From: Paulo Alcantara <palcantara@suse.de>
Date: Wed, 14 Nov 2018 16:01:21 -0200
Subject: [PATCH] cifs: Add DFS cache routines
Git-commit: 54be1f6c1c37498bba557049df646cc239fa37e3
Patch-mainline: v5.0-rc1
References: bsc#1144333
* Add new dfs_cache.[ch] files
* Add new /proc/fs/cifs/dfscache file
- dump current cache when read
- clear current cache when writing "0" to it
* Add delayed_work to periodically refresh cache entries
The new interface will be used for caching DFS referrals, as well as
supporting client target failover.
The DFS cache is a hashtable that maps UNC paths to cache entries.
A cache entry contains:
- the UNC path it is mapped on
- how much the the UNC path the entry consumes
- flags
- a Time-To-Live after which the entry expires
- a list of possible targets (linked lists of UNC paths)
- a "hint target" pointing the last known working target or the first
target if none were tried. This hint lets cifs.ko remember and try
working targets first.
* Looking for an entry in the cache is done with dfs_cache_find()
- if no valid entries are found, a DFS query is made, stored in the
cache and returned
- the full target list can be copied and returned to avoid race
conditions and looped on with the help with the
dfs_cache_tgt_iterator
* Updating the target hint to the next target is done with
dfs_cache_update_tgthint()
These functions have a dfs_cache_noreq_XXX() version that doesn't
fetches referrals if no entries are found. These versions don't
require the tcp/ses/tcon/cifs_sb parameters as a result.
Expired entries cannot be used and since they have a pretty short TTL
[1] in order for them to be useful for failover the DFS cache adds a
delayed work called periodically to keep them fresh.
Since we might not have available connections to issue the referral
request when refreshing we need to store volume_info structs with
credentials and other needed info to be able to connect to the right
server.
1: Windows defaults: 5mn for domain-based referrals, 30mn for regular
links
Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
fs/cifs/Makefile | 2 +-
fs/cifs/cifs_debug.c | 12 +
fs/cifs/cifsglob.h | 5 +
fs/cifs/cifsproto.h | 3 +
fs/cifs/connect.c | 2 +-
fs/cifs/dfs_cache.c | 1365 ++++++++++++++++++++++++++++++++++++++++++++++++++
fs/cifs/dfs_cache.h | 97 ++++
7 files changed, 1484 insertions(+), 2 deletions(-)
create mode 100644 fs/cifs/dfs_cache.c
create mode 100644 fs/cifs/dfs_cache.h
diff --git a/fs/cifs/Makefile b/fs/cifs/Makefile
index 85817991ee68..51af69a1a328 100644
--- a/fs/cifs/Makefile
+++ b/fs/cifs/Makefile
@@ -17,7 +17,7 @@ cifs-$(CONFIG_CIFS_ACL) += cifsacl.o
cifs-$(CONFIG_CIFS_UPCALL) += cifs_spnego.o
-cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o cifs_dfs_ref.o
+cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o cifs_dfs_ref.o dfs_cache.o
cifs-$(CONFIG_CIFS_FSCACHE) += fscache.o cache.o
diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index ba178b09de0b..593fb422d0f3 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -30,6 +30,9 @@
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifsfs.h"
+#ifdef CONFIG_CIFS_DFS_UPCALL
+#include "dfs_cache.h"
+#endif
#ifdef CONFIG_CIFS_SMB_DIRECT
#include "smbdirect.h"
#endif
@@ -629,6 +632,11 @@ cifs_proc_init(void)
&cifs_security_flags_proc_fops);
proc_create("LookupCacheEnabled", 0644, proc_fs_cifs,
&cifs_lookup_cache_proc_fops);
+
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ proc_create("dfscache", 0644, proc_fs_cifs, &dfscache_proc_fops);
+#endif
+
#ifdef CONFIG_CIFS_SMB_DIRECT
proc_create("rdma_readwrite_threshold", 0644, proc_fs_cifs,
&cifs_rdma_readwrite_threshold_proc_fops);
@@ -663,6 +671,10 @@ cifs_proc_clean(void)
remove_proc_entry("SecurityFlags", proc_fs_cifs);
remove_proc_entry("LinuxExtensionsEnabled", proc_fs_cifs);
remove_proc_entry("LookupCacheEnabled", proc_fs_cifs);
+
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ remove_proc_entry("dfscache", proc_fs_cifs);
+#endif
#ifdef CONFIG_CIFS_SMB_DIRECT
remove_proc_entry("rdma_readwrite_threshold", proc_fs_cifs);
remove_proc_entry("smbd_max_frmr_depth", proc_fs_cifs);
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 3b1aa12708a0..66c487634c9e 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1014,6 +1014,11 @@ struct cifs_tcon {
struct list_head pending_opens; /* list of incomplete opens */
struct cached_fid crfid; /* Cached root fid */
/* BB add field for back pointer to sb struct(s)? */
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ char *dfs_path;
+ int remap:2;
+ struct list_head ulist; /* cache update list */
+#endif
};
/*
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index f4dd2a3795dd..efa5e36b3762 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -527,6 +527,9 @@ extern int SMBencrypt(unsigned char *passwd, const unsigned char *c8,
extern void
cifs_cleanup_volume_info_contents(struct smb_vol *volume_info);
+extern struct TCP_Server_Info *
+cifs_find_tcp_session(struct smb_vol *vol);
+
void cifs_readdata_release(struct kref *refcount);
int cifs_async_readv(struct cifs_readdata *rdata);
int cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index d0de4fb8ee43..5feb3bf97d70 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2295,7 +2295,7 @@ static int match_server(struct TCP_Server_Info *server, struct smb_vol *vol)
return 1;
}
-static struct TCP_Server_Info *
+struct TCP_Server_Info *
cifs_find_tcp_session(struct smb_vol *vol)
{
struct TCP_Server_Info *server;
diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
new file mode 100644
index 000000000000..1af078e531c1
--- /dev/null
+++ b/fs/cifs/dfs_cache.c
@@ -0,0 +1,1365 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DFS referral cache routines
+ *
+ * Copyright (c) 2018 Paulo Alcantara <palcantara@suse.de>
+ */
+
+#include <linux/rcupdate.h>
+#include <linux/rculist.h>
+#include <linux/jhash.h>
+#include <linux/ktime.h>
+#include <linux/slab.h>
+#include <linux/nls.h>
+#include <linux/workqueue.h>
