Commit 4a367dc0 authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French
Browse files

cifs: Add support for failover in cifs_mount() 



This patch adds support for failover when failing to connect in
cifs_mount().

Signed-off-by: default avatarPaulo Alcantara <palcantara@suse.de>
Reviewed-by: default avatarAurelien Aptel <aaptel@suse.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 5a650501

fs/cifs/cifs_dfs_ref.c

+15 −5
Original line number Diff line number Diff line
@@ -255,20 +255,30 @@ static struct vfsmount *cifs_dfs_do_refmount(struct dentry *mntpt, 
{

	struct vfsmount *mnt;

	char *mountdata;

	char *devname = NULL;

	char *devname;



	/*

	 * Always pass down the DFS full path to smb3_do_mount() so we

	 * can use it later for failover.

	 */

	devname = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);

	if (!devname)

		return ERR_PTR(-ENOMEM);



	convert_delimiter(devname, '/');



	/* strip first '\' from fullpath */

	mountdata = cifs_compose_mount_options(cifs_sb->mountdata,

			fullpath + 1, ref, &devname);



	if (IS_ERR(mountdata))

					       fullpath + 1, ref, NULL);

	if (IS_ERR(mountdata)) {

		kfree(devname);

		return (struct vfsmount *)mountdata;

	}



	mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);

	kfree(mountdata);

	kfree(devname);

	return mnt;



}



static void dump_referral(const struct dfs_info3_param *ref)

fs/cifs/connect.c

+218 −10
Original line number Diff line number Diff line
@@ -3891,10 +3891,11 @@ static int mount_setup_tlink(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses, 
 */

static char *

build_unc_path_to_root(const struct smb_vol *vol,

		const struct cifs_sb_info *cifs_sb)

		       const struct cifs_sb_info *cifs_sb, bool useppath)

{

	char *full_path, *pos;

	unsigned int pplen = vol->prepath ? strlen(vol->prepath) + 1 : 0;

	unsigned int pplen = useppath && vol->prepath ?

		strlen(vol->prepath) + 1 : 0;

	unsigned int unc_len = strnlen(vol->UNC, MAX_TREE_SIZE + 1);



	full_path = kmalloc(unc_len + pplen + 1, GFP_KERNEL);
@@ -3939,7 +3940,7 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses, 
	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)

		return -EREMOTE;



	full_path = build_unc_path_to_root(volume_info, cifs_sb);

	full_path = build_unc_path_to_root(volume_info, cifs_sb, true);

	if (IS_ERR(full_path))

		return PTR_ERR(full_path);
@@ -3971,6 +3972,143 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses, 
	kfree(full_path);

	return rc;

}



static inline int get_next_dfs_tgt(const char *path,

				   struct dfs_cache_tgt_list *tgt_list,

				   struct dfs_cache_tgt_iterator **tgt_it)

{

	if (!*tgt_it)

		*tgt_it = dfs_cache_get_tgt_iterator(tgt_list);

	else

		*tgt_it = dfs_cache_get_next_tgt(tgt_list, *tgt_it);

	return !*tgt_it ? -EHOSTDOWN : 0;

}



static int update_vol_info(const struct dfs_cache_tgt_iterator *tgt_it,

			   struct smb_vol *fake_vol, struct smb_vol *vol)

{

	const char *tgt = dfs_cache_get_tgt_name(tgt_it);

	int len = strlen(tgt) + 2;

	char *new_unc;



	new_unc = kmalloc(len, GFP_KERNEL);

	if (!new_unc)

		return -ENOMEM;

	snprintf(new_unc, len, "\\%s", tgt);



	kfree(vol->UNC);

	vol->UNC = new_unc;



	if (fake_vol->prepath) {

		kfree(vol->prepath);

		vol->prepath = fake_vol->prepath;

		fake_vol->prepath = NULL;

	}

	memcpy(&vol->dstaddr, &fake_vol->dstaddr, sizeof(vol->dstaddr));



	return 0;

}



static int setup_dfs_tgt_conn(const char *path,

			      const struct dfs_cache_tgt_iterator *tgt_it,

			      struct cifs_sb_info *cifs_sb,

			      struct smb_vol *vol,

			      unsigned int *xid,

			      struct TCP_Server_Info **server,

			      struct cifs_ses **ses,

			      struct cifs_tcon **tcon)

