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authorUlrich Drepper <drepper@redhat.com>2006-01-19 04:43:53 +0300
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-19 06:20:29 +0300
commit5590ff0d5528b60153c0b4e7b771472b5a95e297 (patch)
tree5fdccf2354269702f71beb8e0a2942e4167fd992 /include/linux/namei.h
parente2f99018eb7b29954747a2dd78e9fc0c36a60f0f (diff)
downloadlinux-5590ff0d5528b60153c0b4e7b771472b5a95e297.tar.xz
[PATCH] vfs: *at functions: core
Here is a series of patches which introduce in total 13 new system calls which take a file descriptor/filename pair instead of a single file name. These functions, openat etc, have been discussed on numerous occasions. They are needed to implement race-free filesystem traversal, they are necessary to implement a virtual per-thread current working directory (think multi-threaded backup software), etc. We have in glibc today implementations of the interfaces which use the /proc/self/fd magic. But this code is rather expensive. Here are some results (similar to what Jim Meyering posted before). The test creates a deep directory hierarchy on a tmpfs filesystem. Then rm -fr is used to remove all directories. Without syscall support I get this: real 0m31.921s user 0m0.688s sys 0m31.234s With syscall support the results are much better: real 0m20.699s user 0m0.536s sys 0m20.149s The interfaces are for obvious reasons currently not much used. But they'll be used. coreutils (and Jeff's posixutils) are already using them. Furthermore, code like ftw/fts in libc (maybe even glob) will also start using them. I expect a patch to make follow soon. Every program which is walking the filesystem tree will benefit. Signed-off-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/namei.h')
-rw-r--r--include/linux/namei.h7
1 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/namei.h b/include/linux/namei.h
index b699e427c00c..e6698013e4d0 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -56,10 +56,11 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
#define LOOKUP_ACCESS (0x0400)
extern int FASTCALL(__user_walk(const char __user *, unsigned, struct nameidata *));
+extern int FASTCALL(__user_walk_fd(int dfd, const char __user *, unsigned, struct nameidata *));
#define user_path_walk(name,nd) \
- __user_walk(name, LOOKUP_FOLLOW, nd)
+ __user_walk_fd(AT_FDCWD, name, LOOKUP_FOLLOW, nd)
#define user_path_walk_link(name,nd) \
- __user_walk(name, 0, nd)
+ __user_walk_fd(AT_FDCWD, name, 0, nd)
extern int FASTCALL(path_lookup(const char *, unsigned, struct nameidata *));
extern int FASTCALL(path_walk(const char *, struct nameidata *));
extern int FASTCALL(link_path_walk(const char *, struct nameidata *));
@@ -67,7 +68,7 @@ extern void path_release(struct nameidata *);
extern void path_release_on_umount(struct nameidata *);
extern int __user_path_lookup_open(const char __user *, unsigned lookup_flags, struct nameidata *nd, int open_flags);
-extern int path_lookup_open(const char *, unsigned lookup_flags, struct nameidata *, int open_flags);
+extern int path_lookup_open(int dfd, const char *name, unsigned lookup_flags, struct nameidata *, int open_flags);
extern struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
int (*open)(struct inode *, struct file *));
extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);