[CIFS] Migrate from prefixpath logic

Now we point superblock to a server share root and set a root dentry
appropriately. This let us share superblock between mounts like
//server/sharename/foo/bar and //server/sharename/foo further.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>

Signed-off-by: Steve French <sfrench@us.ibm.com>

7 files changed, 189 insertions, 148 deletions

diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index a9d5692e0c20..c96b44b4e262 100644
--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -56,8 +56,6 @@ struct cifs_sb_info {
         mode_t  mnt_file_mode;
         mode_t  mnt_dir_mode;
         unsigned int mnt_cifs_flags;
-        int     prepathlen;
-        char   *prepath; /* relative path under the share to mount to */
         char   *mountdata; /* options received at mount time or via DFS refs */
         struct backing_dev_info bdi;
         struct delayed_work prune_tlinks;
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 1d2a93c60e75..46fdd55cf427 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -415,8 +415,6 @@ cifs_show_options(struct seq_file *s, struct vfsmount *m)
                 seq_printf(s, ",nocase");
         if (tcon->retry)
                 seq_printf(s, ",hard");
-        if (cifs_sb->prepath)
-                seq_printf(s, ",prepath=%s", cifs_sb->prepath);
         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)
                 seq_printf(s, ",posixpaths");
         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID)
@@ -530,6 +528,100 @@ static const struct super_operations cifs_super_ops = {
 #endif
 };
 
+/*
+ * Get root dentry from superblock according to prefix path mount option.
+ * Return dentry with refcount + 1 on success and NULL otherwise.
+ */
+static struct dentry *
+cifs_get_root(struct smb_vol *vol, struct super_block *sb)
+{
+        int xid, rc;
+        struct inode *inode;
+        struct qstr name;
+        struct dentry *dparent = NULL, *dchild = NULL, *alias;
+        struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+        unsigned int i, full_len, len;
+        char *full_path = NULL, *pstart;
+        char sep;
+
+        full_path = cifs_build_path_to_root(vol, cifs_sb,
+                                            cifs_sb_master_tcon(cifs_sb));
+        if (full_path == NULL)
+                return NULL;
+
+        cFYI(1, "Get root dentry for %s", full_path);
+
+        xid = GetXid();
+        sep = CIFS_DIR_SEP(cifs_sb);
+        dparent = dget(sb->s_root);
+        full_len = strlen(full_path);
+        full_path[full_len] = sep;
+        pstart = full_path + 1;
+
+        for (i = 1, len = 0; i <= full_len; i++) {
+                if (full_path[i] != sep || !len) {
+                        len++;
+                        continue;
+                }
+
+                full_path[i] = 0;
+                cFYI(1, "get dentry for %s", pstart);
+
+                name.name = pstart;
+                name.len = len;
+                name.hash = full_name_hash(pstart, len);
+                dchild = d_lookup(dparent, &name);
+                if (dchild == NULL) {
+                        cFYI(1, "not exists");
+                        dchild = d_alloc(dparent, &name);
+                        if (dchild == NULL) {
+                                dput(dparent);
+                                dparent = NULL;
+                                goto out;
+                        }
+                }
+
+                cFYI(1, "get inode");
+                if (dchild->d_inode == NULL) {
+                        cFYI(1, "not exists");
+                        inode = NULL;
+                        if (cifs_sb_master_tcon(CIFS_SB(sb))->unix_ext)
+                                rc = cifs_get_inode_info_unix(&inode, full_path,
+                                                              sb, xid);
+                        else
+                                rc = cifs_get_inode_info(&inode, full_path,
+                                                         NULL, sb, xid, NULL);
+                        if (rc) {
+                                dput(dchild);
+                                dput(dparent);
+                                dparent = NULL;
+                                goto out;
+                        }
+                        alias = d_materialise_unique(dchild, inode);
+                        if (alias != NULL) {
+                                dput(dchild);
+                                if (IS_ERR(alias)) {
+                                        dput(dparent);
+                                        dparent = NULL;
+                                        goto out;
+                                }
+                                dchild = alias;
+                        }
+                }
+                cFYI(1, "parent %p, child %p", dparent, dchild);
+
+                dput(dparent);
+                dparent = dchild;
+                len = 0;
+                pstart = full_path + i + 1;
+                full_path[i] = sep;
+        }
+out:
+        _FreeXid(xid);
+        kfree(full_path);
+        return dparent;
+}
+
 static struct dentry *
 cifs_do_mount(struct file_system_type *fs_type,
               int flags, const char *dev_name, void *data)
@@ -585,7 +677,10 @@ cifs_do_mount(struct file_system_type *fs_type,
 
         sb->s_flags |= MS_ACTIVE;
 
