diff options
Diffstat (limited to 'sys-utils/mount.8')
| -rw-r--r-- | sys-utils/mount.8 | 878 |
1 files changed, 467 insertions, 411 deletions
diff --git a/sys-utils/mount.8 b/sys-utils/mount.8 index a3a658297..073f18a7f 100644 --- a/sys-utils/mount.8 +++ b/sys-utils/mount.8 @@ -1,5 +1,6 @@ +'\" t .\" Copyright (c) 1996-2004 Andries Brouwer -.\" Copyright (C) 2006-2012 Karel Zak <kzak@redhat.com> +.\" Copyright (C) 2006-2012 Karel Zak <kzak@redhat.com> .\" .\" This page is somewhat derived from a page that was .\" (c) 1980, 1989, 1991 The Regents of the University of California @@ -35,7 +36,8 @@ mount \- mount a filesystem .B mount .RB [ \-lhV ] .LP -.BI "mount \-a +.\" Quote used to include space between arguments +.B "mount \-a .RB [ \-fFnrsvw ] .RB [ \-t .IR vfstype ] @@ -100,14 +102,14 @@ If only directory or device is given, for example: .RE then mount looks for a mountpoint and if not found then for a device in the /etc/fstab file. It's possible to use -.B --target +.B \-\-target or -.B --source +.B \-\-source options to avoid ambivalent interpretation of the given argument. For example .RS .br -.BI "mount --target /mountpoint" +.BI "mount \-\-target /mountpoint" .br .RE @@ -123,7 +125,7 @@ For more robust and definable output use mountpoint name are replaced with '?'. .TP -.BR "mount " [ -l "] [" "-t \fItype\fP" ] +.BR "mount " [ \-l "] [" "\-t \fItype\/\fP" ] lists all mounted filesystems (of type .IR type ). The option \-l adds the labels in this listing. @@ -148,8 +150,13 @@ partition .B PARTUUID or .B PARTLABEL -(partition identifiers are supported for GUID Partition Table (GPT) and MAC -partition tables only). +(partition identifiers are supported for example for GUID Partition Table (GPT) +partition tables). + +Don't forget that there is no guarantee that UUIDs and labels are really +unique, especially if you move, share or copy the device. Use +.B "lsblk \-o +UUID,PARTUUID" +to verify that the UUIDs are really unique in your system. The recommended setup is to use tags (e.g. LABEL=<label>) rather than .B /dev/disk/by-{label,uuid,partuuid,partlabel} @@ -157,7 +164,7 @@ udev symlinks in the /etc/fstab file. The tags are more readable, robust and portable. The .BR mount (8) command internally uses udev -symlinks, so use the symlinks in /etc/fstab has no advantage over the tags. +symlinks, so the use of symlinks in /etc/fstab has no advantage over the tags. For more details see .BR libblkid (3). @@ -190,7 +197,7 @@ The file may contain lines describing what devices are usually mounted where, using which options. The default location of the .BR fstab (5) -file could be overridden by --fstab <path> command line option (see below for +file could be overridden by \-\-fstab <path> command line option (see below for more details). .LP The command @@ -214,9 +221,9 @@ option will make mount fork, so that the filesystems are mounted simultaneously. .LP When mounting a filesystem mentioned in -.IR fstab +.I fstab or -.IR mtab, +.IR mtab , it suffices to give only the device, or only the mount point. @@ -249,7 +256,7 @@ If you want to override mount options from you have to use: .RS .sp -.B "mount device|dir -o <options>" +.B "mount device|dir \-o <options>" .sp .RE and then the mount options from command line will be appended to @@ -268,7 +275,7 @@ and .I /proc/mounts have very similar contents. The former has somewhat more information, such as the mount options used, -but is not necessarily up-to-date (cf. the +but is not necessarily up-to-date (cf.\& the .B \-n option below). It is possible to replace .I /etc/mtab @@ -323,7 +330,7 @@ The option is similar to the .B user option, with the restriction that the user must be the owner -of the special file. This may be useful e.g. for +of the special file. This may be useful e.g.\& for .I /dev/fd if a login script makes the console user owner of this device. The @@ -340,13 +347,13 @@ Since Linux 2.4.0 it is possible to remount part of the file hierarchy somewhere else. The call is .RS .br -.B mount --bind +.B mount \-\-bind .I olddir newdir .RE or shortoption .RS .br -.B mount -B +.B mount \-B .I olddir newdir .RE or fstab entry is: @@ -354,7 +361,7 @@ or fstab entry is: .br .I /olddir .I /newdir -.B none bind +.B none bind .RE After this call the same contents is accessible in two places. @@ -364,7 +371,7 @@ directory, for example: .RS .br -.B mount --bind +.B mount \-\-bind .I foo foo .RE @@ -374,7 +381,7 @@ a second place using .RS .br -.B mount --rbind +.B mount \-\-rbind .I olddir newdir .RE @@ -382,22 +389,22 @@ or shortoption .RS .br -.B mount -R +.B mount \-R .I olddir newdir .RE .\" available since Linux 2.4.11. Note that the filesystem mount options will remain the same as those -on the original mount point, and cannot be changed by passing the -o -option along with --bind/--rbind. The mount options can be +on the original mount point, and cannot be changed by passing the \-o +option along with \-\-bind/\-\-rbind. The mount options can be changed by a separate remount command, for example: .RS .br -.B mount --bind +.B mount \-\-bind .I olddir newdir .br -.B mount -o remount,ro +.B mount \-o remount,ro .I newdir .RE @@ -410,10 +417,10 @@ command (then mount(8) does not read /etc/mtab), then you have to use bind flag .RS .br -.B mount --bind +.B mount \-\-bind .I olddir newdir .br -.B mount -o remount,ro,bind +.B mount \-o remount,ro,bind .I olddir newdir .RE @@ -434,13 +441,13 @@ Since Linux 2.5.1 it is possible to atomically move a to another place. The call is .RS .br -.B mount --move +.B mount \-\-move .I olddir newdir .RE or shortoption .RS .br -.B mount -M +.B mount \-M .I olddir newdir .RE This will cause the contents which previously appeared under olddir to be @@ -451,7 +458,7 @@ has to be a mountpoint. Note that moving a mount residing under a shared mount is invalid and unsupported. Use -.B findmnt -o TARGET,PROPAGATION /dir +.B findmnt \-o TARGET,PROPAGATION /dir to see the current propagation flags. .RE @@ -461,7 +468,7 @@ Since Linux 2.6.15 it is possible to mark a mount and its submounts as shared, private, slave or unbindable. A shared mount provides ability to create mirrors of that mount such that mounts and umounts within any of the mirrors propagate to the other mirror. A slave mount receives propagation from its master, but -any not vice-versa. A private mount carries no propagation abilities. A +any not vice-versa. A private mount carries no propagation abilities. An unbindable mount is a private mount which cannot be cloned through a bind operation. Detailed semantics is documented in .B Documentation/filesystems/sharedsubtree.txt @@ -470,10 +477,10 @@ file in the kernel source tree. Supported operations: .RS .nf -.BI "mount --make-shared " mountpoint -.BI "mount --make-slave " mountpoint -.BI "mount --make-private " mountpoint -.BI "mount --make-unbindable " mountpoint +.BI "mount \-\-make-shared " mountpoint +.BI "mount \-\-make-slave " mountpoint +.BI "mount \-\-make-private " mountpoint +.BI "mount \-\-make-unbindable " mountpoint .fi .RE @@ -482,17 +489,17 @@ mounts under a given mountpoint. .RS .nf -.BI "mount --make-rshared " mountpoint -.BI "mount --make-rslave " mountpoint -.BI "mount --make-rprivate " mountpoint -.BI "mount --make-runbindable " mountpoint +.BI "mount \-\-make-rshared " mountpoint +.BI "mount \-\-make-rslave " mountpoint +.BI "mount \-\-make-rprivate " mountpoint +.BI "mount \-\-make-runbindable " mountpoint .fi .RE .BR mount (8) .B does not read .BR fstab (5) -when --make-* operation is requested. All necessary information has to be +when \-\-make-* operation is requested. All necessary information has to be specified on command line. Note that Linux kernel does not allow to change more propagation flags by one @@ -518,7 +525,7 @@ as mount options For example .RS .nf -.BI "mount --make-private --make-unbindable /dev/sda1 /A" +.BI "mount \-\-make-private \-\-make-unbindable /dev/sda1 /A" .fi .RE @@ -526,8 +533,8 @@ is the same as .RS .nf .BI "mount /dev/sda1 /A" -.BI "mount --make-private /A" -.BI "mount --make-unbindable /A" +.BI "mount \-\-make-private /A" +.BI "mount \-\-make-unbindable /A" .fi .RE .RE @@ -548,14 +555,17 @@ Command line options available for the .B mount command: .IP "\fB\-V, \-\-version\fP" -Output version. +Display version information and exit. .IP "\fB\-h, \-\-help\fP" -Print a help message. +Display help text and exit. .IP "\fB\-v, \-\-verbose\fP" Verbose mode. .IP "\fB\-a, \-\-all\fP" Mount all filesystems (of the given types) mentioned in -.IR fstab . +.I fstab +(except for those whose line contains the +.B noauto +keyword). .IP "\fB\-F, \-\-fork\fP" (Used in conjunction with .BR \-a .) @@ -576,53 +586,52 @@ conjunction with the flag to determine what the .B mount command is trying to do. It can also be used to add entries for devices -that were mounted earlier with the -n option. The -f option checks for +that were mounted earlier with the \-n option. The \-f option checks for existing record in /etc/mtab and fails when the record already exists (with regular non-fake mount, this check is done by kernel). -.IP "\fB\-i, \-\-internal\-only\fP" +.IP "\fB\-i, \-\-internal-only\fP" Don't call the /sbin/mount.