mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 08:19:28 +00:00
![Kinglong Mee](/assets/img/avatar_default.png)
If register_shrinker() failed, nfsd will cause a NULL pointer access as, [ 9250.875465] nfsd: last server has exited, flushing export cache [ 9251.427270] BUG: unable to handle kernel NULL pointer dereference at (null) [ 9251.427393] IP: [<ffffffff8136fc29>] __list_del_entry+0x29/0xd0 [ 9251.427579] PGD 13e4d067 PUD 13e4c067 PMD 0 [ 9251.427633] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC [ 9251.427706] Modules linked in: ip6t_rpfilter ip6t_REJECT bnep bluetooth xt_conntrack cfg80211 rfkill ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw btrfs xfs microcode ppdev serio_raw pcspkr xor libcrc32c raid6_pq e1000 parport_pc parport i2c_piix4 i2c_core nfsd(OE-) auth_rpcgss nfs_acl lockd sunrpc(E) ata_generic pata_acpi [ 9251.428240] CPU: 0 PID: 1557 Comm: rmmod Tainted: G OE 3.16.0-rc2+ #22 [ 9251.428366] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013 [ 9251.428496] task: ffff880000849540 ti: ffff8800136f4000 task.ti: ffff8800136f4000 [ 9251.428593] RIP: 0010:[<ffffffff8136fc29>] [<ffffffff8136fc29>] __list_del_entry+0x29/0xd0 [ 9251.428696] RSP: 0018:ffff8800136f7ea0 EFLAGS: 00010207 [ 9251.428751] RAX: 0000000000000000 RBX: ffffffffa0116d48 RCX: dead000000200200 [ 9251.428814] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffa0116d48 [ 9251.428876] RBP: ffff8800136f7ea0 R08: ffff8800136f4000 R09: 0000000000000001 [ 9251.428939] R10: 8080808080808080 R11: 0000000000000000 R12: ffffffffa011a5a0 [ 9251.429002] R13: 0000000000000800 R14: 0000000000000000 R15: 00000000018ac090 [ 9251.429064] FS: 00007fb9acef0740(0000) GS:ffff88003fa00000(0000) knlGS:0000000000000000 [ 9251.429164] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 9251.429221] CR2: 0000000000000000 CR3: 0000000031a17000 CR4: 00000000001407f0 [ 9251.429306] Stack: [ 9251.429410] ffff8800136f7eb8 ffffffff8136fcdd ffffffffa0116d20 ffff8800136f7ed0 [ 9251.429511] ffffffff8118a0f2 0000000000000000 ffff8800136f7ee0 ffffffffa00eb765 [ 9251.429610] ffff8800136f7ef0 ffffffffa010e93c ffff8800136f7f78 ffffffff81104ac2 [ 9251.429709] Call Trace: [ 9251.429755] [<ffffffff8136fcdd>] list_del+0xd/0x30 [ 9251.429896] [<ffffffff8118a0f2>] unregister_shrinker+0x22/0x40 [ 9251.430037] [<ffffffffa00eb765>] nfsd_reply_cache_shutdown+0x15/0x90 [nfsd] [ 9251.430106] [<ffffffffa010e93c>] exit_nfsd+0x9/0x6cd [nfsd] [ 9251.430192] [<ffffffff81104ac2>] SyS_delete_module+0x162/0x200 [ 9251.430280] [<ffffffff81013b69>] ? do_notify_resume+0x59/0x90 [ 9251.430395] [<ffffffff816f2369>] system_call_fastpath+0x16/0x1b [ 9251.430457] Code: 00 00 55 48 8b 17 48 b9 00 01 10 00 00 00 ad de 48 8b 47 08 48 89 e5 48 39 ca 74 29 48 b9 00 02 20 00 00 00 ad de 48 39 c8 74 7a <4c> 8b 00 4c 39 c7 75 53 4c 8b 42 08 4c 39 c7 75 2b 48 89 42 08 [ 9251.430691] RIP [<ffffffff8136fc29>] __list_del_entry+0x29/0xd0 [ 9251.430755] RSP <ffff8800136f7ea0> [ 9251.430805] CR2: 0000000000000000 [ 9251.431033] ---[ end trace 080f3050d082b4ea ]--- Signed-off-by: Kinglong Mee <kinglongmee@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
637 lines
16 KiB
C
637 lines
16 KiB
C
/*
|
|
* Request reply cache. This is currently a global cache, but this may
|
|
* change in the future and be a per-client cache.
