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authorPaulo Alcantara <palcantara@suse.de>2018-11-14 21:01:21 +0300
committerSteve French <stfrench@microsoft.com>2018-12-28 19:05:58 +0300
commit54be1f6c1c37498bba557049df646cc239fa37e3 (patch)
tree71a4c9b969eb2a2ac3f5d650840f7dadb7ea8c8f /fs/cifs/dfs_cache.h
parente7b602f43719fc6173ae86d2de8f6f07c6858ddd (diff)
downloadlinux-54be1f6c1c37498bba557049df646cc239fa37e3.tar.xz
cifs: Add DFS cache routines
* 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>
Diffstat (limited to 'fs/cifs/dfs_cache.h')
-rw-r--r--fs/cifs/dfs_cache.h97
1 files changed, 97 insertions, 0 deletions
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 */