![Ulrich Drepper](/assets/img/avatar_default.png)
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>
451 lines
10 KiB
C
451 lines
10 KiB
C
/*
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* linux/fs/stat.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/mm.h>
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#include <linux/errno.h>
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#include <linux/file.h>
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#include <linux/smp_lock.h>
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#include <linux/highuid.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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void generic_fillattr(struct inode *inode, struct kstat *stat)
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{
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stat->dev = inode->i_sb->s_dev;
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stat->ino = inode->i_ino;
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stat->mode = inode->i_mode;
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stat->nlink = inode->i_nlink;
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stat->uid = inode->i_uid;
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stat->gid = inode->i_gid;
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stat->rdev = inode->i_rdev;
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stat->atime = inode->i_atime;
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stat->mtime = inode->i_mtime;
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stat->ctime = inode->i_ctime;
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stat->size = i_size_read(inode);
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stat->blocks = inode->i_blocks;
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stat->blksize = inode->i_blksize;
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}
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EXPORT_SYMBOL(generic_fillattr);
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int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
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{
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struct inode *inode = dentry->d_inode;
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int retval;
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retval = security_inode_getattr(mnt, dentry);
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if (retval)
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return retval;
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if (inode->i_op->getattr)
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return inode->i_op->getattr(mnt, dentry, stat);
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generic_fillattr(inode, stat);
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if (!stat->blksize) {
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struct super_block *s = inode->i_sb;
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unsigned blocks;
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blocks = (stat->size+s->s_blocksize-1) >> s->s_blocksize_bits;
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stat->blocks = (s->s_blocksize / 512) * blocks;
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stat->blksize = s->s_blocksize;
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}
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return 0;
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}
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EXPORT_SYMBOL(vfs_getattr);
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int vfs_stat_fd(int dfd, char __user *name, struct kstat *stat)
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{
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struct nameidata nd;
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int error;
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error = __user_walk_fd(dfd, name, LOOKUP_FOLLOW, &nd);
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if (!error) {
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error = vfs_getattr(nd.mnt, nd.dentry, stat);
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path_release(&nd);
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}
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return error;
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}
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int vfs_stat(char __user *name, struct kstat *stat)
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{
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return vfs_stat_fd(AT_FDCWD, name, stat);
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}
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EXPORT_SYMBOL(vfs_stat);
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int vfs_lstat_fd(int dfd, char __user *name, struct kstat *stat)
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{
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struct nameidata nd;
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int error;
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error = __user_walk_fd(dfd, name, 0, &nd);
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if (!error) {
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error = vfs_getattr(nd.mnt, nd.dentry, stat);
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path_release(&nd);
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}
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return error;
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}
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int vfs_lstat(char __user *name, struct kstat *stat)
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{
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return vfs_lstat_fd(AT_FDCWD, name, stat);
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}
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EXPORT_SYMBOL(vfs_lstat);
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int vfs_fstat(unsigned int fd, struct kstat *stat)
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{
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struct file *f = fget(fd);
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int error = -EBADF;
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if (f) {
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error = vfs_getattr(f->f_vfsmnt, f->f_dentry, stat);
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fput(f);
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}
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return error;
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}
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EXPORT_SYMBOL(vfs_fstat);
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#ifdef __ARCH_WANT_OLD_STAT
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/*
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* For backward compatibility? Maybe this should be moved
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* into arch/i386 instead?