|
|
*
|
|
* This code is heavily inspired by the 44BSD implementation, although
|
|
* it does things a bit differently.
|
|
*
|
|
* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
|
|
*/
|
|
|
|
#include <linux/slab.h>
|
|
#include <linux/sunrpc/addr.h>
|
|
#include <linux/highmem.h>
|
|
#include <linux/log2.h>
|
|
#include <linux/hash.h>
|
|
#include <net/checksum.h>
|
|
|
|
#include "nfsd.h"
|
|
#include "cache.h"
|
|
|
|
#define NFSDDBG_FACILITY NFSDDBG_REPCACHE
|
|
|
|
/*
|
|
* We use this value to determine the number of hash buckets from the max
|
|
* cache size, the idea being that when the cache is at its maximum number
|
|
* of entries, then this should be the average number of entries per bucket.
|
|
*/
|
|
#define TARGET_BUCKET_SIZE 64
|
|
|
|
struct nfsd_drc_bucket {
|
|
struct list_head lru_head;
|
|
spinlock_t cache_lock;
|
|
};
|
|
|
|
static struct nfsd_drc_bucket *drc_hashtbl;
|
|
static struct kmem_cache *drc_slab;
|
|
|
|
/* max number of entries allowed in the cache */
|
|
static unsigned int max_drc_entries;
|
|
|
|
/* number of significant bits in the hash value */
|
|
static unsigned int maskbits;
|
|
static unsigned int drc_hashsize;
|
|
|
|
/*
|
|
* Stats and other tracking of on the duplicate reply cache. All of these and
|
|
* the "rc" fields in nfsdstats are protected by the cache_lock
|
|
*/
|
|
|
|
/* total number of entries */
|
|
static atomic_t num_drc_entries;
|
|
|
|
/* cache misses due only to checksum comparison failures */
|
|
static unsigned int payload_misses;
|
|
|
|
/* amount of memory (in bytes) currently consumed by the DRC */
|
|
static unsigned int drc_mem_usage;
|
|
|
|
/* longest hash chain seen */
|
|
static unsigned int longest_chain;
|
|
|
|
/* size of cache when we saw the longest hash chain */
|
|
static unsigned int longest_chain_cachesize;
|
|
|
|
static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec);
|
|
static void cache_cleaner_func(struct work_struct *unused);
|
|
static unsigned long nfsd_reply_cache_count(struct shrinker *shrink,
|
|
struct shrink_control *sc);
|
|
static unsigned long nfsd_reply_cache_scan(struct shrinker *shrink,
|
|
struct shrink_control *sc);
|
|
|
|
static struct shrinker nfsd_reply_cache_shrinker = {
|
|
.scan_objects = nfsd_reply_cache_scan,
|
|
.count_objects = nfsd_reply_cache_count,
|
|
.seeks = 1,
|
|
};
|
|
|
|
/*
|
|
* locking for the reply cache:
|
|
* A cache entry is "single use" if c_state == RC_INPROG
|
|
* Otherwise, it when accessing _prev or _next, the lock must be held.
|
|
*/
|
|
static DECLARE_DELAYED_WORK(cache_cleaner, cache_cleaner_func);
|
|
|
|
/*
|
|
* Put a cap on the size of the DRC based on the amount of available
|
|
* low memory in the machine.
|
|
*
|
|
* 64MB: 8192
|
|
* 128MB: 11585
|
|
* 256MB: 16384
|
|
* 512MB: 23170
|
|
* 1GB: 32768
|
|
* 2GB: 46340
|
|
* 4GB: 65536
|
|
* 8GB: 92681
|
|
* 16GB: 131072
|
|
*
|
|
* ...with a hard cap of 256k entries. In the worst case, each entry will be
|
|
* ~1k, so the above numbers should give a rough max of the amount of memory
|
|
* used in k.
