How does NFS handle this use case?
On Tue, Nov 19, 2013 at 10:33 AM, <shirishpargaonkar@xxxxxxxxx> wrote:
> From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
>
>
> Allow cifs mounts for a prefixpath with intermediate paths without access,
> so as to continue with the shared superblock model.
>
> For the intermediate path entries that do not allow access, create "placeholder"
> inodes and instantiate dentries with those inodes.
> If and when such a path entry becomes accessible it is filled with correct
> info.
>
> Reference: Samba bugzilla 6950
>
> Signed-off-by: Shirish Pargaonkar <spargaonkar@xxxxxxxx>
>
> ---
> fs/cifs/cifsfs.c | 17 +++++++++++++++--
> fs/cifs/cifsproto.h | 3 +++
> fs/cifs/inode.c | 16 ++++++++++++++++
> 3 files changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 849f613..bce185c 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -584,6 +584,9 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
> char *full_path = NULL;
> char *s, *p;
> char sep;
> + struct inode *dir, *phinode;
> + struct dentry *child;
> + struct cifs_fattr phfattr;
>
> full_path = cifs_build_path_to_root(vol, cifs_sb,
> cifs_sb_master_tcon(cifs_sb));
> @@ -592,13 +595,13 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
>
> cifs_dbg(FYI, "Get root dentry for %s\n", full_path);
>
> + fill_phfattr(&phfattr, sb);
> sep = CIFS_DIR_SEP(cifs_sb);
> dentry = dget(sb->s_root);
> p = s = full_path;
>
> do {
> - struct inode *dir = dentry->d_inode;
> - struct dentry *child;
> + dir = dentry->d_inode;
>
> if (!dir) {
> dput(dentry);
> @@ -626,6 +629,16 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
> mutex_unlock(&dir->i_mutex);
> dput(dentry);
> dentry = child;
> + if (!IS_ERR(dentry)) {
> + if (*s) {
> + /* EACCESS on an intermediate dir */
> + if (!dentry->d_inode) {
> + phinode = cifs_iget(sb, &phfattr);
> + if (phinode)
> + d_instantiate(dentry, phinode);
> + }
> + }
> + }
> } while (!IS_ERR(dentry));
> kfree(full_path);
> return dentry;
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index aa33976..9a84e5c 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -498,4 +498,7 @@ void cifs_writedata_release(struct kref *refcount);
> int open_query_close_cifs_symlink(const unsigned char *path, char *pbuf,
> unsigned int *pbytes_read, struct cifs_sb_info *cifs_sb,
> unsigned int xid);
> +
> +extern void fill_phfattr(struct cifs_fattr *, struct super_block *);
> +
> #endif /* _CIFSPROTO_H */
> diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
> index 36f9ebb..4f5a09a 100644
> --- a/fs/cifs/inode.c
> +++ b/fs/cifs/inode.c
> @@ -322,6 +322,22 @@ cifs_create_dfs_fattr(struct cifs_fattr *fattr, struct super_block *sb)
> fattr->cf_flags |= CIFS_FATTR_DFS_REFERRAL;
> }
>
> +void
> +fill_phfattr(struct cifs_fattr *cf, struct super_block *sb)
> +{
> + struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
> +
> + memset(cf, 0, sizeof(*cf));
> + cf->cf_uniqueid = iunique(sb, ROOT_I);
> + cf->cf_nlink = 1;
> + cf->cf_atime = CURRENT_TIME;
> + cf->cf_ctime = CURRENT_TIME;
> + cf->cf_mtime = CURRENT_TIME;
> + cf->cf_mode = S_IFDIR | S_IXUGO | S_IRWXU;
> + cf->cf_uid = cifs_sb->mnt_uid;
> + cf->cf_gid = cifs_sb->mnt_gid;
> +}
> +
> static int
> cifs_get_file_info_unix(struct file *filp)
> {
> --
> 1.8.3.2
>
--
Thanks,
Steve
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