+#include "cifsglob.h"
+#include "smb2pdu.h"
+#include "smb2proto.h"
+#include "cifsproto.h"
+#include "cifs_debug.h"
+#include "cifs_unicode.h"
+#include "smb2glob.h"
+
+#include "dfs_cache.h"
+
+#define DFS_CACHE_HTABLE_SIZE 32
+#define DFS_CACHE_MAX_ENTRIES 64
+
+#define IS_INTERLINK_SET(v) ((v) & (DFSREF_REFERRAL_SERVER | \
+ DFSREF_STORAGE_SERVER))
+
+struct dfs_cache_tgt {
+ char *t_name;
+ struct list_head t_list;
+};
+
+struct dfs_cache_entry {
+ struct hlist_node ce_hlist;
+ const char *ce_path;
+ int ce_ttl;
+ int ce_srvtype;
+ int ce_flags;
+ struct timespec64 ce_etime;
+ int ce_path_consumed;
+ int ce_numtgts;
+ struct list_head ce_tlist;
+ struct dfs_cache_tgt *ce_tgthint;
+ struct rcu_head ce_rcu;
+};
+
+static struct kmem_cache *dfs_cache_slab __read_mostly;
+
+struct dfs_cache_vol_info {
+ char *vi_fullpath;
+ struct smb_vol vi_vol;
+ struct list_head vi_list;
+};
+
+struct dfs_cache {
+ struct mutex dc_lock;
+ struct nls_table *dc_nlsc;
+ struct list_head dc_vol_list;
+ int dc_ttl;
+ struct delayed_work dc_refresh;
+};
+
+static struct dfs_cache dfs_cache;
+
+/*
+ * Number of entries in the cache
+ */
+static size_t dfs_cache_count;
+
+static DEFINE_MUTEX(dfs_cache_list_lock);
+static struct hlist_head dfs_cache_htable[DFS_CACHE_HTABLE_SIZE];
+
+static void refresh_cache_worker(struct work_struct *work);
+
+static inline bool is_path_valid(const char *path)
+{
+ return path && (strchr(path + 1, '\\') || strchr(path + 1, '/'));
+}
+
+static inline int get_normalized_path(const char *path, char **npath)
+{
+ if (*path == '\\') {
+ *npath = (char *)path;
+ } else {
+ *npath = kstrndup(path, strlen(path), GFP_KERNEL);
+ if (!*npath)
+ return -ENOMEM;
+ convert_delimiter(*npath, '\\');
+ }
+ return 0;
+}
+
+static inline void free_normalized_path(const char *path, char *npath)
+{
+ if (path != npath)
+ kfree(npath);
+}
+
+static inline bool cache_entry_expired(const struct dfs_cache_entry *ce)
+{
+ struct timespec64 ts;
+
+ ts = current_kernel_time64();
+ return timespec64_compare(&ts, &ce->ce_etime) >= 0;
+}
+
+static inline void free_tgts(struct dfs_cache_entry *ce)
+{
+ struct dfs_cache_tgt *t, *n;
+
+ list_for_each_entry_safe(t, n, &ce->ce_tlist, t_list) {
+ list_del(&t->t_list);
+ kfree(t->t_name);
+ kfree(t);
+ }
+}
+
+static void free_cache_entry(struct rcu_head *rcu)
+{
+ struct dfs_cache_entry *ce = container_of(rcu, struct dfs_cache_entry,
+ ce_rcu);
+ kmem_cache_free(dfs_cache_slab, ce);
+}
+
+static inline void flush_cache_ent(struct dfs_cache_entry *ce)
+{
+ if (hlist_unhashed(&ce->ce_hlist))
+ return;
+
+ hlist_del_init_rcu(&ce->ce_hlist);
+ kfree(ce->ce_path);
+ free_tgts(ce);
+ dfs_cache_count--;
+ call_rcu(&ce->ce_rcu, free_cache_entry);
+}
+
+static void flush_cache_ents(void)
+{
+ int i;
+
+ rcu_read_lock();
+ for (i = 0; i < DFS_CACHE_HTABLE_SIZE; i++) {
+ struct hlist_head *l = &dfs_cache_htable[i];
+ struct dfs_cache_entry *ce;
+
+ hlist_for_each_entry_rcu(ce, l, ce_hlist)
+ flush_cache_ent(ce);
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * dfs cache /proc file
+ */
+static int dfscache_proc_show(struct seq_file *m, void *v)
+{
+ int bucket;
+ struct dfs_cache_entry *ce;
+ struct dfs_cache_tgt *t;
+
+ seq_puts(m, "DFS cache\n---------\n");
+
+ mutex_lock(&dfs_cache_list_lock);
+
+ rcu_read_lock();
+ hash_for_each_rcu(dfs_cache_htable, bucket, ce, ce_hlist) {
+ seq_printf(m,
+ "cache entry: path=%s,type=%s,ttl=%d,etime=%ld,"
+ "interlink=%s,path_consumed=%d,expired=%s\n",
+ ce->ce_path,
+ ce->ce_srvtype == DFS_TYPE_ROOT ? "root" : "link",
+ ce->ce_ttl, ce->ce_etime.tv_nsec,
+ IS_INTERLINK_SET(ce->ce_flags) ? "yes" : "no",
+ ce->ce_path_consumed,
+ cache_entry_expired(ce) ? "yes" : "no");
+
+ list_for_each_entry(t, &ce->ce_tlist, t_list) {
+ seq_printf(m, " %s%s\n",
+ t->t_name,
+ ce->ce_tgthint == t ? " (target hint)" : "");
+ }
+
+ }
+ rcu_read_unlock();
+
+ mutex_unlock(&dfs_cache_list_lock);
+ return 0;
+}
+
+static ssize_t dfscache_proc_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos)
+{
+ char c;
+ int rc;
+
+ rc = get_user(c, buffer);
+ if (rc)
+ return rc;
+
+ if (c != '0')
+ return -EINVAL;
+
+ cifs_dbg(FYI, "clearing dfs cache");
+ mutex_lock(&dfs_cache_list_lock);
+ flush_cache_ents();
+ mutex_unlock(&dfs_cache_list_lock);
+
+ return count;
+}
+
+static int dfscache_proc_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, dfscache_proc_show, NULL);
+}
+
+const struct file_operations dfscache_proc_fops = {
+ .open = dfscache_proc_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+ .write = dfscache_proc_write,
+};
+
+#ifdef CONFIG_CIFS_DEBUG2
+static inline void dump_tgts(const struct dfs_cache_entry *ce)
+{
+ struct dfs_cache_tgt *t;
+
+ cifs_dbg(FYI, "target list:\n");
+ list_for_each_entry(t, &ce->ce_tlist, t_list) {
+ cifs_dbg(FYI, " %s%s\n", t->t_name,
+ ce->ce_tgthint == t ? " (target hint)" : "");
+ }
+}
+
+static inline void dump_ce(const struct dfs_cache_entry *ce)
+{
+ cifs_dbg(FYI, "cache entry: path=%s,type=%s,ttl=%d,etime=%ld,"
+ "interlink=%s,path_consumed=%d,expired=%s\n", ce->ce_path,
+ ce->ce_srvtype == DFS_TYPE_ROOT ? "root" : "link", ce->ce_ttl,
+ ce->ce_etime.tv_nsec,
+ IS_INTERLINK_SET(ce->ce_flags) ? "yes" : "no",
+ ce->ce_path_consumed,
+ cache_entry_expired(ce) ? "yes" : "no");
+ dump_tgts(ce);
+}
+
+static inline void dump_refs(const struct dfs_info3_param *refs, int numrefs)
+{
+ int i;
+
+ cifs_dbg(FYI, "DFS referrals returned by the server:\n");
+ for (i = 0; i < numrefs; i++) {
+ const struct dfs_info3_param *ref = &refs[i];
+
+ cifs_dbg(FYI,
+ "\n"
+ "flags: 0x%x\n"
+ "path_consumed: %d\n"
+ "server_type: 0x%x\n"
+ "ref_flag: 0x%x\n"
+ "path_name: %s\n"
+ "node_name: %s\n"
+ "ttl: %d (%dm)\n",
+ ref->flags, ref->path_consumed, ref->server_type,
+ ref->ref_flag, ref->path_name, ref->node_name,
+ ref->ttl, ref->ttl / 60);
+ }
+}
+#else
+#define dump_tgts(e)
+#define dump_ce(e)
+#define dump_refs(r, n)
+#endif
+
+/**
+ * dfs_cache_init - Initialize DFS referral cache.
