Don't write changes to the backup superblocks by default
This patch changes ext2fs_open() to set EXT2_FLAG_MASTER_SB_ONLY by
default. This avoids some problems in e2fsck (reported by Jim Garlick)
where a corrupt journal can end up writing the bad superblock to the
backups. In general, only e2fsck (after the filesystem is clean),
tune2fs, and resize2fs should change the backup superblocks by default.
Most callers of ext2fs_open() should not be touching anything where the
backups should be touched. So let's change the defaults to avoid
potential problems.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/e2fsck/ChangeLog b/e2fsck/ChangeLog
index fa40d28..3fbeef2 100644
--- a/e2fsck/ChangeLog
+++ b/e2fsck/ChangeLog
@@ -1,3 +1,10 @@
+2007-06-18 Theodore Tso <tytso@mit.edu>
+
+ * journal.c (e2fsck_run_ext3_journal), unix.c (main): Explicitly
+ add the EXT2_FLAG_MASTER_SB_ONLY flag to make sure we
+ won't write out the backup superblocks until we're sure
+ that we want write them out.
+
2007-06-04 Theodore Tso <tytso@mit.edu>
* super.c (check_super_block, e2fsck_get_device_size),
diff --git a/e2fsck/journal.c b/e2fsck/journal.c
index f1e3ad0..519df48 100644
--- a/e2fsck/journal.c
+++ b/e2fsck/journal.c
@@ -832,6 +832,7 @@
}
ctx->fs->priv_data = ctx;
ctx->fs->now = ctx->now;
+ ctx->fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
/* Set the superblock flags */
e2fsck_clear_recover(ctx, recover_retval);
diff --git a/e2fsck/unix.c b/e2fsck/unix.c
index 7957894..72091f8 100644
--- a/e2fsck/unix.c
+++ b/e2fsck/unix.c
@@ -981,6 +981,18 @@
fix_problem(ctx, PR_0_SB_CORRUPT, &pctx);
fatal_error(ctx, 0);
}
+ /*
+ * We only update the master superblock because (a) paranoia;
+ * we don't want to corrupt the backup superblocks, and (b) we
+ * don't need to update the mount count and last checked
+ * fields in the backup superblock (the kernel doesn't update
+ * the backup superblocks anyway). With newer versions of the
+ * library this flag is set by ext2fs_open2(), but we set this
+ * here just to be sure. (No, we don't support e2fsck running
+ * with some other libext2fs than the one that it was shipped
+ * with, but just in case....)
+ */
+ fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
if (!(ctx->flags & E2F_FLAG_GOT_DEVSIZE)) {
__u32 blocksize = EXT2_BLOCK_SIZE(fs->super);
@@ -1127,15 +1139,6 @@
!(ctx->options & E2F_OPT_READONLY))
ext2fs_mark_super_dirty(fs);
- /*
- * We only update the master superblock because (a) paranoia;
- * we don't want to corrupt the backup superblocks, and (b) we
- * don't need to update the mount count and last checked
- * fields in the backup superblock (the kernel doesn't
- * update the backup superblocks anyway).
- */
- fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
-
ehandler_init(fs->io);
if (ctx->superblock)
diff --git a/lib/ext2fs/ChangeLog b/lib/ext2fs/ChangeLog
index 9eb5ef9..02604b5 100644
--- a/lib/ext2fs/ChangeLog
+++ b/lib/ext2fs/ChangeLog
@@ -1,3 +1,10 @@
+2007-06-12 Theodore Tso <tytso@mit.edu>
+
+ * openfs.c (ext2fs_open2): We now set EXT2_FLAG_MASTER_SB_ONLY
+ when we open a filesystem. Applications that want to
+ write changes to the backup superblocks need to explicitly
+ clear this flag.
+
2007-05-31 Theodore Tso <tytso@mit.edu>
* tst_super_size.c (main): Add sanity check to make sure the
diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index ea10373..55cc077 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -101,6 +101,8 @@
memset(fs, 0, sizeof(struct struct_ext2_filsys));
fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
fs->flags = flags;
+ /* don't overwrite sb backups unless flag is explicitly cleared */
+ fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
fs->umask = 022;
retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
if (retval)
diff --git a/misc/ChangeLog b/misc/ChangeLog
index 5b680c5..d1b4b79 100644
--- a/misc/ChangeLog
+++ b/misc/ChangeLog
@@ -1,3 +1,9 @@
+2007-06-12 Theodore Tso <tytso@mit.edu>
+
+ * tune2fs.c (main): Clear the EXT2_FLAG_MASTER_SB_ONLY flag
+ because we want tune2fs changes to get written to the
+ backup blocks.
+
2007-06-04 Theodore Tso <tytso@mit.edu>
* badblocks.c (main): Fix error checking of the last-block and
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 967b589..833b994 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -780,6 +780,7 @@
exit(1);
}
sb = fs->super;
+ fs->flags &= ~EXT2_FLAG_MASTER_SB_ONLY;
if (print_label) {
/* For e2label emulation */
printf("%.*s\n", (int) sizeof(sb->s_volume_name),
diff --git a/resize/ChangeLog b/resize/ChangeLog
index e1f616b..9c8a8c2 100644
--- a/resize/ChangeLog
+++ b/resize/ChangeLog
@@ -1,3 +1,9 @@
+2007-06-12 Theodore Tso <tytso@mit.edu>
+
+ * resize2fs.c (resize_fs): Clear the EXT2_FLAG_MASTER_SB_ONLY flag
+ to make sure the superblock changes are written out to the
+ backup superblocks.
+
2007-05-22 Theodore Tso <tytso@mit.edu>
* sim_progress.c (ext2fs_progress_init): Fix type-punning warning.
diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index a25cb05..0d6a082 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -138,6 +138,7 @@
if (retval)
goto errout;
+ rfs->new_fs->flags &= ~EXT2_FLAG_MASTER_SB_ONLY;
retval = ext2fs_close(rfs->new_fs);
if (retval)
goto errout;