nfsd: support ext4 i_version
ext4 supports a real NFSv4 change attribute, which is bumped whenever
the ctime would be updated, including times when two updates arrive
within a jiffy of each other. (Note that although ext4 has space for
nanosecond-precision ctime, the real resolution is lower: it actually
uses jiffies as the time-source.) This ensures clients will invalidate
their caches when they need to.
There is some fear that keeping the i_version up-to-date could have
performance drawbacks, so for now it's turned on only by a mount option.
We hope to do something better eventually.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Theodore Tso <tytso@mit.edu>
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 17d0dd9..01d4ec1 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -272,6 +272,7 @@
err = vfs_getattr(fhp->fh_export->ex_path.mnt, fhp->fh_dentry,
&fhp->fh_post_attr);
+ fhp->fh_post_change = fhp->fh_dentry->d_inode->i_version;
if (err)
fhp->fh_post_saved = 0;
else