<filesystem> helper even if it exists. -.IP "\fB\-l, \-\-show\-labels\fP" +.IP "\fB\-l, \-\-show-labels\fP" Add the labels in the mount output. Mount must have -permission to read the disk device (e.g. be suid root) for this to work. +permission to read the disk device (e.g.\& be suid root) for this to work. One can set such a label for ext2, ext3 or ext4 using the .BR e2label (8) utility, or for XFS using .BR xfs_admin (8), or for reiserfs using .BR reiserfstune (8). -.IP "\fB\-n, \-\-no\-mtab\fP" +.IP "\fB\-n, \-\-no-mtab\fP" Mount without writing in .IR /etc/mtab . This is necessary for example when .I /etc is on a read-only filesystem. -.IP "\fB\-c, \-\-no\-canonicalize\fP" -Don't canonicalize paths. The mount command canonicalizes all paths -(from command line or fstab) and stores canonicalized paths to the -.IR /etc/mtab +.IP "\fB\-c, \-\-no-canonicalize\fP" +Don't canonicalize paths. The mount command canonicalizes all paths +(from command line or fstab) and stores canonicalized paths to the +.I /etc/mtab file. This option can be used together with the .B \-f flag for already canonicalized absolute paths. .IP "\fB\-s\fP" -Tolerate sloppy mount options rather than failing. This will ignore -mount options not supported by a filesystem type. Not all filesystems -support this option. This option exists for support of the Linux -autofs\-based automounter. +Tolerate sloppy mount options rather than failing. This will ignore mount +options not supported by a filesystem type. Not all filesystems support this +option. Currently it's supported by the mount.nfs mount helper only. .IP "\fB\-\-source \fIsrc\fP" If only one argument for the mount command is given then the argument might be interpreted as target (mountpoint) or source (device). This option allows to explicitly define that the argument is mount source. -.IP "\fB\-r, \-\-read\-only\fP" +.IP "\fB\-r, \-\-read-only\fP" Mount the filesystem read-only. A synonym is .BR "\-o ro" . Note that, depending on the filesystem type, state and kernel behavior, the -system may still write to the device. For example, Ext3 or ext4 will replay its +system may still write to the device. For example, ext3 or ext4 will replay its journal if the filesystem is dirty. To prevent this kind of write access, you may want to mount ext3 or ext4 filesystem with "ro,noload" mount options or set the block device to read-only mode, see command .BR blockdev (8). -.IP "\fB\-w, \-\-rw, \-\-read\-write\fP" +.IP "\fB\-w, \-\-rw, \-\-read-write\fP" Mount the filesystem read/write. This is the default. A synonym is .BR "\-o rw" . .IP "\fB\-L, \-\-label \fIlabel\fP" @@ -638,7 +647,7 @@ These two options require the file Specifies alternative fstab file. If the \fIpath\fP is directory then the files in the directory are sorted by .BR strverscmp (3), -files that starts with "." or without .fstab extension are ignored. The option +files that starts with "."\& or without \&.fstab extension are ignored. The option can be specified more than once. This option is mostly designed for initramfs or chroot scripts where additional configuration is specified outside standard system configuration. @@ -699,7 +708,7 @@ Note that coherent, sysv and xenix are equivalent and that .I xenix and .I coherent -will be removed at some point in the future \(em use +will be removed at some point in the future \(en use .I sysv instead. Since kernel version 2.1.21 the types .I ext @@ -719,7 +728,7 @@ and support filesystem subtypes. The subtype is defined by '.subtype' suffix. For example 'fuse.sshfs'. It's recommended to use subtype notation rather than add any prefix to the mount source (for example 'sshfs#example.com' is -depreacated). +deprecated). For most types all the .B mount @@ -870,7 +879,7 @@ in the system kernel. To check the current setting see the options in /proc/mounts. The following options apply to any filesystem that is being -mounted (but not every filesystem actually honors them - e.g., the +mounted (but not every filesystem actually honors them \(en e.g.\&, the .B sync option today has effect only for ext2, ext3, fat, vfat and ufs): @@ -902,14 +911,14 @@ Can only be mounted explicitly (i.e., the .B \-a option will not cause the filesystem to be mounted). .TP -\fBcontext=\fP\fIcontext\fP, \fBfscontext=\fP\fIcontext\fP, \fBdefcontext=\fP\fIcontext\fP and \fBrootcontext=\fP\fIcontext\fP +\fBcontext=\fP\,\fIcontext\fP, \fBfscontext=\fP\,/\fIcontext\fP, \fBdefcontext=\fP\,/\fIcontext\fP and \fBrootcontext=\fP\,\fIcontext\fP The -.BR context= +.B context= option is useful when mounting filesystems that do not support extended attributes, such as a floppy or hard disk formatted with VFAT, or systems that are not normally running under SELinux, such as an ext3 formatted disk from a non-SELinux workstation. You can also use -.BR context= +.B context= on filesystems you do not trust, such as a floppy. It also helps in compatibility with xattr-supporting filesystems on earlier 2.4.<x> kernel versions. Even where xattrs are supported, you can save time not having to label every file by @@ -919,7 +928,7 @@ A commonly used option for removable media is .BR context="system_u:object_r:removable_t" . Two other options are -.BR fscontext= +.B fscontext= and .BR defcontext= , both of which are mutually exclusive of the context option. This means you @@ -927,7 +936,7 @@ can use fscontext and defcontext with each other, but neither can be used with context. The -.BR fscontext= +.B fscontext= option works for all filesystems, regardless of their xattr support. The fscontext option sets the overarching filesystem label to a specific security context. This filesystem label is separate from the @@ -939,35 +948,37 @@ fscontext provides, in addition to supplying the same label for individual files. You can set the default security context for unlabeled files using -.BR defcontext= +.B defcontext= option. This overrides the value set for unlabeled files in the policy and requires a filesystem that supports xattr labeling. The -.BR rootcontext= +.B rootcontext= option allows you to explicitly label the root inode of a FS being mounted -before that FS or inode because visible to userspace. This was found to be +before that FS or inode becomes visible to userspace. This was found to be useful for things like stateless linux. -Note that kernel rejects any remount request that includes the context -option even if unchanged from the current context. +Note that the kernel rejects any remount request that includes the context +option, \fBeven\fP when unchanged from the current context. -.B Warning that \fIcontext\fP value might contains comma -and in this case the value has to be properly quoted otherwise +.BR "Warning: the \fIcontext\fP value might contain commas" , +in which case the value has to be properly quoted, otherwise .BR mount (8) -will interpret the comma as separator between mount options. Don't forget that -shell strips off quotes and -.BR "double quoting is required" , -for example: +will interpret the comma as a separator between mount options. Don't forget that +the shell strips off quotes and thus +.BR "double quoting is