On Thu, Jun 22, 2017 at 06:27:08PM -0400, Theodore Ts'o wrote: > On Thu, Jun 22, 2017 at 01:40:25PM -0600, Andreas Dilger wrote: > > > > The EXT4_XATTR_MAX_LARGE_EA_SIZE limit of 1MB was also totally arbitrary, > > but a reasonable upper limit for the atomic get/set interface used by > > xattrs. The underlying disk format could actually store xattrs of any size. > > > > I'd think if we want to get huge xattrs that they should be handled by > > having separate streams (e.g. open file descriptor, ioctl/syscall to select > > a different stream number on that file) so that the data doesn't have to be > > completely rewritten any time it is modified, but streams are frowned upon > > by many Linux developers for security reasons so will probably be a no-go. > > This has been discussed before. Most of the arguments (both pro and > con) can be found on this thread (2016): > > https://www.spinics.net/lists/linux-nfs/msg57055.html > > Jeremy Allison used to pester me for alternate data stream support > many years ago, but he has since completely changed his opinion on the > matter: > > http://www.spinics.net/lists/linux-fsdevel/msg96083.html > > So if jra@ doesn't add support for this interface to Samba, the thing > I'd ask is who is actually going to used such an interface; because if > there aren't any user space applications lining up to use it, it's > probably not worth adding it until we can find a flagship user of the > proposed new API. Heh, ok, that's about what I expected to hear. :) > There are plenty of other things we could add that Jeremy has asked > for, that *would* improve Samba performance. (For example, adding a > mount option which provides case-insensitive lookup; the one thing > that makes this hard is that while Android doesn't seem to care about > I18N --- they are currently using an ascii-only tolower() in their > sdcardfs hack --- Samba/Windows does care about I18N done right, so we > wouldn't have to get a Unicode case folding implementation into the > kernel.) So I'd argue that those are probably more interesting > projects than O_XATTR support. --D > > - Ted
