unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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smb: client: improve purging of cached referrals

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Purge cached referrals that have a single target when reaching maximum
of cache size as the client won't need them to failover.  Otherwise
remove oldest cache entry.

Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2024-09-18 02:03:45 -03:00 committed by Steve French
parent 242d23efc9
commit 9190cc0c97
1 changed files with 15 additions and 17 deletions
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32
fs/smb/client/dfs_cache.c
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@ -126,6 +126,7 @@ static inline void free_tgts(struct cache_entry *ce)
static inline void flush_cache_ent(struct cache_entry *ce)
{
cifs_dbg(FYI, "%s: %s\n", __func__, ce->path);
hlist_del_init(&ce->hlist);
kfree(ce->path);
free_tgts(ce);
@ -441,34 +442,31 @@ static struct cache_entry *alloc_cache_entry(struct dfs_info3_param *refs, int n
return ce;
}
static void remove_oldest_entry_locked(void)
/* Remove all referrals that have a single target or oldest entry */
static void purge_cache(void)
{
int i;
struct cache_entry *ce;
struct cache_entry *to_del = NULL;
WARN_ON(!rwsem_is_locked(&htable_rw_lock));
struct cache_entry *oldest = NULL;
for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
struct hlist_head *l = &cache_htable[i];
struct hlist_node *n;
hlist_for_each_entry(ce, l, hlist) {
hlist_for_each_entry_safe(ce, n, l, hlist) {
if (hlist_unhashed(&ce->hlist))
continue;
if (!to_del || timespec64_compare(&ce->etime,
&to_del->etime) < 0)
to_del = ce;
if (ce->numtgts == 1)
flush_cache_ent(ce);
else if (!oldest ||
timespec64_compare(&ce->etime,
&oldest->etime) < 0)
oldest = ce;
}
}
if (!to_del) {
cifs_dbg(FYI, "%s: no entry to remove\n", __func__);
return;
}
cifs_dbg(FYI, "%s: removing entry\n", __func__);
dump_ce(to_del);
flush_cache_ent(to_del);
if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES && oldest)
flush_cache_ent(oldest);
}
/* Add a new DFS cache entry */
@ -484,7 +482,7 @@ static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs,
if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES) {
cifs_dbg(FYI, "%s: reached max cache size (%d)\n", __func__, CACHE_MAX_ENTRIES);
remove_oldest_entry_locked();
purge_cache();
}
rc = cache_entry_hash(refs[0].path_name, strlen(refs[0].path_name), &hash);