required" . +For example: .RS .RS .sp -mount -t tmpfs none /mnt \-o 'context="system_u:object_r:tmp_t:s0:c127,c456",noexec' +.nf +.B mount \-t tmpfs none /mnt \-o \e +.B 'context="system_u:object_r:tmp_t:s0:c127,c456",noexec' +.fi .sp .RE - For more details, see -.BR selinux (8) +.BR selinux (8). .RE .TP @@ -1071,8 +1082,7 @@ effect. .TP .B nosuid Do not allow set-user-identifier or set-group-identifier bits to take -effect. (This seems safe, but is in fact rather unsafe if you have -suidperl(1) installed.) +effect. .TP .B silent Turn on the silent flag. @@ -1096,22 +1106,22 @@ readonly filesystem writable. It does not change device or mount point. The remount functionality follows the standard way how the mount command works with options from fstab. It means the mount command doesn't read fstab (or mtab) only when a -.IR device +.I device and -.IR dir +.I dir are fully specified. -.BR "mount -o remount,rw /dev/foo /dir" +.B "mount \-o remount,rw /dev/foo /dir" After this call all old mount options are replaced and arbitrary stuff from fstab is ignored, except the loop= option which is internally generated and maintained by the mount command. -.BR "mount -o remount,rw /dir" +.B "mount \-o remount,rw /dir" After this call mount reads fstab (or mtab) and merges these options with -options from command line ( -.B -o +options from command line (\c +.B \-o\c ). .TP .B ro @@ -1122,7 +1132,7 @@ Mount the filesystem read-write. .TP .B sync All I/O to the filesystem should be done synchronously. In case of media with limited number of write cycles -(e.g. some flash drives) "sync" may cause life-cycle shortening. +(e.g.\& some flash drives) "sync" may cause life-cycle shortening. .TP .B user Allow an ordinary user to mount the filesystem. @@ -1148,13 +1158,13 @@ This option implies the options All options prefixed with "x-" are interpreted as comments or userspace applications specific options. These options are not stored to mtab file, send to mount.<type> helpers or -.B mount(2) -system call. The suggested format is x-<appname>.<option> (e.g. x-systemd.automount). +.BR mount (2) +system call. The suggested format is x-<appname>.<option> (e.g.\& x-systemd.automount). .TP .B x-mount.mkdir[=<mode>] Allow to make a target directory (mountpoint). The optional argument <mode> specifies the file system access mode used for -.B mkdir (2) +.BR mkdir (2) in octal notation. The default mode is 0755. This functionality is supported only for root users. @@ -1170,17 +1180,17 @@ More info may be found in the kernel source subdirectory .SH "Mount options for adfs" .TP -\fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP +\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP Set the owner and group of the files in the filesystem (default: uid=gid=0). .TP -\fBownmask=\fP\fIvalue\fP and \fBothmask=\fP\fIvalue\fP +\fBownmask=\fP\,\fIvalue\fP and \fBothmask=\fP\,\fIvalue\fP Set the permission mask for ADFS 'owner' permissions and 'other' permissions, respectively (default: 0700 and 0077, respectively). See also .IR /usr/src/linux/Documentation/filesystems/adfs.txt . .SH "Mount options for affs" .TP -\fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP +\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP Set the owner and group of the root of the filesystem (default: uid=gid=0, but with option .B uid @@ -1188,7 +1198,7 @@ or .B gid without specified value, the uid and gid of the current process are taken). .TP -\fBsetuid=\fP\fIvalue\fP and \fBsetgid=\fP\fIvalue\fP +\fBsetuid=\fP\,\fIvalue\fP and \fBsetgid=\fP\,\fIvalue\fP Set the owner and group of all files. .TP .BI mode= value @@ -1258,7 +1268,7 @@ the number of the pseudo terminal is then made available to the process and the pseudo terminal slave can be accessed as .IR /dev/pts/ <number>. .TP -\fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP +\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP This sets the owner or the group of newly created PTYs to the specified values. When nothing is specified, they will be set to the UID and GID of the creating process. @@ -1294,33 +1304,33 @@ only if CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the kernel configuration. To use this option effectively, -.IR /dev/ptmx +.I /dev/ptmx must be a symbolic link to -.IR pts/ptmx. +.I pts/ptmx. See -.IR Documentation/filesystems/devpts.txt +.I Documentation/filesystems/devpts.txt in the linux kernel source tree for details. .TP .BI ptmxmode= value Set the mode for the new -.IR ptmx +.I ptmx device node in the devpts filesystem. With the support for multiple instances of devpts (see .B newinstance option above), each instance has a private -.IR ptmx +.I ptmx node in the root of the devpts filesystem (typically -.IR /dev/pts/ptmx). +.IR /dev/pts/ptmx ). For compatibility with older versions of the kernel, the default mode of the new -.IR ptmx +.I ptmx node is 0000. .BI ptmxmode= value specifies a more useful mode for the -.IR ptmx +.I ptmx node and is highly recommended when the .B newinstance option is specified. @@ -1358,16 +1368,25 @@ field the total number of blocks of the filesystem, while the .B bsddf behaviour (which is the default) is to subtract the overhead blocks used by the ext2 filesystem and not available for file storage. Thus -.nf - -% mount /k -o minixdf; df /k; umount /k -Filesystem 1024-blocks Used Available Capacity Mounted on -/dev/sda6 2630655 86954 2412169 3% /k -% mount /k -o bsddf; df /k; umount /k -Filesystem 1024-blocks Used Available Capacity Mounted on -/dev/sda6 2543714 13 2412169 0% /k - -.fi +.sp 1 +% mount /k \-o minixdf; df /k; umount /k +.TS +tab(#); +l2 l2 r2 l2 l2 l +l c r c c l. +Filesystem#1024-blocks#Used#Available#Capacity#Mounted on +/dev/sda6#2630655#86954#2412169#3%#/k +.TE +.sp 1 +% mount /k \-o bsddf; df /k; umount /k +.TS +tab(#); +l2 l2 r2 l2 l2 l +l c r c c l. +Filesystem#1024-blocks#Used#Available#Capacity#Mounted on +/dev/sda6#2543714#13#2412169#0%#/k +.TE +.sp 1 (Note that this example shows that one can add command line options to the options given in .IR /etc/fstab .) @@ -1377,7 +1396,7 @@ to the options given in No checking is done at mount time. This is the default. This is fast. It is wise to invoke .BR e2fsck (8) -every now and then, e.g. at boot time. The non-default behavior is unsupported +every now and then, e.g.\& at boot time. The non-default behavior is unsupported (check=normal and check=strict options have been removed). Note that these mount options don't have to be supported if ext4 kernel driver is used for ext2 and ext3 filesystems. .TP @@ -1395,7 +1414,7 @@ changed using .BR grpid | bsdgroups " and " nogrpid | sysvgroups These options define what group id a newly created file gets. When -.BR grpid +.B grpid is set, it takes the group id of the directory in which it is created; otherwise (the default) it takes the fsgid of the current process, unless the directory has the setgid bit set, in which case it takes the gid @@ -1407,14 +1426,14 @@ The usrquota (same as quota) mount option enables user quota support on the filesystem. grpquota enables group quotas support. You need the quota utilities to actually enable and manage the quota system. .TP -.BR nouid32 +.B nouid32 Disables 32-bit UIDs and GIDs. This is for interoperability with older kernels which only store and expect 16-bit values. .TP .BR oldalloc " or " orlov Use old allocator or Orlov allocator for new inodes. Orlov is default. .TP -\fBresgid=\fP\fIn\fP and \fBresuid=\fP\fIn\fP +\fBresgid=\fP\,\fIn\fP and \fBresuid=\fP\,\fIn\fP The ext2 filesystem reserves a certain percentage of the available space (by default 5%, see .BR mke2fs (8) @@ -1428,7 +1447,7 @@ Instead of block 1, use block .I n as superblock. This could be useful when the filesystem has been damaged. (Earlier, copies of the superblock would be made every 8192 blocks: in -block 1, 8193, 16385, ... (and one got thousands of copies on +block 1, 8193, 16385, \&...\& (and one got thousands of copies on a big filesystem). Since version 1.08, .B mke2fs has a \-s (sparse superblock) option to reduce the number of backup @@ -1436,8 +1455,8 @@ superblocks, and since version 1.15 this is the default. Note that this may mean that ext2 filesystems created by a recent .B mke2fs cannot be mounted r/w under Linux 2.0.