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*/
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static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
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{
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static int warncount = 5;
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struct __old_kernel_stat tmp;
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if (warncount > 0) {
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warncount--;
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printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
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current->comm);
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} else if (warncount < 0) {
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/* it's laughable, but... */
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warncount = 0;
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}
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memset(&tmp, 0, sizeof(struct __old_kernel_stat));
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tmp.st_dev = old_encode_dev(stat->dev);
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tmp.st_ino = stat->ino;
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tmp.st_mode = stat->mode;
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tmp.st_nlink = stat->nlink;
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if (tmp.st_nlink != stat->nlink)
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return -EOVERFLOW;
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SET_UID(tmp.st_uid, stat->uid);
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SET_GID(tmp.st_gid, stat->gid);
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tmp.st_rdev = old_encode_dev(stat->rdev);
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#if BITS_PER_LONG == 32
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if (stat->size > MAX_NON_LFS)
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return -EOVERFLOW;
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#endif
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tmp.st_size = stat->size;
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tmp.st_atime = stat->atime.tv_sec;
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tmp.st_mtime = stat->mtime.tv_sec;
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tmp.st_ctime = stat->ctime.tv_sec;
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return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
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}
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asmlinkage long sys_stat(char __user * filename, struct __old_kernel_stat __user * statbuf)
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{
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struct kstat stat;
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int error = vfs_stat_fd(AT_FDCWD, filename, &stat);
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if (!error)
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error = cp_old_stat(&stat, statbuf);
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return error;
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}
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asmlinkage long sys_lstat(char __user * filename, struct __old_kernel_stat __user * statbuf)
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{
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struct kstat stat;
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int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);
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if (!error)
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error = cp_old_stat(&stat, statbuf);
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return error;
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}
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asmlinkage long sys_fstat(unsigned int fd, struct __old_kernel_stat __user * statbuf)
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{
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struct kstat stat;
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int error = vfs_fstat(fd, &stat);
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if (!error)
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error = cp_old_stat(&stat, statbuf);
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return error;
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}
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#endif /* __ARCH_WANT_OLD_STAT */
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static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
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{
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struct stat tmp;
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#if BITS_PER_LONG == 32
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if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
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return -EOVERFLOW;
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#else
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if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
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return -EOVERFLOW;
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#endif
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memset(&tmp, 0, sizeof(tmp));
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#if BITS_PER_LONG == 32
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tmp.st_dev = old_encode_dev(stat->dev);
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#else
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tmp.st_dev = new_encode_dev(stat->dev);
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#endif
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tmp.st_ino = stat->ino;
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tmp.st_mode = stat->mode;
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tmp.st_nlink = stat->nlink;
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if (tmp.st_nlink != stat->nlink)
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return -EOVERFLOW;
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SET_UID(tmp.st_uid, stat->uid);
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SET_GID(tmp.st_gid, stat->gid);
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#if BITS_PER_LONG == 32
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tmp.st_rdev = old_encode_dev(stat->rdev);
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#else
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tmp.st_rdev = new_encode_dev(stat->rdev);
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#endif
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#if BITS_PER_LONG == 32
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if (stat->size > MAX_NON_LFS)
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return -EOVERFLOW;
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#endif
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tmp.st_size = stat->size;
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tmp.st_atime = stat->atime.tv_sec;
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tmp.st_mtime = stat->mtime.tv_sec;
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tmp.st_ctime = stat->ctime.tv_sec;
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#ifdef STAT_HAVE_NSEC
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tmp.st_atime_nsec = stat->atime.tv_nsec;
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tmp.st_mtime_nsec = stat->mtime.tv_nsec;
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tmp.st_ctime_nsec = stat->ctime.tv_nsec;
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#endif
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tmp.st_blocks = stat->blocks;
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tmp.st_blksize = stat->blksize;
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return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
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}
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asmlinkage long sys_newstat(char __user *filename, struct stat __user *statbuf)
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{
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struct kstat stat;
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int error = vfs_stat_fd(AT_FDCWD, filename, &stat);
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if (!error)
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error = cp_new_stat(&stat, statbuf);
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return error;
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}
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asmlinkage long sys_newlstat(char __user *filename, struct stat __user *statbuf)
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{
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struct kstat stat;
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int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);
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if (!error)
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error = cp_new_stat(&stat, statbuf);
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return error;
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}
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asmlinkage long sys_newfstatat(int dfd, char __user *filename,
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struct stat __user *statbuf, int flag)
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{
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struct kstat stat;
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int error = -EINVAL;
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if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
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goto out;
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if (flag & AT_SYMLINK_NOFOLLOW)
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error = vfs_lstat_fd(dfd, filename, &stat);
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else
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error = vfs_stat_fd(dfd, filename, &stat);
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if (!error)
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error = cp_new_stat(&stat, statbuf);
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out:
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return error;
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}
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asmlinkage long sys_newfstat(unsigned int fd, struct stat __user *statbuf)
