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sunrpc: use seconds since boot in expiry cache
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This protects us from confusion when the wallclock time changes.

We convert to and from wallclock when  setting or reading expiry
times.

Also use seconds since boot for last_clost time.

Signed-off-by: NeilBrown <[email protected]>
Signed-off-by: J. Bruce Fields <[email protected]>
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@neilbrown
neilbrown authored and J. Bruce Fields committed Sep 7, 2010
1 parent 17cebf6 commit c5b29f8
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Showing 4 changed files with 48 additions and 24 deletions.
6 changes: 3 additions & 3 deletions fs/nfs/dns_resolve.c
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Original file line number Diff line number Diff line change
Expand Up @@ -167,7 +167,7 @@ static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
return 0;
}
item = container_of(h, struct nfs_dns_ent, h);
ttl = (long)item->h.expiry_time - (long)get_seconds();
ttl = item->h.expiry_time - seconds_since_boot();
if (ttl < 0)
ttl = 0;

Expand Down Expand Up @@ -239,7 +239,7 @@ static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
ttl = get_expiry(&buf);
if (ttl == 0)
goto out;
key.h.expiry_time = ttl + get_seconds();
key.h.expiry_time = ttl + seconds_since_boot();

ret = -ENOMEM;
item = nfs_dns_lookup(cd, &key);
Expand Down Expand Up @@ -301,7 +301,7 @@ static int do_cache_lookup_nowait(struct cache_detail *cd,
goto out_err;
ret = -ETIMEDOUT;
if (!test_bit(CACHE_VALID, &(*item)->h.flags)
|| (*item)->h.expiry_time < get_seconds()
|| (*item)->h.expiry_time < seconds_since_boot()
|| cd->flush_time > (*item)->h.last_refresh)
goto out_put;
ret = -ENOENT;
Expand Down
2 changes: 1 addition & 1 deletion fs/nfsd/nfs4idmap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -550,7 +550,7 @@ do_idmap_lookup_nowait(struct ent *(*lookup_fn)(struct ent *),
goto out_err;
ret = -ETIMEDOUT;
if (!test_bit(CACHE_VALID, &(*item)->h.flags)
|| (*item)->h.expiry_time < get_seconds()
|| (*item)->h.expiry_time < seconds_since_boot()
|| detail->flush_time > (*item)->h.last_refresh)
goto out_put;
ret = -ENOENT;
Expand Down
28 changes: 25 additions & 3 deletions include/linux/sunrpc/cache.h
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Original file line number Diff line number Diff line change
Expand Up @@ -218,20 +218,42 @@ static inline int get_int(char **bpp, int *anint)
return 0;
}

/*
* timestamps kept in the cache are expressed in seconds
* since boot. This is the best for measuring differences in
* real time.
*/
static inline time_t seconds_since_boot(void)
{
struct timespec boot;
getboottime(&boot);
return get_seconds() - boot.tv_sec;
}

static inline time_t convert_to_wallclock(time_t sinceboot)
{
struct timespec boot;
getboottime(&boot);
return boot.tv_sec + sinceboot;
}

static inline time_t get_expiry(char **bpp)
{
int rv;
struct timespec boot;

if (get_int(bpp, &rv))
return 0;
if (rv < 0)
return 0;
return rv;
getboottime(&boot);
return rv - boot.tv_sec;
}

static inline void sunrpc_invalidate(struct cache_head *h,
struct cache_detail *detail)
{
h->expiry_time = get_seconds() - 1;
detail->nextcheck = get_seconds();
h->expiry_time = seconds_since_boot() - 1;
detail->nextcheck = seconds_since_boot();
}
#endif /* _LINUX_SUNRPC_CACHE_H_ */
36 changes: 19 additions & 17 deletions net/sunrpc/cache.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ static void cache_revisit_request(struct cache_head *item);

static void cache_init(struct cache_head *h)
{
time_t now = get_seconds();
time_t now = seconds_since_boot();
h->next = NULL;
h->flags = 0;
kref_init(&h->ref);
Expand All @@ -52,7 +52,7 @@ static void cache_init(struct cache_head *h)

static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
{
return (h->expiry_time < get_seconds()) ||
return (h->expiry_time < seconds_since_boot()) ||
(detail->flush_time > h->last_refresh);
}

