84a2bd3940
The rules for nd->root are messy: * if we have LOOKUP_ROOT, it doesn't contribute to refcounts * if we have LOOKUP_RCU, it doesn't contribute to refcounts * if nd->root.mnt is NULL, it doesn't contribute to refcounts * otherwise it does contribute terminate_walk() needs to drop the references if they are contributing. So everything else should be careful not to confuse it, leading to rather convoluted code. It's easier to keep track of whether we'd grabbed the reference(s) explicitly. Use a new flag for that. Don't bother with zeroing nd->root.mnt on unlazy failures and in terminate_walk - it's not needed anymore (terminate_walk() won't care and the next path_init() will zero nd->root in !LOOKUP_ROOT case anyway). Resulting rules for nd->root refcounts are much simpler: they are contributing iff LOOKUP_ROOT_GRABBED is set in nd->flags. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
95 lines
3.3 KiB
C
95 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_NAMEI_H
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#define _LINUX_NAMEI_H
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#include <linux/kernel.h>
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#include <linux/path.h>
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#include <linux/fcntl.h>
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#include <linux/errno.h>
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enum { MAX_NESTED_LINKS = 8 };
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#define MAXSYMLINKS 40
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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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/* pathwalk mode */
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#define LOOKUP_FOLLOW 0x0001 /* follow links at the end */
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#define LOOKUP_DIRECTORY 0x0002 /* require a directory */
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#define LOOKUP_AUTOMOUNT 0x0004 /* force terminal automount */
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#define LOOKUP_EMPTY 0x4000 /* accept empty path [user_... only] */
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#define LOOKUP_DOWN 0x8000 /* follow mounts in the starting point */
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#define LOOKUP_REVAL 0x0020 /* tell ->d_revalidate() to trust no cache */
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#define LOOKUP_RCU 0x0040 /* RCU pathwalk mode; semi-internal */
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/* These tell filesystem methods that we are dealing with the final component... */
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#define LOOKUP_OPEN 0x0100 /* ... in open */
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#define LOOKUP_CREATE 0x0200 /* ... in object creation */
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#define LOOKUP_EXCL 0x0400 /* ... in exclusive creation */
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#define LOOKUP_RENAME_TARGET 0x0800 /* ... in destination of rename() */
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/* internal use only */
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#define LOOKUP_PARENT 0x0010
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#define LOOKUP_NO_REVAL 0x0080
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#define LOOKUP_JUMPED 0x1000
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#define LOOKUP_ROOT 0x2000
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#define LOOKUP_ROOT_GRABBED 0x0008
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extern int path_pts(struct path *path);
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extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
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static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
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struct path *path)
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{
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return user_path_at_empty(dfd, name, flags, path, NULL);
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}
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extern int kern_path(const char *, unsigned, struct path *);
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extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
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extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
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extern void done_path_create(struct path *, struct dentry *);
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extern struct dentry *kern_path_locked(const char *, struct path *);
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extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
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extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
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extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
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extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
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extern int follow_down_one(struct path *);
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extern int follow_down(struct path *);
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extern int follow_up(struct path *);
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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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extern void nd_jump_link(struct path *path);
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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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/**
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* retry_estale - determine whether the caller should retry an operation
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* @error: the error that would currently be returned
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* @flags: flags being used for next lookup attempt
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*
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* Check to see if the error code was -ESTALE, and then determine whether
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* to retry the call based on whether "flags" already has LOOKUP_REVAL set.
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*
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* Returns true if the caller should try the operation again.
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*/
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static inline bool
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retry_estale(const long error, const unsigned int flags)
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{
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return error == -ESTALE && !(flags & LOOKUP_REVAL);
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}
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#endif /* _LINUX_NAMEI_H */
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