{

	int rc;

	struct dfs_info3_param ref = {0};

	char *mdata = NULL, *fake_devname = NULL;

	struct smb_vol fake_vol = {0};



	cifs_dbg(FYI, "%s: dfs path: %s\n", __func__, path);



	rc = dfs_cache_get_tgt_referral(path, tgt_it, &ref);

	if (rc)

		return rc;



	mdata = cifs_compose_mount_options(cifs_sb->mountdata, path, &ref,

					   &fake_devname);

	free_dfs_info_param(&ref);



	if (IS_ERR(mdata)) {

		rc = PTR_ERR(mdata);

		mdata = NULL;

	} else {

		cifs_dbg(FYI, "%s: fake_devname: %s\n", __func__, fake_devname);

		rc = cifs_setup_volume_info(&fake_vol, mdata, fake_devname,

					    false);

	}

	kfree(mdata);

	kfree(fake_devname);



	if (!rc) {

		/*

		 * We use a 'fake_vol' here because we need pass it down to the

		 * mount_{get,put} functions to test connection against new DFS

		 * targets.

		 */

		mount_put_conns(cifs_sb, *xid, *server, *ses, *tcon);

		rc = mount_get_conns(&fake_vol, cifs_sb, xid, server, ses,

				     tcon);

		if (!rc) {

			/*

			 * We were able to connect to new target server.

			 * Update current volume info with new target server.

			 */

			rc = update_vol_info(tgt_it, &fake_vol, vol);

		}

	}

	cifs_cleanup_volume_info_contents(&fake_vol);

	return rc;

}



static int mount_do_dfs_failover(const char *path,

				 struct cifs_sb_info *cifs_sb,

				 struct smb_vol *vol,

				 struct cifs_ses *root_ses,

				 unsigned int *xid,

				 struct TCP_Server_Info **server,

				 struct cifs_ses **ses,

				 struct cifs_tcon **tcon)

{

	int rc;

	struct dfs_cache_tgt_list tgt_list;

	struct dfs_cache_tgt_iterator *tgt_it = NULL;



	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)

		return -EOPNOTSUPP;



	rc = dfs_cache_noreq_find(path, NULL, &tgt_list);

	if (rc)

		return rc;



	for (;;) {

		/* Get next DFS target server - if any */

		rc = get_next_dfs_tgt(path, &tgt_list, &tgt_it);

		if (rc)

			break;

		/* Connect to next DFS target */

		rc = setup_dfs_tgt_conn(path, tgt_it, cifs_sb, vol, xid, server,

					ses, tcon);

		if (!rc || rc == -EACCES || rc == -EOPNOTSUPP)

			break;

	}

	if (!rc) {

		/*

		 * Update DFS target hint in DFS referral cache with the target

		 * server we successfully reconnected to.

		 */

		rc = dfs_cache_update_tgthint(*xid, root_ses ? root_ses : *ses,

					      cifs_sb->local_nls,

					      cifs_remap(cifs_sb), path,

					      tgt_it);

	}

	dfs_cache_free_tgts(&tgt_list);

	return rc;

}

#endif



static int
@@ -4123,22 +4261,47 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) 
	int rc = 0;

	unsigned int xid;

	struct cifs_ses *ses;

	struct cifs_tcon *root_tcon = NULL;

	struct cifs_tcon *tcon = NULL;

	struct TCP_Server_Info *server;

	char *root_path = NULL, *full_path = NULL;

	char *old_mountdata;

	int count;



	rc = mount_get_conns(vol, cifs_sb, &xid, &server, &ses, &tcon);

	if (!rc && tcon) {

		/* If not a standalone DFS root, then check if path is remote */

		rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,

				    cifs_remap(cifs_sb), vol->UNC + 1, NULL,

				    NULL);

		if (rc) {

			rc = is_path_remote(cifs_sb, vol, xid, server, tcon);

			if (!rc)

				goto out;

			if (rc != -EREMOTE)

				goto error;

		}

	if ((rc == -EACCES) || (rc == -EOPNOTSUPP) || (ses == NULL) || (server == NULL))

	}

	/*

	 * If first DFS target server went offline and we failed to connect it,

	 * server and ses pointers are NULL at this point, though we still have

	 * chance to get a cached DFS referral in expand_dfs_referral() and

	 * retry next target available in it.

