fs: add do_mknodat() helper and ksys_mknod() wrapper; remove in-kernel calls to syscall
Using the fs-internal do_mknodat() helper allows us to get rid of fs-internal calls to the sys_mknodat() syscall. Introducing the ksys_mknod() wrapper allows us to avoid the in-kernel calls to sys_mknod() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_mknod(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
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@ -55,6 +55,8 @@ extern void __init chrdev_init(void);
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extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
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extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
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const char *, unsigned int, struct path *);
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long do_mknodat(int dfd, const char __user *filename, umode_t mode,
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unsigned int dev);
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long do_mkdirat(int dfd, const char __user *pathname, umode_t mode);
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long do_rmdir(int dfd, const char __user *pathname);
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long do_unlinkat(int dfd, struct filename *name);
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12
fs/namei.c
12
fs/namei.c
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@ -3728,8 +3728,8 @@ static int may_mknod(umode_t mode)
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}
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}
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SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
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unsigned, dev)
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long do_mknodat(int dfd, const char __user *filename, umode_t mode,
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unsigned int dev)
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{
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struct dentry *dentry;
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struct path path;
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@ -3772,9 +3772,15 @@ out:
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return error;
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}
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SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
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unsigned int, dev)
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{
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return do_mknodat(dfd, filename, mode, dev);
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}
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SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev)
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{
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return sys_mknodat(AT_FDCWD, filename, mode, dev);
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return do_mknodat(AT_FDCWD, filename, mode, dev);
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}
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int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
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@ -988,4 +988,13 @@ static inline long ksys_symlink(const char __user *oldname,
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return do_symlinkat(oldname, AT_FDCWD, newname);
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}
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extern long do_mknodat(int dfd, const char __user *filename, umode_t mode,
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unsigned int dev);
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static inline long ksys_mknod(const char __user *filename, umode_t mode,
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unsigned int dev)
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{
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return do_mknodat(AT_FDCWD, filename, mode, dev);
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}
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#endif
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@ -17,7 +17,7 @@ extern int root_mountflags;
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static inline int create_dev(char *name, dev_t dev)
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{
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ksys_unlink(name);
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return sys_mknod(name, S_IFBLK|0600, new_encode_dev(dev));
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return ksys_mknod(name, S_IFBLK|0600, new_encode_dev(dev));
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}
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static inline u32 bstat(char *name)
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@ -359,7 +359,7 @@ static int __init do_name(void)
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} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
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S_ISFIFO(mode) || S_ISSOCK(mode)) {
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if (maybe_link() == 0) {
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sys_mknod(collected, mode, rdev);
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ksys_mknod(collected, mode, rdev);
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sys_chown(collected, uid, gid);
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sys_chmod(collected, mode);
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do_utime(collected, mtime);
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@ -33,7 +33,7 @@ static int __init default_rootfs(void)
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if (err < 0)
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goto out;
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err = sys_mknod((const char __user __force *) "/dev/console",
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err = ksys_mknod((const char __user __force *) "/dev/console",
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S_IFCHR | S_IRUSR | S_IWUSR,
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new_encode_dev(MKDEV(5, 1)));
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if (err < 0)
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