On 4/20/20 7:04 AM, Michael Kerrisk (man-pages) wrote: > Hello Eric, > > So it seems like this feature eventually got merged in Linux 4.18. Is > this page up to date with what went into the kernel? Yes, I believe that it's all still accurate. Thanks, -Eric > Thanks, > > Michael > > On Thu, 10 May 2018 at 19:29, Eric Sandeen <sandeen@xxxxxxxxxxx> wrote: >> >> This documents the proposed new vfs-level ioctls which can >> get or set a mounted filesytem's label. >> >> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx> >> --- >> >> V2: make primary file ioctl_getfslabel, link ioctl_setfslabel to it >> note that getfslabel requires CAP_SYS_ADMIN >> >> diff --git a/man2/ioctl_getfslabel.2 b/man2/ioctl_getfslabel.2 >> new file mode 100644 >> index 0000000..2c3375c >> --- /dev/null >> +++ b/man2/ioctl_getfslabel.2 >> @@ -0,0 +1,87 @@ >> +.\" Copyright (c) 2018, Red Hat, Inc. All rights reserved. >> +.\" >> +.\" %%%LICENSE_START(GPLv2+_DOC_FULL) >> +.\" This is free documentation; you can redistribute it and/or >> +.\" modify it under the terms of the GNU General Public License as >> +.\" published by the Free Software Foundation; either version 2 of >> +.\" the License, or (at your option) any later version. >> +.\" >> +.\" The GNU General Public License's references to "object code" >> +.\" and "executables" are to be interpreted as the output of any >> +.\" document formatting or typesetting system, including >> +.\" intermediate and printed output. >> +.\" >> +.\" This manual is distributed in the hope that it will be useful, >> +.\" but WITHOUT ANY WARRANTY; without even the implied warranty of >> +.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >> +.\" GNU General Public License for more details. >> +.\" >> +.\" You should have received a copy of the GNU General Public >> +.\" License along with this manual; if not, see >> +.\" <http://www.gnu.org/licenses/>. >> +.\" %%%LICENSE_END >> +.TH IOCTL-FSLABEL 2 2018-05-02 "Linux" "Linux Programmer's Manual" >> +.SH NAME >> +ioctl_fslabel \- get or set a filesystem label >> +.SH SYNOPSIS >> +.br >> +.B #include <sys/ioctl.h> >> +.br >> +.B #include <linux/fs.h> >> +.sp >> +.BI "int ioctl(int " fd ", FS_IOC_GETFSLABEL, char " label [FSLABEL_MAX]); >> +.br >> +.BI "int ioctl(int " fd ", FS_IOC_SETFSLABEL, char " label [FSLABEL_MAX]); >> +.SH DESCRIPTION >> +If a filesystem supports online label manipulation, these >> +.BR ioctl (2) >> +operations can be used to get or set the filesystem label for the filesystem >> +on which >> +.B fd >> +resides. >> +The >> +.B FS_IOC_SETFSLABEL >> +operation requires privilege >> +.RB ( CAP_SYS_ADMIN ). >> +.SH RETURN VALUE >> +On success zero is returned. On error, \-1 is returned, and >> +.I errno >> +is set to indicate the error. >> +.PP >> +.SH ERRORS >> +Error codes can be one of, but are not limited to, the following: >> +.TP >> +.B EINVAL >> +The specified label exceeds the maximum label length for the filesystem. >> +.TP >> +.B ENOTTY >> +This can appear if the filesystem does not support online label manipulation. >> +.TP >> +.B EPERM >> +The calling process does not have sufficient permissions to set the label. >> +.TP >> +.B EFAULT >> +.I label >> +references an inaccessible memory area. >> +.SH VERSIONS >> +These ioctl operations first appeared in Linux 4.18. >> +They were previously known as >> +.B BTRFS_IOC_GET_FSLABEL >> +and >> +.B BTRFS_IOC_SET_FSLABEL >> +and were private to Btrfs. >> +.SH CONFORMING TO >> +This API is Linux-specific. >> +.SH NOTES >> +The maximum string length for this interface is >> +.BR FSLABEL_MAX , >> +including the terminating null byte (\(aq\\0\(aq). >> +Filesystems have differing maximum label lengths, which may or >> +may not include the terminating null. The string provided to >> +.B FS_IOC_SETFSLABEL >> +must always be null-terminated, and the string returned by >> +.B FS_IOC_GETFSLABEL >> +will always be null-terminated. >> +.SH SEE ALSO >> +.BR ioctl (2), >> +.BR blkid (8) >> diff --git a/man2/ioctl_setfslabel.2 b/man2/ioctl_setfslabel.2 >> new file mode 100644 >> index 0000000..2119835 >> --- /dev/null >> +++ b/man2/ioctl_setfslabel.2 >> @@ -0,0 +1 @@ >> +.so man2/ioctl_getfslabel.2 >> > >