-        root = dget(sb->s_root);
+        root = cifs_get_root(volume_info, sb);
+        if (root == NULL)
+                goto out_super;
+        cFYI(1, "dentry root is: %p", root);
         goto out;
 
 out_super:
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 30699d9378e9..68ec457f8476 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -155,6 +155,61 @@ struct cifs_cred {
  *****************************************************************
  */
 
+struct smb_vol {
+        char *username;
+        char *password;
+        char *domainname;
+        char *UNC;
+        char *UNCip;
+        char *iocharset;  /* local code page for mapping to and from Unicode */
+        char source_rfc1001_name[RFC1001_NAME_LEN_WITH_NULL]; /* clnt nb name */
+        char target_rfc1001_name[RFC1001_NAME_LEN_WITH_NULL]; /* srvr nb name */
+        uid_t cred_uid;
+        uid_t linux_uid;
+        gid_t linux_gid;
+        mode_t file_mode;
+        mode_t dir_mode;
+        unsigned secFlg;
+        bool retry:1;
+        bool intr:1;
+        bool setuids:1;
+        bool override_uid:1;
+        bool override_gid:1;
+        bool dynperm:1;
+        bool noperm:1;
+        bool no_psx_acl:1; /* set if posix acl support should be disabled */
+        bool cifs_acl:1;
+        bool no_xattr:1;   /* set if xattr (EA) support should be disabled*/
+        bool server_ino:1; /* use inode numbers from server ie UniqueId */
+        bool direct_io:1;
+        bool strict_io:1; /* strict cache behavior */
+        bool remap:1;      /* set to remap seven reserved chars in filenames */
+        bool posix_paths:1; /* unset to not ask for posix pathnames. */
+        bool no_linux_ext:1;
+        bool sfu_emul:1;
+        bool nullauth:1;   /* attempt to authenticate with null user */
+        bool nocase:1;     /* request case insensitive filenames */
+        bool nobrl:1;      /* disable sending byte range locks to srv */
+        bool mand_lock:1;  /* send mandatory not posix byte range lock reqs */
+        bool seal:1;       /* request transport encryption on share */
+        bool nodfs:1;      /* Do not request DFS, even if available */
+        bool local_lease:1; /* check leases only on local system, not remote */
+        bool noblocksnd:1;
+        bool noautotune:1;
+        bool nostrictsync:1; /* do not force expensive SMBflush on every sync */
+        bool fsc:1;     /* enable fscache */
+        bool mfsymlinks:1; /* use Minshall+French Symlinks */
+        bool multiuser:1;
+        unsigned int rsize;
+        unsigned int wsize;
+        bool sockopt_tcp_nodelay:1;
+        unsigned short int port;
+        unsigned long actimeo; /* attribute cache timeout (jiffies) */
+        char *prepath;
+        struct sockaddr_storage srcaddr; /* allow binding to a local IP */
+        struct nls_table *local_nls;
+};
+
 struct TCP_Server_Info {
         struct list_head tcp_ses_list;
         struct list_head smb_ses_list;
@@ -517,6 +572,26 @@ static inline char CIFS_DIR_SEP(const struct cifs_sb_info *cifs_sb)
                 return '\\';
 }
 
+static inline void
+convert_delimiter(char *path, char delim)
+{
+        int i;
+        char old_delim;
+
+        if (path == NULL)
+                return;
+
+        if (delim == '/')
+                old_delim = '\\';
+        else
+                old_delim = '/';
+
+        for (i = 0; path[i] != '\0'; i++) {
+                if (path[i] == old_delim)
+                        path[i] = delim;
+        }
+}
+
 #ifdef CONFIG_CIFS_STATS
 #define cifs_stats_inc atomic_inc
 
