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> --- btrfs folks, please verify that this accurately describes your current behavior, thanks. diff --git a/man2/ioctl_fslabel.2 b/man2/ioctl_fslabel.2 new file mode 100644 index 0000000..150aa53 --- /dev/null +++ b/man2/ioctl_fslabel.2 @@ -0,0 +1,83 @@ +.\" 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. +.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_getfslabel.2 b/man2/ioctl_getfslabel.2 new file mode 100644 index 0000000..bfa8dca --- /dev/null +++ b/man2/ioctl_getfslabel.2 @@ -0,0 +1 @@ +.so man2/ioctl_fslabel.2 diff --git a/man2/ioctl_setfslabel.2 b/man2/ioctl_setfslabel.2 new file mode 100644 index 0000000..bfa8dca --- /dev/null +++ b/man2/ioctl_setfslabel.2 @@ -0,0 +1 @@ +.so man2/ioctl_fslabel.2