|
|
*/
|
|
static unsigned int
|
|
nfsd_cache_size_limit(void)
|
|
{
|
|
unsigned int limit;
|
|
unsigned long low_pages = totalram_pages - totalhigh_pages;
|
|
|
|
limit = (16 * int_sqrt(low_pages)) << (PAGE_SHIFT-10);
|
|
return min_t(unsigned int, limit, 256*1024);
|
|
}
|
|
|
|
/*
|
|
* Compute the number of hash buckets we need. Divide the max cachesize by
|
|
* the "target" max bucket size, and round up to next power of two.
|
|
*/
|
|
static unsigned int
|
|
nfsd_hashsize(unsigned int limit)
|
|
{
|
|
return roundup_pow_of_two(limit / TARGET_BUCKET_SIZE);
|
|
}
|
|
|
|
static u32
|
|
nfsd_cache_hash(__be32 xid)
|
|
{
|
|
return hash_32(be32_to_cpu(xid), maskbits);
|
|
}
|
|
|
|
static struct svc_cacherep *
|
|
nfsd_reply_cache_alloc(void)
|
|
{
|
|
struct svc_cacherep *rp;
|
|
|
|
rp = kmem_cache_alloc(drc_slab, GFP_KERNEL);
|
|
if (rp) {
|
|
rp->c_state = RC_UNUSED;
|
|
rp->c_type = RC_NOCACHE;
|
|
INIT_LIST_HEAD(&rp->c_lru);
|
|
}
|
|
return rp;
|
|
}
|
|
|
|
static void
|
|
nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
|
|
{
|
|
if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
|
|
drc_mem_usage -= rp->c_replvec.iov_len;
|
|
kfree(rp->c_replvec.iov_base);
|
|
}
|
|
list_del(&rp->c_lru);
|
|
atomic_dec(&num_drc_entries);
|
|
drc_mem_usage -= sizeof(*rp);
|
|
kmem_cache_free(drc_slab, rp);
|
|
}
|
|
|
|
static void
|
|
nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
|
|
{
|
|
spin_lock(&b->cache_lock);
|
|
nfsd_reply_cache_free_locked(rp);
|
|
spin_unlock(&b->cache_lock);
|
|
}
|
|
|
|
int nfsd_reply_cache_init(void)
|
|
{
|
|
unsigned int hashsize;
|
|
unsigned int i;
|
|
int status = 0;
|
|
|
|
max_drc_entries = nfsd_cache_size_limit();
|
|
atomic_set(&num_drc_entries, 0);
|
|
hashsize = nfsd_hashsize(max_drc_entries);
|
|
maskbits = ilog2(hashsize);
|
|
|
|
status = register_shrinker(&nfsd_reply_cache_shrinker);
|
|
if (status)
|
|
return status;
|
|
|
|
drc_slab = kmem_cache_create("nfsd_drc", sizeof(struct svc_cacherep),
|
|
0, 0, NULL);
|
|
if (!drc_slab)
|
|
goto out_nomem;
|
|
|
|
drc_hashtbl = kcalloc(hashsize, sizeof(*drc_hashtbl), GFP_KERNEL);
|
|
if (!drc_hashtbl)
|
|
goto out_nomem;
|
|
for (i = 0; i < hashsize; i++) {
|
|
INIT_LIST_HEAD(&drc_hashtbl[i].lru_head);
|
|
spin_lock_init(&drc_hashtbl[i].cache_lock);
|
|
}
|
|
drc_hashsize = hashsize;
|
|
|
|
return 0;
|
|
out_nomem:
|
|
printk(KERN_ERR "nfsd: failed to allocate reply cache\n");
|
|
nfsd_reply_cache_shutdown();
|
|
return -ENOMEM;
|
|
}
|
|
|
|
void nfsd_reply_cache_shutdown(void)
|
|
{
|
|
struct svc_cacherep *rp;
|
|
unsigned int i;
|
|
|
|
unregister_shrinker(&nfsd_reply_cache_shrinker);
|
|
cancel_delayed_work_sync(&cache_cleaner);
|
|
|
|
for (i = 0; i < drc_hashsize; i++) {
|
|
struct list_head *head = &drc_hashtbl[i].lru_head;
|
|
while (!list_empty(head)) {
|
|
rp = list_first_entry(head, struct svc_cacherep, c_lru);
|
|
nfsd_reply_cache_free_locked(rp);
|
|
}
|
|
}
|
|
|
|
kfree (drc_hashtbl);
|
|
drc_hashtbl = NULL;
|
|
drc_hashsize = 0;
|
|
|
|
if (drc_slab) {
|
|
kmem_cache_destroy(drc_slab);
|
|
drc_slab = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Move cache entry to end of LRU list, and queue the cleaner to run if it's
|
|
* not already scheduled.