*.) -The block number here uses 1k units. Thus, if you want to use logical -block 32768 on a filesystem with 4k blocks, use "sb=131072". +The block number here uses 1\ k units. Thus, if you want to use logical +block 32768 on a filesystem with 4\ k blocks, use "sb=131072". .TP .BR user_xattr | nouser_xattr Support "user." extended attributes (or not). @@ -1452,22 +1471,22 @@ well as the following additions: .\" .BR abort .\" Mount the filesystem in abort mode, as if a fatal error has occurred. .TP -.BR journal=update +.B journal=update Update the ext3 filesystem's journal to the current format. .TP -.BR journal=inum +.B journal=inum When a journal already exists, this option is ignored. Otherwise, it specifies the number of the inode which will represent the ext3 filesystem's -journal file; ext3 will create a new journal, overwriting the old contents +journal file; ext3 will create a new journal, overwriting the old contents of the file whose inode number is .IR inum . .TP -.BR journal_dev=devnum +.BR journal_dev=devnum / journal_path=path When the external journal device's major/minor numbers -have changed, this option allows the user to specify +have changed, these options allow the user to specify the new journal location. The journal device is -identified through its new major/minor numbers encoded -in devnum. +identified either through its new major/minor numbers encoded +in devnum, or via a path to the device. .TP .BR norecovery / noload Don't load the journal on mounting. Note that @@ -1480,7 +1499,7 @@ lead to any number of problems. Specifies the journaling mode for file data. Metadata is always journaled. To use modes other than .B ordered -on the root filesystem, pass the mode to the kernel as boot parameter, e.g. +on the root filesystem, pass the mode to the kernel as boot parameter, e.g.\& .IR rootflags=data=journal . .RS .TP @@ -1493,32 +1512,40 @@ This is the default mode. All data is forced directly out to the main file system prior to its metadata being committed to the journal. .TP .B writeback -Data ordering is not preserved - data may be written into the main +Data ordering is not preserved \(en data may be written into the main filesystem after its metadata has been committed to the journal. This is rumoured to be the highest-throughput option. It guarantees internal filesystem integrity, however it can allow old data to appear in files after a crash and journal recovery. .RE .TP -.BR barrier=0 " / " barrier=1 " -This enables/disables barriers. barrier=0 disables it, barrier=1 enables it. -Write barriers enforce proper on-disk ordering of journal commits, making -volatile disk write caches safe to use, at some performance penalty. The ext3 -filesystem does not enable write barriers by default. Be sure to enable -barriers unless your disks are battery-backed one way or another. Otherwise -you risk filesystem corruption in case of power failure. +.B data_err=ignore +Just print an error message if an error occurs in a file data buffer in +ordered mode. +.TP +.B data_err=abort +Abort the journal if an error occurs in a file data buffer in ordered mode. +.TP +.BR barrier=0 " / " barrier=1 " +This disables / enables the use of write barriers in the jbd code. barrier=0 +disables, barrier=1 enables (default). This also requires an IO stack which can +support barriers, and if jbd gets an error on a barrier write, it will disable +barriers again with a warning. Write barriers enforce proper on-disk ordering +of journal commits, making volatile disk write caches safe to use, at some +performance penalty. If your disks are battery-backed in one way or another, +disabling barriers may safely improve performance. .TP .BI commit= nrsec Sync all data and metadata every .I nrsec seconds. The default value is 5 seconds. Zero means default. .TP -.BR user_xattr +.B user_xattr Enable Extended User Attributes. See the .BR attr (5) manual page. .TP -.BR acl +.B acl Enable POSIX Access Control Lists. See the .BR acl (5) manual page. @@ -1537,32 +1564,26 @@ incorporates scalability and reliability enhancements for supporting large filesystem. The options -.B journal_dev, noload, data, commit, orlov, oldalloc, [no]user_xattr +.B journal_dev, norecovery, noload, data, commit, orlov, oldalloc, [no]user_xattr .B [no]acl, bsddf, minixdf, debug, errors, data_err, grpid, bsdgroups, nogrpid .B sysvgroups, resgid, resuid, sb, quota, noquota, grpquota, usrquota .B usrjquota, grpjquota and jqfmt are backwardly compatible with ext3 or ext2. .TP -.BR journal_checksum +.B journal_checksum Enable checksumming of the journal transactions. This will allow the recovery code in e2fsck and the kernel to detect corruption in the kernel. It is a compatible change and will be ignored by older kernels. .TP -.BR journal_async_commit +.B journal_async_commit Commit block can be written to disk without waiting for descriptor blocks. If enabled older kernels cannot mount the device. This will enable 'journal_checksum' internally. .TP -.BR barrier=0 " / " barrier=1 " / " barrier " / " nobarrier -This enables/disables the use of write barriers in the jbd code. barrier=0 -disables, barrier=1 enables. This also requires an IO stack which can support -barriers, and if jbd gets an error on a barrier write, it will disable again -with a warning. Write barriers enforce proper on-disk ordering of journal -commits, making volatile disk write caches safe to use, at some performance -penalty. If your disks are battery-backed in one way or another, disabling -barriers may safely improve performance. The mount options "barrier" and -"nobarrier" can also be used to enable or disable barriers, for consistency -with other ext4 mount options. +.BR barrier=0 " / " barrier=1 " / " barrier " / " nobarrier +These mount options have the same effect as in ext3. The mount options +"barrier" and "nobarrier" are added for consistency with other ext4 mount +options. The ext4 filesystem enables write barriers by default. .TP @@ -1576,10 +1597,10 @@ Number of filesystem blocks that mballoc will try to use for allocation size and alignment. For RAID5/6 systems this should be the number of data disks * RAID chunk size in filesystem blocks. .TP -.BR delalloc +.B delalloc Deferring block allocation until write-out time. .TP -.BR nodelalloc +.B nodelalloc Disable delayed allocation. Blocks are allocated when data is copied from user to page cache. .TP @@ -1595,7 +1616,7 @@ takes to finish committing a transaction. Call this time the "commit time". If the time that the transaction has been running is less than the commit time, ext4 will try sleeping for the commit time to see if other operations will join the transaction. The commit time is capped by the max_batch_time, which -defaults to 15000us (15ms). This optimization can be turned off entirely by +defaults to 15000\ \[mc]s (15\ ms). This optimization can be turned off entirely by setting max_batch_time to 0. .TP .BI min_batch_time= usec @@ -1610,7 +1631,7 @@ used for I/O operations submitted by kjournald2 during a commit operation. This defaults to 3, which is a slightly higher priority than the default I/O priority. .TP -.BR abort +.B abort Simulate the effects of calling ext4_abort() for debugging purposes. This is normally used while remounting a filesystem which is already mounted. @@ -1619,11 +1640,11 @@ remounting a filesystem which is already mounted. Many broken applications don't use fsync() when replacing existing files via patterns such as -fd = open("foo.new")/write(fd,..)/close(fd)/ rename("foo.new", "foo") +fd = open("foo.new")/write(fd,...)/close(fd)/ rename("foo.new", "foo") or worse yet -fd = open("foo", O_TRUNC)/write(fd,..)/close(fd). +fd = open("foo", O_TRUNC)/write(fd,...)