From 4a367dc0443566f87d73f2cdb94703b0e1374315 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Wed, 14 Nov 2018 16:53:52 -0200 Subject: [PATCH] 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 Reviewed-by: Aurelien Aptel Signed-off-by: Steve French --- fs/cifs/cifs_dfs_ref.c | 20 +++- fs/cifs/connect.c | 228 +++++++++++++++++++++++++++++++++++++++-- fs/cifs/misc.c | 3 + 3 files changed, 236 insertions(+), 15 deletions(-) diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c index 8bd6f6b76da8..d9b99abe1243 100644 --- a/fs/cifs/cifs_dfs_ref.c +++ b/fs/cifs/cifs_dfs_ref.c @@ -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) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 182b16e56749..658a0d191056 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -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) { - rc = is_path_remote(cifs_sb, vol, xid, server, tcon); - if (!rc) - goto out; - if (rc != -EREMOTE) - goto error; + /* 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; } diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c index 10ae1a35b6f7..7c858d4c66f3 100644 --- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -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); } -- GitLab