|
|
*/
|
|
static void
|
|
lru_put_end(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
|
|
{
|
|
rp->c_timestamp = jiffies;
|
|
list_move_tail(&rp->c_lru, &b->lru_head);
|
|
schedule_delayed_work(&cache_cleaner, RC_EXPIRE);
|
|
}
|
|
|
|
static long
|
|
prune_bucket(struct nfsd_drc_bucket *b)
|
|
{
|
|
struct svc_cacherep *rp, *tmp;
|
|
long freed = 0;
|
|
|
|
list_for_each_entry_safe(rp, tmp, &b->lru_head, c_lru) {
|
|
/*
|
|
* Don't free entries attached to calls that are still
|
|
* in-progress, but do keep scanning the list.
|
|
*/
|
|
if (rp->c_state == RC_INPROG)
|
|
continue;
|
|
if (atomic_read(&num_drc_entries) <= max_drc_entries &&
|
|
time_before(jiffies, rp->c_timestamp + RC_EXPIRE))
|
|
break;
|
|
nfsd_reply_cache_free_locked(rp);
|
|
freed++;
|
|
}
|
|
return freed;
|
|
}
|
|
|
|
/*
|
|
* Walk the LRU list and prune off entries that are older than RC_EXPIRE.
|
|
* Also prune the oldest ones when the total exceeds the max number of entries.
|
|
*/
|
|
static long
|
|
prune_cache_entries(void)
|
|
{
|
|
unsigned int i;
|
|
long freed = 0;
|
|
bool cancel = true;
|
|
|
|
for (i = 0; i < drc_hashsize; i++) {
|
|
struct nfsd_drc_bucket *b = &drc_hashtbl[i];
|
|
|
|
if (list_empty(&b->lru_head))
|
|
continue;
|
|
spin_lock(&b->cache_lock);
|
|
freed += prune_bucket(b);
|
|
if (!list_empty(&b->lru_head))
|
|
cancel = false;
|
|
spin_unlock(&b->cache_lock);
|
|
}
|
|
|
|
/*
|
|
* Conditionally rearm the job to run in RC_EXPIRE since we just
|
|
* ran the pruner.
