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Diffstat (limited to 'upstream/opensuse-leap-15-6/man2/umount.2')
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diff --git a/upstream/opensuse-leap-15-6/man2/umount.2 b/upstream/opensuse-leap-15-6/man2/umount.2 new file mode 100644 index 00000000..93991fd5 --- /dev/null +++ b/upstream/opensuse-leap-15-6/man2/umount.2 @@ -0,0 +1,214 @@ +.\" Copyright (C) 1993 Rickard E. Faith <faith@cs.unc.edu> +.\" and Copyright (C) 1994 Andries E. Brouwer <aeb@cwi.nl> +.\" and Copyright (C) 2002, 2005 Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" 2008-10-06, mtk: Created this as a new page by splitting +.\" umount/umount2 material out of mount.2 +.\" +.TH umount 2 2023-03-30 "Linux man-pages 6.04" +.SH NAME +umount, umount2 \- unmount filesystem +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B "#include <sys/mount.h>" +.PP +.BI "int umount(const char *" target ); +.BI "int umount2(const char *" target ", int " flags ); +.fi +.SH DESCRIPTION +.BR umount () +and +.BR umount2 () +remove the attachment of the (topmost) filesystem mounted on +.IR target . +.\" Note: the kernel naming differs from the glibc naming +.\" umount2 is the glibc name for what the kernel now calls umount +.\" and umount is the glibc name for oldumount +.PP +Appropriate privilege (Linux: the +.B CAP_SYS_ADMIN +capability) is required to unmount filesystems. +.PP +Linux 2.1.116 added the +.BR umount2 () +system call, which, like +.BR umount (), +unmounts a target, but allows additional +.I flags +controlling the behavior of the operation: +.TP +.BR MNT_FORCE " (since Linux 2.1.116)" +Ask the filesystem to abort pending requests before attempting the +unmount. +This may allow the unmount to complete without waiting +for an inaccessible server, but could cause data loss. +If, after aborting requests, +some processes still have active references to the filesystem, +the unmount will still fail. +As at Linux 4.12, +.B MNT_FORCE +is supported only on the following filesystems: +9p (since Linux 2.6.16), +ceph (since Linux 2.6.34), +cifs (since Linux 2.6.12), +fuse (since Linux 2.6.16), +lustre (since Linux 3.11), +and NFS (since Linux 2.1.116). +.TP +.BR MNT_DETACH " (since Linux 2.4.11)" +Perform a lazy unmount: make the mount unavailable for new +accesses, immediately disconnect the filesystem and all filesystems +mounted below it from each other and from the mount table, and +actually perform the unmount when the mount ceases to be busy. +.TP +.BR MNT_EXPIRE " (since Linux 2.6.8)" +Mark the mount as expired. +If a mount is not currently in use, then an initial call to +.BR umount2 () +with this flag fails with the error +.BR EAGAIN , +but marks the mount as expired. +The mount remains expired as long as it isn't accessed +by any process. +A second +.BR umount2 () +call specifying +.B MNT_EXPIRE +unmounts an expired mount. +This flag cannot be specified with either +.B MNT_FORCE +or +.BR MNT_DETACH . +.TP +.BR UMOUNT_NOFOLLOW " (since Linux 2.6.34)" +.\" Later added to Linux 2.6.33-stable +Don't dereference +.I target +if it is a symbolic link. +This flag allows security problems to be avoided in set-user-ID-\fIroot\fP +programs that allow unprivileged users to unmount filesystems. +.SH RETURN VALUE +On success, zero is returned. +On error, \-1 is returned, and +.I errno +is set to indicate the error. +.SH ERRORS +The error values given below result from filesystem type independent +errors. +Each filesystem type may have its own special errors and its +own special behavior. +See the Linux kernel source code for details. +.TP +.B EAGAIN +A call to +.BR umount2 () +specifying +.B MNT_EXPIRE +successfully marked an unbusy filesystem as expired. +.TP +.B EBUSY +.I target +could not be unmounted because it is busy. +.TP +.B EFAULT +.I target +points outside the user address space. +.TP +.B EINVAL +.I target +is not a mount point. +.TP +.B EINVAL +.I target +is locked; see +.BR mount_namespaces (7). +.TP +.B EINVAL +.BR umount2 () +was called with +.B MNT_EXPIRE +and either +.B MNT_DETACH +or +.BR MNT_FORCE . +.TP +.BR EINVAL " (since Linux 2.6.34)" +.BR umount2 () +was called with an invalid flag value in +.IR flags . +.TP +.B ENAMETOOLONG +A pathname was longer than +.BR MAXPATHLEN . +.TP +.B ENOENT +A pathname was empty or had a nonexistent component. +.TP +.B ENOMEM +The kernel could not allocate a free page to copy filenames or data into. +.TP +.B EPERM +The caller does not have the required privileges. +.SH STANDARDS +Linux. +.SH HISTORY +.B MNT_DETACH +and +.B MNT_EXPIRE +.\" http://sourceware.org/bugzilla/show_bug.cgi?id=10092 +are available since glibc 2.11. +.PP +The original +.BR umount () +function was called as \fIumount(device)\fP and would return +.B ENOTBLK +when called with something other than a block device. +In Linux 0.98p4, a call \fIumount(dir)\fP was added, in order to +support anonymous devices. +In Linux 2.3.99-pre7, the call \fIumount(device)\fP was removed, +leaving only \fIumount(dir)\fP (since now devices can be mounted +in more than one place, so specifying the device does not suffice). +.SH NOTES +.SS umount() and shared mounts +Shared mounts cause any mount activity on a mount, including +.BR umount () +operations, to be forwarded to every shared mount in the +peer group and every slave mount of that peer group. +This means that +.BR umount () +of any peer in a set of shared mounts will cause all of its +peers to be unmounted and all of their slaves to be unmounted as well. +.PP +This propagation of unmount activity can be particularly surprising +on systems where every mount is shared by default. +On such systems, +recursively bind mounting the root directory of the filesystem +onto a subdirectory and then later unmounting that subdirectory with +.B MNT_DETACH +will cause every mount in the mount namespace to be lazily unmounted. +.PP +To ensure +.BR umount () +does not propagate in this fashion, +the mount may be remounted using a +.BR mount (2) +call with a +.I mount_flags +argument that includes both +.B MS_REC +and +.B MS_PRIVATE +prior to +.BR umount () +being called. +.SH SEE ALSO +.BR mount (2), +.BR mount_namespaces (7), +.BR path_resolution (7), +.BR mount (8), +.BR umount (8) |