| From 23301410972330c0ae9a8afc379ba2005e249cc6 Mon Sep 17 00:00:00 2001 |
| From: Theodore Ts'o <tytso@mit.edu> |
| 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 <tytso@mit.edu> |
| |
| 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" <tytso@mit.edu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ext4/super.c | 20 +++++++++++++------- |
| 1 file changed, 13 insertions(+), 7 deletions(-) |
| |
| --- a/fs/ext4/super.c |
| +++ b/fs/ext4/super.c |
| @@ -3695,16 +3695,22 @@ 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 */ |
