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qubes-linux-kernel/patches.fixes/sunrpc-monotonic-expiry
Joanna Rutkowska d1298d1dfb Keeps patches unpacked for easier history browsing
2010-07-07 13:12:45 +02:00

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From: NeilBrown <neilb@suse.de>
Date: Wed, 17 Feb 2010 16:53:34 +1100
Subject: [PATCH] sunrpc: use monotonic time in expiry cache
Patch-mainline: Submitted for 2.6.34
References: bnc#578668
this protects us from confusion when the wallclock time changes.
We convert to and from wallclock when setting or reading expiry
times.
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: NeilBrown <neilb@suse.de>
---
fs/nfs/dns_resolve.c | 6 +++---
fs/nfsd/export.c | 9 +++------
include/linux/sunrpc/cache.h | 23 ++++++++++++++++++++++-
net/sunrpc/cache.c | 35 +++++++++++++++++++----------------
4 files changed, 47 insertions(+), 26 deletions(-)
--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -143,7 +143,7 @@ static int nfs_dns_show(struct seq_file
return 0;
}
item = container_of(h, struct nfs_dns_ent, h);
- ttl = (long)item->h.expiry_time - (long)get_seconds();
+ ttl = (long)item->h.expiry_time - (long)monotonic_seconds();
if (ttl < 0)
ttl = 0;
@@ -215,7 +215,7 @@ static int nfs_dns_parse(struct cache_de
ttl = get_expiry(&buf);
if (ttl == 0)
goto out;
- key.h.expiry_time = ttl + get_seconds();
+ key.h.expiry_time = ttl + monotonic_seconds();
ret = -ENOMEM;
item = nfs_dns_lookup(cd, &key);
@@ -277,7 +277,7 @@ static int do_cache_lookup_nowait(struct
goto out_err;
ret = -ETIMEDOUT;
if (!test_bit(CACHE_VALID, &(*item)->h.flags)
- || (*item)->h.expiry_time < get_seconds()
+ || (*item)->h.expiry_time < monotonic_seconds()
|| cd->flush_time > (*item)->h.last_refresh)
goto out_put;
ret = -ENOENT;
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -946,10 +946,9 @@ static void exp_fsid_unhash(struct svc_e
ek = exp_get_fsid_key(exp->ex_client, exp->ex_fsid);
if (!IS_ERR(ek)) {
- ek->h.expiry_time = get_seconds()-1;
+ sunrpc_invalidate(&ek->h, &svc_expkey_cache);
cache_put(&ek->h, &svc_expkey_cache);
}
- svc_expkey_cache.nextcheck = get_seconds();
}
static int exp_fsid_hash(svc_client *clp, struct svc_export *exp)
@@ -984,10 +983,9 @@ static void exp_unhash(struct svc_export
ek = exp_get_key(exp->ex_client, inode->i_sb->s_dev, inode->i_ino);
if (!IS_ERR(ek)) {
- ek->h.expiry_time = get_seconds()-1;
+ sunrpc_invalidate(&ek->h, &svc_expkey_cache);
cache_put(&ek->h, &svc_expkey_cache);
}
- svc_expkey_cache.nextcheck = get_seconds();
}
/*
@@ -1108,8 +1106,7 @@ out:
static void
exp_do_unexport(svc_export *unexp)
{
- unexp->h.expiry_time = get_seconds()-1;
- svc_export_cache.nextcheck = get_seconds();
+ sunrpc_invalidate(&unexp->h, &svc_export_cache);
exp_unhash(unexp);
exp_fsid_unhash(unexp);
}
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -220,14 +220,35 @@ static inline int get_int(char **bpp, in
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 unsigned long monotonic_seconds(void)
+{
+ struct timespec boot;
+ getboottime(&boot);
+ return get_seconds() - boot.tv_sec;
+}
+
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 = monotonic_seconds() - 1;
+ detail->nextcheck = monotonic_seconds();
+}
