diff options
author | Paulo Alcantara <pc@manguebit.com> | 2023-04-27 10:40:08 +0300 |
---|---|---|
committer | Steve French <stfrench@microsoft.com> | 2023-05-04 07:29:47 +0300 |
commit | 6be2ea33a4093402252724a00c4af8033725184c (patch) | |
tree | 79c111db007aed6fab0cb82837480909e17eaabb /fs/cifs/dfs_cache.c | |
parent | 3dc9c433c9dde15477d02b609ccb4328e2adb6dc (diff) | |
download | linux-6be2ea33a4093402252724a00c4af8033725184c.tar.xz |
cifs: avoid potential races when handling multiple dfs tcons
Now that a DFS tcon manages its own list of DFS referrals and
sessions, there is no point in having a single worker to refresh
referrals of all DFS tcons. Make it faster and less prone to race
conditions when having several mounts by queueing a worker per DFS
tcon that will take care of refreshing only the DFS referrals related
to it.
Cc: stable@vger.kernel.org # v6.2+
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/dfs_cache.c')
-rw-r--r-- | fs/cifs/dfs_cache.c | 137 |
1 files changed, 60 insertions, 77 deletions
diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c index 6557d7b2798a..1513b2709889 100644 --- a/fs/cifs/dfs_cache.c +++ b/fs/cifs/dfs_cache.c @@ -20,12 +20,14 @@ #include "cifs_unicode.h" #include "smb2glob.h" #include "dns_resolve.h" +#include "dfs.h" #include "dfs_cache.h" -#define CACHE_HTABLE_SIZE 32 -#define CACHE_MAX_ENTRIES 64 -#define CACHE_MIN_TTL 120 /* 2 minutes */ +#define CACHE_HTABLE_SIZE 32 +#define CACHE_MAX_ENTRIES 64 +#define CACHE_MIN_TTL 120 /* 2 minutes */ +#define CACHE_DEFAULT_TTL 300 /* 5 minutes */ #define IS_DFS_INTERLINK(v) (((v) & DFSREF_REFERRAL_SERVER) && !((v) & DFSREF_STORAGE_SERVER)) @@ -50,10 +52,9 @@ struct cache_entry { }; static struct kmem_cache *cache_slab __read_mostly; -static struct workqueue_struct *dfscache_wq __read_mostly; +struct workqueue_struct *dfscache_wq; -static int cache_ttl; -static DEFINE_SPINLOCK(cache_ttl_lock); +atomic_t dfs_cache_ttl; static struct nls_table *cache_cp; @@ -65,10 +66,6 @@ static atomic_t cache_count; static struct hlist_head cache_htable[CACHE_HTABLE_SIZE]; static DECLARE_RWSEM(htable_rw_lock); -static void refresh_cache_worker(struct work_struct *work); - -static DECLARE_DELAYED_WORK(refresh_task, refresh_cache_worker); - /** * dfs_cache_canonical_path - get a canonical DFS path * @@ -290,7 +287,9 @@ int dfs_cache_init(void) int rc; int i; - dfscache_wq = alloc_workqueue("cifs-dfscache", WQ_FREEZABLE | WQ_UNBOUND, 1); + dfscache_wq = alloc_workqueue("cifs-dfscache", + WQ_UNBOUND|WQ_FREEZABLE|WQ_MEM_RECLAIM, + 0); if (!dfscache_wq) return -ENOMEM; @@ -306,6 +305,7 @@ int dfs_cache_init(void) INIT_HLIST_HEAD(&cache_htable[i]); atomic_set(&cache_count, 0); + atomic_set(&dfs_cache_ttl, CACHE_DEFAULT_TTL); cache_cp = load_nls("utf8"); if (!cache_cp) cache_cp = load_nls_default(); @@ -480,6 +480,7 @@ static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs, int rc; struct cache_entry *ce; unsigned int hash; + int ttl; WARN_ON(!rwsem_is_locked(&htable_rw_lock)); @@ -496,15 +497,8 @@ static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs, if (IS_ERR(ce)) return ce; - spin_lock(&cache_ttl_lock); - if (!cache_ttl) { - cache_ttl = ce->ttl; - queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ); - } else { - cache_ttl = min_t(int, cache_ttl, ce->ttl); - mod_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ); - } - spin_unlock(&cache_ttl_lock); + ttl = min_t(int, atomic_read(&dfs_cache_ttl), ce->ttl); + atomic_set(&dfs_cache_ttl, ttl); hlist_add_head(&ce->hlist, &cache_htable[hash]); dump_ce(ce); @@ -616,7 +610,6 @@ static struct cache_entry *lookup_cache_entry(const char *path) */ void dfs_cache_destroy(void) { - cancel_delayed_work_sync(&refresh_task); unload_nls(cache_cp); flush_cache_ents(); kmem_cache_destroy(cache_slab); @@ -1142,6 +1135,7 @@ static bool target_share_equal(struct TCP_Server_Info *server, const char *s1, c * target shares in @refs. */ static void mark_for_reconnect_if_needed(struct TCP_Server_Info *server, + const char *path, struct dfs_cache_tgt_list *old_tl, struct dfs_cache_tgt_list *new_tl) { @@ -1153,8 +1147,10 @@ static void mark_for_reconnect_if_needed(struct TCP_Server_Info *server, nit = dfs_cache_get_next_tgt(new_tl, nit)) { if (target_share_equal(server, dfs_cache_get_tgt_name(oit), - dfs_cache_get_tgt_name(nit))) + dfs_cache_get_tgt_name(nit))) { + dfs_cache_noreq_update_tgthint(path, nit); return; + } } } @@ -1162,13 +1158,28 @@ static void mark_for_reconnect_if_needed(struct