/close(fd). If auto_da_alloc is enabled, ext4 will detect the replace-via-rename and replace-via-truncate patterns and force that any delayed allocation blocks are @@ -1633,26 +1654,31 @@ operation is committed. This provides roughly the same level of guarantees as ext3, and avoids the "zero-length" problem that can happen when a system crashes before the delayed allocation blocks are forced to disk. .TP +.B noinit_itable +Do not initialize any uninitialized inode table blocks in the background. This +feature may be used by installation CD's so that the install process can +complete as quickly as possible; the inode table initialization process would +then be deferred until the next time the filesystem is mounted. +.TP +.B init_itable=n +The lazy itable init code will wait n times the number of milliseconds it took +to zero out the previous block group's inode table. This minimizes the impact on +system performance while the filesystem's inode table is being initialized. +.TP .BR discard / nodiscard Controls whether ext4 should issue discard/TRIM commands to the underlying block device when blocks are freed. This is useful for SSD devices and sparse/thinly-provisioned LUNs, but it is off by default until sufficient testing has been done. .TP -.BR nouid32 +.B nouid32 Disables 32-bit UIDs and GIDs. This is for interoperability with older kernels which only store and expect 16-bit values. .TP -.BR resize -Allows to resize filesystem to the end of the last -existing block group, further resize has to be done -with resize2fs either online, or offline. It can be -used only with conjunction with remount. -.TP .BR block_validity / noblock_validity This options allows to enables/disables the in-kernel facility for tracking -filesystem metadata blocks within internal data structures. This allows multi- +filesystem metadata blocks within internal data structures. This allows multi-\c block allocator and other routines to quickly locate extents which might overlap with filesystem metadata blocks. This option is intended for debugging purposes and since it negatively affects the performance, it is off by default. @@ -1666,9 +1692,17 @@ scalability on high speed storages. However this does not work with data journaling and dioread_nolock option will be ignored with kernel warning. Note that dioread_nolock code path is only used for extent-based files. Because of the restrictions this options comprises it is off by default -(e.g. dioread_lock). +(e.g.\& dioread_lock). .TP -.BR i_version +.B max_dir_size_kb=n +This limits the size of the directories so that any attempt to expand them +beyond the specified limit in kilobytes will cause an ENOSPC error. This is +useful in memory-constrained environments, where a very large directory can +cause severe performance problems or even provoke the Out Of Memory killer. (For +example, if there is only 512\ MB memory available, a 176\ MB directory may +seriously cramp the system's style.) +.TP +.B i_version Enable 64-bit inode version support. This option is off by default. .SH "Mount options for fat" @@ -1684,7 +1718,7 @@ filesystems.) .BR blocksize= { 512 | 1024 | 2048 } Set blocksize (default 512). This option is obsolete. .TP -\fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP +\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP Set the owner and group of all files. (Default: the uid and gid of the current process.) .TP @@ -1718,7 +1752,7 @@ Other users can change timestamp. .PP The default is set from `dmask' option. (If the directory is writable, .BR utime (2) -is also allowed. I.e. ~dmask & 022) +is also allowed. I.e.\& \s+3~\s0dmask & 022) Normally .BR utime (2) @@ -1728,12 +1762,12 @@ normal check is too inflexible. With this option you can relax it. .RE .TP .BI check= value -Three different levels of pickyness can be chosen: +Three different levels of pickiness can be chosen: .RS .TP .BR r [ elaxed ] Upper and lower case are accepted and equivalent, long name parts are -truncated (e.g. +truncated (e.g.\& .I verylongname.foobar becomes .IR verylong.foo ), @@ -1835,7 +1869,7 @@ although they fail. Use with caution! .TP .B showexec If set, the execute permission bits of the file will be allowed only if -the extension part of the name is .EXE, .COM, or .BAT. Not set by default. +the extension part of the name is \&.EXE, \&.COM, or \&.BAT. Not set by default. .TP .B sys_immutable If set, ATTR_SYS attribute on FAT is handled as IMMUTABLE flag on Linux. @@ -1886,7 +1920,7 @@ Don't complain about invalid mount options. .SH "Mount options for hpfs" .TP -\fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP +\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP Set the owner and group of all files. (Default: the uid and gid of the current process.) .TP @@ -1955,7 +1989,7 @@ and (Default: .BR check=strict .) .TP -\fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP +\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP Give all files in the filesystem the indicated user or group id, possibly overriding the information found in the Rock Ridge extensions. (Default: @@ -1972,12 +2006,12 @@ no name translation is done. See .BR map=normal .) .B map=acorn is like -.BR map=normal +.B map=normal but also apply Acorn extensions if present. .TP .BI mode= value For non-Rock Ridge volumes, give all files the indicated mode. -(Default: read permission for everybody.) +(Default: read and execute permission for everybody.) Since Linux 2.1.37 one no longer needs to specify the mode in decimal. (Octal is indicated by a leading 0.) .TP @@ -2001,7 +2035,7 @@ possibly leading to silent data corruption.) .B cruft If the high byte of the file length contains other garbage, set this mount option to ignore the high order bits of the file length. -This implies that a file cannot be larger than 16MB. +This implies that a file cannot be larger than 16\ MB. .TP .BI session= x Select number of session on multisession CD. (Since 2.3.4.) @@ -2107,7 +2141,7 @@ New name for the option earlier called .IR iocharset . .\" since 2.5.11 .TP -.BR utf8 +.B utf8 Use UTF-8 for converting file names. .TP .BR uni_xlate= { 0 | 1 | 2 } @@ -2122,14 +2156,14 @@ If enabled (posix=1), the filesystem distinguishes between upper and lower case. The 8.3 alias names are presented as hard links instead of being suppressed. This option is obsolete. .TP -\fBuid=\fP\fIvalue\fP, \fBgid=\fP\fIvalue\fP and \fBumask=\fP\fIvalue\fP +\fBuid=\fP\,\fIvalue\fP, \fBgid=\fP\,\fIvalue\fP and \fBumask=\fP\,\fIvalue\fP Set the file permission on the filesystem. The umask value is given in octal. By default, the files are owned by root and not readable by somebody else. .SH "Mount options for proc" .TP -\fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP +\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP These options are recognized, but have no effect as far as I can see. .SH "Mount options for ramfs" @@ -2140,7 +2174,7 @@ There are no mount options. .SH "Mount options for reiserfs" Reiserfs is a journaling filesystem. .TP -.BR conv +.B conv Instructs version 3.6 reiserfs software to mount a version 3.5 filesystem, using the 3.6 format for newly created objects. This filesystem will no longer be compatible with reiserfs 3.5 tools. @@ -2168,41 +2202,41 @@ unusual file-name patterns. .TP .B detect Instructs -.IR mount +.I mount to detect which hash function is in use by examining -the filesystem being mounted, and to write this information into +the filesystem being mounted, and to write this information into the reiserfs superblock. This is only useful on the first mount of an old format filesystem. .RE .TP -.BR hashed_relocation +.B hashed_relocation Tunes the block allocator. This may provide performance improvements in some situations. .TP -.BR no_unhashed_relocation +.B no_unhashed_relocation Tunes the block allocator. This may provide performance improvements in some situations. .TP -.BR noborder +.B noborder Disable the border allocator algorithm invented by Yury Yu. Rupasov. This may provide performance improvements in some situations. .TP -.BR nolog +.B nolog Disable journaling. This will provide slight performance improvements in some situations at the cost of losing reiserfs's fast recovery from crashes. Even with this option turned on, reiserfs still performs all journaling operations, save for actual writes into its journaling area. Implementation of -.IR nolog +.I nolog is a work in progress. .TP -.BR notail +.B notail By default, reiserfs stores small files and `file tails' directly