From 48d240bf00af943db6f069a53f090e444e85f760 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Tue, 17 Jan 2023 19:00:38 -0300 Subject: 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: Paulo Alcantara (SUSE) Signed-off-by: Steve French --- fs/cifs/dfs_cache.c | 58 +++++++++++++++++++++++++++++++---------------------- 1 file changed, 34 insertions(+), 24 deletions(-) (limited to 'fs') diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c index a6d7ae5f49a4..755a00c4cba1 100644 --- a/fs/cifs/dfs_cache.c +++ b/fs/cifs/dfs_cache.c @@ -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); -- cgit v1.2.3