|
|
*/
|
|
if (!cancel)
|
|
mod_delayed_work(system_wq, &cache_cleaner, RC_EXPIRE);
|
|
return freed;
|
|
}
|
|
|
|
static void
|
|
cache_cleaner_func(struct work_struct *unused)
|
|
{
|
|
prune_cache_entries();
|
|
}
|
|
|
|
static unsigned long
|
|
nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc)
|
|
{
|
|
return atomic_read(&num_drc_entries);
|
|
}
|
|
|
|
static unsigned long
|
|
nfsd_reply_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
|
|
{
|
|
return prune_cache_entries();
|
|
}
|
|
/*
|
|
* Walk an xdr_buf and get a CRC for at most the first RC_CSUMLEN bytes
|
|
*/
|
|
static __wsum
|
|
nfsd_cache_csum(struct svc_rqst *rqstp)
|
|
{
|
|
int idx;
|
|
unsigned int base;
|
|
__wsum csum;
|
|
struct xdr_buf *buf = &rqstp->rq_arg;
|
|
const unsigned char *p = buf->head[0].iov_base;
|
|
size_t csum_len = min_t(size_t, buf->head[0].iov_len + buf->page_len,
|
|
RC_CSUMLEN);
|
|
size_t len = min(buf->head[0].iov_len, csum_len);
|
|
|
|
/* rq_arg.head first */
|
|
csum = csum_partial(p, len, 0);
|
|
csum_len -= len;
|
|
|
|
/* Continue into page array */
|
|
idx = buf->page_base / PAGE_SIZE;
|
|
base = buf->page_base & ~PAGE_MASK;
|
|
while (csum_len) {
|
|
p = page_address(buf->pages[idx]) + base;
|
|
len = min_t(size_t, PAGE_SIZE - base, csum_len);
|
|
csum = csum_partial(p, len, csum);
|
|
csum_len -= len;
|
|
base = 0;
|
|
++idx;
|
|
}
|
|
return csum;
|
|
}
|
|
|
|
static bool
|
|
nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp)
|
|
{
|
|
/* Check RPC XID first */
|
|
if (rqstp->rq_xid != rp->c_xid)
|
|
return false;
|
|
/* compare checksum of NFS data */
|
|
if (csum != rp->c_csum) {
|
|
++payload_misses;
|
|
return false;
|
|
}
|
|
|
|
/* Other discriminators */
|
|
if (rqstp->rq_proc != rp->c_proc ||
|
|
rqstp->rq_prot != rp->c_prot ||
|
|
rqstp->rq_vers != rp->c_vers ||
|
|
rqstp->rq_arg.len != rp->c_len ||
|
|
!rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) ||
|
|
rpc_get_port(svc_addr(rqstp)) != rpc_get_port((struct sockaddr *)&rp->c_addr))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Search the request hash for an entry that matches the given rqstp.
|
|
* Must be called with cache_lock held. Returns the found entry or
|
|
* NULL on failure.
|
|
*/
|
|
static struct svc_cacherep *
|
|
nfsd_cache_search(struct nfsd_drc_bucket *b, struct svc_rqst *rqstp,
|
|
__wsum csum)
|
|
{
|
|
struct svc_cacherep *rp, *ret = NULL;
|
|
struct list_head *rh = &b->lru_head;
|
|
unsigned int entries = 0;
|
|
|
|
list_for_each_entry(rp, rh, c_lru) {
|
|
++entries;
|
|
if (nfsd_cache_match(rqstp, csum, rp)) {
|
|
ret = rp;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* tally hash chain length stats */
|
|
if (entries > longest_chain) {
|
|
longest_chain = entries;
|
|
longest_chain_cachesize = atomic_read(&num_drc_entries);
|
|
} else if (entries == longest_chain) {
|
|
/* prefer to keep the smallest cachesize possible here */
|
|
longest_chain_cachesize = min_t(unsigned int,
|
|
longest_chain_cachesize,
|
|
atomic_read(&num_drc_entries));
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Try to find an entry matching the current call in the cache. When none
|
|
* is found, we try to grab the oldest expired entry off the LRU list. If
|
|
* a suitable one isn't there, then drop the cache_lock and allocate a
|
|
* new one, then search again in case one got inserted while this thread
|
|
* didn't hold the lock.
|
|
*/
|
|
int
|
|
nfsd_cache_lookup(struct svc_rqst *rqstp)
|
|
{
|
|
struct svc_cacherep *rp, *found;
|
|
__be32 xid = rqstp->rq_xid;
|
|
u32 proto = rqstp->rq_prot,
|
|
vers = rqstp->rq_vers,
|
|
proc = rqstp->rq_proc;
|
|
__wsum csum;
|
|
u32 hash = nfsd_cache_hash(xid);
|
|
struct nfsd_drc_bucket *b = &drc_hashtbl[hash];
|
|
unsigned long age;
|
|
int type = rqstp->rq_cachetype;
|
|
int rtn = RC_DOIT;
|
|
|
|
rqstp->rq_cacherep = NULL;
|
|
if (type == RC_NOCACHE) {
|
|
nfsdstats.rcnocache++;
|
|
return rtn;
|
|
}
|
|
|
|
csum = nfsd_cache_csum(rqstp);
|
|
|
|
/*
|
|
* Since the common case is a cache miss followed by an insert,
|
|
* preallocate an entry.
