This is a note to let you know that I've just added the patch titled

    ext4: don't try to modify s_flags if the the file system is read-only

to the 3.4-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ext4-don-t-try-to-modify-s_flags-if-the-the-file-system-is-read-only.patch
and it can be found in the queue-3.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


>From 23301410972330c0ae9a8afc379ba2005e249cc6 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <[email protected]>
Date: Wed, 12 Feb 2014 12:16:04 -0500
Subject: ext4: don't try to modify s_flags if the the file system is read-only

From: Theodore Ts'o <[email protected]>

commit 23301410972330c0ae9a8afc379ba2005e249cc6 upstream.

If an ext4 file system is created by some tool other than mke2fs
(perhaps by someone who has a pathalogical fear of the GPL) that
doesn't set one or the other of the EXT2_FLAGS_{UN}SIGNED_HASH flags,
and that file system is then mounted read-only, don't try to modify
the s_flags field.  Otherwise, if dm_verity is in use, the superblock
will change, causing an dm_verity failure.

Signed-off-by: "Theodore Ts'o" <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 fs/ext4/super.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3370,16 +3370,22 @@ static int ext4_fill_super(struct super_
        for (i = 0; i < 4; i++)
                sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]);
        sbi->s_def_hash_version = es->s_def_hash_version;
-       i = le32_to_cpu(es->s_flags);
-       if (i & EXT2_FLAGS_UNSIGNED_HASH)
-               sbi->s_hash_unsigned = 3;
-       else if ((i & EXT2_FLAGS_SIGNED_HASH) == 0) {
+       if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_DIR_INDEX)) {
+               i = le32_to_cpu(es->s_flags);
+               if (i & EXT2_FLAGS_UNSIGNED_HASH)
+                       sbi->s_hash_unsigned = 3;
+               else if ((i & EXT2_FLAGS_SIGNED_HASH) == 0) {
 #ifdef __CHAR_UNSIGNED__
-               es->s_flags |= cpu_to_le32(EXT2_FLAGS_UNSIGNED_HASH);
-               sbi->s_hash_unsigned = 3;
+                       if (!(sb->s_flags & MS_RDONLY))
+                               es->s_flags |=
+                                       cpu_to_le32(EXT2_FLAGS_UNSIGNED_HASH);
+                       sbi->s_hash_unsigned = 3;
 #else
-               es->s_flags |= cpu_to_le32(EXT2_FLAGS_SIGNED_HASH);
+                       if (!(sb->s_flags & MS_RDONLY))
+                               es->s_flags |=
+                                       cpu_to_le32(EXT2_FLAGS_SIGNED_HASH);
 #endif
+               }
        }
 
        /* Handle clustersize */


Patches currently in stable-queue which might be from [email protected] are

queue-3.4/ext4-fix-online-resize-with-a-non-standard-blocks-per-group-setting.patch
queue-3.4/ext4-don-t-try-to-modify-s_flags-if-the-the-file-system-is-read-only.patch
queue-3.4/ext4-don-t-leave-i_crtime.tv_sec-uninitialized.patch
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