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nfsd4: simplify idr allocation 

We don't really need to preallocate at all; just allocate and initialize
everything at once, but leave the sc_type field initially 0 to prevent
finding the stateid till it's fully initialized.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2013-02-03 12:23:01 -05:00
parent 2d32b29a1c
commit 3abdb60712
1 changed files with 54 additions and 31 deletions
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85
fs/nfsd/nfs4state.c
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@ -261,33 +261,46 @@ static inline int get_new_stid(struct nfs4_stid *stid)
return new_stid;
}
static void init_stid(struct nfs4_stid *stid, struct nfs4_client *cl, unsigned char type)
{
stateid_t *s = &stid->sc_stateid;
int new_id;
stid->sc_type = type;
stid->sc_client = cl;
s->si_opaque.so_clid = cl->cl_clientid;
new_id = get_new_stid(stid);
s->si_opaque.so_id = (u32)new_id;
/* Will be incremented before return to client: */
s->si_generation = 0;
}
static struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct kmem_cache *slab)
static struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct
kmem_cache *slab)
{
struct idr *stateids = &cl->cl_stateids;
static int min_stateid = 0;
struct nfs4_stid *stid;
int new_id;
stid = kmem_cache_alloc(slab, GFP_KERNEL);
if (!stid)
return NULL;
if (!idr_pre_get(stateids, GFP_KERNEL))
return NULL;
goto out_free;
if (idr_get_new_above(stateids, stid, min_stateid, &new_id))
goto out_free;
stid->sc_client = cl;
stid->sc_type = 0;
stid->sc_stateid.si_opaque.so_id = new_id;
stid->sc_stateid.si_opaque.so_clid = cl->cl_clientid;
/* Will be incremented before return to client: */
stid->sc_stateid.si_generation = 0;
/*
* Note: if we fail here (or any time between now and the time
* we actually get the new idr), we won't need to undo the idr
* preallocation, since the idr code caps the number of
* preallocated entries.
* It shouldn't be a problem to reuse an opaque stateid value.
* I don't think it is for 4.1. But with 4.0 I worry that, for
* example, a stray write retransmission could be accepted by
* the server when it should have been rejected. Therefore,
* adopt a trick from the sctp code to attempt to maximize the
* amount of time until an id is reused, by ensuring they always
* "increase" (mod INT_MAX):
*/
return kmem_cache_alloc(slab, GFP_KERNEL);
min_stateid = new_id+1;
if (min_stateid == INT_MAX)
min_stateid = 0;
return stid;
out_free:
kfree(stid);
return NULL;
}
static struct nfs4_ol_stateid * nfs4_alloc_stateid(struct nfs4_client *clp)
@ -316,7 +329,7 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv
dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab));
if (dp == NULL)
return dp;
init_stid(&dp->dl_stid, clp, NFS4_DELEG_STID);
dp->dl_stid.sc_type = NFS4_DELEG_STID;
/*
* delegation seqid's are never incremented. The 4.1 special
* meaning of seqid 0 isn't meaningful, really, but let's avoid
@ -337,13 +350,21 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv
return dp;
}
void free_stid(struct nfs4_stid *s, struct kmem_cache *slab)
{
struct idr *stateids = &s->sc_client->cl_stateids;
idr_remove(stateids, s->sc_stateid.si_opaque.so_id);
kmem_cache_free(slab, s);
}
void
nfs4_put_delegation(struct nfs4_delegation *dp)
{
if (atomic_dec_and_test(&dp->dl_count)) {
dprintk("NFSD: freeing dp %p\n",dp);
put_nfs4_file(dp->dl_file);
kmem_cache_free(deleg_slab, dp);
free_stid(&dp->dl_stid, deleg_slab);
num_delegations--;
}
}
@ -360,9 +381,7 @@ static void nfs4_put_deleg_lease(struct nfs4_file *fp)
static void unhash_stid(struct nfs4_stid *s)
{
struct idr *stateids = &s->sc_client->cl_stateids;
idr_remove(stateids, s->sc_stateid.si_opaque.so_id);
s->sc_type = 0;
}
/* Called under the state lock. */
@ -519,7 +538,7 @@ static void close_generic_stateid(struct nfs4_ol_stateid *stp)
static void free_generic_stateid(struct nfs4_ol_stateid *stp)
{
kmem_cache_free(stateid_slab, stp);
free_stid(&stp->st_stid, stateid_slab);
}
static void release_lock_stateid(struct nfs4_ol_stateid *stp)
@ -1260,7 +1279,12 @@ static void gen_confirm(struct nfs4_client *clp)
static struct nfs4_stid *find_stateid(struct nfs4_client *cl, stateid_t *t)
{
return idr_find(&cl->cl_stateids, t->si_opaque.so_id);
struct nfs4_stid *ret;
ret = idr_find(&cl->cl_stateids, t->si_opaque.so_id);
if (!ret || !ret->sc_type)
return NULL;
return ret;
}
static struct nfs4_stid *find_stateid_by_type(struct nfs4_client *cl, stateid_t *t, char typemask)
@ -2446,9 +2470,8 @@ alloc_init_open_stateowner(unsigned int strhashval, struct nfs4_client *clp, str
static void init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp, struct nfsd4_open *open) {
struct nfs4_openowner *oo = open->op_openowner;
struct nfs4_client *clp = oo->oo_owner.so_client;
init_stid(&stp->st_stid, clp, NFS4_OPEN_STID);
stp->st_stid.sc_type = NFS4_OPEN_STID;
INIT_LIST_HEAD(&stp->st_lockowners);
list_add(&stp->st_perstateowner, &oo->oo_owner.so_stateids);
list_add(&stp->st_perfile, &fp->fi_stateids);
@ -4034,7 +4057,7 @@ alloc_init_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp, struct
stp = nfs4_alloc_stateid(clp);
if (stp == NULL)
return NULL;
init_stid(&stp->st_stid, clp, NFS4_LOCK_STID);
stp->st_stid.sc_type = NFS4_LOCK_STID;
list_add(&stp->st_perfile, &fp->fi_stateids);
list_add(&stp->st_perstateowner, &lo->lo_owner.so_stateids);
stp->st_stateowner = &lo->lo_owner;