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cifs: Add support for failover in cifs_mount()
This patch adds support for failover when failing to connect in cifs_mount(). Signed-off-by: Paulo Alcantara <palcantara@suse.de> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara
Steve French
parent
5a650501eb
commit
4a367dc044
@ -255,20 +255,30 @@ static struct vfsmount *cifs_dfs_do_refmount(struct dentry *mntpt,
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{
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struct vfsmount *mnt;
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char *mountdata;
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char *devname = NULL;
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char *devname;
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/*
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* Always pass down the DFS full path to smb3_do_mount() so we
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* can use it later for failover.
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*/
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devname = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
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if (!devname)
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return ERR_PTR(-ENOMEM);
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convert_delimiter(devname, '/');
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/* strip first '\' from fullpath */
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mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
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fullpath + 1, ref, &devname);
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if (IS_ERR(mountdata))
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fullpath + 1, ref, NULL);
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if (IS_ERR(mountdata)) {
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kfree(devname);
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return (struct vfsmount *)mountdata;
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}
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mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
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kfree(mountdata);
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kfree(devname);
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return mnt;
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}
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static void dump_referral(const struct dfs_info3_param *ref)
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@ -3891,10 +3891,11 @@ static int mount_setup_tlink(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
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*/
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static char *
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build_unc_path_to_root(const struct smb_vol *vol,
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const struct cifs_sb_info *cifs_sb)
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const struct cifs_sb_info *cifs_sb, bool useppath)
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{
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char *full_path, *pos;
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unsigned int pplen = vol->prepath ? strlen(vol->prepath) + 1 : 0;
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unsigned int pplen = useppath && vol->prepath ?
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strlen(vol->prepath) + 1 : 0;
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unsigned int unc_len = strnlen(vol->UNC, MAX_TREE_SIZE + 1);
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full_path = kmalloc(unc_len + pplen + 1, GFP_KERNEL);
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@ -3939,7 +3940,7 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses,
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if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)
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return -EREMOTE;
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full_path = build_unc_path_to_root(volume_info, cifs_sb);
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full_path = build_unc_path_to_root(volume_info, cifs_sb, true);
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if (IS_ERR(full_path))
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return PTR_ERR(full_path);
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@ -3971,6 +3972,143 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses,
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kfree(full_path);
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return rc;
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}
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static inline int get_next_dfs_tgt(const char *path,
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struct dfs_cache_tgt_list *tgt_list,
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struct dfs_cache_tgt_iterator **tgt_it)
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{
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if (!*tgt_it)
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*tgt_it = dfs_cache_get_tgt_iterator(tgt_list);
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else
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*tgt_it = dfs_cache_get_next_tgt(tgt_list, *tgt_it);
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return !*tgt_it ? -EHOSTDOWN : 0;
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}
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static int update_vol_info(const struct dfs_cache_tgt_iterator *tgt_it,
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struct smb_vol *fake_vol, struct smb_vol *vol)
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{
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const char *tgt = dfs_cache_get_tgt_name(tgt_it);
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int len = strlen(tgt) + 2;
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char *new_unc;
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new_unc = kmalloc(len, GFP_KERNEL);
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if (!new_unc)
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return -ENOMEM;
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snprintf(new_unc, len, "\\%s", tgt);
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kfree(vol->UNC);
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vol->UNC = new_unc;
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if (fake_vol->prepath) {
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kfree(vol->prepath);
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vol->prepath = fake_vol->prepath;
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fake_vol->prepath = NULL;
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}
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memcpy(&vol->dstaddr, &fake_vol->dstaddr, sizeof(vol->dstaddr));
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return 0;
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}
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static int setup_dfs_tgt_conn(const char *path,
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const struct dfs_cache_tgt_iterator *tgt_it,
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struct cifs_sb_info *cifs_sb,
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struct smb_vol *vol,
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unsigned int *xid,
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struct TCP_Server_Info **server,
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struct cifs_ses **ses,
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struct cifs_tcon **tcon)
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{
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int rc;
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struct dfs_info3_param ref = {0};
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char *mdata = NULL, *fake_devname = NULL;
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struct smb_vol fake_vol = {0};
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cifs_dbg(FYI, "%s: dfs path: %s\n", __func__, path);
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rc = dfs_cache_get_tgt_referral(path, tgt_it, &ref);
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if (rc)
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return rc;
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mdata = cifs_compose_mount_options(cifs_sb->mountdata, path, &ref,
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&fake_devname);
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free_dfs_info_param(&ref);
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if (IS_ERR(mdata)) {
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rc = PTR_ERR(mdata);
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mdata = NULL;
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} else {
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cifs_dbg(FYI, "%s: fake_devname: %s\n", __func__, fake_devname);
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rc = cifs_setup_volume_info(&fake_vol, mdata, fake_devname,
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false);
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}
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kfree(mdata);
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kfree(fake_devname);
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if (!rc) {
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/*
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* We use a 'fake_vol' here because we need pass it down to the
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* mount_{get,put} functions to test connection against new DFS
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* targets.
