Re: [PATCH 11/11] ext4: add cross rename support

[Miklos Szeredi]

> On Wed, Jan 15, 2014 at 7:23 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
> > Do you have a man page update somewhere for the two new flags?

Here's the updated man page (and attached the patch)

Michael, could you please review the interface?

I forgot to CC you when posing the patch series.  I can resend it if you want,
or you can fetch the latest version of the cross-rename series from:

  git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git cross-rename

Thanks,
Miklos
----

RENAMEAT(2)                Linux Programmer's Manual               RENAMEAT(2)



NAME
       renameat, renameat2 - rename a file relative to directory file descrip-
       tors

SYNOPSIS
       #include <fcntl.h> /* Definition of AT_* constants */
       #include <stdio.h>

       int renameat(int olddirfd, const char *oldpath,
                    int newdirfd, const char *newpath);

       int renameat2(int olddirfd, const char *oldpath,
                     int newdirfd, const char *newpath, unsigned int flags);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       renameat():
           Since glibc 2.10:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _ATFILE_SOURCE

DESCRIPTION
       The renameat() and renameat2() system calls operate in exactly the same
       way  as  rename(2), except for the differences described in this manual
       page.

       If the pathname given in oldpath is relative, then  it  is  interpreted
       relative  to  the directory referred to by the file descriptor olddirfd
       (rather than relative to the current working directory of  the  calling
       process, as is done by rename(2) for a relative pathname).

       If oldpath is relative and olddirfd is the special value AT_FDCWD, then
       oldpath is interpreted relative to the current working directory of the
       calling process (like rename(2)).

       If oldpath is absolute, then olddirfd is ignored.

       The interpretation of newpath is as for oldpath, except that a relative
       pathname is interpreted relative to the directory referred  to  by  the
       file descriptor newdirfd.

       renameat2()  has an additional flags argument.  renameat2() call with a
       zero flags argument is equivalent to renameat().

       The flags argument is a bitfield consisting of zero or more of the fol-
       lowing constants defined in <linux/fs.h>:

       RENAME_NOREPLACE
              Don't  overwrite  the  target of the rename.  Return an error if
              the target would be overwritten.

       RENAME_EXCHANGE
              Atomically exchange the source and destination.  Both must exist
              but  may  be of a different type (e.g. one a non-empty directory
              and the other a symbolic link).

RETURN VALUE
       On success, renameat() and renameat2()  return  0.   On  error,  -1  is
       returned and errno is set to indicate the error.

ERRORS
       The  same errors that occur for rename(2) can also occur for renameat()
       and  renameat2().   The  following  additional  errors  can  occur  for
       renameat() and renameat2():

       EBADF  olddirfd or newdirfd is not a valid file descriptor.

       ENOTDIR
              oldpath  is relative and olddirfd is a file descriptor referring
              to a file other than a directory; or  similar  for  newpath  and
              newdirfd

       The following additional errors are defined for renameat2():

       EOPNOTSUPP
              The filesystem does not support a flag in flags

       EINVAL Invalid combination of flags

       EEXIST flags  contain  RENAME_NOREPLACE  and  the  target of the rename
              exists

       ENOENT flags contain RENAME_EXCHANGE and the target of the rename  does
              not exist

VERSIONS
       renameat()  was  added  to  Linux in kernel 2.6.16; library support was
       added to glibc in version 2.4.

CONFORMING TO
       renameat() is specified in POSIX.1-2008.

NOTES
       See openat(2) for an explanation of the need for renameat().

SEE ALSO
       openat(2), rename(2), path_resolution(7)



Linux                             2012-05-04                       RENAMEAT(2)
diff --git a/man2/renameat.2 b/man2/renameat.2
index 432ddfd..e2f80d8 100644
--- a/man2/renameat.2
+++ b/man2/renameat.2
@@ -24,7 +24,7 @@
 .\"
 .TH RENAMEAT 2 2012-05-04 "Linux" "Linux Programmer's Manual"
 .SH NAME
-renameat \- rename a file relative to directory file descriptors
+renameat, renameat2 \- rename a file relative to directory file descriptors
 .SH SYNOPSIS
 .nf
 .B #include <fcntl.h>           /* Definition of AT_* constants */
@@ -32,6 +32,9 @@ renameat \- rename a file relative to directory file descriptors
 .sp
 .BI "int renameat(int " olddirfd ", const char *" oldpath ,
 .BI "             int " newdirfd ", const char *" newpath );
+
+.BI "int renameat2(int " olddirfd ", const char *" oldpath ,
+.BI "              int " newdirfd ", const char *" newpath ", unsigned int " flags );
 .fi
 .sp
 .in -4n
@@ -55,7 +58,9 @@ _ATFILE_SOURCE
 .SH DESCRIPTION
 The
 .BR renameat ()
-system call operates in exactly the same way as
+and
+.BR renameat2 ()
+system calls operate in exactly the same way as
 .BR rename (2),
 except for the differences described in this manual page.
 
@@ -94,10 +99,37 @@ is as for
 except that a relative pathname is interpreted relative
 to the directory referred to by the file descriptor
 .IR newdirfd .
+
+.BR renameat2 ()
+has an additional
+.I flags
+argument.
+.BR renameat2 ()
+call with a zero
+.I flags
+argument is equivalent to
+.BR renameat ().
+
+The
+.I flags
+argument is a bitfield consisting of zero or more of the following
+constants defined in
+.IR <linux/fs.h> :
+.TP
+.B RENAME_NOREPLACE
+Don't overwrite the target of the rename.  Return an error
+if the target would be overwritten.
+.TP
+.B RENAME_EXCHANGE
+Atomically exchange the source and destination.  Both must exist
+but may be of a different type (e.g. one a non-empty directory
+and the other a symbolic link).
 .SH RETURN VALUE
 On success,
 .BR renameat ()
-returns 0.
+and
+.BR renameat2 ()
+return 0.
 On error, \-1 is returned and
 .I errno
 is set to indicate the error.
@@ -105,9 +137,13 @@ is set to indicate the error.
 The same errors that occur for
 .BR rename (2)
 can also occur for
-.BR renameat ().
+.BR renameat ()
+and
+.BR renameat2 ().
 The following additional errors can occur for
-.BR renameat ():
+.BR renameat ()
+and
+.BR renameat2 ():
 .TP
 .B EBADF
 .I olddirfd
@@ -124,12 +160,37 @@ or similar for
 .I newpath
 and
 .I newdirfd
+.RE
+.PP
+The following additional errors are defined for
+.BR renameat2 ():
+.TP
+.B EOPNOTSUPP
+The filesystem does not support a flag in
+.I flags
+.TP 
+.B EINVAL
+Invalid combination of
+.I flags
+.TP
+.B EEXIST
+.I flags
+contain
+.B RENAME_NOREPLACE
+and the target of the rename exists
+.TP
+.B ENOENT
+.I flags
+contain
+.B RENAME_EXCHANGE
+and the target of the rename does not exist
 .SH VERSIONS
 .BR renameat ()
 was added to Linux in kernel 2.6.16;
 library support was added to glibc in version 2.4.
 .SH CONFORMING TO
-POSIX.1-2008.
+.BR renameat ()
+is specified in POSIX.1-2008.
 .SH NOTES
 See
 .BR openat (2)