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- xfs_chver - change the version of a filesystem to enable the extent
- unwritten version.
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- xxxxffffssss____cccchhhhvvvveeeerrrr [ ----ffff ] devices
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- DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
- _x_f_s__c_h_v_e_r uses the _x_f_s__d_b command to change the version of a filesystem
- to enable the extent unwritten version. This version is needed to close
- a security hole where a process can sometimes read old data off disk.
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- The command must be run by the super-user. The command either does all
- devices found in _f_s_t_a_b(_4) when the -a option is used or the given devices
- from the second form above.
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- The command either does the changes or creates scripts which can later be
- applied using the _x_f_s__d_b command. If the -f option is used, scripts are
- created and not applied. Without the -f option, the scripts are created,
- applied using _x_f_s__d_b, and removed.
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- Devices that are mounted cannot be converted. This is always true for
- the root filesystem. Administrators must unmount filesystems before
- _x_f_s__c_h_v_e_r or _x_f_s__d_b can convert the version. If a device being converted
- is found in _m_t_a_b(_4), the conversion is not attempted and an appropriate
- message is printed. It is safe to run this command on mounted devices as
- they are just skipped.
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- It is also safe to re-run the command multiple times on the same devices.
- If the device is already converted or inaccessible, a simple message is
- printed and the command continues with the next device.
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- The -f option causes the xfs_chver command to reduce error checking and
- create file(s) which can be passed to _x_f_s__d_b. These files are created in
- the current directory in the form <device>.xfs_chver. These files can be
- applied to the filesystem, invoke the following command:
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- xfs_db -x <device> < <device>.xfs_chver
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- When the -f options is given, the following conditions are not checked
- for the device(s):
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- o - is the device the root filesystem,
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- o - is the device mounted,
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- o - can the user write to the device.
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- When the -f option is not used, the device is checked with /dev/root. If
- a device has the same _s_t__r_d_e_v, as the root device, i.e. /dev/root, the
- conversion is not attempted and a message is printed. The root can only
- be converted if another filesystem is used as a root and the "current
- root" filesystem is accessed from the other root.
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- Another alternative to convert the root is to use the -f option. The
- created file should be saved on the root to convert. Next, boot the
- miniroot and mount the root to convert. Next, copy the file just created
- with the -f option and the _x_f_s__d_b command (usually found in
- /usr/sbin/xfs_db) onto the mini root. Now, unmount the root to convert.
- Then run the command:
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- xfs_db -x <device> < <script>
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- where <device> is the root device and <script> is the file created with
- the -f option above.
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- A status of 1 is returned if the usage is incorrect, e.g. -a is used with
- a device name or an unrecognized parameter is detected. All other cases
- return a status of 0, even if a filesystem is skipped.
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- BBBBUUUUGGGGSSSS
- The xfs_db man page does not exist, yet.
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- cat <script> | xfs_db -x <device> does not work. Use xfs_db -x <device>
- < <script>.
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- SSSSEEEEEEEE AAAALLLLSSSSOOOO
- xfs_db(1M), mstat(4), fstab(4), mkfs_xfs(1M), xfs(4).
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