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nfsd4: clean up session allocation 

Changes:
	- make sure session memory reservation is released on failure
	  path.
	- use min_t()/min() for more compact code in several places.
	- break alloc_init_session into smaller pieces.
	- miscellaneous other cleanup.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
J. Bruce Fields 2010-09-27 17:12:05 -04:00
parent dd93842457
commit 5b6feee960
1 changed files with 89 additions and 122 deletions
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211
fs/nfsd/nfs4state.c
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@ -533,94 +533,6 @@ gen_sessionid(struct nfsd4_session *ses)
*/
#define NFSD_MIN_HDR_SEQ_SZ (24 + 12 + 44)
/*
* Give the client the number of ca_maxresponsesize_cached slots it
* requests, of size bounded by NFSD_SLOT_CACHE_SIZE,
* NFSD_MAX_MEM_PER_SESSION, and nfsd_drc_max_mem. Do not allow more
* than NFSD_MAX_SLOTS_PER_SESSION.
*
* If we run out of reserved DRC memory we should (up to a point)
* re-negotiate active sessions and reduce their slot usage to make
* rooom for new connections. For now we just fail the create session.
*/
static int set_forechannel_drc_size(struct nfsd4_channel_attrs *fchan)
{
int mem, size = fchan->maxresp_cached;
if (fchan->maxreqs < 1)
return nfserr_inval;
if (size < NFSD_MIN_HDR_SEQ_SZ)
size = NFSD_MIN_HDR_SEQ_SZ;
size -= NFSD_MIN_HDR_SEQ_SZ;
if (size > NFSD_SLOT_CACHE_SIZE)
size = NFSD_SLOT_CACHE_SIZE;
/* bound the maxreqs by NFSD_MAX_MEM_PER_SESSION */
mem = fchan->maxreqs * size;
if (mem > NFSD_MAX_MEM_PER_SESSION) {
fchan->maxreqs = NFSD_MAX_MEM_PER_SESSION / size;
if (fchan->maxreqs > NFSD_MAX_SLOTS_PER_SESSION)
fchan->maxreqs = NFSD_MAX_SLOTS_PER_SESSION;
mem = fchan->maxreqs * size;
}
spin_lock(&nfsd_drc_lock);
/* bound the total session drc memory ussage */
if (mem + nfsd_drc_mem_used > nfsd_drc_max_mem) {
fchan->maxreqs = (nfsd_drc_max_mem - nfsd_drc_mem_used) / size;
mem = fchan->maxreqs * size;
}
nfsd_drc_mem_used += mem;
spin_unlock(&nfsd_drc_lock);
if (fchan->maxreqs == 0)
return nfserr_jukebox;
fchan->maxresp_cached = size + NFSD_MIN_HDR_SEQ_SZ;
return 0;
}
/*
* fchan holds the client values on input, and the server values on output
* sv_max_mesg is the maximum payload plus one page for overhead.
*/
static int init_forechannel_attrs(struct svc_rqst *rqstp,
struct nfsd4_channel_attrs *session_fchan,
struct nfsd4_channel_attrs *fchan)
{
int status = 0;
__u32 maxcount = nfsd_serv->sv_max_mesg;
/* headerpadsz set to zero in encode routine */
/* Use the client's max request and max response size if possible */
if (fchan->maxreq_sz > maxcount)
fchan->maxreq_sz = maxcount;
session_fchan->maxreq_sz = fchan->maxreq_sz;
if (fchan->maxresp_sz > maxcount)
fchan->maxresp_sz = maxcount;
session_fchan->maxresp_sz = fchan->maxresp_sz;
/* Use the client's maxops if possible */
if (fchan->maxops > NFSD_MAX_OPS_PER_COMPOUND)
fchan->maxops = NFSD_MAX_OPS_PER_COMPOUND;
session_fchan->maxops = fchan->maxops;
/* FIXME: Error means no more DRC pages so the server should
* recover pages from existing sessions. For now fail session
* creation.
*/
status = set_forechannel_drc_size(fchan);
session_fchan->maxresp_cached = fchan->maxresp_cached;
session_fchan->maxreqs = fchan->maxreqs;
dprintk("%s status %d\n", __func__, status);
return status;
}
static void
free_session_slots(struct nfsd4_session *ses)
{
@ -639,63 +551,118 @@ static inline int slot_bytes(struct nfsd4_channel_attrs *ca)
return ca->maxresp_cached - NFSD_MIN_HDR_SEQ_SZ;
}
static __be32 alloc_init_session(struct svc_rqst *rqstp, struct nfs4_client *clp, struct nfsd4_create_session *cses)
static int nfsd4_sanitize_slot_size(u32 size)
{
struct nfsd4_session *new, tmp;
struct nfsd4_slot *sp;
int idx, slotsize, cachesize, i;
int status;
size -= NFSD_MIN_HDR_SEQ_SZ; /* We don't cache the rpc header */
size = min_t(u32, size, NFSD_SLOT_CACHE_SIZE);
memset(&tmp, 0, sizeof(tmp));
return size;
}
/* FIXME: For now, we just accept the client back channel attributes. */
tmp.se_bchannel = cses->back_channel;
status = init_forechannel_attrs(rqstp, &tmp.se_fchannel,
&cses->fore_channel);
if (status)
goto out;
/*
* 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
* rooom for new connections. For now we just fail the create session.
