nfsd4: do idr preallocation with stateid allocation

Move idr preallocation out of stateid initialization, into stateid
allocation, so that we no longer have to handle any errors from the
former.

This is a little subtle due to the way the idr code manages these
preallocated items--document that in comments.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 37 insertions, 39 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index ae5d25075f6..1f8c781c2a2 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -215,13 +215,12 @@ static inline int get_new_stid(struct nfs4_stid *stid)
         int new_stid;
         int error;
 
-        if (!idr_pre_get(stateids, GFP_KERNEL))
-                return -ENOMEM;
-
         error = idr_get_new_above(stateids, stid, min_stateid, &new_stid);
         /*
-         * All this code is currently serialized; the preallocation
-         * above should still be ours:
+         * Note: the necessary preallocation was done in
+         * nfs4_alloc_stateid().  The idr code caps the number of
+         * preallocations that can exist at a time, but the state lock
+         * prevents anyone from using ours before we get here:
          */
         BUG_ON(error);
         /*
@@ -240,7 +239,7 @@ static inline int get_new_stid(struct nfs4_stid *stid)
         return new_stid;
 }
 
-static inline __be32 init_stid(struct nfs4_stid *stid, struct nfs4_client *cl, unsigned char type)
+static void init_stid(struct nfs4_stid *stid, struct nfs4_client *cl, unsigned char type)
 {
         stateid_t *s = &stid->sc_stateid;
         int new_id;
@@ -249,12 +248,24 @@ static inline __be32 init_stid(struct nfs4_stid *stid, struct nfs4_client *cl, u
         stid->sc_client = cl;
         s->si_opaque.so_clid = cl->cl_clientid;
         new_id = get_new_stid(stid);
-        if (new_id < 0)
-                return nfserr_jukebox;
         s->si_opaque.so_id = (u32)new_id;
         /* Will be incremented before return to client: */
         s->si_generation = 0;
-        return 0;
+}
+
+static struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct kmem_cache *slab)
+{
+        struct idr *stateids = &cl->cl_stateids;
+
+        if (!idr_pre_get(stateids, GFP_KERNEL))
+                return NULL;
+        /*
+         * 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.
+         */
+        return kmem_cache_alloc(slab, GFP_KERNEL);
 }
 
 static struct nfs4_delegation *
@@ -262,7 +273,6 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv
 {
         struct nfs4_delegation *dp;
         struct nfs4_file *fp = stp->st_file;
-        __be32 status;
 
         dprintk("NFSD alloc_init_deleg\n");
         /*
@@ -276,14 +286,10 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv
                 return NULL;
         if (num_delegations > max_delegations)
                 return NULL;
-        dp = kmem_cache_alloc(deleg_slab, GFP_KERNEL);
+        dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab));
         if (dp == NULL)
                 return dp;
-        status = init_stid(&dp->dl_stid, clp, NFS4_DELEG_STID);
-        if (status) {
-                kmem_cache_free(deleg_slab, dp);
-                return NULL;
-        }
+        init_stid(&dp->dl_stid, clp, 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
@@ -2331,14 +2337,11 @@ alloc_init_open_stateowner(unsigned int strhashval, struct nfs4_client *clp, str
         return oo;
 }
 
-static inline __be32 init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp, struct nfsd4_open *open) {
+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;
-        __be32 status;
 
-        status = init_stid(&stp->st_stid, clp, NFS4_OPEN_STID);
-        if (status)
-                return status;
+        init_stid(&stp->st_stid, clp, 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);
@@ -2350,7 +2353,6 @@ static inline __be32 init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_
         __set_bit(open->op_share_access, &stp->st_access_bmap);
         __set_bit(open->op_share_deny, &stp->st_deny_bmap);
         stp->st_openstp = NULL;
-        return nfs_ok;
 }
 
 static void
@@ -2614,10 +2616,14 @@ nfs4_check_open(struct nfs4_file *fp, struct nfsd4_open *open, struct nfs4_ol_st
         return nfs_ok;
 }
 
-static inline struct nfs4_ol_stateid *
-nfs4_alloc_stateid(void)
+static struct nfs4_ol_stateid * nfs4_alloc_stateid(struct nfs4_client *clp)
 {
-        return kmem_cache_alloc(stateid_slab, GFP_KERNEL);
+        return openlockstateid(nfs4_alloc_stid(clp, stateid_slab));
+}
+
+static void nfs4_free_stateid(struct nfs4_ol_stateid *s)
+{
+        kmem_cache_free(stateid_slab, s);
 }
 
 static inline int nfs4_access_to_access(u32 nfs4_access)
@@ -2661,15 +2667,16 @@ nfs4_new_open(struct svc_rqst *rqstp, struct nfs4_ol_stateid **stpp,
                 struct nfsd4_open *open)
 {
         struct nfs4_ol_stateid *stp;
+        struct nfs4_client *cl = open->op_openowner->oo_owner.so_client;
         __be32 status;
 
-        stp = nfs4_alloc_stateid();
+        stp = nfs4_alloc_stateid(cl);
         if (stp == NULL)
                 return nfserr_jukebox;
 
         status = nfs4_get_vfs_file(rqstp, fp, cur_fh, open);
         if (status) {
-                kmem_cache_free(stateid_slab, stp);
+                nfs4_free_stateid(stp);
                 return status;
         }
         *stpp = stp;
@@ -2912,11 +2919,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
                 status = nfs4_new_open(rqstp, &stp, fp, current_fh, open);
                 if (status)
                         goto out;
-                status = init_open_stateid(stp, fp, open);
-                if (status) {
-                        release_open_stateid(stp);
-                        goto out;
-                }
+                init_open_stateid(stp, fp, open);
                 status = nfsd4_truncate(rqstp, current_fh, open);
                 if (status) {
                         release_open_stateid(stp);
@@ -3812,16 +3815,11 @@ alloc_init_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp, struct
 {
         struct nfs4_ol_stateid *stp;
         struct nfs4_client *clp = lo->lo_owner.so_client;
-        __be32 status;
 
-        stp = nfs4_alloc_stateid();
+        stp = nfs4_alloc_stateid(clp);
         if (stp == NULL)
                 return NULL;
-        status = init_stid(&stp->st_stid, clp, NFS4_LOCK_STID);
-        if (status) {
-                free_generic_stateid(stp);
-                return NULL;
-        }
+        init_stid(&stp->st_stid, clp, 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;