Acked-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
On Fri, Feb 21, 2020 at 8:50 AM Paulo Alcantara (SUSE) <pc@xxxxxx> wrote:
>
> 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) <pc@xxxxxx>
> ---
> 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 89eaaf46d1ca..af8e79b58b94 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -601,6 +601,11 @@ 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 3c89569e7210..b6fa575d2d3f 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 abc0a0512181..49b15a488ede 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;
> }
> --
> 2.25.0
>
