From bacd704a95ad0b93af995aae4a523aa046f46563 Mon Sep 17 00:00:00 2001 From: "Paulo Alcantara (SUSE)" Date: Thu, 20 Feb 2020 19:49:34 -0300 Subject: [PATCH] cifs: handle prefix paths in reconnect For the case where we have a DFS path like below and we're currently connected to targetA: //dfsroot/link -> //targetA/share/foo, //targetB/share/bar after failover, we should make sure to update cifs_sb->prepath so the next operations will use the new prefix path "/bar". Besides, in order to simplify the use of different prefix paths, enforce CIFS_MOUNT_USE_PREFIX_PATH for DFS mounts so we don't have to revalidate the root dentry every time we set a new prefix path. Signed-off-by: Paulo Alcantara (SUSE) Acked-by: Ronnie Sahlberg Reviewed-by: Aurelien Aptel Signed-off-by: Steve French --- fs/cifs/cifsproto.h | 5 +++ fs/cifs/cifssmb.c | 19 ++++++++--- fs/cifs/connect.c | 63 +++++++---------------------------- fs/cifs/dfs_cache.c | 38 +++++++++++++++++++++ fs/cifs/dfs_cache.h | 4 +++ fs/cifs/misc.c | 80 +++++++++++++++++++++++++++++++++++++++++++++ fs/cifs/smb2pdu.c | 19 ++++++++--- 7 files changed, 169 insertions(+), 59 deletions(-) diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h index e5cb681ec138..12a895e02db4 100644 --- a/fs/cifs/cifsproto.h +++ b/fs/cifs/cifsproto.h @@ -602,6 +602,11 @@ int smb2_parse_query_directory(struct cifs_tcon *tcon, struct kvec *rsp_iov, int resp_buftype, struct cifs_search_info *srch_inf); +struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server); +void cifs_put_tcp_super(struct super_block *sb); +int update_super_prepath(struct cifs_tcon *tcon, const char *prefix, + size_t prefix_len); + #ifdef CONFIG_CIFS_DFS_UPCALL static inline int get_dfs_path(const unsigned int xid, struct cifs_ses *ses, const char *old_path, diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index 6f6fb3606a5d..6e95ee69dd18 100644 --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -162,9 +162,18 @@ static int __cifs_reconnect_tcon(const struct nls_table *nlsc, for (it = dfs_cache_get_tgt_iterator(&tl); it; it = dfs_cache_get_next_tgt(&tl, it)) { - const char *tgt = dfs_cache_get_tgt_name(it); + const char *share, *prefix; + size_t share_len, prefix_len; - extract_unc_hostname(tgt, &dfs_host, &dfs_host_len); + rc = dfs_cache_get_tgt_share(it, &share, &share_len, &prefix, + &prefix_len); + if (rc) { + cifs_dbg(VFS, "%s: failed to parse target share %d\n", + __func__, rc); + continue; + } + + extract_unc_hostname(share, &dfs_host, &dfs_host_len); if (dfs_host_len != tcp_host_len || strncasecmp(dfs_host, tcp_host, dfs_host_len) != 0) { @@ -175,11 +184,13 @@ static int __cifs_reconnect_tcon(const struct nls_table *nlsc, continue; } - scnprintf(tree, MAX_TREE_SIZE, "\\%s", tgt); + scnprintf(tree, MAX_TREE_SIZE, "\\%.*s", (int)share_len, share); rc = CIFSTCon(0, tcon->ses, tree, tcon, nlsc); - if (!rc) + if (!rc) { + rc = update_super_prepath(tcon, prefix, prefix_len); break; + } if (rc == -EREMOTE) break; } diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 4804d1df8c1c..e2196b363765 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -57,7 +57,6 @@ #include "smb2proto.h" #include "smbdirect.h" #include "dns_resolve.h" -#include "cifsfs.h" #ifdef CONFIG_CIFS_DFS_UPCALL #include "dfs_cache.h" #endif @@ -389,54 +388,7 @@ static inline int reconn_set_ipaddr(struct TCP_Server_Info *server) #endif #ifdef CONFIG_CIFS_DFS_UPCALL -struct super_cb_data { - struct TCP_Server_Info *server; - struct super_block *sb; -}; - /* These functions must be called with server->srv_mutex held */ - -static void super_cb(struct super_block *sb, void *arg) -{ - struct