Expand Down Expand Up @@ -127,7 +127,7 @@ static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
static void cache_fresh_locked(struct cache_head *head, time_t expiry)
{
head->expiry_time = expiry;
head->last_refresh = get_seconds();
head->last_refresh = seconds_since_boot();
set_bit(CACHE_VALID, &head->flags);
}

Expand Down Expand Up @@ -238,7 +238,7 @@ int cache_check(struct cache_detail *detail,

/* now see if we want to start an upcall */
refresh_age = (h->expiry_time - h->last_refresh);
age = get_seconds() - h->last_refresh;
age = seconds_since_boot() - h->last_refresh;

if (rqstp == NULL) {
if (rv == -EAGAIN)
Expand All @@ -253,7 +253,7 @@ int cache_check(struct cache_detail *detail,
cache_revisit_request(h);
if (rv == -EAGAIN) {
set_bit(CACHE_NEGATIVE, &h->flags);
cache_fresh_locked(h, get_seconds()+CACHE_NEW_EXPIRY);
cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY);
cache_fresh_unlocked(h, detail);
rv = -ENOENT;
}
Expand Down Expand Up @@ -388,11 +388,11 @@ static int cache_clean(void)
return -1;
}
current_detail = list_entry(next, struct cache_detail, others);
if (current_detail->nextcheck > get_seconds())
if (current_detail->nextcheck > seconds_since_boot())
current_index = current_detail->hash_size;
else {
current_index = 0;
current_detail->nextcheck = get_seconds()+30*60;
current_detail->nextcheck = seconds_since_boot()+30*60;
}
}

Expand Down Expand Up @@ -477,7 +477,7 @@ EXPORT_SYMBOL_GPL(cache_flush);
void cache_purge(struct cache_detail *detail)
{
detail->flush_time = LONG_MAX;
detail->nextcheck = get_seconds();
detail->nextcheck = seconds_since_boot();
cache_flush();
detail->flush_time = 1;
}
Expand Down Expand Up @@ -902,7 +902,7 @@ static int cache_release(struct inode *inode, struct file *filp,
filp->private_data = NULL;
kfree(rp);

cd->last_close = get_seconds();
cd->last_close = seconds_since_boot();
atomic_dec(&cd->readers);
}
module_put(cd->owner);
Expand Down Expand Up @@ -1034,7 +1034,7 @@ int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h,
int len;

if (atomic_read(&detail->readers) == 0 &&
detail->last_close < get_seconds() - 30) {
detail->last_close < seconds_since_boot() - 30) {
warn_no_listener(detail);
return -EINVAL;
}
Expand Down Expand Up @@ -1219,7 +1219,8 @@ static int c_show(struct seq_file *m, void *p)

ifdebug(CACHE)
seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
cp->expiry_time, atomic_read(&cp->ref.refcount), cp->flags);
convert_to_wallclock(cp->expiry_time),
atomic_read(&cp->ref.refcount), cp->flags);
cache_get(cp);
if (cache_check(cd, cp, NULL))
/* cache_check does a cache_put on failure */
Expand Down Expand Up @@ -1285,7 +1286,7 @@ static ssize_t read_flush(struct file *file, char __user *buf,
unsigned long p = *ppos;
size_t len;

sprintf(tbuf, "%lu\n", cd->flush_time);
sprintf(tbuf, "%lu\n", convert_to_wallclock(cd->flush_time));
len = strlen(tbuf);
if (p >= len)
return 0;
Expand All @@ -1303,19 +1304,20 @@ static ssize_t write_flush(struct file *file, const char __user *buf,
struct cache_detail *cd)
{
char tbuf[20];
char *ep;
long flushtime;
char *bp, *ep;

if (*ppos || count > sizeof(tbuf)-1)
return -EINVAL;
if (copy_from_user(tbuf, buf, count))
return -EFAULT;
tbuf[count] = 0;
flushtime = simple_strtoul(tbuf, &ep, 0);
simple_strtoul(tbuf, &ep, 0);
if (*ep && *ep != '\n')
return -EINVAL;

cd->flush_time = flushtime;
cd->nextcheck = get_seconds();
bp = tbuf;
cd->flush_time = get_expiry(&bp);
cd->nextcheck = seconds_since_boot();
cache_flush();

*ppos += count;
Expand Down

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