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index eb3b58d9668f..e41f6071cdd2 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -57,8 +57,9 @@ extern int init_cifs_idmap(void);
 extern void exit_cifs_idmap(void);
 extern void cifs_destroy_idmaptrees(void);
 extern char *build_path_from_dentry(struct dentry *);
-extern char *cifs_build_path_to_root(struct cifs_sb_info *cifs_sb,
-                                        struct cifsTconInfo *tcon);
+extern char *cifs_build_path_to_root(struct smb_vol *vol,
+                                     struct cifs_sb_info *cifs_sb,
+                                     struct cifsTconInfo *tcon);
 extern char *build_wildcard_path_from_dentry(struct dentry *direntry);
 extern char *cifs_compose_mount_options(const char *sb_mountdata,
                 const char *fullpath, const struct dfs_info3_param *ref,
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 581654fb174d..495688115988 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -57,61 +57,6 @@
 
 extern mempool_t *cifs_req_poolp;
 
-struct smb_vol {
-        char *username;
-        char *password;
-        char *domainname;
-        char *UNC;
-        char *UNCip;
-        char *iocharset;  /* local code page for mapping to and from Unicode */
-        char source_rfc1001_name[RFC1001_NAME_LEN_WITH_NULL]; /* clnt nb name */
-        char target_rfc1001_name[RFC1001_NAME_LEN_WITH_NULL]; /* srvr nb name */
-        uid_t cred_uid;
-        uid_t linux_uid;
-        gid_t linux_gid;
-        mode_t file_mode;
-        mode_t dir_mode;
-        unsigned secFlg;
-        bool retry:1;
-        bool intr:1;
-        bool setuids:1;
-        bool override_uid:1;
-        bool override_gid:1;
-        bool dynperm:1;
-        bool noperm:1;
-        bool no_psx_acl:1; /* set if posix acl support should be disabled */
-        bool cifs_acl:1;
-        bool no_xattr:1;   /* set if xattr (EA) support should be disabled*/
-        bool server_ino:1; /* use inode numbers from server ie UniqueId */
-        bool direct_io:1;
-        bool strict_io:1; /* strict cache behavior */
-        bool remap:1;      /* set to remap seven reserved chars in filenames */
-        bool posix_paths:1; /* unset to not ask for posix pathnames. */
-        bool no_linux_ext:1;
-        bool sfu_emul:1;
-        bool nullauth:1;   /* attempt to authenticate with null user */
-        bool nocase:1;     /* request case insensitive filenames */
-        bool nobrl:1;      /* disable sending byte range locks to srv */
-        bool mand_lock:1;  /* send mandatory not posix byte range lock reqs */
-        bool seal:1;       /* request transport encryption on share */
-        bool nodfs:1;      /* Do not request DFS, even if available */
-        bool local_lease:1; /* check leases only on local system, not remote */
-        bool noblocksnd:1;
-        bool noautotune:1;
-        bool nostrictsync:1; /* do not force expensive SMBflush on every sync */
-        bool fsc:1;     /* enable fscache */
-        bool mfsymlinks:1; /* use Minshall+French Symlinks */
-        bool multiuser:1;
-        unsigned int rsize;
-        unsigned int wsize;
-        bool sockopt_tcp_nodelay:1;
-        unsigned short int port;
-        unsigned long actimeo; /* attribute cache timeout (jiffies) */
-        char *prepath;
-        struct sockaddr_storage srcaddr; /* allow binding to a local IP */
-        struct nls_table *local_nls;
-};
-
 /* FIXME: should these be tunable? */
 #define TLINK_ERROR_EXPIRE      (1 * HZ)
 #define TLINK_IDLE_EXPIRE       (600 * HZ)
@@ -2569,12 +2514,6 @@ void reset_cifs_unix_caps(int xid, struct cifsTconInfo *tcon,
                                         CIFS_MOUNT_POSIX_PATHS;
                 }
 
-                /* We might be setting the path sep back to a different
-                form if we are reconnecting and the server switched its
-                posix path capability for this share */
-                if (sb && (CIFS_SB(sb)->prepathlen > 0))
-                        CIFS_SB(sb)->prepath[0] = CIFS_DIR_SEP(CIFS_SB(sb));
-
                 if (sb && (CIFS_SB(sb)->rsize > 127 * 1024)) {
                         if ((cap & CIFS_UNIX_LARGE_READ_CAP) == 0) {
                                 CIFS_SB(sb)->rsize = 127 * 1024;
@@ -2619,26 +2558,6 @@ void reset_cifs_unix_caps(int xid, struct cifsTconInfo *tcon,
         }
 }
 