+ *
+ * Return zero if initialized successfully, otherwise non-zero.
+ */
+int dfs_cache_init(void)
+{
+ int i;
+
+ dfs_cache_slab = kmem_cache_create("cifs_dfs_cache",
+ sizeof(struct dfs_cache_entry), 0,
+ SLAB_HWCACHE_ALIGN, NULL);
+ if (!dfs_cache_slab)
+ return -ENOMEM;
+
+ for (i = 0; i < DFS_CACHE_HTABLE_SIZE; i++)
+ INIT_HLIST_HEAD(&dfs_cache_htable[i]);
+
+ INIT_LIST_HEAD(&dfs_cache.dc_vol_list);
+ mutex_init(&dfs_cache.dc_lock);
+ INIT_DELAYED_WORK(&dfs_cache.dc_refresh, refresh_cache_worker);
+ dfs_cache.dc_ttl = -1;
+ dfs_cache.dc_nlsc = load_nls_default();
+
+ cifs_dbg(FYI, "%s: initialized DFS referral cache\n", __func__);
+ return 0;
+}
+
+static inline unsigned int cache_entry_hash(const void *data, int size)
+{
+ unsigned int h;
+
+ h = jhash(data, size, 0);
+ return h & (DFS_CACHE_HTABLE_SIZE - 1);
+}
+
+/* Check whether second path component of @path is SYSVOL or NETLOGON */
+static inline bool is_sysvol_or_netlogon(const char *path)
+{
+ const char *s;
+ char sep = path[0];
+
+ s = strchr(path + 1, sep) + 1;
+ return !strncasecmp(s, "sysvol", strlen("sysvol")) ||
+ !strncasecmp(s, "netlogon", strlen("netlogon"));
+}
+
+/* Return target hint of a DFS cache entry */
+static inline char *get_tgt_name(const struct dfs_cache_entry *ce)
+{
+ struct dfs_cache_tgt *t = ce->ce_tgthint;
+
+ return t ? t->t_name : ERR_PTR(-ENOENT);
+}
+
+/* Return expire time out of a new entry's TTL */
+static inline struct timespec64 get_expire_time(int ttl)
+{
+ struct timespec64 ts = {
+ .tv_sec = ttl,
+ .tv_nsec = 0,
+ };
+
+ return timespec64_add(current_kernel_time64(), ts);
+}
+
+/* Allocate a new DFS target */
+static inline struct dfs_cache_tgt *alloc_tgt(const char *name)
+{
+ struct dfs_cache_tgt *t;
+
+ t = kmalloc(sizeof(*t), GFP_KERNEL);
+ if (!t)
+ return ERR_PTR(-ENOMEM);
+ t->t_name = kstrndup(name, strlen(name), GFP_KERNEL);
+ if (!t->t_name) {
+ kfree(t);
+ return ERR_PTR(-ENOMEM);
+ }
+ INIT_LIST_HEAD(&t->t_list);
+ return t;
+}
+
+/*
+ * Copy DFS referral information to a cache entry and conditionally update
+ * target hint.
+ */
+static int copy_ref_data(const struct dfs_info3_param *refs, int numrefs,
+ struct dfs_cache_entry *ce, const char *tgthint)
+{
+ int i;
+
+ ce->ce_ttl = refs[0].ttl;
+ ce->ce_etime = get_expire_time(ce->ce_ttl);
+ ce->ce_srvtype = refs[0].server_type;
+ ce->ce_flags = refs[0].ref_flag;
+ ce->ce_path_consumed = refs[0].path_consumed;
+
+ for (i = 0; i < numrefs; i++) {
+ struct dfs_cache_tgt *t;
+
+ t = alloc_tgt(refs[i].node_name);
+ if (IS_ERR(t)) {
+ free_tgts(ce);
+ return PTR_ERR(t);
+ }
+ if (tgthint && !strcasecmp(t->t_name, tgthint)) {
+ list_add(&t->t_list, &ce->ce_tlist);
+ tgthint = NULL;
+ } else {
+ list_add_tail(&t->t_list, &ce->ce_tlist);
+ }
+ ce->ce_numtgts++;
+ }
+
+ ce->ce_tgthint = list_first_entry_or_null(&ce->ce_tlist,
+ struct dfs_cache_tgt, t_list);
+
+ return 0;
+}
+
+/* Allocate a new cache entry */
+static struct dfs_cache_entry *
+alloc_cache_entry(const char *path, const struct dfs_info3_param *refs,
+ int numrefs)
+{
+ struct dfs_cache_entry *ce;
+ int rc;
+
+ ce = kmem_cache_zalloc(dfs_cache_slab, GFP_KERNEL);
+ if (!ce)
+ return ERR_PTR(-ENOMEM);
+
+ ce->ce_path = kstrdup_const(path, GFP_KERNEL);
+ if (!ce->ce_path) {
+ kfree(ce);
+ return ERR_PTR(-ENOMEM);
+ }
+ INIT_HLIST_NODE(&ce->ce_hlist);
+ INIT_LIST_HEAD(&ce->ce_tlist);
+
+ rc = copy_ref_data(refs, numrefs, ce, NULL);
+ if (rc) {
+ kfree(ce->ce_path);
+ kfree(ce);
+ ce = ERR_PTR(rc);
+ }
+ return ce;
+}
+
+static void remove_oldest_entry(void)
+{
+ int bucket;
+ struct dfs_cache_entry *ce;
+ struct dfs_cache_entry *to_del = NULL;
+
+ rcu_read_lock();
+ hash_for_each_rcu(dfs_cache_htable, bucket, ce, ce_hlist) {
+ if (!to_del || timespec64_compare(&ce->ce_etime,
+ &to_del->ce_etime) < 0)
+ to_del = ce;
+ }
+ if (!to_del) {
+ cifs_dbg(FYI, "%s: no entry to remove", __func__);
+ goto out;
+ }
+ cifs_dbg(FYI, "%s: removing entry", __func__);
+ dump_ce(to_del);
+ flush_cache_ent(to_del);
+out:
+ rcu_read_unlock();
+}
+
+/* Add a new DFS cache entry */
+static inline struct dfs_cache_entry *
+add_cache_entry(unsigned int hash, const char *path,
+ const struct dfs_info3_param *refs, int numrefs)
+{
+ struct dfs_cache_entry *ce;
+
+ ce = alloc_cache_entry(path, refs, numrefs);
+ if (IS_ERR(ce))
+ return ce;
+
+ hlist_add_head_rcu(&ce->ce_hlist, &dfs_cache_htable[hash]);
+
+ mutex_lock(&dfs_cache.dc_lock);
+ if (dfs_cache.dc_ttl < 0) {
+ dfs_cache.dc_ttl = ce->ce_ttl;
+ queue_delayed_work(cifsiod_wq, &dfs_cache.dc_refresh,
+ dfs_cache.dc_ttl * HZ);
+ } else {
