch "ext4: fix unjournalled bg descriptor while initializing inode bitmap" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ext4: fix unjournalled bg descriptor while initializing inode bitmap

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 0dbce07b15915edf81112ee757ccf1d0fc61c639 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso at mit.edu>
Date: Sat, 5 Jul 2014 16:28:35 -0400
Subject: [PATCH 12/41] ext4: fix unjournalled bg descriptor while initializing
 inode bitmap

commit 61c219f5814277ecb71d64cb30297028d6665979 upstream.

The first time that we allocate from an uninitialized inode allocation
bitmap, if the block allocation bitmap is also uninitalized, we need
to get write access to the block group descriptor before we start
modifying the block group descriptor flags and updating the free block
count, etc.  Otherwise, there is the potential of a bad journal
checksum (if journal checksums are enabled), and of the file system
becoming inconsistent if we crash at exactly the wrong time.

Signed-off-by: Theodore Ts'o <tytso at mit.edu>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/ext4/ialloc.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 8bf5999875ee..0ecc14028477 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -781,6 +781,13 @@ got:
 		goto out;
 	}

+	BUFFER_TRACE(group_desc_bh, "get_write_access");
+	err = ext4_journal_get_write_access(handle, group_desc_bh);
+	if (err) {
+		ext4_std_error(sb, err);
+		goto out;
+	}
+
 	/* We may have to initialize the block bitmap if it isn't already */
 	if (ext4_has_group_desc_csum(sb) &&
 	    gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
@@ -817,13 +824,6 @@ got:
 		}
 	}

-	BUFFER_TRACE(group_desc_bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, group_desc_bh);
-	if (err) {
-		ext4_std_error(sb, err);
-		goto out;
-	}
-
 	/* Update the relevant bg descriptor fields */
 	if (ext4_has_group_desc_csum(sb)) {
 		int free;
--
1.9.1