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authorPaulo Alcantara <pc@cjr.nz>2023-01-17 19:00:38 -0300
committerSteve French <stfrench@microsoft.com>2023-01-18 10:45:58 -0600
commit48d240bf00af943db6f069a53f090e444e85f760 (patch)
tree2960f54a83efb8e1355048e06f1b1a4a4f319c02 /fs
parent9fb0db40513e27537fde63287aea920b60557a69 (diff)
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) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/cifs/dfs_cache.c58
1 files changed, 34 insertions, 24 deletions
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);