+ dfs_cache.dc_ttl = min_t(int, dfs_cache.dc_ttl, ce->ce_ttl);
+ mod_delayed_work(cifsiod_wq, &dfs_cache.dc_refresh,
+ dfs_cache.dc_ttl * HZ);
+ }
+ mutex_unlock(&dfs_cache.dc_lock);
+
+ return ce;
+}
+
+static struct dfs_cache_entry *__find_cache_entry(unsigned int hash,
+ const char *path)
+{
+ struct dfs_cache_entry *ce;
+ bool found = false;
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(ce, &dfs_cache_htable[hash], ce_hlist) {
+ if (!strcasecmp(path, ce->ce_path)) {
+#ifdef CONFIG_CIFS_DEBUG2
+ char *name = get_tgt_name(ce);
+
+ if (unlikely(IS_ERR(name))) {
+ rcu_read_unlock();
+ return ERR_CAST(name);
+ }
+ cifs_dbg(FYI, "%s: cache hit\n", __func__);
+ cifs_dbg(FYI, "%s: target hint: %s\n", __func__, name);
+#endif
+ found = true;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ return found ? ce : ERR_PTR(-ENOENT);
+}
+
+/*
+ * Find a DFS cache entry in hash table and optionally check prefix path against
+ * @path.
+ * Use whole path components in the match.
+ * Return ERR_PTR(-ENOENT) if the entry is not found.
+ */
+static inline struct dfs_cache_entry *find_cache_entry(const char *path,
+ unsigned int *hash)
+{
+ *hash = cache_entry_hash(path, strlen(path));
+ return __find_cache_entry(*hash, path);
+}
+
+static inline void destroy_slab_cache(void)
+{
+ rcu_barrier();
+ kmem_cache_destroy(dfs_cache_slab);
+}
+
+static inline void free_vol(struct dfs_cache_vol_info *vi)
+{
+ list_del(&vi->vi_list);
+ kfree(vi->vi_fullpath);
+ cifs_cleanup_volume_info_contents(&vi->vi_vol);
+ kfree(vi);
+}
+
+static inline void free_vol_list(void)
+{
+ struct dfs_cache_vol_info *vi, *nvi;
+
+ list_for_each_entry_safe(vi, nvi, &dfs_cache.dc_vol_list, vi_list)
+ free_vol(vi);
+}
+
+/**
+ * dfs_cache_destroy - destroy DFS referral cache
+ */
+void dfs_cache_destroy(void)
+{
+ cancel_delayed_work_sync(&dfs_cache.dc_refresh);
+ unload_nls(dfs_cache.dc_nlsc);
+ free_vol_list();
+ mutex_destroy(&dfs_cache.dc_lock);
+
+ flush_cache_ents();
+ destroy_slab_cache();
+ mutex_destroy(&dfs_cache_list_lock);
+
+ cifs_dbg(FYI, "%s: destroyed DFS referral cache\n", __func__);
+}
+
+static inline struct dfs_cache_entry *
+__update_cache_entry(const char *path, const struct dfs_info3_param *refs,
+ int numrefs)
+{
+ int rc;
+ unsigned int h;
+ struct dfs_cache_entry *ce;
+ char *s, *th = NULL;
+
+ ce = find_cache_entry(path, &h);
+ if (IS_ERR(ce))
+ return ce;
+
+ if (ce->ce_tgthint) {
+ s = ce->ce_tgthint->t_name;
+ th = kstrndup(s, strlen(s), GFP_KERNEL);
+ if (!th)
+ return ERR_PTR(-ENOMEM);
+ }
+
+ free_tgts(ce);
+ ce->ce_numtgts = 0;
+
+ rc = copy_ref_data(refs, numrefs, ce, th);
+ kfree(th);
+
+ if (rc)
+ ce = ERR_PTR(rc);
+
+ return ce;
+}
+
+/* Update an expired cache entry by getting a new DFS referral from server */
+static struct dfs_cache_entry *
+update_cache_entry(const unsigned int xid, struct cifs_ses *ses,
+ const struct nls_table *nls_codepage, int remap,
+ const char *path, struct dfs_cache_entry *ce)
+{
+ int rc;
+ struct dfs_info3_param *refs = NULL;
+ int numrefs = 0;
+
+ cifs_dbg(FYI, "%s: update expired cache entry\n", __func__);
+ /*
+ * Check if caller provided enough parameters to update an expired
+ * entry.
+ */
+ if (!ses || !ses->server || !ses->server->ops->get_dfs_refer)
+ return ERR_PTR(-ETIME);
+ if (unlikely(!nls_codepage))
+ return ERR_PTR(-ETIME);
+
+ cifs_dbg(FYI, "%s: DFS referral request for %s\n", __func__, path);
+
+ rc = ses->server->ops->get_dfs_refer(xid, ses, path, &refs, &numrefs,
+ nls_codepage, remap);
+ if (rc)
+ ce = ERR_PTR(rc);
+ else
+ ce = __update_cache_entry(path, refs, numrefs);
+
+ dump_refs(refs, numrefs);
+ free_dfs_info_array(refs, numrefs);
+
+ return ce;
+}
+
+/*
+ * Find, create or update a DFS cache entry.
+ *
+ * If the entry wasn't found, it will create a new one. Or if it was found but
+ * expired, then it will update the entry accordingly.
+ *
+ * For interlinks, __cifs_dfs_mount() and expand_dfs_referral() are supposed to
+ * handle them properly.
+ */
+static struct dfs_cache_entry *
+do_dfs_cache_find(const unsigned int xid, struct cifs_ses *ses,
+ const struct nls_table *nls_codepage, int remap,
+ const char *path, bool noreq)
+{
+ int rc;
+ unsigned int h;
+ struct dfs_cache_entry *ce;
+ struct dfs_info3_param *nrefs;
+ int numnrefs;
+
+ cifs_dbg(FYI, "%s: search path: %s\n", __func__, path);
+
+ ce = find_cache_entry(path, &h);
+ if (IS_ERR(ce)) {
+ cifs_dbg(FYI, "%s: cache miss\n", __func__);
+ /*
+ * If @noreq is set, no requests will be sent to the server for
+ * either updating or getting a new DFS referral.