into its tree. This confuses some utilities such as .BR LILO (8). This option is used to disable packing of files into the tree. .TP -.BR replayonly +.B replayonly Replay the transactions which are in the journal, but do not actually mount the filesystem. Mainly used by .IR reiserfsck . @@ -2219,24 +2253,24 @@ There is a special utility which can be obtained from .IR ftp://ftp.namesys.com/pub/reiserfsprogs . .TP -.BR user_xattr +.B user_xattr Enable Extended User Attributes. See the .BR attr (5) manual page. .TP -.BR acl +.B acl Enable POSIX Access Control Lists. See the .BR acl (5) manual page. .TP -.BR barrier=none " / " barrier=flush " -This enables/disables the use of write barriers in the journaling code. -barrier=none disables it, barrier=flush enables it. Write barriers enforce +.BR barrier=none " / " barrier=flush " +This disables / enables the use of write barriers in the journaling code. +barrier=none disables, barrier=flush enables (default). This also requires an +IO stack which can support barriers, and if reiserfs gets an error on a barrier +write, it will disable barriers again with a warning. Write barriers enforce proper on-disk ordering of journal commits, making volatile disk write caches -safe to use, at some performance penalty. The reiserfs filesystem does not -enable write barriers by default. Be sure to enable barriers unless your disks -are battery-backed one way or another. Otherwise you risk filesystem -corruption in case of power failure. +safe to use, at some performance penalty. If your disks are battery-backed in +one way or another, disabling barriers may safely improve performance. .SH "Mount options for romfs" None. @@ -2276,7 +2310,7 @@ is half of the number of your physical RAM pages, or (on a machine with highmem) the number of lowmem RAM pages, whichever is the lower. .PP -The tmpfs mount options for sizing ( +The tmpfs mount options for sizing (\c .BR size , .BR nr_blocks , and @@ -2286,7 +2320,7 @@ accept a suffix .B m or .B g -for Ki, Mi, Gi (binary kilo, mega and giga) and can be changed on remount. +for Ki, Mi, Gi (binary kilo (kibi), binary mega (mebi) and binary giga (gibi)) and can be changed on remount. .TP .B mode= @@ -2300,8 +2334,8 @@ The group id. .TP .B mpol=[default|prefer:Node|bind:NodeList|interleave|interleave:NodeList] Set the NUMA memory allocation policy for all files in that -instance (if the kernel CONFIG_NUMA is enabled) - which can be adjusted on the -fly via 'mount -o remount ...' +instance (if the kernel CONFIG_NUMA is enabled) \(en which can be adjusted on the +fly via 'mount \-o remount \&...' .RS .TP .B default @@ -2320,8 +2354,8 @@ prefers to allocate from each node in turn allocates from each node of NodeList in turn. .PP The NodeList format is a comma-separated list of decimal numbers and ranges, a -range being two hyphen-separated decimal numbers, the smallest and largest node -numbers in the range. For example, mpol=bind:0-3,5,7,9-15 +range being two "hyphen-minus"-separated decimal numbers, the smallest and largest node +numbers in the range. For example, mpol=bind:0\(en3,5,7,9\(en15 Note that trying to mount a tmpfs with an mpol option will fail if the running kernel does not support NUMA; and will fail if its nodelist @@ -2330,7 +2364,7 @@ tmpfs being mounted, but from time to time runs a kernel built without NUMA capability (perhaps a safe recovery kernel), or with fewer nodes online, then it is advisable to omit the mpol option from automatic mount options. It can be added later, when the tmpfs is already mounted -on MountPoint, by 'mount -o remount,mpol=Policy:NodeList MountPoint'. +on MountPoint, by 'mount \-o remount,mpol=Policy:NodeList MountPoint'. .SH "Mount options for ubifs" UBIFS is a flash file system which works on top of UBI volumes. Note that @@ -2371,19 +2405,19 @@ separator may be used instead of .TP The following mount options are available: .TP -.BR bulk_read +.B bulk_read Enable bulk-read. VFS read-ahead is disabled because it slows down the file system. Bulk-Read is an internal optimization. Some flashes may read faster if the data are read at one go, rather than at several read requests. For example, OneNAND can do "read-while-load" if it reads more than one NAND page. .TP -.BR no_bulk_read +.B no_bulk_read Do not bulk-read. This is the default. .TP -.BR chk_data_crc +.B chk_data_crc Check data CRC-32 checksums. This is the default. .TP -.BR no_chk_data_crc. +.BR no_chk_data_crc . Do not check data CRC-32 checksums. With this option, the filesystem does not check CRC-32 checksum for data, but it does check it for the internal indexing information. This option only affects reading, not writing. CRC-32 is always @@ -2469,7 +2503,7 @@ Old format of ufs, this is the default, read only. (Don't forget to give the \-r option.) .TP .B 44bsd -For filesystems created by a BSD-like system (NetBSD,FreeBSD,OpenBSD). +For filesystems created by a BSD-like system (NetBSD, FreeBSD, OpenBSD). .TP .B ufs2 Used in FreeBSD 5.x supported as read-write. @@ -2532,7 +2566,7 @@ Translate unhandled Unicode characters to special escaped sequences. This lets you backup and restore filenames that are created with any Unicode characters. Without this option, a '?' is used when no translation is possible. The escape character is ':' because it is -otherwise illegal on the vfat filesystem. The escape sequence +otherwise invalid on the vfat filesystem. The escape sequence that gets used, where u is the unicode character, is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12). .TP @@ -2543,7 +2577,7 @@ This option is obsolete. .B nonumtail First try to make a short name without sequence number, before trying -.IR name~num.ext . +.IR name\s+3~\s0num.ext . .TP .B utf8 UTF8 is the filesystem safe 8-bit encoding of Unicode that is used by the @@ -2579,15 +2613,15 @@ all upper case. This mode is the default since Linux 2.6.32. .SH "Mount options for usbfs" .TP -\fBdevuid=\fP\fIuid\fP and \fBdevgid=\fP\fIgid\fP and \fBdevmode=\fP\fImode\fP +\fBdevuid=\fP\,\fIuid\fP and \fBdevgid=\fP\,\fIgid\fP and \fBdevmode=\fP\,\fImode\fP Set the owner and group and mode of the device files in the usbfs filesystem (default: uid=gid=0, mode=0644). The mode is given in octal. .TP -\fBbusuid=\fP\fIuid\fP and \fBbusgid=\fP\fIgid\fP and \fBbusmode=\fP\fImode\fP +\fBbusuid=\fP\,\fIuid\fP and \fBbusgid=\fP\,\fIgid\fP and \fBbusmode=\fP\,\fImode\fP Set the owner and group and mode of the bus directories in the usbfs filesystem (default: uid=gid=0, mode=0555). The mode is given in octal. .TP -\fBlistuid=\fP\fIuid\fP and \fBlistgid=\fP\fIgid\fP and \fBlistmode=\fP\fImode\fP +\fBlistuid=\fP\,\fIuid\fP and \fBlistgid=\fP\,\fIgid\fP and \fBlistmode=\fP\,\fImode\fP Set the owner and group and mode of the file .I devices (default: uid=gid=0, mode=0444). The mode is given in octal. @@ -2597,198 +2631,200 @@ None. .SH "Mount options for xfs" .TP -.BI allocsize= size +.B allocsize=size Sets the buffered I/O end-of-file preallocation size when -doing delayed allocation writeout (default size is 64KiB). -Valid values for this option are page size (typically 4KiB) -through to 1GiB, inclusive, in power-of-2 increments. +doing delayed allocation writeout (default size is 64\ KiB). +Valid values for this option are page size (typically 4\ KiB) +through to 1\ GiB, inclusive, in power-of-2 increments. +.sp +The default behaviour is for dynamic end-of-file +preallocation size, which uses a set of heuristics to +optimise the preallocation size based on the current +allocation patterns within the file and the access patterns +to the file. Specifying a fixed allocsize value turns off +the dynamic behaviour. .TP .BR attr2 | noattr2 -The options enable/disable (default is enabled) an "opportunistic" -improvement to be made in the way inline extended attributes are -stored on-disk. -When the new form is used for the first time (by setting or -removing extended attributes) the on-disk superblock feature -bit field will be updated to reflect this format being in use. -.TP -.B barrier -Enables the use of block layer write barriers for writes into -the journal and unwritten extent conversion. This allows for -drive