diff options
| -rw-r--r-- | Documentation/btrfstune.asciidoc | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/Documentation/btrfstune.asciidoc b/Documentation/btrfstune.asciidoc index db9a97b9..f5cf15e7 100644 --- a/Documentation/btrfstune.asciidoc +++ b/Documentation/btrfstune.asciidoc @@ -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 to the filesystem and will capture all writes keeping the seeding device intact. -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:: -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:: -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:: Allow dangerous changes, e.g. clear the seeding flag or change fsid. Make sure 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 operation in case it was interrupted. -U <UUID>:: -Change fsid to <UUID>. +Change fsid to 'UUID'. + -The <UUID> should be a 36 bytes string in `printf`(3) format -"%08x-%04x-%04x-%04x-%012x". +The 'UUID' should be a 36 bytes string in `printf`(3) format +'"%08x-%04x-%04x-%04x-%012x"'. 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 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 device will become unmountable. Setting the seeding flag back will not fix 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 to throw away all filesystems built on top of the previous base. |