super_cb_data *d = arg; - struct cifs_sb_info *cifs_sb; - struct cifs_tcon *tcon; - - if (d->sb) - return; - - cifs_sb = CIFS_SB(sb); - tcon = cifs_sb_master_tcon(cifs_sb); - if (tcon->ses->server == d->server) - d->sb = sb; -} - -static struct super_block *get_tcp_super(struct TCP_Server_Info *server) -{ - struct super_cb_data d = { - .server = server, - .sb = NULL, - }; - - iterate_supers_type(&cifs_fs_type, super_cb, &d); - - if (unlikely(!d.sb)) - return ERR_PTR(-ENOENT); - /* - * Grab an active reference in order to prevent automounts (DFS links) - * of expiring and then freeing up our cifs superblock pointer while - * we're doing failover. - */ - cifs_sb_active(d.sb); - return d.sb; -} - -static inline void put_tcp_super(struct super_block *sb) -{ - if (!IS_ERR_OR_NULL(sb)) - cifs_sb_deactive(sb); -} - static void reconn_inval_dfs_target(struct TCP_Server_Info *server, struct cifs_sb_info *cifs_sb, struct dfs_cache_tgt_list *tgt_list, @@ -508,7 +460,7 @@ cifs_reconnect(struct TCP_Server_Info *server) server->nr_targets = 1; #ifdef CONFIG_CIFS_DFS_UPCALL spin_unlock(&GlobalMid_Lock); - sb = get_tcp_super(server); + sb = cifs_get_tcp_super(server); if (IS_ERR(sb)) { rc = PTR_ERR(sb); cifs_dbg(FYI, "%s: will not do DFS failover: rc = %d\n", @@ -535,7 +487,7 @@ cifs_reconnect(struct TCP_Server_Info *server) spin_unlock(&GlobalMid_Lock); #ifdef CONFIG_CIFS_DFS_UPCALL dfs_cache_free_tgts(&tgt_list); - put_tcp_super(sb); + cifs_put_tcp_super(sb); #endif return rc; } else @@ -666,7 +618,7 @@ cifs_reconnect(struct TCP_Server_Info *server) } - put_tcp_super(sb); + cifs_put_tcp_super(sb); #endif if (server->tcpStatus == CifsNeedNegotiate) mod_delayed_work(cifsiod_wq, &server->echo, 0); @@ -4999,6 +4951,15 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) * dentry revalidation to think the dentry are stale (ESTALE). */ cifs_autodisable_serverino(cifs_sb); + /* + * Force the use of prefix path to support failover on DFS paths that + * resolve to targets that have different prefix paths. + */ + cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH; + kfree(cifs_sb->prepath); + cifs_sb->prepath = vol->prepath; + vol->prepath = NULL; + out: free_xid(xid); cifs_try_adding_channels(ses); diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c index 43c1b43a07ec..a67f88bf7ae1 100644 --- a/fs/cifs/dfs_cache.c +++ b/fs/cifs/dfs_cache.c @@ -1260,6 +1260,44 @@ void dfs_cache_del_vol(const char *fullpath) kref_put(&vi->refcnt, vol_release); } +/** + * dfs_cache_get_tgt_share - parse a DFS target + * + * @it: DFS target iterator. + * @share: tree name. + * @share_len: length of tree name. + * @prefix: prefix path. + * @prefix_len: length of prefix path. + * + * Return zero if target was parsed correctly, otherwise non-zero. + */ +int dfs_cache_get_tgt_share(const struct dfs_cache_tgt_iterator *it, + const char **share, size_t *share_len, + const char **prefix, size_t *prefix_len) +{ + char *s, sep; + + if (!it || !share || !share_len || !prefix || !prefix_len) + return -EINVAL; + + sep = it->it_name[0]; + if (sep != '\\' && sep != '/') + return -EINVAL; + + s = strchr(it->it_name + 1, sep); + if (!s) + return -EINVAL; + + s = strchrnul(s + 1, sep); + + *share = it->it_name; + *share_len = s - it->it_name; + *prefix = *s ? s + 1 : s; + *prefix_len = &it->it_name[strlen(it->it_name)] - *prefix; + + return 0; +} + /* 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) { diff --git a/fs/cifs/dfs_cache.h b/fs/cifs/dfs_cache.h index 99ee44f8ad07..bf94d08cfb5a 100644 --- a/fs/cifs/dfs_cache.h +++ b/fs/cifs/dfs_cache.h @@ -49,6 +49,10 @@ extern int dfs_cache_update_vol(const char *fullpath, struct TCP_Server_Info *server); extern void dfs_cache_del_vol(const char *fullpath); +extern int dfs_cache_get_tgt_share(const struct dfs_cache_tgt_iterator *it, + const char **share, size_t *share_len, + const char **prefix, size_t *prefix_len); + static inline struct dfs_cache_tgt_iterator * dfs_cache_get_next_tgt(struct dfs_cache_tgt_list *tl, struct dfs_cache_tgt_iterator *it) diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c index 40ca394fd5de..a456febd4109 100644 --- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -31,6 +31,7 @@ #include "nterr.h" #include "cifs_unicode.h" #include "smb2pdu.h" +#include "cifsfs.h" extern mempool_t *cifs_sm_req_poolp; extern mempool_t *cifs_req_poolp; @@ -1022,3 +1023,82 @@ int copy_path_name(char *dst, const char *src) name_len++; return name_len; } + +struct super_cb_data { + struct TCP_Server_Info *server; + struct super_block *sb; +}; + +static void super_cb(struct super_block *sb, void *arg) +{ + struct super_cb_data *d = arg; + struct cifs_sb_info *cifs_sb; + struct cifs_tcon *tcon; + + if (d->sb) + return; + + cifs_sb = CIFS_SB(sb); + tcon = cifs_sb_master_tcon(cifs_sb); + if (tcon->ses->server == d->server) + d->sb = sb; +} + +struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server) +{ + struct super_cb_data d = { + .server = server, + .sb = NULL, + }; + + iterate_supers_type(&cifs_fs_type, super_cb, &d); + + if (unlikely(!d.sb)) + return ERR_PTR(-ENOENT); + /* + * Grab an active reference in order to prevent automounts (DFS links) + * of expiring and then freeing up our cifs superblock pointer while + * we're doing failover. + */ + cifs_sb_active(d.sb); + return d.sb; +} + +void cifs_put_tcp_super(struct super_block *sb) +{ + if (!IS_ERR_OR_NULL(sb)) + cifs_sb_deactive(sb); +} + +int update_super_prepath(struct cifs_tcon *tcon, const char *prefix, + size_t prefix_len) +{ + struct super_block *sb; + struct cifs_sb_info *cifs_sb; + int rc = 0; + + sb = cifs_get_tcp_super(tcon->ses->server); + if (IS_ERR(sb)) + return PTR_ERR(sb); + + cifs_sb = CIFS_SB(sb); + + kfree(cifs_sb->prepath); + + if (*prefix && prefix_len) { + cifs_sb->prepath = kstrndup(prefix, prefix_len, GFP_ATOMIC); + if (!cifs_sb->prepath) { + rc = -ENOMEM; + goto out; + } + + convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb)); + } else + cifs_sb->prepath = NULL; + + cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH; + +out: + cifs_put_tcp_super(sb); + return rc; +} diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index 28c0be5e69b7..8c23c10cafd2 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -193,9 +193,18 @@ static int __smb2_reconnect(const struct nls_table *nlsc, for (it = dfs_cache_get_tgt_iterator(&tl); it; it = dfs_cache_get_next_tgt(&tl, it)) { - const char *tgt = dfs_cache_get_tgt_name(it); + const char *share, *prefix; + size_t share_len, prefix_len; - extract_unc_hostname(tgt, &dfs_host, &dfs_host_len); + rc = dfs_cache_get_tgt_share(it, &share, &share_len, &prefix, + &prefix_len); + if (rc) { + cifs_dbg(VFS, "%s: failed to parse target share %d\n", + __func__, rc); + continue; + } + + extract_unc_hostname(share, &dfs_host, &dfs_host_len); if (dfs_host_len != tcp_host_len || strncasecmp(dfs_host, tcp_host, dfs_host_len) != 0) { @@ -206,11 +215,13 @@ static int __smb2_reconnect(const struct nls_table *nlsc, continue; } - scnprintf(tree, MAX_TREE_SIZE, "\\%s", tgt); + scnprintf(tree, MAX_TREE_SIZE, "\\%.*s", (int)share_len, share); rc = SMB2_tcon(0, tcon->ses, tree, tcon, nlsc); - if (!rc) + if (!rc) { + rc = update_super_prepath(tcon, prefix, prefix_len); break; + } if (rc == -EREMOTE) break; }