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SUNRPC: Allow the cache_detail to specify alternative upcall mechanisms

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For events that are rare, such as referral DNS lookups, it makes limited
sense to have a daemon constantly listening for upcalls on a channel. An
alternative in those cases might simply be to run the app that fills the
cache using call_usermodehelper_exec() and friends.

The following patch allows the cache_detail to specify alternative upcall
mechanisms for these particular cases.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust
2009-08-09 15:14:29 -04:00
parent da77005f0d
commit bc74b4f5e6
6 changed files with 72 additions and 18 deletions
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26
net/sunrpc/cache.c
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@@ -176,7 +176,13 @@ struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
}
EXPORT_SYMBOL_GPL(sunrpc_cache_update);
static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
static int cache_make_upcall(struct cache_detail *cd, struct cache_head *h)
{
if (!cd->cache_upcall)
return -EINVAL;
return cd->cache_upcall(cd, h);
}
/*
* This is the generic cache management routine for all
* the authentication caches.
@@ -322,7 +328,7 @@ static int create_cache_proc_entries(struct cache_detail *cd)
if (p == NULL)
goto out_nomem;
if (cd->cache_request || cd->cache_parse) {
if (cd->cache_upcall || cd->cache_parse) {
p = proc_create_data("channel", S_IFREG|S_IRUSR|S_IWUSR,
cd->proc_ent, &cache_file_operations, cd);
cd->channel_ent = p;
@@ -1080,10 +1086,16 @@ static void warn_no_listener(struct cache_detail *detail)
}
/*
* register an upcall request to user-space.
* register an upcall request to user-space and queue it up for read() by the
* upcall daemon.
*
* Each request is at most one page long.
*/
static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h,
void (*cache_request)(struct cache_detail *,
struct cache_head *,
char **,
int *))
{
char *buf;
@@ -1091,9 +1103,6 @@ static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
char *bp;
int len;
if (detail->cache_request == NULL)
return -EINVAL;
if (atomic_read(&detail->readers) == 0 &&
detail->last_close < get_seconds() - 30) {
warn_no_listener(detail);
@@ -1112,7 +1121,7 @@ static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
bp = buf; len = PAGE_SIZE;
detail->cache_request(detail, h, &bp, &len);
cache_request(detail, h, &bp, &len);
if (len < 0) {
kfree(buf);
@@ -1130,6 +1139,7 @@ static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
wake_up(&queue_wait);
return 0;
}
EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
/*
* parse a message from user-space and pass it