[1/2] cifs: handle prefix paths in reconnect
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Message ID 20200220224935.12541-1-pc@cjr.nz
State New
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  • [1/2] cifs: handle prefix paths in reconnect
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Commit Message

Paulo Alcantara Feb. 20, 2020, 10:49 p.m. UTC
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@cjr.nz>
---
 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(-)

Comments

ronnie sahlberg Feb. 21, 2020, 12:08 a.m. UTC | #1
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>

On Fri, Feb 21, 2020 at 8:50 AM Paulo Alcantara (SUSE) <pc@cjr.nz> 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@cjr.nz>
> ---
>  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
>
Steve French Feb. 21, 2020, 12:30 a.m. UTC | #2
merged both into cifs-2.6.git for-next (the 2nd one earlier, so it
could be sent to a 5.6-rc ie before 5.7)

On Thu, Feb 20, 2020 at 6:08 PM ronnie sahlberg
<ronniesahlberg@gmail.com> wrote:
>
> Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
>
> On Fri, Feb 21, 2020 at 8:50 AM Paulo Alcantara (SUSE) <pc@cjr.nz> 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@cjr.nz>
> > ---
> >  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
> >
Steve French Feb. 21, 2020, 12:33 a.m. UTC | #3
And kicked off DFS automated tests in buildbot (after updating github
tree as well)
http://smb3-test-rhel-75.southcentralus.cloudapp.azure.com/#/builders/3/builds/69

On Thu, Feb 20, 2020 at 6:30 PM Steve French <smfrench@gmail.com> wrote:
>
> merged both into cifs-2.6.git for-next (the 2nd one earlier, so it
> could be sent to a 5.6-rc ie before 5.7)
>
> On Thu, Feb 20, 2020 at 6:08 PM ronnie sahlberg
> <ronniesahlberg@gmail.com> wrote:
> >
> > Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
> >
> > On Fri, Feb 21, 2020 at 8:50 AM Paulo Alcantara (SUSE) <pc@cjr.nz> 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@cjr.nz>
> > > ---
> > >  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
> > >
>
>
>
> --
> Thanks,
>
> Steve
Aurélien Aptel Feb. 25, 2020, 4:50 p.m. UTC | #4
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
for both patch

Cheers,

Patch
diff mbox series

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;
 	}