	 *

	 * If a NULL ses ptr is passed to dfs_cache_find(), a lookup will be

	 * performed against DFS path and *no* requests will be sent to server

	 * for any new DFS referrals. Hence it's safe to skip checking whether

	 * server or ses ptr is NULL.

	 */

	if (rc == -EACCES || rc == -EOPNOTSUPP)

		goto error;



	root_path = build_unc_path_to_root(vol, cifs_sb, false);

	if (IS_ERR(root_path)) {

		rc = PTR_ERR(root_path);

		root_path = NULL;

		goto error;

	}



	/*

	 * Perform an unconditional check for whether there are DFS
@@ -4163,8 +4326,36 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) 
	if (rc) {

		if (rc == -EACCES || rc == -EOPNOTSUPP)

			goto error;

		/* Perform DFS failover to any other DFS targets */

		rc = mount_do_dfs_failover(root_path + 1, cifs_sb, vol, NULL,

					   &xid, &server, &ses, &tcon);

		if (rc)

			goto error;

	}



	kfree(root_path);

	root_path = build_unc_path_to_root(vol, cifs_sb, false);

	if (IS_ERR(root_path)) {

		rc = PTR_ERR(root_path);

		root_path = NULL;

		goto error;

	}

	/* Cache out resolved root server */

	(void)dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),

			     root_path + 1, NULL, NULL);

	/*

	 * Save root tcon for additional DFS requests to update or create a new

	 * DFS cache entry, or even perform DFS failover.

	 */

	spin_lock(&cifs_tcp_ses_lock);

	tcon->tc_count++;

	tcon->dfs_path = root_path;

	root_path = NULL;

	tcon->remap = cifs_remap(cifs_sb);

	spin_unlock(&cifs_tcp_ses_lock);



	root_tcon = tcon;



	for (count = 1; ;) {

		if (!rc && tcon) {

			rc = is_path_remote(cifs_sb, vol, xid, server, tcon);
@@ -4182,8 +4373,16 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) 
			break;

		}



		kfree(full_path);

		full_path = build_unc_path_to_root(vol, cifs_sb, true);

		if (IS_ERR(full_path)) {

			rc = PTR_ERR(full_path);

			full_path = NULL;

			break;

		}



		old_mountdata = cifs_sb->mountdata;

		rc = expand_dfs_referral(xid, tcon->ses, vol, cifs_sb,

		rc = expand_dfs_referral(xid, root_tcon->ses, vol, cifs_sb,

					 true);

		if (rc)

			break;
@@ -4194,11 +4393,18 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) 
					     &tcon);

		}

		if (rc) {

			if (rc == -EACCES || rc == -EOPNOTSUPP)

				break;

			/* Perform DFS failover to any other DFS targets */

			rc = mount_do_dfs_failover(full_path + 1, cifs_sb, vol,

						   root_tcon->ses, &xid,

						   &server, &ses, &tcon);

			if (rc == -EACCES || rc == -EOPNOTSUPP || !server ||

			    !ses)

				goto error;

		}

	}

	cifs_put_tcon(root_tcon);



	if (rc)

		goto error;
@@ -4214,6 +4420,8 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) 
	return mount_setup_tlink(cifs_sb, ses, tcon);



error:

	kfree(full_path);

	kfree(root_path);

	mount_put_conns(cifs_sb, xid, server, ses, tcon);

	return rc;

}

fs/cifs/misc.c

+3 −0
Original line number Diff line number Diff line
@@ -146,6 +146,9 @@ tconInfoFree(struct cifs_tcon *buf_to_free) 
	kfree(buf_to_free->nativeFileSystem);

	kzfree(buf_to_free->password);

	kfree(buf_to_free->crfid.fid);

#ifdef CONFIG_CIFS_DFS_UPCALL

	kfree(buf_to_free->dfs_path);

#endif

	kfree(buf_to_free);

}