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nfsd: support ext4 i_version

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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
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1
fs/nfsd/nfs3xdr.c
View file

@ -272,6 +272,7 @@ void fill_post_wcc(struct svc_fh *fhp)
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

63
fs/nfsd/nfs4xdr.c
View file

@ -1490,13 +1490,41 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
memcpy(p, ptr, nbytes); \
p += XDR_QUADLEN(nbytes); \
}} while (0)
#define WRITECINFO(c) do { \
*p++ = htonl(c.atomic); \
*p++ = htonl(c.before_ctime_sec); \
*p++ = htonl(c.before_ctime_nsec); \
*p++ = htonl(c.after_ctime_sec); \
*p++ = htonl(c.after_ctime_nsec); \
} while (0)
static void write32(__be32 **p, u32 n)
{
*(*p)++ = n;
}
static void write64(__be32 **p, u64 n)
{
write32(p, (u32)(n >> 32));
write32(p, (u32)n);
}
static void write_change(__be32 **p, struct kstat *stat, struct inode *inode)
{
if (IS_I_VERSION(inode)) {
write64(p, inode->i_version);
} else {
write32(p, stat->ctime.tv_sec);
write32(p, stat->ctime.tv_nsec);
}
}
static void write_cinfo(__be32 **p, struct nfsd4_change_info *c)
{
write32(p, c->atomic);
if (c->change_supported) {
write64(p, c->before_change);
write64(p, c->after_change);
} else {
write32(p, c->before_ctime_sec);
write32(p, c->before_ctime_nsec);
write32(p, c->after_ctime_sec);
write32(p, c->after_ctime_nsec);
}
}
#define RESERVE_SPACE(nbytes) do { \
p = resp->p; \
@ -1849,16 +1877,9 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
WRITE32(NFS4_FH_PERSISTENT|NFS4_FH_VOL_RENAME);
}
if (bmval0 & FATTR4_WORD0_CHANGE) {
/*
* Note: This _must_ be consistent with the scheme for writing
* change_info, so any changes made here must be reflected there
* as well. (See xdr4.h:set_change_info() and the WRITECINFO()
* macro above.)
*/
if ((buflen -= 8) < 0)
goto out_resource;
WRITE32(stat.ctime.tv_sec);
WRITE32(stat.ctime.tv_nsec);
write_change(&p, &stat, dentry->d_inode);
}
if (bmval0 & FATTR4_WORD0_SIZE) {
if ((buflen -= 8) < 0)
@ -2364,7 +2385,7 @@ nfsd4_encode_create(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_
if (!nfserr) {
RESERVE_SPACE(32);
WRITECINFO(create->cr_cinfo);
write_cinfo(&p, &create->cr_cinfo);
WRITE32(2);
WRITE32(create->cr_bmval[0]);
WRITE32(create->cr_bmval[1]);
@ -2475,7 +2496,7 @@ nfsd4_encode_link(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_li
if (!nfserr) {
RESERVE_SPACE(20);
WRITECINFO(link->li_cinfo);
write_cinfo(&p, &link->li_cinfo);
ADJUST_ARGS();
}
return nfserr;
@ -2493,7 +2514,7 @@ nfsd4_encode_open(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_op
nfsd4_encode_stateid(resp, &open->op_stateid);
RESERVE_SPACE(40);
WRITECINFO(open->op_cinfo);
write_cinfo(&p, &open->op_cinfo);
WRITE32(open->op_rflags);
WRITE32(2);
WRITE32(open->op_bmval[0]);
@ -2771,7 +2792,7 @@ nfsd4_encode_remove(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_
if (!nfserr) {
RESERVE_SPACE(20);
WRITECINFO(remove->rm_cinfo);
write_cinfo(&p, &remove->rm_cinfo);
ADJUST_ARGS();
}
return nfserr;
@ -2784,8 +2805,8 @@ nfsd4_encode_rename(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_
if (!nfserr) {
RESERVE_SPACE(40);
WRITECINFO(rename->rn_sinfo);
WRITECINFO(rename->rn_tinfo);
write_cinfo(&p, &rename->rn_sinfo);
write_cinfo(&p, &rename->rn_tinfo);
ADJUST_ARGS();
}
return nfserr;

7
include/linux/nfsd/nfsfh.h
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;
}
}

9
include/linux/nfsd/xdr4.h
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 {
@ -503,11 +506,17 @@ 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->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 *);
int nfs4svc_decode_compoundargs(struct svc_rqst *, __be32 *,