+ */
+ if (noreq)
+ return ce;
+ /*
+ * No cache entry was found, so check for valid parameters that
+ * will be required to get a new DFS referral and then create a
+ * new cache entry.
+ */
+ if (!ses || !ses->server || !ses->server->ops->get_dfs_refer) {
+ ce = ERR_PTR(-EOPNOTSUPP);
+ return ce;
+ }
+ if (unlikely(!nls_codepage)) {
+ ce = ERR_PTR(-EINVAL);
+ return ce;
+ }
+
+ nrefs = NULL;
+ numnrefs = 0;
+
+ cifs_dbg(FYI, "%s: DFS referral request for %s\n", __func__,
+ path);
+
+ rc = ses->server->ops->get_dfs_refer(xid, ses, path, &nrefs,
+ &numnrefs, nls_codepage,
+ remap);
+ if (rc) {
+ ce = ERR_PTR(rc);
+ return ce;
+ }
+
+ dump_refs(nrefs, numnrefs);
+
+ cifs_dbg(FYI, "%s: new cache entry\n", __func__);
+
+ if (dfs_cache_count >= DFS_CACHE_MAX_ENTRIES) {
+ cifs_dbg(FYI, "%s: reached max cache size (%d)",
+ __func__, DFS_CACHE_MAX_ENTRIES);
+ remove_oldest_entry();
+ }
+ ce = add_cache_entry(h, path, nrefs, numnrefs);
+ free_dfs_info_array(nrefs, numnrefs);
+
+ if (IS_ERR(ce))
+ return ce;
+
+ dfs_cache_count++;
+ }
+
+ dump_ce(ce);
+
+ /* Just return the found cache entry in case @noreq is set */
+ if (noreq)
+ return ce;
+
+ if (cache_entry_expired(ce)) {
+ cifs_dbg(FYI, "%s: expired cache entry\n", __func__);
+ ce = update_cache_entry(xid, ses, nls_codepage, remap, path,
+ ce);
+ if (IS_ERR(ce)) {
+ cifs_dbg(FYI, "%s: failed to update expired entry\n",
+ __func__);
+ }
+ }
+ return ce;
+}
+
+/* Set up a new DFS referral from a given cache entry */
+static int setup_ref(const char *path, const struct dfs_cache_entry *ce,
+ struct dfs_info3_param *ref, const char *tgt)
+{
+ int rc;
+
+ cifs_dbg(FYI, "%s: set up new ref\n", __func__);
+
+ memset(ref, 0, sizeof(*ref));
+
+ ref->path_name = kstrndup(path, strlen(path), GFP_KERNEL);
+ if (!ref->path_name)
+ return -ENOMEM;
+
+ ref->path_consumed = ce->ce_path_consumed;
+
+ ref->node_name = kstrndup(tgt, strlen(tgt), GFP_KERNEL);
+ if (!ref->node_name) {
+ rc = -ENOMEM;
+ goto err_free_path;
+ }
+
+ ref->ttl = ce->ce_ttl;
+ ref->server_type = ce->ce_srvtype;
+ ref->ref_flag = ce->ce_flags;
+
+ return 0;
+
+err_free_path:
+ kfree(ref->path_name);
+ ref->path_name = NULL;
+ return rc;
+}
+
+/* Return target list of a DFS cache entry */
+static int get_tgt_list(const struct dfs_cache_entry *ce,
+ struct dfs_cache_tgt_list *tl)
+{
+ int rc;
+ struct list_head *head = &tl->tl_list;
+ struct dfs_cache_tgt *t;
+ struct dfs_cache_tgt_iterator *it, *nit;
+
+ memset(tl, 0, sizeof(*tl));
+ INIT_LIST_HEAD(head);
+
+ list_for_each_entry(t, &ce->ce_tlist, t_list) {
+ it = kzalloc(sizeof(*it), GFP_KERNEL);
+ if (!it) {
+ rc = -ENOMEM;
+ goto err_free_it;
+ }
+
+ it->it_name = kstrndup(t->t_name, strlen(t->t_name),
+ GFP_KERNEL);
+ if (!it->it_name) {
+ rc = -ENOMEM;
+ goto err_free_it;
+ }
+
+ if (ce->ce_tgthint == t)
+ list_add(&it->it_list, head);
+ else
+ list_add_tail(&it->it_list, head);
+ }
+ tl->tl_numtgts = ce->ce_numtgts;
+
+ return 0;
+
+err_free_it:
+ list_for_each_entry_safe(it, nit, head, it_list) {
+ kfree(it->it_name);
+ kfree(it);
+ }
+ return rc;
+}
+
+/**
+ * dfs_cache_find - find a DFS cache entry
+ *
+ * If it doesn't find the cache entry, then it will get a DFS referral
+ * for @path and create a new entry.
+ *
+ * In case the cache entry exists but expired, it will get a DFS referral
+ * for @path and then update the respective cache entry.
+ *
+ * These parameters are passed down to the get_dfs_refer() call if it
+ * needs to be issued:
+ * @xid: syscall xid
+ * @ses: smb session to issue the request on
+ * @nls_codepage: charset conversion
+ * @remap: path character remapping type
+ * @path: path to lookup in DFS referral cache.
+ *
+ * @ref: when non-NULL, store single DFS referral result in it.
+ * @tgt_list: when non-NULL, store complete DFS target list in it.
+ *
+ * Return zero if the target was found, otherwise non-zero.
+ */
+int dfs_cache_find(const unsigned int xid, struct cifs_ses *ses,
+ const struct nls_table *nls_codepage, int remap,
+ const char *path, struct dfs_info3_param *ref,
+ struct dfs_cache_tgt_list *tgt_list)
+{
+ int rc;
+ char *npath;
+ struct dfs_cache_entry *ce;
+
+ if (unlikely(!is_path_valid(path)))
+ return -EINVAL;
+
+ rc = get_normalized_path(path, &npath);
+ if (rc)
+ return rc;
+
+ mutex_lock(&dfs_cache_list_lock);
+ ce = do_dfs_cache_find(xid, ses, nls_codepage, remap, npath, false);
+ if (!IS_ERR(ce)) {
+ if (ref)
+ rc = setup_ref(path, ce, ref, get_tgt_name(ce));
+ else
+ rc = 0;
+ if (!rc && tgt_list)
+ rc = get_tgt_list(ce, tgt_list);
+ } else {
+ rc = PTR_ERR(ce);
+ }
+ mutex_unlock(&dfs_cache_list_lock);
+ free_normalized_path(path, npath);
+ return rc;
+}
+
+/**
+ * dfs_cache_noreq_find - find a DFS cache entry without sending any requests to
+ * the currently connected server.
+ *
+ * NOTE: This function will neither update a cache entry in case it was
+ * expired, nor create a new cache entry if @path hasn't been found. It heavily
+ * relies on an existing cache entry.