level write caching to be enabled, for devices that -support write barriers. -.TP -.B dmapi -Enable the DMAPI (Data Management API) event callouts. -Use with the -.B mtpt -option. -.TP -.BR grpid | bsdgroups " and " nogrpid | sysvgroups -These options define what group ID a newly created file gets. -When grpid is set, it takes the group ID of the directory in -which it is created; otherwise (the default) it takes the fsgid -of the current process, unless the directory has the setgid bit -set, in which case it takes the gid from the parent directory, -and also gets the setgid bit set if it is a directory itself. -.TP -.BI ihashsize= value -Sets the number of hash buckets available for hashing the -in-memory inodes of the specified mount point. If a value -of zero is used, the value selected by the default algorithm -will be displayed in -.IR /proc/mounts . +The options enable/disable an "opportunistic" improvement to +be made in the way inline extended attributes are stored +on-disk. When the new form is used for the first time when +attr2 is selected (either when setting or removing extended +attributes) the on-disk superblock feature bit field will be +updated to reflect this format being in use. +.sp +The default behaviour is determined by the on-disk feature +bit indicating that attr2 behaviour is active. If either +mount option it set, then that becomes the new default used +by the filesystem. +.sp +CRC enabled filesystems always use the attr2 format, and so +will reject the noattr2 mount option if it is set. +.TP +.BR barrier | nobarrier +Enables/disables the use of block layer write barriers for +writes into the journal and for data integrity operations. +This allows for drive level write caching to be enabled, for +devices that support write barriers. +.TP +.BR discard | nodiscard +Enable/disable the issuing of commands to let the block +device reclaim space freed by the filesystem. This is +useful for SSD devices, thinly provisioned LUNs and virtual +machine images, but may have a performance impact. +.sp +Note: It is currently recommended that you use the fstrim +application to discard unused blocks rather than the discard +mount option because the performance impact of this option +is quite severe. +.TP +.BR grpid | bsdgroups | nogrpid | sysvgroups +These options define what group ID a newly created file +gets. When grpid is set, it takes the group ID of the +directory in which it is created; otherwise it takes the +fsgid of the current process, unless the directory has the +setgid bit set, in which case it takes the gid from the +parent directory, and also gets the setgid bit set if it is +a directory itself. +.TP +.B filestreams +Make the data allocator use the filestreams allocation mode +across the entire filesystem rather than just on directories +configured to use it. .TP .BR ikeep | noikeep -When inode clusters are emptied of inodes, keep them around -on the disk (ikeep) - this is the traditional XFS behaviour -and is still the default for now. Using the noikeep option, -inode clusters are returned to the free space pool. -.TP -.B inode64 -Indicates that XFS is allowed to create inodes at any location -in the filesystem, including those which will result in inode -numbers occupying more than 32 bits of significance. This is -provided for backwards compatibility, but causes problems for -backup applications that cannot handle large inode numbers. -.TP -.BR largeio | nolargeio -If -.B nolargeio -is specified, the optimal I/O reported in -st_blksize by -.BR stat (2) -will be as small as possible to allow user -applications to avoid inefficient read/modify/write I/O. -If -.B largeio -is specified, a filesystem that has a -.B swidth -specified -will return the -.B swidth -value (in bytes) in st_blksize. If the -filesystem does not have a -.B swidth -specified but does specify -an -.B allocsize -then -.B allocsize -(in bytes) will be returned -instead. -If neither of these two options are specified, then filesystem -will behave as if -.B nolargeio -was specified. -.TP -.BI logbufs= value -Set the number of in-memory log buffers. Valid numbers range -from 2-8 inclusive. -The default value is 8 buffers for any recent kernel. -.TP -.BI logbsize= value -Set the size of each in-memory log buffer. -Size may be specified in bytes, or in kilobytes with a "k" suffix. -Valid sizes for version 1 and version 2 logs are 16384 (16k) and -32768 (32k). Valid sizes for version 2 logs also include -65536 (64k), 131072 (128k) and 262144 (256k). -The default value for any recent kernel is 32768. -.TP -\fBlogdev=\fP\fIdevice\fP and \fBrtdev=\fP\fIdevice\fP +When ikeep is specified, XFS does not delete empty inode +clusters and keeps them around on disk. When noikeep is +specified, empty inode clusters are returned to the free +space pool. +.TP +.BR inode32 | inode64 +When inode32 is specified, it indicates that XFS limits +inode creation to locations which will not result in inode +numbers with more than 32 bits of significance. +.sp +When inode64 is specified, it indicates that XFS is allowed +to create inodes at any location in the filesystem, +including those which will result in inode numbers occupying +more than 32 bits of significance. +.sp +inode32 is provided for backwards compatibility with older +systems and applications, since 64 bits inode numbers might +cause problems for some applications that cannot handle +large inode numbers. If applications are in use which do +not handle inode numbers bigger than 32 bits, the inode32 +option should be specified. +.TP +.BR largeio | nolargeio +If "nolargeio" is specified, the optimal I/O reported in +st_blksize by stat(2) will be as small as possible to allow +user applications to avoid inefficient read/modify/write +I/O. This is typically the page size of the machine, as +this is the granularity of the page cache. +.sp +If "largeio" specified, a filesystem that was created with a +"swidth" specified will return the "swidth" value (in bytes) +in st_blksize. If the filesystem does not have a "swidth" +specified but does specify an "allocsize" then "allocsize" +(in bytes) will be returned instead. Otherwise the behaviour +is the same as if "nolargeio" was specified. +.TP +.B logbufs=value +Set the number of in-memory log buffers. Valid numbers +range from 2\(en8 inclusive. +.sp +The default value is 8 buffers. +.sp +If the memory cost of 8 log buffers is too high on small +systems, then it may be reduced at some cost to performance +on metadata intensive workloads. The logbsize option below +controls the size of each buffer and so is also relevant to +this case. +.TP +.B logbsize=value +Set the size of each in-memory log buffer. The size may be +specified in bytes, or in kibibytes (KiB) with a "k" suffix. +Valid sizes for version 1 and version 2 logs are 16384 (value=16k) +and 32768 (value=32k). Valid sizes for version 2 logs also +include 65536 (value=64k), 131072 (value=128k) and 262144 (value=256k). The +logbsize must be an integer multiple of the log +stripe unit configured at mkfs time. +.sp +The default value for version 1 logs is 32768, while the +default value for version 2 logs is MAX(32768, log_sunit). +.TP +.BR logdev=device and rtdev=device Use an external log (metadata journal) and/or real-time device. -An XFS filesystem has up to three parts: a data section, a log section, -and a real-time section. -The real-time section is optional, and the log section can be separate -from the data section or contained within it. -Refer to -.BR xfs (5). -.TP -.BI mtpt= mountpoint -Use with the -.B dmapi -option. The value specified here will be -included in the DMAPI mount event, and should be the path of -the actual mountpoint that is used. +An XFS filesystem has up to three parts: a data section, a log +section, and a real-time section. The real-time section is +optional, and the log section can be separate from the data +section or contained within it. .TP .B noalign -Data allocations will not be aligned at stripe unit boundaries. -.TP -.B noatime -Access timestamps are not updated when a file is read. +Data allocations will not be aligned at stripe unit +boundaries. This is only relevant