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namecache: delegation-related fixes

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open_update_cache() wasn't retrying insert after the open_delegation_return() error case
nfs41_name_cache_delegreturn() needs a check for if (attributes->delegated) to avoid an extra deref when the call to nfs41_name_cache_insert() failed
added a TODO comment to nfs41_client_delegation_return_lru() for improvements to the naive algorithm

Signed-off-by: Casey Bodley <cbodley@citi.umich.edu>
This commit is contained in:
Casey Bodley 2011-08-25 13:53:39 -04:00 • committed by unknown
parent 48fa809fc5
commit 0d86c68138
3 changed files with 19 additions and 17 deletions
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9
daemon/delegation.c
View file

@ -806,8 +806,13 @@ int nfs41_client_delegation_return_lru(
nfs41_delegation_state *state = NULL;
int status = NFS4ERR_BADHANDLE;
/* starting from the least recently opened, find a delegation
* that's not 'in use' and return it */
/* starting from the least recently opened, find and return
* the first delegation that's not 'in use' (currently open) */
/* TODO: use a more robust algorithm, taking into account:
* -number of total opens
* -time since last operation on an associated open, or
* -number of operations/second over last n seconds */
EnterCriticalSection(&client->state.lock);
list_for_each(entry, &client->state.delegations) {
state = deleg_entry(entry);

24
daemon/name_cache.c
View file

@ -78,14 +78,6 @@ static __inline bool_t is_delegation(
return type == OPEN_DELEGATE_READ || type == OPEN_DELEGATE_WRITE;
}
static __inline bool_t deleg_entry_limit(
IN uint32_t delegations,
IN uint32_t max_entries)
{
/* limit the number of delegations to 50% of the cache capacity */
return delegations >= max_entries / 2;
}
/* attribute cache */
struct attr_cache_entry {
@ -365,8 +357,9 @@ struct nfs41_name_cache {
struct list_entry exp_entries; /* list of entries by expiry */
uint32_t expiration;
uint32_t entries;
uint32_t delegations;
uint32_t max_entries;
uint32_t delegations;
uint32_t max_delegations;
SRWLOCK lock;
};
@ -724,6 +717,7 @@ int nfs41_name_cache_create(
list_init(&cache->exp_entries);
cache->expiration = NAME_CACHE_EXPIRATION;
cache->max_entries = NAME_CACHE_MAX_ENTRIES;
cache->max_delegations = NAME_CACHE_MAX_ENTRIES / 2;
InitializeSRWLock(&cache->lock);
/* allocate a pool of entries */
@ -899,8 +893,8 @@ int nfs41_name_cache_insert(
}
/* limit the number of delegations to prevent attr cache starvation */
if (is_delegation(delegation) && deleg_entry_limit(
cache->delegations, cache->max_entries)) {
if (is_delegation(delegation) &&
cache->delegations >= cache->max_delegations) {
status = ERROR_TOO_MANY_OPEN_FILES;
goto out_unlock;
}
@ -998,9 +992,11 @@ int nfs41_name_cache_delegreturn(
}
/* release the reference from name_cache_entry_update() */
attributes->delegated = FALSE;
attr_cache_entry_deref(&cache->attributes, attributes);
cache->delegations--;
if (attributes->delegated) {
attributes->delegated = FALSE;
attr_cache_entry_deref(&cache->attributes, attributes);
cache->delegations--;
}
status = NO_ERROR;
out_unlock:

3
daemon/nfs41_ops.c
View file

@ -361,10 +361,11 @@ retry_cache_insert:
goto retry_cache_insert;
}
if (status) {
if (status && delegation->type != OPEN_DELEGATE_NONE) {
/* if we can't make room in the cache, return this
* delegation immediately to free resources on the server */
open_delegation_return(session, file, delegation);
goto retry_cache_insert;
}
}