On Thu, Jun 09, 2016 at 11:51:12AM -0500, Eric Sandeen wrote: > > > On 6/9/16 11:36 AM, Eric Sandeen wrote: > > Ok, this more or less works; not really up to snuff > > for submission or merging, just sketching it out, but some > > questions first: > > > > 1) Is there really any point to this? :) We did have one > > request, and btrfs can do it ... > > Seems reasonable to me. Any details on the use case for the request? > > 2) Is using m_growlock horrible? growfs is the only other > > thing that writes all supers, so I grabbed it. We don't > > want multiple relabels stepping on each other. > > > > 3) Is there some way to actually force the primary to disk? > > Right now the label change isn't actually visible on the > > primary until unmount, which defeats the purpose. I'm not > > sure if there's a straightforward/safe way to make it > > visible... > > Oh, sorry - I guess it is getting written out, but it's only > available via an O_DIRECT read from userspace; it's not > invalidating the cache. > > # io/xfs_io -c "label derp" /mnt/test > label = "derp" > > # dd if=/dev/sdb2 bs=512 count=1 | hexdump -C > ... > 00000060 00 00 0a 00 b4 e5 02 00 02 00 00 08 66 6f 6f 00 |............foo.| > ... > > # dd if=/dev/sdb2 iflag=direct bs=512 count=1 | hexdump -C > ... > 00000060 00 00 0a 00 b4 e5 02 00 02 00 00 08 64 65 72 70 |............derp| > ... > > # dd if=/dev/sdb2 bs=512 count=1 | hexdump -C > ... > 00000060 00 00 0a 00 b4 e5 02 00 02 00 00 08 66 6f 6f 00 |............foo.| > ... > > Guess I need to think about this some more. > Isn't this to be expected? You're directly accessing the block device of a mounted filesystem. I would think this is expected behavior, so long as the set/get interfaces through the fs are consistent. Brian > -Eric > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