*/
static int nfsd4_get_drc_mem(int slotsize, u32 num)
{
int avail;
num = min_t(u32, num, NFSD_MAX_SLOTS_PER_SESSION);
spin_lock(&nfsd_drc_lock);
avail = min_t(int, NFSD_MAX_MEM_PER_SESSION,
nfsd_drc_max_mem - nfsd_drc_mem_used);
num = min_t(int, num, avail / slotsize);
nfsd_drc_mem_used += num * slotsize;
spin_unlock(&nfsd_drc_lock);
return num;
}
static void nfsd4_put_drc_mem(int slotsize, int num)
{
spin_lock(&nfsd_drc_lock);
nfsd_drc_mem_used -= slotsize * num;
spin_unlock(&nfsd_drc_lock);
}
static struct nfsd4_session *alloc_session(int slotsize, int numslots)
{
struct nfsd4_session *new;
int mem, i;
BUILD_BUG_ON(NFSD_MAX_SLOTS_PER_SESSION * sizeof(struct nfsd4_slot *)
+ sizeof(struct nfsd4_session) > PAGE_SIZE);
+ sizeof(struct nfsd4_session) > PAGE_SIZE);
mem = numslots * sizeof(struct nfsd4_slot *);
status = nfserr_jukebox;
/* allocate struct nfsd4_session and slot table pointers in one piece */
slotsize = tmp.se_fchannel.maxreqs * sizeof(struct nfsd4_slot *);
new = kzalloc(sizeof(*new) + slotsize, GFP_KERNEL);
new = kzalloc(sizeof(*new) + mem, GFP_KERNEL);
if (!new)
goto out;
memcpy(new, &tmp, sizeof(*new));
return NULL;
/* allocate each struct nfsd4_slot and data cache in one piece */
cachesize = slot_bytes(&new->se_fchannel);
for (i = 0; i < new->se_fchannel.maxreqs; i++) {
sp = kzalloc(sizeof(*sp) + cachesize, GFP_KERNEL);
if (!sp)
for (i = 0; i < numslots; i++) {
mem = sizeof(struct nfsd4_slot) + slotsize;
new->se_slots[i] = kzalloc(mem, GFP_KERNEL);
if (!new->se_slots[i])
goto out_free;
new->se_slots[i] = sp;
}
return new;
out_free:
while (i--)
kfree(new->se_slots[i]);
kfree(new);
return NULL;
}
static void init_forechannel_attrs(struct nfsd4_channel_attrs *new, struct nfsd4_channel_attrs *req, int numslots, int slotsize)
{
u32 maxrpc = nfsd_serv->sv_max_mesg;
new->maxreqs = numslots;
new->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 __be32 alloc_init_session(struct svc_rqst *rqstp, struct nfs4_client *clp, struct nfsd4_create_session *cses)
{
struct nfsd4_session *new;
struct nfsd4_channel_attrs *fchan = &cses->fore_channel;
int numslots, slotsize;
int idx;
/*
* 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);
new = alloc_session(slotsize, numslots);
if (!new) {
nfsd4_put_drc_mem(slotsize, fchan->maxreqs);
return nfserr_jukebox;
}
init_forechannel_attrs(&new->se_fchannel, fchan, numslots, slotsize);
new->se_client = clp;
gen_sessionid(new);
idx = hash_sessionid(&new->se_sessionid);
memcpy(clp->cl_sessionid.data, new->se_sessionid.data,
NFS4_MAX_SESSIONID_LEN);
new->se_flags = cses->flags;
kref_init(&new->se_ref);
idx = hash_sessionid(&new->se_sessionid);
spin_lock(&client_lock);
list_add(&new->se_hash, &sessionid_hashtbl[idx]);
list_add(&new->se_perclnt, &clp->cl_sessions);
spin_unlock(&client_lock);
status = nfs_ok;
out:
return status;
out_free:
free_session_slots(new);
kfree(new);
goto out;
return nfs_ok;
}
/* caller must hold client_lock */