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 <liubo2009@xxxxxxxxxxxxxx> wrote: > >> When the filesystem is readonly, avoid transaction stuff by checking MS_RDONLY > >> at start transaction time. > >> > >> Signed-off-by: Liu Bo <liubo2009@xxxxxxxxxxxxxx> > >> --- > >> 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. > > 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. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
