diff options
Diffstat (limited to 'fs/nfsd/nfsfh.h')
| -rw-r--r-- | fs/nfsd/nfsfh.h | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h index f84fe6bf9aee..e47cf6c2ac28 100644 --- a/fs/nfsd/nfsfh.h +++ b/fs/nfsd/nfsfh.h @@ -241,6 +241,28 @@ fh_clear_wcc(struct svc_fh *fhp) } /* + * We could use i_version alone as the change attribute. However, + * i_version can go backwards after a reboot. On its own that doesn't + * necessarily cause a problem, but if i_version goes backwards and then + * is incremented again it could reuse a value that was previously used + * before boot, and a client who queried the two values might + * incorrectly assume nothing changed. + * + * By using both ctime and the i_version counter we guarantee that as + * long as time doesn't go backwards we never reuse an old value. + */ +static inline u64 nfsd4_change_attribute(struct inode *inode) +{ + u64 chattr; + + chattr = inode->i_ctime.tv_sec; + chattr <<= 30; + chattr += inode->i_ctime.tv_nsec; + chattr += inode->i_version; + return chattr; +} + +/* * Fill in the pre_op attr for the wcc data */ static inline void @@ -253,7 +275,7 @@ fill_pre_wcc(struct svc_fh *fhp) fhp->fh_pre_mtime = inode->i_mtime; fhp->fh_pre_ctime = inode->i_ctime; fhp->fh_pre_size = inode->i_size; - fhp->fh_pre_change = inode->i_version; + fhp->fh_pre_change = nfsd4_change_attribute(inode); fhp->fh_pre_saved = true; } } |