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{
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struct kstat stat;
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int error = vfs_fstat(fd, &stat);
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if (!error)
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error = cp_new_stat(&stat, statbuf);
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return error;
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}
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asmlinkage long sys_readlinkat(int dfd, const char __user *path,
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char __user *buf, int bufsiz)
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{
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struct nameidata nd;
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int error;
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if (bufsiz <= 0)
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return -EINVAL;
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error = __user_walk_fd(dfd, path, 0, &nd);
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if (!error) {
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struct inode * inode = nd.dentry->d_inode;
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error = -EINVAL;
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if (inode->i_op && inode->i_op->readlink) {
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error = security_inode_readlink(nd.dentry);
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if (!error) {
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touch_atime(nd.mnt, nd.dentry);
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error = inode->i_op->readlink(nd.dentry, buf, bufsiz);
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}
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}
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path_release(&nd);
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}
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return error;
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}
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asmlinkage long sys_readlink(const char __user *path, char __user *buf,
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int bufsiz)
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{
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return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
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}
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/* ---------- LFS-64 ----------- */
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#ifdef __ARCH_WANT_STAT64
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static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
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{
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struct stat64 tmp;
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memset(&tmp, 0, sizeof(struct stat64));
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#ifdef CONFIG_MIPS
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/* mips has weird padding, so we don't get 64 bits there */
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if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
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return -EOVERFLOW;
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tmp.st_dev = new_encode_dev(stat->dev);
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tmp.st_rdev = new_encode_dev(stat->rdev);
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#else
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tmp.st_dev = huge_encode_dev(stat->dev);
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tmp.st_rdev = huge_encode_dev(stat->rdev);
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#endif
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tmp.st_ino = stat->ino;
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#ifdef STAT64_HAS_BROKEN_ST_INO
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tmp.__st_ino = stat->ino;
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#endif
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tmp.st_mode = stat->mode;
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tmp.st_nlink = stat->nlink;
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tmp.st_uid = stat->uid;
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tmp.st_gid = stat->gid;
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tmp.st_atime = stat->atime.tv_sec;
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tmp.st_atime_nsec = stat->atime.tv_nsec;
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tmp.st_mtime = stat->mtime.tv_sec;
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tmp.st_mtime_nsec = stat->mtime.tv_nsec;
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tmp.st_ctime = stat->ctime.tv_sec;
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tmp.st_ctime_nsec = stat->ctime.tv_nsec;
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tmp.st_size = stat->size;
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tmp.st_blocks = stat->blocks;
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tmp.st_blksize = stat->blksize;
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return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
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}
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asmlinkage long sys_stat64(char __user * filename, struct stat64 __user * statbuf)
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{
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struct kstat stat;
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int error = vfs_stat(filename, &stat);
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if (!error)
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error = cp_new_stat64(&stat, statbuf);
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return error;
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}
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asmlinkage long sys_lstat64(char __user * filename, struct stat64 __user * statbuf)
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{
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struct kstat stat;
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int error = vfs_lstat(filename, &stat);
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if (!error)
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error = cp_new_stat64(&stat, statbuf);
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return error;
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}
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asmlinkage long sys_fstat64(unsigned long fd, struct stat64 __user * statbuf)
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{
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struct kstat stat;
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int error = vfs_fstat(fd, &stat);
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if (!error)
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error = cp_new_stat64(&stat, statbuf);
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return error;
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}
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#endif /* __ARCH_WANT_STAT64 */
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void inode_add_bytes(struct inode *inode, loff_t bytes)
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{
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spin_lock(&inode->i_lock);
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inode->i_blocks += bytes >> 9;
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bytes &= 511;
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inode->i_bytes += bytes;
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if (inode->i_bytes >= 512) {
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inode->i_blocks++;
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inode->i_bytes -= 512;
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}
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spin_unlock(&inode->i_lock);
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}
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EXPORT_SYMBOL(inode_add_bytes);
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void inode_sub_bytes(struct inode *inode, loff_t bytes)
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{
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spin_lock(&inode->i_lock);
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inode->i_blocks -= bytes >> 9;
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bytes &= 511;
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if (inode->i_bytes < bytes) {
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inode->i_blocks--;
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inode->i_bytes += 512;
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}
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inode->i_bytes -= bytes;
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spin_unlock(&inode->i_lock);
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}
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EXPORT_SYMBOL(inode_sub_bytes);
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loff_t inode_get_bytes(struct inode *inode)
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{
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loff_t ret;
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spin_lock(&inode->i_lock);
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ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
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spin_unlock(&inode->i_lock);
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return ret;
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}
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EXPORT_SYMBOL(inode_get_bytes);
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void inode_set_bytes(struct inode *inode, loff_t bytes)
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{
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/* Caller is here responsible for sufficient locking
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* (ie. inode->i_lock) */
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inode->i_blocks = bytes >> 9;
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inode->i_bytes = bytes & 511;
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}
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EXPORT_SYMBOL(inode_set_bytes);
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