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btrfs-progs: docs: enhance manual page for btrfstune 

Signed-off-by: David Sterba <dsterba@suse.com>
master
David Sterba 2015-11-02 11:08:57 +01:00
parent a2d66e0962
commit b44e84a650
1 changed files with 11 additions and 8 deletions
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19
Documentation/btrfstune.asciidoc
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@ -26,11 +26,14 @@ Enable seeding on a given device. Value 1 will enable seeding, 0 will disable it
A seeding filesystem is forced to be mounted read-only. A new device can be added A seeding filesystem is forced to be mounted read-only. A new device can be added
to the filesystem and will capture all writes keeping the seeding device intact. to the filesystem and will capture all writes keeping the seeding device intact.
-r:: -r::
Enable extended inode refs (hardlink limit per file in a directory is 65536). Since kernel 3.7. Enable extended inode refs (hardlink limit per file in a directory is 65536),
enabled by mkfs feature 'extref'. Since kernel 3.7.
-x:: -x::
Enable skinny metadata extent refs (more efficient representation of extents). Since kernel 3.10. Enable skinny metadata extent refs (more efficient representation of extents),
enabled by mkfs feature 'skinny-metadata'. Since kernel 3.10.
-n:: -n::
Enable no-holes feature (more efficient representation of file holes). Since kernel 3.14. Enable no-holes feature (more efficient representation of file holes), enabled
by mkfs feature 'no-holes'. Since kernel 3.14.
-f:: -f::
Allow dangerous changes, e.g. clear the seeding flag or change fsid. Make sure Allow dangerous changes, e.g. clear the seeding flag or change fsid. Make sure
that you are aware of the dangers. that you are aware of the dangers.
@ -38,12 +41,12 @@ that you are aware of the dangers.
Change fsid to a randomly generated UUID or continue previous fsid change Change fsid to a randomly generated UUID or continue previous fsid change
operation in case it was interrupted. operation in case it was interrupted.
-U <UUID>:: -U <UUID>::
Change fsid to <UUID>. Change fsid to 'UUID'.
+ +
The <UUID> should be a 36 bytes string in `printf`(3) format The 'UUID' should be a 36 bytes string in `printf`(3) format
"%08x-%04x-%04x-%04x-%012x". '"%08x-%04x-%04x-%04x-%012x"'.
If there is a previous unfinished fsid change, it will continue only if the If there is a previous unfinished fsid change, it will continue only if the
<UUID> matches the unfinished one or if you use the option '-u'. 'UUID' matches the unfinished one or if you use the option '-u'.
WARNING: Cancelling or interrupting a UUID change operation will make the WARNING: Cancelling or interrupting a UUID change operation will make the
filesystem temporarily unmountable. To fix it, rerun 'btrfstune -u' to restore filesystem temporarily unmountable. To fix it, rerun 'btrfstune -u' to restore
@ -53,7 +56,7 @@ WARNING: Clearing the seeding flag on a device may be dangerous.
If a previously-seeding device is changed, all filesystems that used that If a previously-seeding device is changed, all filesystems that used that
device will become unmountable. Setting the seeding flag back will not fix device will become unmountable. Setting the seeding flag back will not fix
that. + that. +
A valid usecase is "seeding device as a base image". Clear the seeding A valid usecase is 'seeding device as a base image'. Clear the seeding
flag, update the filesystem and make it seeding again, provided that it's ok flag, update the filesystem and make it seeding again, provided that it's ok
to throw away all filesystems built on top of the previous base. to throw away all filesystems built on top of the previous base.