+ *
+ * @path: path to lookup in the DFS referral cache.
+ * @ref: when non-NULL, store single DFS referral result in it.
+ * @tgt_list: when non-NULL, store complete DFS target list in it.
+ *
+ * Return 0 if successful.
+ * Return -ENOENT if the entry was not found.
+ * Return non-zero for other errors.
+ */
+int dfs_cache_noreq_find(const char *path, struct dfs_info3_param *ref,
+ struct dfs_cache_tgt_list *tgt_list)
+{
+ int rc;
+ char *npath;
+ struct dfs_cache_entry *ce;
+
+ if (unlikely(!is_path_valid(path)))
+ return -EINVAL;
+
+ rc = get_normalized_path(path, &npath);
+ if (rc)
+ return rc;
+
+ mutex_lock(&dfs_cache_list_lock);
+ ce = do_dfs_cache_find(0, NULL, NULL, 0, npath, true);
+ if (IS_ERR(ce)) {
+ rc = PTR_ERR(ce);
+ goto out;
+ }
+
+ if (ref)
+ rc = setup_ref(path, ce, ref, get_tgt_name(ce));
+ else
+ rc = 0;
+ if (!rc && tgt_list)
+ rc = get_tgt_list(ce, tgt_list);
+out:
+ mutex_unlock(&dfs_cache_list_lock);
+ free_normalized_path(path, npath);
+ return rc;
+}
+
+/**
+ * dfs_cache_update_tgthint - update target hint of a DFS cache entry
+ *
+ * If it doesn't find the cache entry, then it will get a DFS referral for @path
+ * and create a new entry.
+ *
+ * In case the cache entry exists but expired, it will get a DFS referral
+ * for @path and then update the respective cache entry.
+ *
+ * @xid: syscall id
+ * @ses: smb session
+ * @nls_codepage: charset conversion
+ * @remap: type of character remapping for paths
+ * @path: path to lookup in DFS referral cache.
+ * @it: DFS target iterator
+ *
+ * Return zero if the target hint was updated successfully, otherwise non-zero.
+ */
+int dfs_cache_update_tgthint(const unsigned int xid, struct cifs_ses *ses,
+ const struct nls_table *nls_codepage, int remap,
+ const char *path,
+ const struct dfs_cache_tgt_iterator *it)
+{
+ int rc;
+ char *npath;
+ struct dfs_cache_entry *ce;
+ struct dfs_cache_tgt *t;
+
+ if (unlikely(!is_path_valid(path)))
+ return -EINVAL;
+
+ rc = get_normalized_path(path, &npath);
+ if (rc)
+ return rc;
+
+ cifs_dbg(FYI, "%s: path: %s\n", __func__, npath);
+
+ mutex_lock(&dfs_cache_list_lock);
+ ce = do_dfs_cache_find(xid, ses, nls_codepage, remap, npath, false);
+ if (IS_ERR(ce)) {
+ rc = PTR_ERR(ce);
+ goto out;
+ }
+
+ rc = 0;
+
+ t = ce->ce_tgthint;
+
+ if (likely(!strcasecmp(it->it_name, t->t_name)))
+ goto out;
+
+ list_for_each_entry(t, &ce->ce_tlist, t_list) {
+ if (!strcasecmp(t->t_name, it->it_name)) {
+ ce->ce_tgthint = t;
+ cifs_dbg(FYI, "%s: new target hint: %s\n", __func__,
+ it->it_name);
+ break;
+ }
+ }
+
+out:
+ mutex_unlock(&dfs_cache_list_lock);
+ free_normalized_path(path, npath);
+ return rc;
+}
+
+/**
+ * dfs_cache_noreq_update_tgthint - update target hint of a DFS cache entry
+ * without sending any requests to the currently connected server.
+ *
+ * NOTE: This function will neither update a cache entry in case it was
+ * expired, nor create a new cache entry if @path hasn't been found. It heavily
+ * relies on an existing cache entry.
+ *
+ * @path: path to lookup in DFS referral cache.
+ * @it: target iterator which contains the target hint to update the cache
+ * entry with.
+ *
+ * Return zero if the target hint was updated successfully, otherwise non-zero.
+ */
+int dfs_cache_noreq_update_tgthint(const char *path,
+ const struct dfs_cache_tgt_iterator *it)
+{
+ int rc;
+ char *npath;
+ struct dfs_cache_entry *ce;
+ struct dfs_cache_tgt *t;
+
+ if (unlikely(!is_path_valid(path)) || !it)
+ return -EINVAL;
+
+ rc = get_normalized_path(path, &npath);
+ if (rc)
+ return rc;
+
+ cifs_dbg(FYI, "%s: path: %s\n", __func__, npath);
+
+ mutex_lock(&dfs_cache_list_lock);
+
+ ce = do_dfs_cache_find(0, NULL, NULL, 0, npath, true);
+ if (IS_ERR(ce)) {
+ rc = PTR_ERR(ce);
+ goto out;
+ }
+
+ rc = 0;
+
+ t = ce->ce_tgthint;
+
+ if (unlikely(!strcasecmp(it->it_name, t->t_name)))
+ goto out;
+
+ list_for_each_entry(t, &ce->ce_tlist, t_list) {
+ if (!strcasecmp(t->t_name, it->it_name)) {
+ ce->ce_tgthint = t;
+ cifs_dbg(FYI, "%s: new target hint: %s\n", __func__,
+ it->it_name);
+ break;
+ }
+ }
+
+out:
+ mutex_unlock(&dfs_cache_list_lock);
+ free_normalized_path(path, npath);
+ return rc;
+}
+
+/**
+ * dfs_cache_get_tgt_referral - returns a DFS referral (@ref) from a given
+ * target iterator (@it).
+ *
+ * @path: path to lookup in DFS referral cache.
+ * @it: DFS target iterator.
+ * @ref: DFS referral pointer to set up the gathered information.
+ *
+ * Return zero if the DFS referral was set up correctly, otherwise non-zero.