|
|
*/
|
|
rp = nfsd_reply_cache_alloc();
|
|
spin_lock(&b->cache_lock);
|
|
if (likely(rp)) {
|
|
atomic_inc(&num_drc_entries);
|
|
drc_mem_usage += sizeof(*rp);
|
|
}
|
|
|
|
/* go ahead and prune the cache */
|
|
prune_bucket(b);
|
|
|
|
found = nfsd_cache_search(b, rqstp, csum);
|
|
if (found) {
|
|
if (likely(rp))
|
|
nfsd_reply_cache_free_locked(rp);
|
|
rp = found;
|
|
goto found_entry;
|
|
}
|
|
|
|
if (!rp) {
|
|
dprintk("nfsd: unable to allocate DRC entry!\n");
|
|
goto out;
|
|
}
|
|
|
|
nfsdstats.rcmisses++;
|
|
rqstp->rq_cacherep = rp;
|
|
rp->c_state = RC_INPROG;
|
|
rp->c_xid = xid;
|
|
rp->c_proc = proc;
|
|
rpc_copy_addr((struct sockaddr *)&rp->c_addr, svc_addr(rqstp));
|
|
rpc_set_port((struct sockaddr *)&rp->c_addr, rpc_get_port(svc_addr(rqstp)));
|
|
rp->c_prot = proto;
|
|
rp->c_vers = vers;
|
|
rp->c_len = rqstp->rq_arg.len;
|
|
rp->c_csum = csum;
|
|
|
|
lru_put_end(b, rp);
|
|
|
|
/* release any buffer */
|
|
if (rp->c_type == RC_REPLBUFF) {
|
|
drc_mem_usage -= rp->c_replvec.iov_len;
|
|
kfree(rp->c_replvec.iov_base);
|
|
rp->c_replvec.iov_base = NULL;
|
|
}
|
|
rp->c_type = RC_NOCACHE;
|
|
out:
|
|
spin_unlock(&b->cache_lock);
|
|
return rtn;
|
|
|
|
found_entry:
|
|
nfsdstats.rchits++;
|
|
/* We found a matching entry which is either in progress or done. */
|
|
age = jiffies - rp->c_timestamp;
|
|
lru_put_end(b, rp);
|
|
|
|
rtn = RC_DROPIT;
|
|
/* Request being processed or excessive rexmits */
|
|
if (rp->c_state == RC_INPROG || age < RC_DELAY)
|
|
goto out;
|
|
|
|
/* From the hall of fame of impractical attacks:
|
|
* Is this a user who tries to snoop on the cache? */
|
|
rtn = RC_DOIT;
|
|
if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && rp->c_secure)
|
|
goto out;
|
|
|
|
/* Compose RPC reply header */
|
|
switch (rp->c_type) {
|
|
case RC_NOCACHE:
|
|
break;
|
|
case RC_REPLSTAT:
|
|
svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat);
|
|
rtn = RC_REPLY;
|
|
break;
|
|
case RC_REPLBUFF:
|
|
if (!nfsd_cache_append(rqstp, &rp->c_replvec))
|
|
goto out; /* should not happen */
|
|
rtn = RC_REPLY;
|
|
break;
|
|
default:
|
|
printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type);
|
|
nfsd_reply_cache_free_locked(rp);
|
|
}
|
|
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Update a cache entry. This is called from nfsd_dispatch when
|
|
* the procedure has been executed and the complete reply is in
|
|
* rqstp->rq_res.
|
|
*
|
|
* We're copying around data here rather than swapping buffers because
|
|
* the toplevel loop requires max-sized buffers, which would be a waste
|
|
* of memory for a cache with a max reply size of 100 bytes (diropokres).
|
|
*
|
|
* If we should start to use different types of cache entries tailored
|
|
* specifically for attrstat and fh's, we may save even more space.
|
|
*
|
|
* Also note that a cachetype of RC_NOCACHE can legally be passed when
|
|
* nfsd failed to encode a reply that otherwise would have been cached.
|
|
* In this case, nfsd_cache_update is called with statp == NULL.