to filesystems created +with non-zero data alignment parameters (sunit, swidth) by +mkfs. .TP .B norecovery The filesystem will be mounted without running log recovery. If the filesystem was not cleanly unmounted, it is likely to -be inconsistent when mounted in -.B norecovery -mode. +be inconsistent when mounted in "norecovery" mode. Some files or directories may not be accessible because of this. -Filesystems mounted -.B norecovery -must be mounted read-only or the mount will fail. +Filesystems mounted "norecovery" must be mounted read-only or +the mount will fail. .TP .B nouuid -Don't check for double mounted filesystems using the filesystem uuid. -This is useful to mount LVM snapshot volumes. -.TP -.B osyncisosync -Make O_SYNC writes implement true O_SYNC. WITHOUT this option, -Linux XFS behaves as if an -.B osyncisdsync -option is used, -which will make writes to files opened with the O_SYNC flag set -behave as if the O_DSYNC flag had been used instead. -This can result in better performance without compromising -data safety. -However if this option is not in effect, timestamp updates from -O_SYNC writes can be lost if the system crashes. -If timestamp updates are critical, use the -.B osyncisosync -option. +Don't check for double mounted file systems using the file +system uuid. This is useful to mount LVM snapshot volumes, +and often used in combination with "norecovery" for mounting +read-only snapshots. .TP -.BR uquota | usrquota | uqnoenforce | quota +.B noquota +Forcibly turns off all quota accounting and enforcement +within the filesystem. +.TP +.B uquota/usrquota/uqnoenforce/quota User disk quota accounting enabled, and limits (optionally) -enforced. Refer to -.BR xfs_quota (8) -for further details. +enforced. Refer to xfs_quota(8) for further details. .TP -.BR gquota | grpquota | gqnoenforce +.B gquota/grpquota/gqnoenforce Group disk quota accounting enabled and limits (optionally) -enforced. Refer to -.BR xfs_quota (8) -for further details. +enforced. Refer to xfs_quota(8) for further details. .TP -.BR pquota | prjquota | pqnoenforce +.B pquota/prjquota/pqnoenforce Project disk quota accounting enabled and limits (optionally) -enforced. Refer to -.BR xfs_quota (8) -for further details. +enforced. Refer to xfs_quota(8) for further details. .TP -\fBsunit=\fP\fIvalue\fP and \fBswidth=\fP\fIvalue\fP -Used to specify the stripe unit and width for a RAID device or a stripe -volume. -.I value -must be specified in 512-byte block units. -If this option is not specified and the filesystem was made on a stripe -volume or the stripe width or unit were specified for the RAID device at -mkfs time, then the mount system call will restore the value from the -superblock. -For filesystems that are made directly on RAID devices, these options can be -used to override the information in the superblock if the underlying disk -layout changes after the filesystem has been created. -The -.B swidth -option is required if the -.B sunit -option has been specified, -and must be a multiple of the -.B sunit -value. +.BR sunit=value " and " swidth=value +Used to specify the stripe unit and width for a RAID device +or a stripe volume. "value" must be specified in 512-byte +block units. These options are only relevant to filesystems +that were created with non-zero data alignment parameters. +.sp +The sunit and swidth parameters specified must be compatible +with the existing filesystem alignment characteristics. In +general, that means the only valid changes to sunit are +increasing it by a power-of-2 multiple. Valid swidth values +are any integer multiple of a valid sunit value. +.sp +Typically the only time these mount options are necessary if +after an underlying RAID device has had it's geometry +modified, such as adding a new disk to a RAID5 lun and +reshaping it. .TP .B swalloc Data allocations will be rounded up to stripe width boundaries when the current end of file is being extended and the file size is larger than the stripe width size. +.TP +.B wsync +When specified, all filesystem namespace operations are +executed synchronously. This ensures that when the namespace +operation (create, unlink, etc) completes, the change to the +namespace is on stable storage. This is useful in HA setups +where failover must not result in clients seeing +inconsistent namespace presentation during or after a +failover event. .SH "Mount options for xiafs" None. Although nothing is wrong with xiafs, it is not used much, @@ -2800,7 +2836,7 @@ One further possible type is a mount via the loop device. For example, the command .RS .sp -.B "mount /tmp/disk.img /mnt -t vfat -o loop=/dev/loop" +.B "mount /tmp/disk.img /mnt \-t vfat \-o loop=/dev/loop" .sp .RE will set up the loop device @@ -2816,7 +2852,7 @@ If no explicit loop device is mentioned will try to find some unused loop device and use that, for example .RS .sp -.B "mount /tmp/disk.img /mnt -o loop" +.B "mount /tmp/disk.img /mnt \-o loop" .sp .RE The mount command @@ -2827,7 +2863,7 @@ not specified or the filesystem is known for libblkid, for example: .sp .B "mount /tmp/disk.img /mnt" .sp -.B "mount -t ext3 /tmp/disk.img /mnt" +.B "mount \-t ext3 /tmp/disk.img /mnt" .sp .RE This type of mount knows about four options, namely @@ -2845,43 +2881,43 @@ will be freed by independently on .IR /etc/mtab . -You can also free a loop device by hand, using `losetup -d' or `umount -d`. +You can also free a loop device by hand, using `losetup \-d' or `umount \-d`. .SH RETURN CODES .B mount has the following return codes (the bits can be ORed): .TP -.BR 0 +.B 0 success .TP -.BR 1 +.B 1 incorrect invocation or permissions .TP -.BR 2 +.B 2 system error (out of memory, cannot fork, no more loop devices) .TP -.BR 4 +.B 4 internal .B mount bug .TP -.BR 8 +.B 8 user interrupt .TP -.BR 16 +.B 16 problems writing or locking /etc/mtab .TP -.BR 32 +.B 32 mount failure .TP -.BR 64 +.B 64 some mount succeeded .RE -The command mount -a returns 0 (all success), 32 (all failed) or 64 (some +The command mount \-a returns 0 (all success), 32 (all failed) or 64 (some failed, some success). -.SH NOTES +.SH "EXTERNAL HELPERS" The syntax of external mount helpers is: .RS @@ -2896,7 +2932,27 @@ The syntax of external mount helpers is: where the <type> is filesystem type and \-sfnvo options have same meaning like standard mount options. The \-t option is used for filesystems with subtypes -support (for example /sbin/mount.fuse -t fuse.sshfs). +support (for example /sbin/mount.fuse \-t fuse.sshfs). + +The command mount does not pass mount options +.BR unbindable , +.BR runbindable , +.BR private , +.BR rprivate , +.BR slave , +.BR rslave , +.BR shared , +.BR rshared , +.BR auto , +.BR noauto , +.BR comment , +.BR x-* , +.BR loop , +.B offset +and +.B sizelimit +to mount.<suffix> helpers. The all others options are +used in comma delimited list as argument for the option \-o. .SH FILES .TP 18n @@ -2906,7 +2962,7 @@ filesystem table .I /etc/mtab table of mounted filesystems .TP -.I /etc/mtab~ +.I /etc/mtab\s+3~\s0 lock file .TP .I /etc/mtab.tmp @@ -2953,7 +3009,7 @@ The may not be able to change mount parameters (all .IR ext2fs -specific parameters, except -.BR sb , +.BR sb , are changeable with a remount, for example, but you can't change .B gid or @@ -2962,19 +3018,19 @@ for the .IR fatfs ). .PP It is possible that files -.IR /etc/mtab +.I /etc/mtab and -.IR /proc/mounts +.I /proc/mounts don't match. The first file is based only on the mount command options, but the -content of the second file also depends on the kernel and others settings (e.g. +content of the second file also depends on the kernel and others settings (e.g.\& remote NFS server. In particular case the mount command may reports unreliable information about a NFS mount point and the /proc/mounts file usually contains more reliable information.) .PP -Checking files on NFS filesystem referenced by file descriptors (i.e. the -.BR fcntl +Checking files on NFS filesystem referenced by file descriptors (i.e.\& the +.B fcntl and -.BR ioctl +.B ioctl families of functions) may lead to inconsistent result due to the lack of consistency check in kernel even if noac is used. .PP |