Re: [PATCH 03/12] ext4: prevent a fs without journal from being resized
From: Yongqiang Yang <hidden>
Date: 2011-07-18 03:44:59
On Mon, Jul 18, 2011 at 11:28 AM, Yongqiang Yang [off-list ref] wrote:
On Mon, Jul 18, 2011 at 11:17 AM, Tao Ma [off-list ref] wrote:quoted
On 07/18/2011 10:52 AM, Yongqiang Yang wrote:quoted
This patch prevents a fs without journal from being resized, because it is easy to detroy the fs.Why you want to do this? You see any corruption? At least in our product system, no-journal mode is heavily used and we really don't want to disable this feature.
Let's assume a situation without journal. If the online resizing is done successfully, it dirties super block and returns, then the added groups could be used and some data are written to the added groups, now comes an error before the super block are flushed. Could e2fsck can find data in the added groups? If not, this may bring something strange to users. It seems that super block should be flushed by online resizing, not just be dirtied. :-) Yongqiang.
I did not see any corruption. If there is no journal in a fs, then if an error happens during online resizing, the filesystem will be destroyed easily, I thought. Just my thought:-) It needs much more feedbacks. Thanks, Yongqiang.quoted
Thanks Taoquoted
Signed-off-by: Yongqiang Yang <redacted> --- fs/ext4/resize.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-)diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 53d9795..33ab40d 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c@@ -33,6 +33,16 @@ int ext4_resize_begin(struct super_block *sb)return -EPERM; } + /* + * We are not allowed to do online-resizing on a filesystem without + * journal, otherwise, it is easy to destroy the filesystem. + */ + if (!EXT4_SB(sb)->s_journal) { + ext4_warning(sb, "There is no journal for the filesystem, " + "so online resizing is not allowed\n"); + return -EPERM; + } + if (test_and_set_bit_lock(EXT4_RESIZING, &EXT4_SB(sb)->s_resize_flags)) ret = -EBUSY;-- Best Wishes Yongqiang Yang
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