Commit bacd704a authored by Paulo Alcantara (SUSE)'s avatar Paulo Alcantara (SUSE) Committed by Steve French
Browse files

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: default avatarPaulo Alcantara (SUSE) <pc@cjr.nz>
Acked-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: default avatarAurelien Aptel <aaptel@suse.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent ffdec8d6

fs/cifs/cifsproto.h

+5 −0
Original line number Diff line number Diff line
@@ -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,

fs/cifs/cifssmb.c

+15 −4
Original line number Diff line number Diff line
@@ -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;

	}

fs/cifs/connect.c

+12 −51
Original line number Diff line number Diff line
@@ -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);

fs/cifs/dfs_cache.c

+38 −0
Original line number Diff line number Diff line
@@ -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)

{

fs/cifs/dfs_cache.h

+4 −0
Original line number Diff line number Diff line
@@ -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)

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