+ */
+int dfs_cache_get_tgt_referral(const char *path,
+ const struct dfs_cache_tgt_iterator *it,
+ struct dfs_info3_param *ref)
+{
+ int rc;
+ char *npath;
+ struct dfs_cache_entry *ce;
+ unsigned int h;
+
+ if (!it || !ref)
+ return -EINVAL;
+ if (unlikely(!is_path_valid(path)))
+ return -EINVAL;
+
+ rc = get_normalized_path(path, &npath);
+ if (rc)
+ return rc;
+
+ cifs_dbg(FYI, "%s: path: %s\n", __func__, npath);
+
+ mutex_lock(&dfs_cache_list_lock);
+
+ ce = find_cache_entry(npath, &h);
+ if (IS_ERR(ce)) {
+ rc = PTR_ERR(ce);
+ goto out;
+ }
+
+ cifs_dbg(FYI, "%s: target name: %s\n", __func__, it->it_name);
+
+ rc = setup_ref(path, ce, ref, it->it_name);
+
+out:
+ mutex_unlock(&dfs_cache_list_lock);
+ free_normalized_path(path, npath);
+ return rc;
+}
+
+static int dup_vol(struct smb_vol *vol, struct smb_vol *new)
+{
+ memcpy(new, vol, sizeof(*new));
+
+ if (vol->username) {
+ new->username = kstrndup(vol->username, strlen(vol->username),
+ GFP_KERNEL);
+ if (!new->username)
+ return -ENOMEM;
+ }
+ if (vol->password) {
+ new->password = kstrndup(vol->password, strlen(vol->password),
+ GFP_KERNEL);
+ if (!new->password)
+ goto err_free_username;
+ }
+ if (vol->UNC) {
+ cifs_dbg(FYI, "%s: vol->UNC: %s\n", __func__, vol->UNC);
+ new->UNC = kstrndup(vol->UNC, strlen(vol->UNC), GFP_KERNEL);
+ if (!new->UNC)
+ goto err_free_password;
+ }
+ if (vol->domainname) {
+ new->domainname = kstrndup(vol->domainname,
+ strlen(vol->domainname), GFP_KERNEL);
+ if (!new->domainname)
+ goto err_free_unc;
+ }
+ if (vol->iocharset) {
+ new->iocharset = kstrndup(vol->iocharset,
+ strlen(vol->iocharset), GFP_KERNEL);
+ if (!new->iocharset)
+ goto err_free_domainname;
+ }
+ if (vol->prepath) {
+ cifs_dbg(FYI, "%s: vol->prepath: %s\n", __func__, vol->prepath);
+ new->prepath = kstrndup(vol->prepath, strlen(vol->prepath),
+ GFP_KERNEL);
+ if (!new->prepath)
+ goto err_free_iocharset;
+ }
+
+ return 0;
+
+err_free_iocharset:
+ kfree(new->iocharset);
+err_free_domainname:
+ kfree(new->domainname);
+err_free_unc:
+ kfree(new->UNC);
+err_free_password:
+ kfree(new->password);
+err_free_username:
+ kfree(new->username);
+ kfree(new);
+ return -ENOMEM;
+}
+
+/**
+ * dfs_cache_add_vol - add a cifs volume during mount() that will be handled by
+ * DFS cache refresh worker.
+ *
+ * @vol: cifs volume.
+ * @fullpath: origin full path.
+ *
+ * Return zero if volume was set up correctly, otherwise non-zero.
+ */
+int dfs_cache_add_vol(struct smb_vol *vol, const char *fullpath)
+{
+ int rc;
+ struct dfs_cache_vol_info *vi;
+
+ if (!vol || !fullpath)
+ return -EINVAL;
+
+ cifs_dbg(FYI, "%s: fullpath: %s\n", __func__, fullpath);
+
+ vi = kzalloc(sizeof(*vi), GFP_KERNEL);
+ if (!vi)
+ return -ENOMEM;
+
+ vi->vi_fullpath = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
+ if (!vi->vi_fullpath) {
+ rc = -ENOMEM;
+ goto err_free_vi;
+ }
+
+ rc = dup_vol(vol, &vi->vi_vol);
+ if (rc)
+ goto err_free_fullpath;
+
+ mutex_lock(&dfs_cache.dc_lock);
+ list_add_tail(&vi->vi_list, &dfs_cache.dc_vol_list);
+ mutex_unlock(&dfs_cache.dc_lock);
+ return 0;
+
+err_free_fullpath:
+ kfree(vi->vi_fullpath);
+err_free_vi:
+ kfree(vi);
+ return rc;
+}
+
+static inline struct dfs_cache_vol_info *find_vol(const char *fullpath)
+{
+ struct dfs_cache_vol_info *vi;
+
+ list_for_each_entry(vi, &dfs_cache.dc_vol_list, vi_list) {
+ cifs_dbg(FYI, "%s: vi->vi_fullpath: %s\n", __func__,
+ vi->vi_fullpath);
+ if (!strcasecmp(vi->vi_fullpath, fullpath))
+ return vi;
+ }
+ return ERR_PTR(-ENOENT);
+}
+
+/**
+ * dfs_cache_update_vol - update vol info in DFS cache after failover
+ *
+ * @fullpath: fullpath to look up in volume list.
+ * @server: TCP ses pointer.
+ *
+ * Return zero if volume was updated, otherwise non-zero.
+ */
+int dfs_cache_update_vol(const char *fullpath, struct TCP_Server_Info *server)
+{
+ int rc;
+ struct dfs_cache_vol_info *vi;
+
+ if (!fullpath || !server)
+ return -EINVAL;
+
+ cifs_dbg(FYI, "%s: fullpath: %s\n", __func__, fullpath);
+
+ mutex_lock(&dfs_cache.dc_lock);
+
+ vi = find_vol(fullpath);
+ if (IS_ERR(vi)) {
+ rc = PTR_ERR(vi);
+ goto out;
+ }
+
+ cifs_dbg(FYI, "%s: updating volume info\n", __func__);
+ memcpy(&vi->vi_vol.dstaddr, &server->dstaddr,
+ sizeof(vi->vi_vol.dstaddr));
+ rc = 0;
+
+out:
+ mutex_unlock(&dfs_cache.dc_lock);
+ return rc;
+}
+
+/**
+ * dfs_cache_del_vol - remove volume info in DFS cache during umount()
+ *
+ * @fullpath: fullpath to look up in volume list.