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*/
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mount_put_conns(cifs_sb, *xid, *server, *ses, *tcon);
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rc = mount_get_conns(&fake_vol, cifs_sb, xid, server, ses,
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tcon);
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if (!rc) {
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/*
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* We were able to connect to new target server.
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* Update current volume info with new target server.
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*/
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rc = update_vol_info(tgt_it, &fake_vol, vol);
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}
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}
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cifs_cleanup_volume_info_contents(&fake_vol);
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return rc;
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}
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static int mount_do_dfs_failover(const char *path,
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struct cifs_sb_info *cifs_sb,
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struct smb_vol *vol,
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struct cifs_ses *root_ses,
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unsigned int *xid,
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struct TCP_Server_Info **server,
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struct cifs_ses **ses,
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struct cifs_tcon **tcon)
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{
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int rc;
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struct dfs_cache_tgt_list tgt_list;
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struct dfs_cache_tgt_iterator *tgt_it = NULL;
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if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)
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return -EOPNOTSUPP;
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rc = dfs_cache_noreq_find(path, NULL, &tgt_list);
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if (rc)
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return rc;
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for (;;) {
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/* Get next DFS target server - if any */
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rc = get_next_dfs_tgt(path, &tgt_list, &tgt_it);
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if (rc)
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break;
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/* Connect to next DFS target */
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rc = setup_dfs_tgt_conn(path, tgt_it, cifs_sb, vol, xid, server,
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ses, tcon);
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if (!rc || rc == -EACCES || rc == -EOPNOTSUPP)
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break;
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}
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if (!rc) {
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/*
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* Update DFS target hint in DFS referral cache with the target
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* server we successfully reconnected to.
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*/
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rc = dfs_cache_update_tgthint(*xid, root_ses ? root_ses : *ses,
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cifs_sb->local_nls,
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cifs_remap(cifs_sb), path,
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tgt_it);
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}
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dfs_cache_free_tgts(&tgt_list);
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return rc;
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}
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#endif
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static int
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@ -4123,22 +4261,47 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
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int rc = 0;
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unsigned int xid;
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struct cifs_ses *ses;
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struct cifs_tcon *root_tcon = NULL;
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struct cifs_tcon *tcon = NULL;
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struct TCP_Server_Info *server;
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char *root_path = NULL, *full_path = NULL;
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char *old_mountdata;
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int count;
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rc = mount_get_conns(vol, cifs_sb, &xid, &server, &ses, &tcon);
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if (!rc && tcon) {
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rc = is_path_remote(cifs_sb, vol, xid, server, tcon);
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if (!rc)
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goto out;
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if (rc != -EREMOTE)
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goto error;
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/* If not a standalone DFS root, then check if path is remote */
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rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
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cifs_remap(cifs_sb), vol->UNC + 1, NULL,
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NULL);
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if (rc) {
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rc = is_path_remote(cifs_sb, vol, xid, server, tcon);
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if (!rc)
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goto out;
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if (rc != -EREMOTE)
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goto error;
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}
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}
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if ((rc == -EACCES) || (rc == -EOPNOTSUPP) || (ses == NULL) || (server == NULL))
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/*
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* If first DFS target server went offline and we failed to connect it,
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* server and ses pointers are NULL at this point, though we still have
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* chance to get a cached DFS referral in expand_dfs_referral() and
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* retry next target available in it.