-static void
-convert_delimiter(char *path, char delim)
-{
-        int i;
-        char old_delim;
-
-        if (path == NULL)
-                return;
-
-        if (delim == '/')
-                old_delim = '\\';
-        else
-                old_delim = '/';
-
-        for (i = 0; path[i] != '\0'; i++) {
-                if (path[i] == old_delim)
-                        path[i] = delim;
-        }
-}
-
 void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
                         struct cifs_sb_info *cifs_sb)
 {
@@ -2659,18 +2578,6 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
                 /* Windows ME may prefer this */
                 cFYI(1, "readsize set to minimum: 2048");
         }
-        /* calculate prepath */
-        cifs_sb->prepath = pvolume_info->prepath;
-        if (cifs_sb->prepath) {
-                cifs_sb->prepathlen = strlen(cifs_sb->prepath);
-                /* we can not convert the / to \ in the path
-                separators in the prefixpath yet because we do not
-                know (until reset_cifs_unix_caps is called later)
-                whether POSIX PATH CAP is available. We normalize
-                the / to \ after reset_cifs_unix_caps is called */
-                pvolume_info->prepath = NULL;
-        } else
-                cifs_sb->prepathlen = 0;
         cifs_sb->mnt_uid = pvolume_info->linux_uid;
         cifs_sb->mnt_gid = pvolume_info->linux_gid;
         cifs_sb->mnt_file_mode = pvolume_info->file_mode;
@@ -2834,24 +2741,13 @@ build_unc_path_to_root(const struct smb_vol *volume_info,
         char *full_path;
 
         int unc_len = strnlen(volume_info->UNC, MAX_TREE_SIZE + 1);
-        full_path = kmalloc(unc_len + cifs_sb->prepathlen + 1, GFP_KERNEL);
+        full_path = kmalloc(unc_len + 1, GFP_KERNEL);
         if (full_path == NULL)
                 return ERR_PTR(-ENOMEM);
 
         strncpy(full_path, volume_info->UNC, unc_len);
-        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {
-                int i;
-                for (i = 0; i < unc_len; i++) {
-                        if (full_path[i] == '\\')
-                                full_path[i] = '/';
-                }
-        }
-
-        if (cifs_sb->prepathlen)
-                strncpy(full_path + unc_len, cifs_sb->prepath,
-                                cifs_sb->prepathlen);
-
-        full_path[unc_len + cifs_sb->prepathlen] = 0; /* add trailing null */
+        full_path[unc_len] = 0; /* add trailing null */
+        convert_delimiter(full_path, CIFS_DIR_SEP(cifs_sb));
         return full_path;
 }
 
@@ -3049,10 +2945,6 @@ try_mount_again:
                 CIFSSMBQFSAttributeInfo(xid, tcon);
         }
 
-        /* convert forward to back slashes in prepath here if needed */
-        if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) == 0)
-                convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
-
         if ((tcon->unix_ext == 0) && (cifs_sb->rsize > (1024 * 127))) {
                 cifs_sb->rsize = 1024 * 127;
                 cFYI(DBG2, "no very large read support, rsize now 127K");
@@ -3082,10 +2974,10 @@ remote_path_check:
         }
 #endif
 
-        /* check if a whole path (including prepath) is not remote */
+        /* check if a whole path is not remote */
         if (!rc && tcon) {
                 /* build_path_to_root works only when we have a valid tcon */
-                full_path = cifs_build_path_to_root(cifs_sb, tcon);
+                full_path = cifs_build_path_to_root(volume_info, cifs_sb, tcon);
                 if (full_path == NULL) {
                         rc = -ENOMEM;
                         goto mount_fail_check;
@@ -3111,10 +3003,6 @@ remote_path_check:
                         rc = -ELOOP;
                         goto mount_fail_check;
                 }
-                /* convert forward to back slashes in prepath here if needed */
-                if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) == 0)
-                        convert_delimiter(cifs_sb->prepath,
-                                        CIFS_DIR_SEP(cifs_sb));
 
                 rc = expand_dfs_referral(xid, pSesInfo, volume_info, cifs_sb,
                                          true);
@@ -3340,7 +3228,6 @@ cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
         struct rb_root *root = &cifs_sb->tlink_tree;
         struct rb_node *node;
         struct tcon_link *tlink;
-        char *tmp;
 
         cancel_delayed_work_sync(&cifs_sb->prune_tlinks);
 