+ */
+void dfs_cache_del_vol(const char *fullpath)
+{
+ struct dfs_cache_vol_info *vi;
+
+ if (!fullpath || !*fullpath)
+ return;
+
+ cifs_dbg(FYI, "%s: fullpath: %s\n", __func__, fullpath);
+
+ mutex_lock(&dfs_cache.dc_lock);
+ vi = find_vol(fullpath);
+ if (!IS_ERR(vi))
+ free_vol(vi);
+ mutex_unlock(&dfs_cache.dc_lock);
+}
+
+/* Get all tcons that are within a DFS namespace and can be refreshed */
+static void get_tcons(struct TCP_Server_Info *server, struct list_head *head)
+{
+ struct cifs_ses *ses;
+ struct cifs_tcon *tcon;
+
+ INIT_LIST_HEAD(head);
+
+ spin_lock(&cifs_tcp_ses_lock);
+ list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
+ list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
+ if (!tcon->need_reconnect && !tcon->need_reopen_files &&
+ tcon->dfs_path) {
+ tcon->tc_count++;
+ list_add_tail(&tcon->ulist, head);
+ }
+ }
+ if (ses->tcon_ipc && !ses->tcon_ipc->need_reconnect &&
+ ses->tcon_ipc->dfs_path) {
+ list_add_tail(&ses->tcon_ipc->ulist, head);
+ }
+ }
+ spin_unlock(&cifs_tcp_ses_lock);
+}
+
+/* Refresh DFS cache entry from a given tcon */
+static void do_refresh_tcon(struct dfs_cache *dc, struct cifs_tcon *tcon)
+{
+ int rc = 0;
+ unsigned int xid;
+ char *path, *npath;
+ unsigned int h;
+ struct dfs_cache_entry *ce;
+ struct dfs_info3_param *refs = NULL;
+ int numrefs = 0;
+
+ xid = get_xid();
+
+ path = tcon->dfs_path + 1;
+
+ rc = get_normalized_path(path, &npath);
+ if (rc)
+ goto out;
+
+ mutex_lock(&dfs_cache_list_lock);
+ ce = find_cache_entry(npath, &h);
+ mutex_unlock(&dfs_cache_list_lock);
+
+ if (IS_ERR(ce)) {
+ rc = PTR_ERR(ce);
+ goto out;
+ }
+
+ if (!cache_entry_expired(ce))
+ goto out;
+
+ if (unlikely(!tcon->ses->server->ops->get_dfs_refer)) {
+ rc = -EOPNOTSUPP;
+ } else {
+ rc = tcon->ses->server->ops->get_dfs_refer(xid, tcon->ses, path,
+ &refs, &numrefs,
+ dc->dc_nlsc,
+ tcon->remap);
+ if (!rc) {
+ mutex_lock(&dfs_cache_list_lock);
+ ce = __update_cache_entry(npath, refs, numrefs);
+ mutex_unlock(&dfs_cache_list_lock);
+ dump_refs(refs, numrefs);
+ free_dfs_info_array(refs, numrefs);
+ if (IS_ERR(ce))
+ rc = PTR_ERR(ce);
+ }
+ }
+ if (rc)
+ cifs_dbg(FYI, "%s: failed to update expired entry\n", __func__);
+out:
+ free_xid(xid);
+ free_normalized_path(path, npath);
+}
+
+/*
+ * Worker that will refresh DFS cache based on lowest TTL value from a DFS
+ * referral.
+ *
+ * FIXME: ensure that all requests are sent to DFS root for refreshing the
+ * cache.
+ */
+static void refresh_cache_worker(struct work_struct *work)
+{
+ struct dfs_cache *dc = container_of(work, struct dfs_cache,
+ dc_refresh.work);
+ struct dfs_cache_vol_info *vi;
+ struct TCP_Server_Info *server;
+ LIST_HEAD(list);
+ struct cifs_tcon *tcon, *ntcon;
+
+ mutex_lock(&dc->dc_lock);
+
+ list_for_each_entry(vi, &dc->dc_vol_list, vi_list) {
+ server = cifs_find_tcp_session(&vi->vi_vol);
+ if (IS_ERR_OR_NULL(server))
+ continue;
+ if (server->tcpStatus != CifsGood)
+ goto next;
+ get_tcons(server, &list);
+ list_for_each_entry_safe(tcon, ntcon, &list, ulist) {
+ do_refresh_tcon(dc, tcon);
+ list_del_init(&tcon->ulist);
+ cifs_put_tcon(tcon);
+ }
+next:
+ cifs_put_tcp_session(server, 0);
+ }
+ queue_delayed_work(cifsiod_wq, &dc->dc_refresh, dc->dc_ttl * HZ);
+ mutex_unlock(&dc->dc_lock);
+}
diff --git a/fs/cifs/dfs_cache.h b/fs/cifs/dfs_cache.h
new file mode 100644
index 000000000000..22f366514f3a
--- /dev/null
+++ b/fs/cifs/dfs_cache.h
@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * DFS referral cache routines
+ *
+ * Copyright (c) 2018 Paulo Alcantara <palcantara@suse.de>
+ */
+
+#ifndef _CIFS_DFS_CACHE_H
+#define _CIFS_DFS_CACHE_H
+
+#include <linux/nls.h>
+#include <linux/list.h>
+#include "cifsglob.h"
+
+struct dfs_cache_tgt_list {
+ int tl_numtgts;
+ struct list_head tl_list;
+};
+
+struct dfs_cache_tgt_iterator {
+ char *it_name;
+ struct list_head it_list;
+};
+
+extern int dfs_cache_init(void);
+extern void dfs_cache_destroy(void);
+extern const struct file_operations dfscache_proc_fops;
+
+extern int dfs_cache_find(const unsigned int xid, struct cifs_ses *ses,
+ const struct nls_table *nls_codepage, int remap,
+ const char *path, struct dfs_info3_param *ref,
+ struct dfs_cache_tgt_list *tgt_list);
+extern int dfs_cache_noreq_find(const char *path, struct dfs_info3_param *ref,
+ struct dfs_cache_tgt_list *tgt_list);
+extern int dfs_cache_update_tgthint(const unsigned int xid,
+ struct cifs_ses *ses,
+ const struct nls_table *nls_codepage,
+ int remap, const char *path,
+ const struct dfs_cache_tgt_iterator *it);
+extern int
+dfs_cache_noreq_update_tgthint(const char *path,
+ const struct dfs_cache_tgt_iterator *it);
+extern int dfs_cache_get_tgt_referral(const char *path,
+ const struct dfs_cache_tgt_iterator *it,
+ struct dfs_info3_param *ref);
+extern int dfs_cache_add_vol(struct smb_vol *vol, const char *fullpath);
+extern int dfs_cache_update_vol(const char *fullpath,
+ struct TCP_Server_Info *server);
+extern void dfs_cache_del_vol(const char *fullpath);
+
+static inline struct dfs_cache_tgt_iterator *
+dfs_cache_get_next_tgt(struct dfs_cache_tgt_list *tl,
+ struct dfs_cache_tgt_iterator *it)
+{
+ if (!tl || list_empty(&tl->tl_list) || !it ||
+ list_is_last(&it->it_list, &tl->tl_list))
+ return NULL;
+ return list_next_entry(it, it_list);
+}
+
+static inline struct dfs_cache_tgt_iterator *
+dfs_cache_get_tgt_iterator(struct dfs_cache_tgt_list *tl)
+{
+ if (!tl)
+ return NULL;
+ return list_first_entry_or_null(&tl->tl_list,
+ struct dfs_cache_tgt_iterator,
+ it_list);
+}
+
+static inline void dfs_cache_free_tgts(struct dfs_cache_tgt_list *tl)
+{
+ struct dfs_cache_tgt_iterator *it, *nit;
+
+ if (!tl || list_empty(&tl->tl_list))
+ return;
+ list_for_each_entry_safe(it, nit, &tl->tl_list, it_list) {
+ list_del(&it->it_list);
+ kfree(it->it_name);
+ kfree(it);
+ }
+ tl->tl_numtgts = 0;
+}
+
+static inline const char *
+dfs_cache_get_tgt_name(const struct dfs_cache_tgt_iterator *it)
+{
+ return it ? it->it_name : NULL;
+}
+
+static inline int
+dfs_cache_get_nr_tgts(const struct dfs_cache_tgt_list *tl)
+{
+ return tl ? tl->tl_numtgts : 0;
+}
+
+#endif /* _CIFS_DFS_CACHE_H */
--
2.16.4