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authorUlrich Drepper <drepper@redhat.com>2006-01-18 17:43:53 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-18 19:20:29 -0800
commit5590ff0d5528b60153c0b4e7b771472b5a95e297 (patch)
tree5fdccf2354269702f71beb8e0a2942e4167fd992 /fs/stat.c
parente2f99018eb7b29954747a2dd78e9fc0c36a60f0f (diff)
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[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 'fs/stat.c')
-rw-r--r--fs/stat.c66
1 files changed, 53 insertions, 13 deletions
diff --git a/fs/stat.c b/fs/stat.c
index b8a0e5110ab2..24211b030f39 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -63,12 +63,12 @@ int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
EXPORT_SYMBOL(vfs_getattr);
-int vfs_stat(char __user *name, struct kstat *stat)
+int vfs_stat_fd(int dfd, char __user *name, struct kstat *stat)
{
struct nameidata nd;
int error;
- error = user_path_walk(name, &nd);
+ error = __user_walk_fd(dfd, name, LOOKUP_FOLLOW, &nd);
if (!error) {
error = vfs_getattr(nd.mnt, nd.dentry, stat);
path_release(&nd);
@@ -76,14 +76,19 @@ int vfs_stat(char __user *name, struct kstat *stat)
return error;
}
+int vfs_stat(char __user *name, struct kstat *stat)
+{
+ return vfs_stat_fd(AT_FDCWD, name, stat);
+}
+
EXPORT_SYMBOL(vfs_stat);
-int vfs_lstat(char __user *name, struct kstat *stat)
+int vfs_lstat_fd(int dfd, char __user *name, struct kstat *stat)
{
struct nameidata nd;
int error;
- error = user_path_walk_link(name, &nd);
+ error = __user_walk_fd(dfd, name, 0, &nd);
if (!error) {
error = vfs_getattr(nd.mnt, nd.dentry, stat);
path_release(&nd);
@@ -91,6 +96,11 @@ int vfs_lstat(char __user *name, struct kstat *stat)
return error;
}
+int vfs_lstat(char __user *name, struct kstat *stat)
+{
+ return vfs_lstat_fd(AT_FDCWD, name, stat);
+}
+
EXPORT_SYMBOL(vfs_lstat);
int vfs_fstat(unsigned int fd, struct kstat *stat)
@@ -151,7 +161,7 @@ static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * sta
asmlinkage long sys_stat(char __user * filename, struct __old_kernel_stat __user * statbuf)
{
struct kstat stat;
- int error = vfs_stat(filename, &stat);
+ int error = vfs_stat_fd(AT_FDCWD, filename, &stat);
if (!error)
error = cp_old_stat(&stat, statbuf);
@@ -161,7 +171,7 @@ asmlinkage long sys_stat(char __user * filename, struct __old_kernel_stat __user
asmlinkage long sys_lstat(char __user * filename, struct __old_kernel_stat __user * statbuf)
{
struct kstat stat;
- int error = vfs_lstat(filename, &stat);
+ int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);
if (!error)
error = cp_old_stat(&stat, statbuf);
@@ -229,27 +239,50 @@ static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}
-asmlinkage long sys_newstat(char __user * filename, struct stat __user * statbuf)
+asmlinkage long sys_newstat(char __user *filename, struct stat __user *statbuf)
{
struct kstat stat;
- int error = vfs_stat(filename, &stat);
+ int error = vfs_stat_fd(AT_FDCWD, filename, &stat);
if (!error)
error = cp_new_stat(&stat, statbuf);
return error;
}
-asmlinkage long sys_newlstat(char __user * filename, struct stat __user * statbuf)
+
+asmlinkage long sys_newlstat(char __user *filename, struct stat __user *statbuf)
{
struct kstat stat;
- int error = vfs_lstat(filename, &stat);
+ int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);
if (!error)
error = cp_new_stat(&stat, statbuf);
return error;
}
-asmlinkage long sys_newfstat(unsigned int fd, struct stat __user * statbuf)
+
+asmlinkage long sys_newfstatat(int dfd, char __user *filename,
+ struct stat __user *statbuf, int flag)
+{
+ struct kstat stat;
+ int error = -EINVAL;
+
+ if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
+ goto out;
+
+ if (flag & AT_SYMLINK_NOFOLLOW)
+ error = vfs_lstat_fd(dfd, filename, &stat);
+ else
+ error = vfs_stat_fd(dfd, filename, &stat);
+
+ if (!error)
+ error = cp_new_stat(&stat, statbuf);
+
+out:
+ return error;
+}
+
+asmlinkage long sys_newfstat(unsigned int fd, struct stat __user *statbuf)
{
struct kstat stat;
int error = vfs_fstat(fd, &stat);
@@ -260,7 +293,8 @@ asmlinkage long sys_newfstat(unsigned int fd, struct stat __user * statbuf)
return error;
}
-asmlinkage long sys_readlink(const char __user * path, char __user * buf, int bufsiz)
+asmlinkage long sys_readlinkat(int dfd, const char __user *path,
+ char __user *buf, int bufsiz)
{
struct nameidata nd;
int error;
@@ -268,7 +302,7 @@ asmlinkage long sys_readlink(const char __user * path, char __user * buf, int bu
if (bufsiz <= 0)
return -EINVAL;
- error = user_path_walk_link(path, &nd);
+ error = __user_walk_fd(dfd, path, 0, &nd);
if (!error) {
struct inode * inode = nd.dentry->d_inode;
@@ -285,6 +319,12 @@ asmlinkage long sys_readlink(const char __user * path, char __user * buf, int bu
return error;
}
+asmlinkage long sys_readlink(const char __user *path, char __user *buf,
+ int bufsiz)
+{
+ return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
+}
+
/* ---------- LFS-64 ----------- */
#ifdef __ARCH_WANT_STAT64