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#ifndef _LINUX_NAMEI_H
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#define _LINUX_NAMEI_H
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#include <linux/dcache.h>
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#include <linux/linkage.h>
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#include <linux/path.h>
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struct vfsmount;
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struct open_intent {
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int flags;
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int create_mode;
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struct file *file;
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};
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enum { MAX_NESTED_LINKS = 8 };
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struct nameidata {
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struct path path;
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struct qstr last;
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unsigned int flags;
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int last_type;
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unsigned depth;
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char *saved_names[MAX_NESTED_LINKS + 1];
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/* Intent data */
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union {
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struct open_intent open;
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} intent;
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};
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/*
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* Type of the last component on LOOKUP_PARENT
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*/
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enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
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/*
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* The bitmask for a lookup event:
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* - follow links at the end
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* - require a directory
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* - ending slashes ok even for nonexistent files
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* - internal "there are more path compnents" flag
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* - locked when lookup done with dcache_lock held
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* - dentry cache is untrusted; force a real lookup
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*/
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#define LOOKUP_FOLLOW 1
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#define LOOKUP_DIRECTORY 2
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#define LOOKUP_CONTINUE 4
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#define LOOKUP_PARENT 16
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#define LOOKUP_REVAL 64
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/*
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* Intent data
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*/
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#define LOOKUP_OPEN 0x0100
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#define LOOKUP_CREATE 0x0200
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#define LOOKUP_EXCL 0x0400
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#define LOOKUP_RENAME_TARGET 0x0800
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extern int user_path_at(int, const char __user *, unsigned, struct path *);
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#define user_path(name, path) user_path_at(AT_FDCWD, name, LOOKUP_FOLLOW, path)
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#define user_lpath(name, path) user_path_at(AT_FDCWD, name, 0, path)
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#define user_path_dir(name, path) \
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user_path_at(AT_FDCWD, name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, path)
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extern int kern_path(const char *, unsigned, struct path *);
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extern int path_lookup(const char *, unsigned, struct nameidata *);
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fs: introduce vfs_path_lookup
Stackable file systems, among others, frequently need to lookup paths or
path components starting from an arbitrary point in the namespace
(identified by a dentry and a vfsmount). Currently, such file systems use
lookup_one_len, which is frowned upon [1] as it does not pass the lookup
intent along; not passing a lookup intent, for example, can trigger BUG_ON's
when stacking on top of NFSv4.
The first patch introduces a new lookup function to allow lookup starting
from an arbitrary point in the namespace. This approach has been suggested
by Christoph Hellwig [2].
The second patch changes sunrpc to use vfs_path_lookup.
The third patch changes nfsctl.c to use vfs_path_lookup.
The fourth patch marks link_path_walk static.
The fifth, and last patch, unexports path_walk because it is no longer
unnecessary to call it directly, and using the new vfs_path_lookup is
cleaner.
For example, the following snippet of code, looks up "some/path/component"
in a directory pointed to by parent_{dentry,vfsmnt}:
err = vfs_path_lookup(parent_dentry, parent_vfsmnt,
"some/path/component", 0, &nd);
if (!err) {
/* exits */
...
/* once done, release the references */
path_release(&nd);
} else if (err == -ENOENT) {
/* doesn't exist */
} else {
/* other error */
}
VFS functions such as lookup_create can be used on the nameidata structure
to pass the create intent to the file system.
Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
18 years ago
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extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
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const char *, unsigned int, struct nameidata *);
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extern int path_lookup_open(int dfd, const char *name, unsigned lookup_flags, struct nameidata *, int open_flags);
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extern struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
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int (*open)(struct inode *, struct file *));
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extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);
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extern void release_open_intent(struct nameidata *);
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extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
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extern struct dentry *lookup_one_noperm(const char *, struct dentry *);
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extern int follow_down(struct vfsmount **, struct dentry **);
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extern int follow_up(struct vfsmount **, struct dentry **);
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extern struct dentry *lock_rename(struct dentry *, struct dentry *);
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extern void unlock_rename(struct dentry *, struct dentry *);
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static inline void nd_set_link(struct nameidata *nd, char *path)
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{
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nd->saved_names[nd->depth] = path;
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}
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static inline char *nd_get_link(struct nameidata *nd)
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{
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return nd->saved_names[nd->depth];
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}
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static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
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{
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((char *) name)[min(len, maxlen)] = '\0';
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}
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#endif /* _LINUX_NAMEI_H */
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