On Wed, Oct 31, 2018 at 03:23:41PM -0400, Vivek Goyal wrote: > On Wed, Oct 31, 2018 at 08:37:04PM +0200, Amir Goldstein wrote: > > On Wed, Oct 31, 2018 at 6:39 PM Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > > > > > ... > > > > > > > > Yes, but keep in mind that strict=off will NOT be applied to stable > > > > v4.19.y *unless* a real user really reports a bug, a-priori, we assume > > > > that implicit metacopy=on => redirect_dir=on,strict=on is sufficient > > > > to solve the bug, so it is sufficient for stable. > > > > > > Did not understand this. So strict=on will be in stable or not? I mean, > > > all the behavior strict=on enforces will be in 4.19 or not. > > > > > > If it is not, then it will become backward compatibility issue by the > > > time 4.20 releases. > > > > > > If strict=on is not part of 4.19 stable, then you can't switch it > > > on in 4.20. > > > > > > What am I missing. > > > > > > > I guess I haven't thought this through. Let's see: > > > > 1.a. In 4.19, specifying metacopy=on will result in metacopy=on > > OR -EINVAL (a.k.a. "the bug fix") [*] > > > > 1.b. In 4.19, user will not be able to mount with metacopy=on with > > an upper fs that does not support xattr/d_type/RENAME_WHITEOUT. > > Ok, so metacopy will trigger strict=on internally. And that in-turn > will trigger all the checks on upper fs (xattr/d_type/RENAME_WHITEOUT). > > > > > 1.d. In 4.19, mount will fail if given mount option metacopy=on and > > nfs_export is enabled (even if enabled by default) or if redirect_dir > > is disabled (even if disabled by default). > > Ok, so no automatic enable/disable of redirect_dir/nfs_export options. > > > > > 1.d. In 4.19, mount will fail if given mount option metacopy=on, > > index is enabled (even if enabled by default) and underlying fs does > > not support file handles. > > Ok, so index might be enabled by default but we will not disable it > because metacopy=on has triggered strict behavior. Hi Amir, Thinking more about it. What does strict=on mean for default behavior of a knob (configured using module param or Kconfig). Will it mean that default value of knob can't be changed either (disabled if need be). IOW, strict=on will mean that all values of options will be static and can't be changed. It does not matter where these came from. (Override ordering between Kconfig/module/mount option will still be there). If that's the case, then metacopy=on (hence strict=on) and auto enabling of redirect_dir are contradictory. Given strict is on, we are not supposed to change the default value as it came from Kconfig/module? Similarly, we can't disable nfs_export if metacopy=on. IOW, If we limit "strict=on" to values passed as part of mount options, then it will allow to change default values of other options as needed. But if "strict=on" means default values can't be changed, then auto enabling/disabling of redirect_dir/nfs_export is not possible? Thanks Vivek