|
|
*/
|
|
void
|
|
nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
|
|
{
|
|
struct svc_cacherep *rp = rqstp->rq_cacherep;
|
|
struct kvec *resv = &rqstp->rq_res.head[0], *cachv;
|
|
u32 hash;
|
|
struct nfsd_drc_bucket *b;
|
|
int len;
|
|
size_t bufsize = 0;
|
|
|
|
if (!rp)
|
|
return;
|
|
|
|
hash = nfsd_cache_hash(rp->c_xid);
|
|
b = &drc_hashtbl[hash];
|
|
|
|
len = resv->iov_len - ((char*)statp - (char*)resv->iov_base);
|
|
len >>= 2;
|
|
|
|
/* Don't cache excessive amounts of data and XDR failures */
|
|
if (!statp || len > (256 >> 2)) {
|
|
nfsd_reply_cache_free(b, rp);
|
|
return;
|
|
}
|
|
|
|
switch (cachetype) {
|
|
case RC_REPLSTAT:
|
|
if (len != 1)
|
|
printk("nfsd: RC_REPLSTAT/reply len %d!\n",len);
|
|
rp->c_replstat = *statp;
|
|
break;
|
|
case RC_REPLBUFF:
|
|
cachv = &rp->c_replvec;
|
|
bufsize = len << 2;
|
|
cachv->iov_base = kmalloc(bufsize, GFP_KERNEL);
|
|
if (!cachv->iov_base) {
|
|
nfsd_reply_cache_free(b, rp);
|
|
return;
|
|
}
|
|
cachv->iov_len = bufsize;
|
|
memcpy(cachv->iov_base, statp, bufsize);
|
|
break;
|
|
case RC_NOCACHE:
|
|
nfsd_reply_cache_free(b, rp);
|
|
return;
|
|
}
|
|
spin_lock(&b->cache_lock);
|
|
drc_mem_usage += bufsize;
|
|
lru_put_end(b, rp);
|
|
rp->c_secure = test_bit(RQ_SECURE, &rqstp->rq_flags);
|
|
rp->c_type = cachetype;
|
|
rp->c_state = RC_DONE;
|
|
spin_unlock(&b->cache_lock);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Copy cached reply to current reply buffer. Should always fit.
|
|
* FIXME as reply is in a page, we should just attach the page, and
|
|
* keep a refcount....
|
|
*/
|
|
static int
|
|
nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
|
|
{
|
|
struct kvec *vec = &rqstp->rq_res.head[0];
|
|
|
|
if (vec->iov_len + data->iov_len > PAGE_SIZE) {
|
|
printk(KERN_WARNING "nfsd: cached reply too large (%Zd).\n",
|
|
data->iov_len);
|
|
return 0;
|
|
}
|
|
memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len);
|
|
vec->iov_len += data->iov_len;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Note that fields may be added, removed or reordered in the future. Programs
|
|
* scraping this file for info should test the labels to ensure they're
|
|
* getting the correct field.
|
|
*/
|
|
static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v)
|
|
{
|
|
seq_printf(m, "max entries: %u\n", max_drc_entries);
|
|
seq_printf(m, "num entries: %u\n",
|
|
atomic_read(&num_drc_entries));
|
|
seq_printf(m, "hash buckets: %u\n", 1 << maskbits);
|
|
seq_printf(m, "mem usage: %u\n", drc_mem_usage);
|
|
seq_printf(m, "cache hits: %u\n", nfsdstats.rchits);
|
|
seq_printf(m, "cache misses: %u\n", nfsdstats.rcmisses);
|
|
seq_printf(m, "not cached: %u\n", nfsdstats.rcnocache);
|
|
seq_printf(m, "payload misses: %u\n", payload_misses);
|
|
seq_printf(m, "longest chain len: %u\n", longest_chain);
|
|
seq_printf(m, "cachesize at longest: %u\n", longest_chain_cachesize);
|
|
return 0;
|
|
}
|
|
|
|
int nfsd_reply_cache_stats_open(struct inode *inode, struct file *file)
|
|
{
|
|
return single_open(file, nfsd_reply_cache_stats_show, NULL);
|
|
}
|