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nfsd4: fix forechannel attribute negotiation
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Negotiation of the 4.1 session forechannel attributes is a mess.  Fix:

	- Move it all into check_forechannel_attrs instead of spreading
	  it between that, alloc_session, and init_forechannel_attrs.
	- set a minimum "slotsize" so that our drc memory limits apply
	  even for small maxresponsesize_cached.  This also fixes some
	  bugs when slotsize becomes <= 0.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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J. Bruce Fields committed Apr 9, 2013
1 parent 373cd40 commit 55c760c
Showing 1 changed file with 49 additions and 67 deletions.
116 changes: 49 additions & 67 deletions fs/nfsd/nfs4state.c
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Original file line number Diff line number Diff line change
Expand Up @@ -776,30 +776,28 @@ free_session_slots(struct nfsd4_session *ses)
* We don't actually need to cache the rpc and session headers, so we
* can allocate a little less for each slot:
*/
static inline int slot_bytes(struct nfsd4_channel_attrs *ca)
static inline u32 slot_bytes(struct nfsd4_channel_attrs *ca)
{
return ca->maxresp_cached - NFSD_MIN_HDR_SEQ_SZ;
}

static int nfsd4_sanitize_slot_size(u32 size)
{
size -= NFSD_MIN_HDR_SEQ_SZ; /* We don't cache the rpc header */
size = min_t(u32, size, NFSD_SLOT_CACHE_SIZE);
u32 size;

return size;
if (ca->maxresp_cached < NFSD_MIN_HDR_SEQ_SZ)
size = 0;
else
size = ca->maxresp_cached - NFSD_MIN_HDR_SEQ_SZ;
return size + sizeof(struct nfsd4_slot);
}

/*
* XXX: If we run out of reserved DRC memory we could (up to a point)
* re-negotiate active sessions and reduce their slot usage to make
* room for new connections. For now we just fail the create session.
*/
static int nfsd4_get_drc_mem(int slotsize, u32 num)
static u32 nfsd4_get_drc_mem(struct nfsd4_channel_attrs *ca)
{
u32 slotsize = slot_bytes(ca);
u32 num = ca->maxreqs;
int avail;

num = min_t(u32, num, NFSD_MAX_SLOTS_PER_SESSION);

spin_lock(&nfsd_drc_lock);
avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION,
nfsd_drc_max_mem - nfsd_drc_mem_used);
Expand All @@ -810,15 +808,19 @@ static int nfsd4_get_drc_mem(int slotsize, u32 num)
return num;
}

static void nfsd4_put_drc_mem(int slotsize, int num)
static void nfsd4_put_drc_mem(struct nfsd4_channel_attrs *ca)
{
int slotsize = slot_bytes(ca);

spin_lock(&nfsd_drc_lock);
nfsd_drc_mem_used -= slotsize * num;
nfsd_drc_mem_used -= slotsize * ca->maxreqs;
spin_unlock(&nfsd_drc_lock);
}

static struct nfsd4_session *__alloc_session(int slotsize, int numslots)
static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *attrs)
{
int numslots = attrs->maxreqs;
int slotsize = slot_bytes(attrs);
struct nfsd4_session *new;
int mem, i;

Expand All @@ -831,8 +833,7 @@ static struct nfsd4_session *__alloc_session(int slotsize, int numslots)
return NULL;
/* allocate each struct nfsd4_slot and data cache in one piece */
for (i = 0; i < numslots; i++) {
mem = sizeof(struct nfsd4_slot) + slotsize;
new->se_slots[i] = kzalloc(mem, GFP_KERNEL);
new->se_slots[i] = kzalloc(slotsize, GFP_KERNEL);
if (!new->se_slots[i])
goto out_free;
}
Expand All @@ -844,21 +845,6 @@ static struct nfsd4_session *__alloc_session(int slotsize, int numslots)
return NULL;
}

static void init_forechannel_attrs(struct nfsd4_channel_attrs *new,
struct nfsd4_channel_attrs *req,
int numslots, int slotsize,
struct nfsd_net *nn)
{
u32 maxrpc = nn->nfsd_serv->sv_max_mesg;

new->maxreqs = numslots;
new->maxresp_cached = min_t(u32, req->maxresp_cached,
slotsize + NFSD_MIN_HDR_SEQ_SZ);
new->maxreq_sz = min_t(u32, req->maxreq_sz, maxrpc);
new->maxresp_sz = min_t(u32, req->maxresp_sz, maxrpc);
new->maxops = min_t(u32, req->maxops, NFSD_MAX_OPS_PER_COMPOUND);
}

static void free_conn(struct nfsd4_conn *c)
{
svc_xprt_put(c->cn_xprt);
Expand Down Expand Up @@ -960,7 +946,6 @@ static void nfsd4_del_conns(struct nfsd4_session *s)

static void __free_session(struct nfsd4_session *ses)
{
nfsd4_put_drc_mem(slot_bytes(&ses->se_fchannel), ses->se_fchannel.maxreqs);
free_session_slots(ses);
kfree(ses);
}
Expand All @@ -971,35 +956,10 @@ static void free_session(struct nfsd4_session *ses)

