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>
This commit is contained in:
J. Bruce Fields 2009-04-16 17:33:25 -04:00
parent 3352d2c2d0
commit c654b8a9cb
4 changed files with 63 additions and 25 deletions

View file

@ -151,9 +151,15 @@ typedef struct svc_fh {
__u64 fh_pre_size; /* size before operation */
struct timespec fh_pre_mtime; /* mtime before oper */
struct timespec fh_pre_ctime; /* ctime before oper */
/*
* pre-op nfsv4 change attr: note must check IS_I_VERSION(inode)
* to find out if it is valid.
*/
u64 fh_pre_change;
/* Post-op attributes saved in fh_unlock */
struct kstat fh_post_attr; /* full attrs after operation */
u64 fh_post_change; /* nfsv4 change; see above */
#endif /* CONFIG_NFSD_V3 */
} svc_fh;
@ -298,6 +304,7 @@ 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_saved = 1;
}
}

View file

@ -64,10 +64,13 @@ static inline bool nfsd4_has_session(struct nfsd4_compound_state *cs)
struct nfsd4_change_info {
u32 atomic;
bool change_supported;
u32 before_ctime_sec;
u32 before_ctime_nsec;
u64 before_change;
u32 after_ctime_sec;
u32 after_ctime_nsec;
u64 after_change;
};
struct nfsd4_access {
@ -503,10 +506,16 @@ set_change_info(struct nfsd4_change_info *cinfo, struct svc_fh *fhp)
{
BUG_ON(!fhp->fh_pre_saved || !fhp->fh_post_saved);
cinfo->atomic = 1;
cinfo->before_ctime_sec = fhp->fh_pre_ctime.tv_sec;
cinfo->before_ctime_nsec = fhp->fh_pre_ctime.tv_nsec;
cinfo->after_ctime_sec = fhp->fh_post_attr.ctime.tv_sec;
cinfo->after_ctime_nsec = fhp->fh_post_attr.ctime.tv_nsec;
cinfo->change_supported = IS_I_VERSION(fhp->fh_dentry->d_inode);
if (cinfo->change_supported) {
cinfo->before_change = fhp->fh_pre_change;
cinfo->after_change = fhp->fh_post_change;
} else {
cinfo->before_ctime_sec = fhp->fh_pre_ctime.tv_sec;
cinfo->before_ctime_nsec = fhp->fh_pre_ctime.tv_nsec;
cinfo->after_ctime_sec = fhp->fh_post_attr.ctime.tv_sec;
cinfo->after_ctime_nsec = fhp->fh_post_attr.ctime.tv_nsec;
}
}
int nfs4svc_encode_voidres(struct svc_rqst *, __be32 *, void *);