| Message ID | 20161218185727.2209-1-kerolasa@iki.fi (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Dec 18, 2016 at 06:57:27PM +0000, Sami Kerola wrote: > An attempt to freeze a filesystem that does not support such operation is > reported as EOPNOTSUPP to user. Running unfreeze to the same filesystem > returns EINVAL. Later is a little misleading, users can mix that message > with return value from unfreezing when filesystem is not frozen. This is going to break gfs2 with it's odd ->that_super method. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 19 December 2016 at 10:24, Christoph Hellwig <hch@infradead.org> wrote: > On Sun, Dec 18, 2016 at 06:57:27PM +0000, Sami Kerola wrote: >> An attempt to freeze a filesystem that does not support such operation is >> reported as EOPNOTSUPP to user. Running unfreeze to the same filesystem >> returns EINVAL. Later is a little misleading, users can mix that message >> with return value from unfreezing when filesystem is not frozen. > > This is going to break gfs2 with it's odd ->that_super method. Thank you for feedback, there's just one small problem with it. I don't quite understand the breakage. Proposed change uses similar logic as ioctl_fsfreeze()[1] and it works fine. If I am not entirely mistaking freeze and thaw hooks where added[2] to avoid issues with gfs2. And looking gfs2 super_operations init[3] does not make me any wiser what might be wrong. Maybe feedback had typo s/that_super/thaw_super/[4]. But even then it is unclear to me how a null could cause breakage. [1] https://github.com/torvalds/linux/blob/master/fs/ioctl.c#L553 [2] https://github.com/torvalds/linux/commit/48b6bca6b7b8309697fc8a101793befe92d249d9 [3] https://github.com/torvalds/linux/blob/master/fs/gfs2/super.c#L1683 [4] https://github.com/torvalds/linux/blob/master/fs/super.c#L1446
diff --git a/fs/ioctl.c b/fs/ioctl.c index cb9b02940805..1d6372ef4008 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -566,6 +566,10 @@ static int ioctl_fsthaw(struct file *filp) if (!capable(CAP_SYS_ADMIN)) return -EPERM; + /* If filesystem doesn't support thaw feature, return. */ + if (!sb->s_op->unfreeze_fs) + return -EOPNOTSUPP; + /* Thaw */ if (sb->s_op->thaw_super) return sb->s_op->thaw_super(sb);
An attempt to freeze a filesystem that does not support such operation is reported as EOPNOTSUPP to user. Running unfreeze to the same filesystem returns EINVAL. Later is a little misleading, users can mix that message with return value from unfreezing when filesystem is not frozen. Signed-off-by: Sami Kerola <kerolasa@iki.fi> --- fs/ioctl.c | 4 ++++ 1 file changed, 4 insertions(+)