lockdep_assert_held(&nn->client_lock);
nfsd4_del_conns(ses);
nfsd4_put_drc_mem(&ses->se_fchannel);
__free_session(ses);
}

static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *fchan,
struct nfsd_net *nn)
{
struct nfsd4_session *new;
int numslots, slotsize;
/*
* Note decreasing slot size below client's request may
* make it difficult for client to function correctly, whereas
* decreasing the number of slots will (just?) affect
* performance. When short on memory we therefore prefer to
* decrease number of slots instead of their size.
*/
slotsize = nfsd4_sanitize_slot_size(fchan->maxresp_cached);
numslots = nfsd4_get_drc_mem(slotsize, fchan->maxreqs);
if (numslots < 1)
return NULL;

new = __alloc_session(slotsize, numslots);
if (!new) {
nfsd4_put_drc_mem(slotsize, numslots);
return NULL;
}
init_forechannel_attrs(&new->se_fchannel, fchan, numslots, slotsize, nn);
return new;
}

static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, struct nfs4_client *clp, struct nfsd4_create_session *cses)
{
int idx;
Expand All @@ -1022,7 +982,8 @@ static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, stru
list_add(&new->se_perclnt, &clp->cl_sessions);
spin_unlock(&clp->cl_lock);
spin_unlock(&nn->client_lock);

memcpy(&new->se_fchannel, &cses->fore_channel,
sizeof(struct nfsd4_channel_attrs));
if (cses->flags & SESSION4_BACK_CHAN) {
struct sockaddr *sa = svc_addr(rqstp);
/*
Expand Down Expand Up @@ -1803,12 +1764,33 @@ nfsd4_replay_create_session(struct nfsd4_create_session *cr_ses,
/* seqid, slotID, slotID, slotID, status */ \
5 ) * sizeof(__be32))

static __be32 check_forechannel_attrs(struct nfsd4_channel_attrs *ca)
static __be32 check_forechannel_attrs(struct nfsd4_channel_attrs *ca, struct nfsd_net *nn)
{
u32 maxrpc = nn->nfsd_serv->sv_max_mesg;

if (ca->maxreq_sz < NFSD_MIN_REQ_HDR_SEQ_SZ)
return nfserr_toosmall;
if (ca->maxresp_sz < NFSD_MIN_RESP_HDR_SEQ_SZ)
return nfserr_toosmall;
ca->headerpadsz = 0;
ca->maxreq_sz = min_t(u32, ca->maxreq_sz, maxrpc);
ca->maxresp_sz = min_t(u32, ca->maxresp_sz, maxrpc);
ca->maxops = min_t(u32, ca->maxops, NFSD_MAX_OPS_PER_COMPOUND);
ca->maxresp_cached = min_t(u32, ca->maxresp_cached,
NFSD_SLOT_CACHE_SIZE + NFSD_MIN_HDR_SEQ_SZ);
ca->maxreqs = min_t(u32, ca->maxreqs, NFSD_MAX_SLOTS_PER_SESSION);
/*
* Note decreasing slot size below client's request may make it
* difficult for client to function correctly, whereas
* decreasing the number of slots will (just?) affect
* performance. When short on memory we therefore prefer to
* decrease number of slots instead of their size. Clients that
* request larger slots than they need will get poor results:
*/
ca->maxreqs = nfsd4_get_drc_mem(ca);
if (!ca->maxreqs)
return nfserr_jukebox;

return nfs_ok;
}

Expand All @@ -1827,13 +1809,13 @@ nfsd4_create_session(struct svc_rqst *rqstp,

if (cr_ses->flags & ~SESSION4_FLAG_MASK_A)
return nfserr_inval;
status = check_forechannel_attrs(&cr_ses->fore_channel);
status = check_forechannel_attrs(&cr_ses->fore_channel, nn);
if (status)
return status;
new = alloc_session(&cr_ses->fore_channel, nn);
if (!new)
return nfserr_jukebox;
status = nfserr_jukebox;
new = alloc_session(&cr_ses->fore_channel);
if (!new)
goto out_release_drc_mem;
conn = alloc_conn_from_crses(rqstp, cr_ses);
if (!conn)
goto out_free_session;
Expand Down Expand Up @@ -1892,8 +1874,6 @@ nfsd4_create_session(struct svc_rqst *rqstp,

memcpy(cr_ses->sessionid.data, new->se_sessionid.data,
NFS4_MAX_SESSIONID_LEN);
memcpy(&cr_ses->fore_channel, &new->se_fchannel,
sizeof(struct nfsd4_channel_attrs));
cs_slot->sl_seqid++;
cr_ses->seqid = cs_slot->sl_seqid;

Expand All @@ -1906,6 +1886,8 @@ nfsd4_create_session(struct svc_rqst *rqstp,
free_conn(conn);
out_free_session:
__free_session(new);
out_release_drc_mem:
nfsd4_put_drc_mem(&cr_ses->fore_channel);
return status;
}

Expand Down

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