hostfs: support rename flags

Support RENAME_NOREPLACE and RENAME_EXCHANGE flags on hostfs if the
underlying filesystem supports it.

Since renameat2(2) is not yet in any libc, use syscall(2) to invoke the
renameat2 syscall.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/hostfs/hostfs.h b/fs/hostfs/hostfs.h
index 9c88da0..4fcd40d 100644 (file)
--- a/fs/hostfs/hostfs.h
+++ b/fs/hostfs/hostfs.h
@@ -89,6 +89,7 @@ extern int do_mknod(const char *file, int mode, unsigned int major,
 extern int link_file(const char *from, const char *to);
 extern int hostfs_do_readlink(char *file, char *buf, int size);
 extern int rename_file(char *from, char *to);
+extern int rename2_file(char *from, char *to, unsigned int flags);
 extern int do_statfs(char *root, long *bsize_out, long long *blocks_out,
                     long long *bfree_out, long long *bavail_out,
                     long long *files_out, long long *ffree_out,

diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index bb529f3..fd62cae 100644 (file)
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -741,21 +741,31 @@ static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
        return err;
 }
 
-static int hostfs_rename(struct inode *from_ino, struct dentry *from,
-                        struct inode *to_ino, struct dentry *to)
+static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
+                         struct inode *new_dir, struct dentry *new_dentry,
+                         unsigned int flags)
 {
-       char *from_name, *to_name;
+       char *old_name, *new_name;
        int err;
 
-       if ((from_name = dentry_name(from)) == NULL)
+       if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+               return -EINVAL;
+
+       old_name = dentry_name(old_dentry);
+       if (old_name == NULL)
                return -ENOMEM;
-       if ((to_name = dentry_name(to)) == NULL) {
-               __putname(from_name);
+       new_name = dentry_name(new_dentry);
+       if (new_name == NULL) {
+               __putname(old_name);
                return -ENOMEM;
        }
-       err = rename_file(from_name, to_name);
-       __putname(from_name);
-       __putname(to_name);
+       if (!flags)
+               err = rename_file(old_name, new_name);
+       else
+               err = rename2_file(old_name, new_name, flags);
+
+       __putname(old_name);
+       __putname(new_name);
        return err;
 }
 
@@ -867,7 +877,7 @@ static const struct inode_operations hostfs_dir_iops = {
        .mkdir          = hostfs_mkdir,
        .rmdir          = hostfs_rmdir,
        .mknod          = hostfs_mknod,
-       .rename         = hostfs_rename,
+       .rename2        = hostfs_rename2,
        .permission     = hostfs_permission,
        .setattr        = hostfs_setattr,
 };

diff --git a/fs/hostfs/hostfs_user.c b/fs/hostfs/hostfs_user.c
index 67838f3..9765dab 100644 (file)
--- a/fs/hostfs/hostfs_user.c
+++ b/fs/hostfs/hostfs_user.c
@@ -14,6 +14,7 @@
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/vfs.h>
+#include <sys/syscall.h>
 #include "hostfs.h"
 #include <utime.h>
 
@@ -360,6 +361,33 @@ int rename_file(char *from, char *to)
        return 0;
 }
 
+int rename2_file(char *from, char *to, unsigned int flags)
+{
+       int err;
+
+#ifndef SYS_renameat2
+#  ifdef __x86_64__
+#    define SYS_renameat2 316
+#  endif
+#  ifdef __i386__
+#    define SYS_renameat2 353
+#  endif
+#endif
+
+#ifdef SYS_renameat2
+       err = syscall(SYS_renameat2, AT_FDCWD, from, AT_FDCWD, to, flags);
+       if (err < 0) {
+               if (errno != ENOSYS)
+                       return -errno;
+               else
+                       return -EINVAL;
+       }
+       return 0;
+#else
+       return -EINVAL;
+#endif
+}
+
 int do_statfs(char *root, long *bsize_out, long long *blocks_out,
              long long *bfree_out, long long *bavail_out,
              long long *files_out, long long *ffree_out,