On Tue, 24 Aug 2010 14:15:31 -0400 "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > On Thu, Aug 12, 2010 at 04:55:22PM +1000, NeilBrown wrote: > > this protects us from confusion when the wallclock time changes. > > > > We convert to and from wallclock when setting or reading expiry > > times. > > > > Also use monotonic_seconds for last_clost time. > > Looks good to me, thanks--applying for 2.6.37. > > (Apologies for the delay--partly due to my getting fed up with not > understanding time, and feeling I should go read some code. Resulting > notes at http://fieldses.org/~bfields/kernel/time.txt. > > The only thing I noticed was that the timekeeping code consistently uses > the word "monotonic" on functions that return something slightly > different; seconds_since_boot() might be a better name. Yes.... I think I developed this against 2.6.16 which has different naming conventions, and then forward-parted to -current without giving too much thought to the names. seconds_since_boot() does sound better. > > Oh, and > > get_seconds() - monotonic_seconds() > > isn't the most intuitive way possible to say "boot time in seconds". If > you want to fix either of those, fine, otherwise no big deal.) To be fair, I don't use that exactly. I use some_monotonic_based_value - monotonic_seconds() + get_seconds() to turn a monotonic_based value to a wallclock based value. This makes sense to me - subtract the base I don't want, and add the base that I do. I guess you could wrap that in convert_to_wallclock and use getboottime directly: static inline time_t convert_to_wallclock(time_t sinceboot) { struct timespec boot; getboottime(&boot); return sinceboot + boot.tv_sec; } Following is only compile tested. Thanks, NeilBrown ------- Rename monotonic_seconds to seconds_since_boot monotonic has a meaning in Linux timekeeping slight different to what we use in sunrpc_cache, so change the name. Also make the conversion from second_since_boot times to wallclock times less obscure. Signed-off-by: NeilBrown <neilb@xxxxxxx> diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c index 3e6aab2..97c03ca 100644 --- a/fs/nfs/dns_resolve.c +++ b/fs/nfs/dns_resolve.c @@ -144,7 +144,7 @@ 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 = item->h.expiry_time - monotonic_seconds(); + ttl = item->h.expiry_time - seconds_since_boot(); if (ttl < 0) ttl = 0; @@ -216,7 +216,7 @@ 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 + monotonic_seconds(); + key.h.expiry_time = ttl + seconds_since_boot(); ret = -ENOMEM; item = nfs_dns_lookup(cd, &key); @@ -278,7 +278,7 @@ 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 < monotonic_seconds() + || (*item)->h.expiry_time < seconds_since_boot() || cd->flush_time > (*item)->h.last_refresh) goto out_put; ret = -ENOENT; diff --git a/fs/nfsd/nfs4idmap.c b/fs/nfsd/nfs4idmap.c index 6031a90..808b33a 100644 --- a/fs/nfsd/nfs4idmap.c +++ b/fs/nfsd/nfs4idmap.c @@ -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 < monotonic_seconds() + || (*item)->h.expiry_time < seconds_since_boot() || detail->flush_time > (*item)->h.last_refresh) goto out_put; ret = -ENOENT; diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h index df7c19b..ece432b 100644 --- a/include/linux/sunrpc/cache.h +++ b/include/linux/sunrpc/cache.h @@ -223,13 +223,20 @@ static inline int get_int(char **bpp, int *anint) * since boot. This is the best for measuring differences in * real time. */ -static inline time_t monotonic_seconds(void) +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; @@ -246,7 +253,7 @@ static inline time_t get_expiry(char **bpp) static inline void sunrpc_invalidate(struct cache_head *h, struct cache_detail *detail) { - h->expiry_time = monotonic_seconds() - 1; - detail->nextcheck = monotonic_seconds(); + h->expiry_time = seconds_since_boot() - 1; + detail->nextcheck = seconds_since_boot(); } #endif /* _LINUX_SUNRPC_CACHE_H_ */ diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 99d852e..8dc1219 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -42,7 +42,7 @@ static void cache_revisit_request(struct cache_head *item); static void cache_init(struct cache_head *h) { - time_t now = monotonic_seconds(); + time_t now = seconds_since_boot(); h->next = NULL; h->flags = 0; kref_init(&h->ref); @@ -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 < monotonic_seconds()) || + return (h->expiry_time < seconds_since_boot()) || (detail->flush_time > h->last_refresh); } @@ -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 = monotonic_seconds(); + head->last_refresh = seconds_since_boot(); set_bit(CACHE_VALID, &head->flags); } @@ -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 = monotonic_seconds() - h->last_refresh; + age = seconds_since_boot() - h->last_refresh; if (rqstp == NULL) { if (rv == -EAGAIN) @@ -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, monotonic_seconds()+CACHE_NEW_EXPIRY); + cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY); cache_fresh_unlocked(h, detail); rv = -ENOENT; } @@ -388,11 +388,11 @@ static int cache_clean(void) return -1; } current_detail = list_entry(next, struct cache_detail, others); - if (current_detail->nextcheck > monotonic_seconds()) + if (current_detail->nextcheck > seconds_since_boot()) current_index = current_detail->hash_size; else { current_index = 0; - current_detail->nextcheck = monotonic_seconds()+30*60; + current_detail->nextcheck = seconds_since_boot()+30*60; } } @@ -477,7 +477,7 @@ EXPORT_SYMBOL_GPL(cache_flush); void cache_purge(struct cache_detail *detail) { detail->flush_time = LONG_MAX; - detail->nextcheck = monotonic_seconds(); + detail->nextcheck = seconds_since_boot(); cache_flush(); detail->flush_time = 1; } @@ -902,7 +902,7 @@ static int cache_release(struct inode *inode, struct file *filp, filp->private_data = NULL; kfree(rp); - cd->last_close = monotonic_seconds(); + cd->last_close = seconds_since_boot(); atomic_dec(&cd->readers); } module_put(cd->owner); @@ -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 < monotonic_seconds() - 30) { + detail->last_close < seconds_since_boot() - 30) { warn_no_listener(detail); return -EINVAL; } @@ -1219,7 +1219,7 @@ 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 - monotonic_seconds() + get_seconds(), + convert_to_wallclock(cp->expiry_time), atomic_read(&cp->ref.refcount), cp->flags); cache_get(cp); if (cache_check(cd, cp, NULL)) @@ -1286,8 +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 - monotonic_seconds() - + get_seconds())); + sprintf(tbuf, "%lu\n", convert_to_wallclock(cd->flush_time)); len = strlen(tbuf); if (p >= len) return 0; @@ -1318,7 +1317,7 @@ static ssize_t write_flush(struct file *file, const char __user *buf, bp = tbuf; cd->flush_time = get_expiry(&bp); - cd->nextcheck = monotonic_seconds(); + cd->nextcheck = seconds_since_boot(); cache_flush(); *ppos += count; -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
