diff options
| author | Darrick J. Wong <darrick.wong@oracle.com> | 2015-02-12 22:31:21 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2015-02-12 22:31:21 -0500 |
| commit | 2cb5cc8b09c939c77826635956c35995b15c9331 (patch) | |
| tree | a172f96f3dca8c8432786eef7d103138ef859370 | |
| parent | 04ecddb73dd83d1094a904b8d03c57880998daee (diff) | |
| download | linux-2cb5cc8b09c939c77826635956c35995b15c9331.tar.gz linux-2cb5cc8b09c939c77826635956c35995b15c9331.tar.bz2 linux-2cb5cc8b09c939c77826635956c35995b15c9331.zip | |
ext4: support read-only images
Add a rocompat feature, "readonly" to mark a FS image as read-only.
The feature prevents the kernel and e2fsprogs from changing the image;
the flag can be toggled by tune2fs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/ext4.h | 1 | ||||
| -rw-r--r-- | fs/ext4/super.c | 10 |
2 files changed, 10 insertions, 1 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index b7f393df2e4c..7fec2efd8635 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1530,6 +1530,7 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei) * GDT_CSUM bits are mutually exclusive. */ #define EXT4_FEATURE_RO_COMPAT_METADATA_CSUM 0x0400 +#define EXT4_FEATURE_RO_COMPAT_READONLY 0x1000 #define EXT4_FEATURE_INCOMPAT_COMPRESSION 0x0001 #define EXT4_FEATURE_INCOMPAT_FILETYPE 0x0002 diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 95b388cae0ab..60db5a11fbea 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2776,6 +2776,12 @@ static int ext4_feature_set_ok(struct super_block *sb, int readonly) if (readonly) return 1; + if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_READONLY)) { + ext4_msg(sb, KERN_INFO, "filesystem is read-only"); + sb->s_flags |= MS_RDONLY; + return 1; + } + /* Check that feature set is OK for a read-write mount */ if (EXT4_HAS_RO_COMPAT_FEATURE(sb, ~EXT4_FEATURE_RO_COMPAT_SUPP)) { ext4_msg(sb, KERN_ERR, "couldn't mount RDWR because of " @@ -4929,7 +4935,9 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data) ext4_mark_recovery_complete(sb, es); } else { /* Make sure we can mount this feature set readwrite */ - if (!ext4_feature_set_ok(sb, 0)) { + if (EXT4_HAS_RO_COMPAT_FEATURE(sb, + EXT4_FEATURE_RO_COMPAT_READONLY) || + !ext4_feature_set_ok(sb, 0)) { err = -EROFS; goto restore_opts; } |