#endif /* _LINUX_SUNRPC_CACHE_H_ */
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -41,7 +41,7 @@ static void cache_revisit_request(struct
static void cache_init(struct cache_head *h)
{
- time_t now = get_seconds();
+ time_t now = monotonic_seconds();
h->next = NULL;
h->flags = 0;
kref_init(&h->ref);
@@ -108,7 +108,7 @@ static void cache_dequeue(struct cache_d
static void cache_fresh_locked(struct cache_head *head, time_t expiry)
{
head->expiry_time = expiry;
- head->last_refresh = get_seconds();
+ head->last_refresh = monotonic_seconds();
set_bit(CACHE_VALID, &head->flags);
}
@@ -184,7 +184,7 @@ static int cache_make_upcall(struct cach
static inline int cache_is_valid(struct cache_detail *detail, struct cache_head *h)
{
if (!test_bit(CACHE_VALID, &h->flags) ||
- h->expiry_time < get_seconds())
+ h->expiry_time < monotonic_seconds())
return -EAGAIN;
else if (detail->flush_time > h->last_refresh)
return -EAGAIN;
@@ -222,7 +222,7 @@ int cache_check(struct cache_detail *det
/* now see if we want to start an upcall */
refresh_age = (h->expiry_time - h->last_refresh);
- age = get_seconds() - h->last_refresh;
+ age = monotonic_seconds() - h->last_refresh;
if (rqstp == NULL) {
if (rv == -EAGAIN)
@@ -237,7 +237,7 @@ int cache_check(struct cache_detail *det
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, monotonic_seconds()+CACHE_NEW_EXPIRY);
cache_fresh_unlocked(h, detail);
rv = -ENOENT;
}
@@ -372,11 +372,11 @@ 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 > monotonic_seconds())
current_index = current_detail->hash_size;
else {
current_index = 0;
- current_detail->nextcheck = get_seconds()+30*60;
+ current_detail->nextcheck = monotonic_seconds()+30*60;
}
}
@@ -401,7 +401,7 @@ static int cache_clean(void)
for (; ch; cp= & ch->next, ch= *cp) {
if (current_detail->nextcheck > ch->expiry_time)
current_detail->nextcheck = ch->expiry_time+1;
- if (ch->expiry_time >= get_seconds() &&
+ if (ch->expiry_time >= monotonic_seconds() &&
ch->last_refresh >= current_detail->flush_time)
continue;
if (test_and_clear_bit(CACHE_PENDING, &ch->flags))
@@ -465,7 +465,7 @@ EXPORT_SYMBOL_GPL(cache_flush);
void cache_purge(struct cache_detail *detail)
{
detail->flush_time = LONG_MAX;
- detail->nextcheck = get_seconds();
+ detail->nextcheck = monotonic_seconds();
cache_flush();
detail->flush_time = 1;
}
@@ -1249,7 +1249,8 @@ static int c_show(struct seq_file *m, vo
ifdebug(CACHE)
seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
- cp->expiry_time, atomic_read(&cp->ref.refcount), cp->flags);
+ cp->expiry_time - monotonic_seconds() + get_seconds(),
+ atomic_read(&cp->ref.refcount), cp->flags);
cache_get(cp);
if (cache_check(cd, cp, NULL))
/* cache_check does a cache_put on failure */
@@ -1313,7 +1314,8 @@ static ssize_t read_flush(struct file *f
unsigned long p = *ppos;
size_t len;
- sprintf(tbuf, "%lu\n", cd->flush_time);
+ sprintf(tbuf, "%lu\n", (cd->flush_time - monotonic_seconds()
+ + get_seconds()));
len = strlen(tbuf);
if (p >= len)
return 0;
@@ -1331,19 +1333,20 @@ static ssize_t write_flush(struct file *
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 = monotonic_seconds();
cache_flush();
*ppos += count;
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