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Message-Id: <1392225469-5163-1-git-send-email-tytso@mit.edu> Date: Wed, 12 Feb 2014 12:17:49 -0500 From: Theodore Ts'o <tytso@....edu> To: Ext4 Developers List <linux-ext4@...r.kernel.org> Cc: Theodore Ts'o <tytso@....edu>, stable@...r.kernel.org Subject: [PATCH] ext4: don't try to modify s_flags if the the file system is read-only 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@....edu> Cc: stable@...r.kernel.org --- fs/ext4/super.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 0491c81..8161c28 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3695,16 +3695,22 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) 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 */ -- 1.8.5.rc3.362.gdf10213 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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