[PATCH 4/5] cifs: shared-superblock - create a dentry as a disconnected root

[s***@gmail.com]

From: shirish <***@gmail.com>


Create a disconnected root dentry if to an authenticated user, the leaf
directory of a mount is accessible but one or more intermediate paths are not.
In case a server does not provide uniqueid, insert an element for the
disconnected root dentry in a linked list off of superblock.


Signed-off-by: Shirish Pargaonkar <***@suse.com>
---
fs/cifs/cifsfs.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 4e759f6..0942622 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -602,6 +602,46 @@ cifs_alloc_rdelem(char *full_path, struct dentry *rdentry,
return rdelem;
}

+static struct dentry *
+create_root_dis_dentry(struct super_block *sb, struct inode *rinode,
+ char *fpath)
+{
+ int rc;
+ unsigned int xid;
+ struct dentry *dentry = NULL;
+ struct cifs_rdelem *rdelem = NULL;
+ struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+ struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+
+ xid = get_xid();
+ if (tcon->unix_ext)
+ rc = cifs_get_inode_info_unix(&rinode, fpath, sb, xid);
+ else
+ rc = cifs_get_inode_info(&rinode, fpath, NULL, sb, xid, NULL);
+ free_xid(xid);
+
+ if ((rc == 0) && (rinode != NULL)) {
+ dentry = d_obtain_alias(rinode);
+ if (IS_ERR(dentry)) {
+ iput(rinode);
+ goto rdelem_ret;
+ }
+ if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
+ rdelem =
+ cifs_alloc_rdelem(fpath, dentry, rinode);
+ if (IS_ERR(rdelem))
+ goto rdelem_ret;
+ spin_lock(&cifs_sb->rtdislock);
+ list_add(&rdelem->rdlist, &cifs_sb->rtdislist);
+ spin_unlock(&cifs_sb->rtdislock);
+ }
+ return dentry;
+ }
+
+rdelem_ret:
+ return ERR_PTR(-EACCES);
+}
+
/*
* Get root dentry from superblock according to prefix path mount option.
* Return dentry with refcount + 1 on success and NULL otherwise.
@@ -614,9 +654,10 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
char *full_path = NULL;
char *s, *p;
char sep;
+ struct inode *rinode = NULL;
+ struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);

- full_path = cifs_build_path_to_root(vol, cifs_sb,
- cifs_sb_master_tcon(cifs_sb));
+ full_path = cifs_build_path_to_root(vol, cifs_sb, tcon);
if (full_path == NULL)
return ERR_PTR(-ENOMEM);

@@ -657,6 +698,10 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
dput(dentry);
dentry = child;
} while (!IS_ERR(dentry));
+
+ if (IS_ERR(dentry) && (PTR_ERR(dentry) == -EACCES) && *s)
+ dentry = create_root_dis_dentry(sb, rinode, full_path);
+
kfree(full_path);
return dentry;
}