From 2fd02b1f5f50d499b8f19d0cc5e9bc9ed7e686cd Mon Sep 17 00:00:00 2001 From: Dimitri John Ledkov Date: Sat, 26 Jan 2019 00:37:47 +0000 Subject: New upstream release --- Documentation/btrfstune.8 | 104 ++++++++++++++++++++++++++++++---------------- 1 file changed, 68 insertions(+), 36 deletions(-) (limited to 'Documentation/btrfstune.8') diff --git a/Documentation/btrfstune.8 b/Documentation/btrfstune.8 index b83d9e9d..77351c0a 100644 --- a/Documentation/btrfstune.8 +++ b/Documentation/btrfstune.8 @@ -2,12 +2,12 @@ .\" Title: btrfstune .\" Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author] .\" Generator: DocBook XSL Stylesheets vsnapshot -.\" Date: 12/05/2018 +.\" Date: 01/23/2019 .\" Manual: Btrfs Manual -.\" Source: Btrfs v4.19.1 +.\" Source: Btrfs v4.20.1 .\" Language: English .\" -.TH "BTRFSTUNE" "8" "12/05/2018" "Btrfs v4\&.19\&.1" "Btrfs Manual" +.TH "BTRFSTUNE" "8" "01/23/2019" "Btrfs v4\&.20\&.1" "Btrfs Manual" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- @@ -41,30 +41,34 @@ The common usecase is to enable features that were not enabled at mkfs time\&. P Some of the features could be also enabled on a mounted filesystem by other means\&. Please refer to the \fIFILESYSTEM FEATURES\fR in \fBbtrfs\fR(5)\&. .SH "OPTIONS" .PP -\-S \fI<0|1>\fR +\-f .RS 4 -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\&. +Allow dangerous changes, e\&.g\&. clear the seeding flag or change fsid\&. Make sure that you are aware of the dangers\&. .RE .PP -\-r +\-m .RS 4 -(since kernel: 3\&.7) +(since kernel: 5\&.0) .sp -Enable extended inode refs (hardlink limit per file in a directory is 65536), enabled by mkfs feature -\fIextref\fR\&. +change fsid stored as +\fImetadata_uuid\fR +to a randomly generated UUID, see also +\fI\-U\fR .RE .PP -\-x +\-M \fI\fR .RS 4 -(since kernel: 3\&.10) +(since kernel: 5\&.0) .sp -Enable skinny metadata extent refs (more efficient representation of extents), enabled by mkfs feature -\fIskinny\-metadata\fR\&. +change fsid stored as +\fImetadata_uuid\fR +to a given UUID, see also +\fI\-U\fR .sp -All newly created extents will use the new representation\&. To completely switch the entire filesystem, run a full balance of the metadata\&. Please refer to -\fBbtrfs\-balance\fR(8)\&. +The metadata_uuid is stored only in the superblock and is a backward incompatible change\&. The fsid in metadata blocks remains unchanged and is not overwritten, thus the whole operation is significantly faster than +\fI\-U\fR\&. +.sp +The new metadata_uuid can be used for mount by UUID and is also used to identify devices of a multi\-device filesystem\&. .RE .PP \-n @@ -75,9 +79,37 @@ Enable no\-holes feature (more efficient representation of file holes), enabled \fIno\-holes\fR\&. .RE .PP -\-f +\-r .RS 4 -Allow dangerous changes, e\&.g\&. clear the seeding flag or change fsid\&. Make sure that you are aware of the dangers\&. +(since kernel: 3\&.7) +.sp +Enable extended inode refs (hardlink limit per file in a directory is 65536), enabled by mkfs feature +\fIextref\fR\&. +.RE +.PP +\-S \fI<0|1>\fR +.RS 4 +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\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBWarning\fR +.ps -1 +.br +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 +\fIseeding device as a base image\fR\&. Clear the seeding flag, update the filesystem and make it seeding again, provided that it\(cqs OK to throw away all filesystems built on top of the previous base\&. +.sp .5v +.RE .RE .PP \-u @@ -88,7 +120,8 @@ Change fsid to a randomly generated UUID or continue previous fsid change operat \-U \fI\fR .RS 4 Change fsid to -\fIUUID\fR\&. +\fIUUID\fR +in all metadata blocks\&. .sp The \fIUUID\fR @@ -98,7 +131,9 @@ should be a 36 bytes string in \fIUUID\fR matches the unfinished one or if you use the option \fI\-u\fR\&. -.RE +.sp +All metadata blocks are rewritten, this may take some time, but the final filesystem compatibility is unaffected, unlike +\fI\-M\fR\&. .if n \{\ .sp .\} @@ -111,25 +146,22 @@ matches the unfinished one or if you use the option \fBWarning\fR .ps -1 .br -.sp -Cancelling or interrupting a UUID change operation will make the filesystem temporarily unmountable\&. To fix it, rerun \fIbtrfstune \-u\fR to restore the UUID and let it complete\&. +Cancelling or interrupting a UUID change operation will make the filesystem temporarily unmountable\&. To fix it, rerun +\fIbtrfstune \-u\fR +and let it complete\&. .sp .5v .RE -.if n \{\ -.sp -.\} +.RE +.PP +\-x .RS 4 -.it 1 an-trap -.nr an-no-space-flag 1 -.nr an-break-flag 1 -.br -.ps +1 -\fBWarning\fR -.ps -1 -.br +(since kernel: 3\&.10) .sp -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 \fIseeding device as a base image\fR\&. Clear the seeding flag, update the filesystem and make it seeding again, provided that it\(cqs OK to throw away all filesystems built on top of the previous base\&. -.sp .5v +Enable skinny metadata extent refs (more efficient representation of extents), enabled by mkfs feature +\fIskinny\-metadata\fR\&. +.sp +All newly created extents will use the new representation\&. To completely switch the entire filesystem, run a full balance of the metadata\&. Please refer to +\fBbtrfs\-balance\fR(8)\&. .RE .SH "EXIT STATUS" .sp -- cgit v1.2.3