Commit 48d240bf authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French

cifs: avoid re-lookups in dfs_cache_find()

Simply downgrade the write lock on cache updates from
cache_refresh_path() and avoid unnecessary re-lookup in
dfs_cache_find().
Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 9fb0db40
......@@ -558,7 +558,8 @@ static void remove_oldest_entry_locked(void)
}
/* Add a new DFS cache entry */
static int add_cache_entry_locked(struct dfs_info3_param *refs, int numrefs)
static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs,
int numrefs)
{
int rc;
struct cache_entry *ce;
......@@ -573,11 +574,11 @@ static int add_cache_entry_locked(struct dfs_info3_param *refs, int numrefs)
rc = cache_entry_hash(refs[0].path_name, strlen(refs[0].path_name), &hash);
if (rc)
return rc;
return ERR_PTR(rc);
ce = alloc_cache_entry(refs, numrefs);
if (IS_ERR(ce))
return PTR_ERR(ce);
return ce;
spin_lock(&cache_ttl_lock);
if (!cache_ttl) {
......@@ -594,7 +595,7 @@ static int add_cache_entry_locked(struct dfs_info3_param *refs, int numrefs)
atomic_inc(&cache_count);
return 0;
return ce;
}
/* Check if two DFS paths are equal. @s1 and @s2 are expected to be in @cache_cp's charset */
......@@ -767,8 +768,12 @@ static int get_dfs_referral(const unsigned int xid, struct cifs_ses *ses, const
*
* For interlinks, cifs_mount() and expand_dfs_referral() are supposed to
* handle them properly.
*
* On success, return entry with acquired lock for reading, otherwise error ptr.
*/
static int cache_refresh_path(const unsigned int xid, struct cifs_ses *ses, const char *path)
static struct cache_entry *cache_refresh_path(const unsigned int xid,
struct cifs_ses *ses,
const char *path)
{
struct dfs_info3_param *refs = NULL;
struct cache_entry *ce;
......@@ -780,10 +785,9 @@ static int cache_refresh_path(const unsigned int xid, struct cifs_ses *ses, cons
down_read(&htable_rw_lock);
ce = lookup_cache_entry(path);
if (!IS_ERR(ce) && !cache_entry_expired(ce)) {
up_read(&htable_rw_lock);
return 0;
}
if (!IS_ERR(ce) && !cache_entry_expired(ce))
return ce;
/*
* Unlock shared access as we don't want to hold any locks while getting
* a new referral. The @ses used for performing the I/O could be
......@@ -797,8 +801,10 @@ static int cache_refresh_path(const unsigned int xid, struct cifs_ses *ses, cons
* Request a new DFS referral in order to create or update a cache entry.
*/
rc = get_dfs_referral(xid, ses, path, &refs, &numrefs);
if (rc)
if (rc) {
ce = ERR_PTR(rc);
goto out;
}
dump_refs(refs, numrefs);
......@@ -806,16 +812,24 @@ static int cache_refresh_path(const unsigned int xid, struct cifs_ses *ses, cons
/* Re-check as another task might have it added or refreshed already */
ce = lookup_cache_entry(path);
if (!IS_ERR(ce)) {
if (cache_entry_expired(ce))
if (cache_entry_expired(ce)) {
rc = update_cache_entry_locked(ce, refs, numrefs);
if (rc)
ce = ERR_PTR(rc);
}
} else {
rc = add_cache_entry_locked(refs, numrefs);
ce = add_cache_entry_locked(refs, numrefs);
}
up_write(&htable_rw_lock);
if (IS_ERR(ce)) {
up_write(&htable_rw_lock);
goto out;
}
downgrade_write(&htable_rw_lock);
out:
free_dfs_info_array(refs, numrefs);
return rc;
return ce;
}
/*
......@@ -935,15 +949,8 @@ int dfs_cache_find(const unsigned int xid, struct cifs_ses *ses, const struct nl
if (IS_ERR(npath))
return PTR_ERR(npath);
rc = cache_refresh_path(xid, ses, npath);
if (rc)
goto out_free_path;
down_read(&htable_rw_lock);
ce = lookup_cache_entry(npath);
ce = cache_refresh_path(xid, ses, npath);
if (IS_ERR(ce)) {
up_read(&htable_rw_lock);
rc = PTR_ERR(ce);
goto out_free_path;
}
......@@ -1039,10 +1046,13 @@ int dfs_cache_update_tgthint(const unsigned int xid, struct cifs_ses *ses,
cifs_dbg(FYI, "%s: update target hint - path: %s\n", __func__, npath);
rc = cache_refresh_path(xid, ses, npath);
if (rc)
ce = cache_refresh_path(xid, ses, npath);
if (IS_ERR(ce)) {
rc = PTR_ERR(ce);
goto out_free_path;
}
up_read(&htable_rw_lock);
down_write(&htable_rw_lock);
ce = lookup_cache_entry(npath);
......
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