diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/nfsd/nfs3xdr.c | 2 | ||||
| -rw-r--r-- | fs/nfsd/nfs4xdr.c | 2 | ||||
| -rw-r--r-- | fs/nfsd/nfsfh.h | 24 |
3 files changed, 25 insertions, 3 deletions
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c index b8838d3023ff..bf444b664011 100644 --- a/fs/nfsd/nfs3xdr.c +++ b/fs/nfsd/nfs3xdr.c @@ -260,7 +260,7 @@ void fill_post_wcc(struct svc_fh *fhp) printk("nfsd: inode locked twice during operation.\n"); err = fh_getattr(fhp, &fhp->fh_post_attr); - fhp->fh_post_change = d_inode(fhp->fh_dentry)->i_version; + fhp->fh_post_change = nfsd4_change_attribute(d_inode(fhp->fh_dentry)); if (err) { fhp->fh_post_saved = false; /* Grab the ctime anyway - set_change_info might use it */ diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 54e212e3541e..20fbcab97753 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -1973,7 +1973,7 @@ static __be32 *encode_change(__be32 *p, struct kstat *stat, struct inode *inode, *p++ = cpu_to_be32(convert_to_wallclock(exp->cd->flush_time)); *p++ = 0; } else if (IS_I_VERSION(inode)) { - p = xdr_encode_hyper(p, inode->i_version); + p = xdr_encode_hyper(p, nfsd4_change_attribute(inode)); } else { *p++ = cpu_to_be32(stat->ctime.tv_sec); *p++ = cpu_to_be32(stat->ctime.tv_nsec); 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; } } |