-e Enables unwritten extent support on a filesystem that does
not already have this enabled (for legacy filesystems, it
can't be disabled anymore at mkfs time).
This option only applies to the deprecated V4 format.
-f Specifies that the filesystem image to be processed is
stored in a regular file at device (see the mkfs.xfs -d
file option).
-j Enables version 2 log format (journal format supporting
larger log buffers).
This option only applies to the deprecated V4 format.
-l Print the current filesystem label.
-p Enable 32bit project identifier support (PROJID32BIT
feature).
This option only applies to the deprecated V4 format.
-u Print the current filesystem UUID (Universally Unique
IDentifier).
-c 0|1 Enable (1) or disable (0) lazy-counters in the filesystem.
Lazy-counters may not be disabled on Version 5 superblock
filesystems (i.e. those with metadata CRCs enabled).
In other words, this option only applies to the deprecated
V4 format.
This operation may take quite a bit of time on large
filesystems as the entire filesystem needs to be scanned
when this option is changed.
With lazy-counters enabled, the superblock is not modified
or logged on every change of the free-space and inode
counters. Instead, enough information is kept in other
parts of the filesystem to be able to maintain the counter
values without needing to keep them in the superblock.
This gives significant improvements in performance on some
configurations and metadata intensive workloads.
-L label
Set the filesystem label to label. XFS filesystem labels
can be at most 12 characters long; if label is longer than
12 characters, xfs_admin will truncate it and print a
warning message. The filesystem label can be cleared
using the special "--" value for label.
-O feature1=status,feature2=status...
Add or remove features on an existing V5 filesystem. The
features should be specified as a comma-separated list.
status should be either 0 to disable the feature or 1 to
enable the feature. Note, however, that most features
cannot be disabled.
NOTE: Administrators must ensure the filesystem is clean
by running xfs_repair -n to inspect the filesystem before
performing the upgrade. If corruption is found, recovery
procedures (e.g. reformat followed by restoration from
backup; or running xfs_repair without the -n) must be
followed to clean the filesystem.
Supported features are as follows:
inobtcount
Keep a count the number of blocks in each inode btree
in the AGI. This reduces mount time by speeding up
metadata space reservation calculations. The
filesystem cannot be downgraded after this feature is
enabled. Once enabled, the filesystem will not be
writable by older kernels. This feature was added to
Linux 5.10.
bigtime
Upgrade a filesystem to support larger timestamps up
to the year 2486. The filesystem cannot be downgraded
after this feature is enabled. Once enabled, the
filesystem will not be mountable by older kernels.
This feature was added to Linux 5.10.
-U uuid
Set the UUID of the filesystem to uuid. A sample UUID
looks like this: "c1b9d5a2-f162-11cf-9ece-0020afc76f16".
The uuid may also be nil, which will set the filesystem
UUID to the null UUID. The uuid may also be generate,
which will generate a new UUID for the filesystem. Note
that on CRC-enabled filesystems, this will set an
incompatible flag such that older kernels will not be able
to mount the filesystem. To remove this incompatible
flag, use restore, which will restore the original UUID
and remove the incompatible feature flag as needed.
-r rtdev
Specifies the device special file where the filesystem's
realtime section resides. Only for those filesystems
which use a realtime section.
-V Prints the version number and exits.
The mount(8) manual entry describes how to mount a filesystem
using its label or UUID, rather than its block special device
name.
