On 12/16/2010 12:03 AM, Chris Mason wrote: > Excerpts from liubo's message of 2010-12-15 04:12:14 -0500: >> On 12/15/2010 04:45 PM, Yan, Zheng wrote: >>> On Fri, Dec 3, 2010 at 4:16 PM, liubo <liubo2...@cn.fujitsu.com> wrote: >>>> When the filesystem is readonly, avoid transaction stuff by checking >>>> MS_RDONLY >>>> at start transaction time. >>>> >>>> Signed-off-by: Liu Bo <liubo2...@cn.fujitsu.com> >>>> --- >>>> fs/btrfs/transaction.c | 3 +++ >>>> 1 files changed, 3 insertions(+), 0 deletions(-) >>>> >>>> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c >>>> index 1fffbc0..14a597d 100644 >>>> --- a/fs/btrfs/transaction.c >>>> +++ b/fs/btrfs/transaction.c >>>> @@ -181,6 +181,9 @@ static struct btrfs_trans_handle >>>> *start_transaction(struct btrfs_root *root, >>>> struct btrfs_trans_handle *h; >>>> struct btrfs_transaction *cur_trans; >>>> int ret; >>>> + >>>> + if (root->fs_info->sb->s_flags & MS_RDONLY) >>>> + return ERR_PTR(-EROFS); >>>> again: >>>> h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS); >>>> if (!h) >>> There are cases that we need to start transaction when MS_RDONLY flag is >>> set. >>> For example, remount FS into read-only mode and log replay. >> However, is it weird to make changes to disk as fs is in readonly state? >> IMO, btrfs needs to limit the use of these "disk-change while readonly" >> cases, >> as it is not what readonly means. > > reiserfs and ext3 at least have always done this. Log replay is > required even when the FS is readonly. >
My concern is: now we have a forced readonly FS, which is already broken, if we still write something to disk, would it become more broken? >> Since it has been here, we can bypass readonly in those cases(as I did in >> the 5th patch): >> >> ... >> flags = sb->s_flags; >> if (sb->s_flags & MS_RDONLY) >> sb->s_flags &= ~MS_RDONLY > > I think we should have a dedicated flag to reflect a filesystem that is > forced readonly, and check that flag instead. OK, we did have fs_state, a dedicated flag. thanks, Liu Bo > > -chris > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