TCP_Server_Info *server, cifs_signal_cifsd_for_reconnect(server, true); } +static bool is_ses_good(struct cifs_ses *ses) +{ + struct TCP_Server_Info *server = ses->server; + struct cifs_tcon *tcon = ses->tcon_ipc; + bool ret; + + spin_lock(&ses->ses_lock); + spin_lock(&ses->chan_lock); + ret = !cifs_chan_needs_reconnect(ses, server) && + ses->ses_status == SES_GOOD && + !tcon->need_reconnect; + spin_unlock(&ses->chan_lock); + spin_unlock(&ses->ses_lock); + return ret; +} + /* Refresh dfs referral of tcon and mark it for reconnect if needed */ -static int __refresh_tcon(const char *path, struct cifs_tcon *tcon, bool force_refresh) +static int __refresh_tcon(const char *path, struct cifs_ses *ses, bool force_refresh) { struct dfs_cache_tgt_list old_tl = DFS_CACHE_TGT_LIST_INIT(old_tl); struct dfs_cache_tgt_list new_tl = DFS_CACHE_TGT_LIST_INIT(new_tl); - struct cifs_ses *ses = CIFS_DFS_ROOT_SES(tcon->ses); - struct cifs_tcon *ipc = ses->tcon_ipc; + struct TCP_Server_Info *server = ses->server; bool needs_refresh = false; struct cache_entry *ce; unsigned int xid; @@ -1190,20 +1201,19 @@ static int __refresh_tcon(const char *path, struct cifs_tcon *tcon, bool force_r goto out; } - spin_lock(&ipc->tc_lock); - if (ipc->status != TID_GOOD) { - spin_unlock(&ipc->tc_lock); - cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n", __func__); + ses = CIFS_DFS_ROOT_SES(ses); + if (!is_ses_good(ses)) { + cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n", + __func__); goto out; } - spin_unlock(&ipc->tc_lock); ce = cache_refresh_path(xid, ses, path, true); if (!IS_ERR(ce)) { rc = get_targets(ce, &new_tl); up_read(&htable_rw_lock); cifs_dbg(FYI, "%s: get_targets: %d\n", __func__, rc); - mark_for_reconnect_if_needed(tcon->ses->server, &old_tl, &new_tl); + mark_for_reconnect_if_needed(server, path, &old_tl, &new_tl); } out: @@ -1216,10 +1226,11 @@ out: static int refresh_tcon(struct cifs_tcon *tcon, bool force_refresh) { struct TCP_Server_Info *server = tcon->ses->server; + struct cifs_ses *ses = tcon->ses; mutex_lock(&server->refpath_lock); if (server->leaf_fullpath) - __refresh_tcon(server->leaf_fullpath + 1, tcon, force_refresh); + __refresh_tcon(server->leaf_fullpath + 1, ses, force_refresh); mutex_unlock(&server->refpath_lock); return 0; } @@ -1263,60 +1274,32 @@ int dfs_cache_remount_fs(struct cifs_sb_info *cifs_sb) return refresh_tcon(tcon, true); } -/* - * Worker that will refresh DFS cache from all active mounts based on lowest TTL value - * from a DFS referral. - */ -static void refresh_cache_worker(struct work_struct *work) +/* Refresh all DFS referrals related to DFS tcon */ +void dfs_cache_refresh(struct work_struct *work) { struct TCP_Server_Info *server; - struct cifs_tcon *tcon, *ntcon; - struct list_head tcons; + struct dfs_root_ses *rses; + struct cifs_tcon *tcon; struct cifs_ses *ses; - INIT_LIST_HEAD(&tcons); + tcon = container_of(work, struct cifs_tcon, dfs_cache_work.work); + ses = tcon->ses; + server = ses->server; - spin_lock(&cifs_tcp_ses_lock); - list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) { - spin_lock(&server->srv_lock); - if (!server->leaf_fullpath) { - spin_unlock(&server->srv_lock); - continue; - } - spin_unlock(&server->srv_lock); - - list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) { - if (ses->tcon_ipc) { - ses->ses_count++; - list_add_tail(&ses->tcon_ipc->ulist, &tcons); - } - list_for_each_entry(tcon, &ses->tcon_list, tcon_list) { - if (!tcon->ipc) { - tcon->tc_count++; - list_add_tail(&tcon->ulist, &tcons); - } - } - } - } - spin_unlock(&cifs_tcp_ses_lock); - - list_for_each_entry_safe(tcon, ntcon, &tcons, ulist) { - struct TCP_Server_Info *server = tcon->ses->server; - - list_del_init(&tcon->ulist); + mutex_lock(&server->refpath_lock); + if (server->leaf_fullpath) + __refresh_tcon(server->leaf_fullpath + 1, ses, false); + mutex_unlock(&server->refpath_lock); + list_for_each_entry(rses, &tcon->dfs_ses_list, list) { + ses = rses->ses; + server = ses->server; mutex_lock(&server->refpath_lock); if (server->leaf_fullpath) - __refresh_tcon(server->leaf_fullpath + 1, tcon, false); + __refresh_tcon(server->leaf_fullpath + 1, ses, false); mutex_unlock(&server->refpath_lock); - - if (tcon->ipc) - cifs_put_smb_ses(tcon->ses); - else - cifs_put_tcon(tcon); } - spin_lock(&cache_ttl_lock); - queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ); - spin_unlock(&cache_ttl_lock); + queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work, + atomic_read(&dfs_cache_ttl) * HZ); } |