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*
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* If a NULL ses ptr is passed to dfs_cache_find(), a lookup will be
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* performed against DFS path and *no* requests will be sent to server
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* for any new DFS referrals. Hence it's safe to skip checking whether
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* server or ses ptr is NULL.
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*/
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if (rc == -EACCES || rc == -EOPNOTSUPP)
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goto error;
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root_path = build_unc_path_to_root(vol, cifs_sb, false);
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if (IS_ERR(root_path)) {
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rc = PTR_ERR(root_path);
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root_path = NULL;
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goto error;
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}
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/*
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* Perform an unconditional check for whether there are DFS
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@ -4163,8 +4326,36 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
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if (rc) {
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if (rc == -EACCES || rc == -EOPNOTSUPP)
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goto error;
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/* Perform DFS failover to any other DFS targets */
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rc = mount_do_dfs_failover(root_path + 1, cifs_sb, vol, NULL,
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&xid, &server, &ses, &tcon);
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if (rc)
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goto error;
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}
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kfree(root_path);
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root_path = build_unc_path_to_root(vol, cifs_sb, false);
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if (IS_ERR(root_path)) {
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rc = PTR_ERR(root_path);
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root_path = NULL;
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goto error;
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}
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/* Cache out resolved root server */
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(void)dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
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root_path + 1, NULL, NULL);
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/*
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* Save root tcon for additional DFS requests to update or create a new
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* DFS cache entry, or even perform DFS failover.
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*/
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spin_lock(&cifs_tcp_ses_lock);
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tcon->tc_count++;
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tcon->dfs_path = root_path;
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root_path = NULL;
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tcon->remap = cifs_remap(cifs_sb);
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spin_unlock(&cifs_tcp_ses_lock);
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root_tcon = tcon;
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for (count = 1; ;) {
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if (!rc && tcon) {
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rc = is_path_remote(cifs_sb, vol, xid, server, tcon);
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@ -4182,8 +4373,16 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
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break;
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}
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kfree(full_path);
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full_path = build_unc_path_to_root(vol, cifs_sb, true);
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if (IS_ERR(full_path)) {
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rc = PTR_ERR(full_path);
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full_path = NULL;
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break;
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}
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old_mountdata = cifs_sb->mountdata;
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rc = expand_dfs_referral(xid, tcon->ses, vol, cifs_sb,
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rc = expand_dfs_referral(xid, root_tcon->ses, vol, cifs_sb,
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true);
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if (rc)
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break;
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@ -4194,11 +4393,18 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
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&tcon);
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}
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if (rc) {
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if (rc == -EACCES || rc == -EOPNOTSUPP)
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break;
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/* Perform DFS failover to any other DFS targets */
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rc = mount_do_dfs_failover(full_path + 1, cifs_sb, vol,
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root_tcon->ses, &xid,
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&server, &ses, &tcon);
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if (rc == -EACCES || rc == -EOPNOTSUPP || !server ||
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!ses)
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goto error;
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}
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}
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cifs_put_tcon(root_tcon);
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if (rc)
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goto error;
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@ -4214,6 +4420,8 @@ out:
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return mount_setup_tlink(cifs_sb, ses, tcon);
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error:
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kfree(full_path);
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kfree(root_path);
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mount_put_conns(cifs_sb, xid, server, ses, tcon);
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return rc;
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}
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@ -146,6 +146,9 @@ tconInfoFree(struct cifs_tcon *buf_to_free)
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kfree(buf_to_free->nativeFileSystem);
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kzfree(buf_to_free->password);
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kfree(buf_to_free->crfid.fid);
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#ifdef CONFIG_CIFS_DFS_UPCALL
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kfree(buf_to_free->dfs_path);
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#endif
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kfree(buf_to_free);
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}
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