@@ -3357,11 +3244,6 @@ cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
         }
         spin_unlock(&cifs_sb->tlink_tree_lock);
 
-        tmp = cifs_sb->prepath;
-        cifs_sb->prepathlen = 0;
-        cifs_sb->prepath = NULL;
-        kfree(tmp);
-
         return 0;
 }
 
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 0521492f5b3b..aa0669a82922 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -50,7 +50,6 @@ build_path_from_dentry(struct dentry *direntry)
 {
         struct dentry *temp;
         int namelen;
-        int pplen;
         int dfsplen;
         char *full_path;
         char dirsep;
@@ -63,13 +62,12 @@ build_path_from_dentry(struct dentry *direntry)
                 when the server crashed */
 
         dirsep = CIFS_DIR_SEP(cifs_sb);
-        pplen = cifs_sb->prepathlen;
         if (tcon->Flags & SMB_SHARE_IS_IN_DFS)
                 dfsplen = strnlen(tcon->treeName, MAX_TREE_SIZE + 1);
         else
                 dfsplen = 0;
 cifs_bp_rename_retry:
-        namelen = pplen + dfsplen;
+        namelen = dfsplen;
         for (temp = direntry; !IS_ROOT(temp);) {
                 namelen += (1 + temp->d_name.len);
                 temp = temp->d_parent;
@@ -100,7 +98,7 @@ cifs_bp_rename_retry:
                         return NULL;
                 }
         }
-        if (namelen != pplen + dfsplen) {
+        if (namelen != dfsplen) {
                 cERROR(1, "did not end path lookup where expected namelen is %d",
                         namelen);
                 /* presumably this is only possible if racing with a rename
@@ -126,7 +124,6 @@ cifs_bp_rename_retry:
                         }
                 }
         }
-        strncpy(full_path + dfsplen, CIFS_SB(direntry->d_sb)->prepath, pplen);
         return full_path;
 }
 
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 5e278d37912b..53ea6250a51d 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -735,10 +735,10 @@ static const struct inode_operations cifs_ipc_inode_ops = {
         .lookup = cifs_lookup,
 };
 
-char *cifs_build_path_to_root(struct cifs_sb_info *cifs_sb,
-                                struct cifsTconInfo *tcon)
+char *cifs_build_path_to_root(struct smb_vol *vol, struct cifs_sb_info *cifs_sb,
+                              struct cifsTconInfo *tcon)
 {
-        int pplen = cifs_sb->prepathlen;
+        int pplen = vol->prepath ? strlen(vol->prepath) : 0;
         int dfsplen;
         char *full_path = NULL;
 
@@ -772,7 +772,7 @@ char *cifs_build_path_to_root(struct cifs_sb_info *cifs_sb,
                         }
                 }
         }
-        strncpy(full_path + dfsplen, cifs_sb->prepath, pplen);
+        strncpy(full_path + dfsplen, vol->prepath, pplen);
         full_path[dfsplen + pplen] = 0; /* add trailing null */
         return full_path;
 }
@@ -884,19 +884,13 @@ struct inode *cifs_root_iget(struct super_block *sb)
         struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
         struct inode *inode = NULL;
         long rc;
-        char *full_path;
         struct cifsTconInfo *tcon = cifs_sb_master_tcon(cifs_sb);
 
-        full_path = cifs_build_path_to_root(cifs_sb, tcon);
-        if (full_path == NULL)
-                return ERR_PTR(-ENOMEM);
-
         xid = GetXid();
         if (tcon->unix_ext)
-                rc = cifs_get_inode_info_unix(&inode, full_path, sb, xid);
+                rc = cifs_get_inode_info_unix(&inode, "", sb, xid);
         else
-                rc = cifs_get_inode_info(&inode, full_path, NULL, sb,
-                                                xid, NULL);
+                rc = cifs_get_inode_info(&inode, "", NULL, sb, xid, NULL);
 
         if (!inode) {
                 inode = ERR_PTR(rc);
@@ -922,7 +916,6 @@ struct inode *cifs_root_iget(struct super_block *sb)
         }
 
 out:
-        kfree(full_path);
         /* can not call macro FreeXid here since in a void func
          * TODO: This is no longer true
          */