path: root/Documentation
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authorQu Wenruo <>2017-10-19 17:13:55 +0800
committerDavid Sterba <>2018-01-08 18:15:15 +0100
commit1c9c5f7fb3f6a2182d230d469b22b3b1329f24d8 (patch)
tree7bdd2d05a882a68d1883e16d2970f17152f2cff9 /Documentation
parentc28418daed603d4943edc8b213b91f8d1e2b9fe3 (diff)
btrfs-progs: mkfs: Separate shrink from rootdir
Make --shrink a separate option for --rootdir, and change the default to off. The shrinking behaviour is not a commonly used feature but can be useful for creating minimal pre-filled images, in one step, without requiring to mount. Signed-off-by: Qu Wenruo <> [ update changelog and error messages ] Signed-off-by: David Sterba <>
Diffstat (limited to 'Documentation')
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/mkfs.btrfs.asciidoc b/Documentation/mkfs.btrfs.asciidoc
index f69c529d..153bb87e 100644
--- a/Documentation/mkfs.btrfs.asciidoc
+++ b/Documentation/mkfs.btrfs.asciidoc
@@ -101,6 +101,17 @@ Please see the mount option 'discard' for that in `btrfs`(5).
*-r|--rootdir <rootdir>*::
Populate the toplevel subvolume with files from 'rootdir'. This does not
require root permissions and does not mount the filesystem.
+NOTE: This option may enlarge the image or file to ensure it's large enough to
+contain the files from 'rootdir'.
+Shrink the filesystem to its minimal size, only works with *-r|--rootdir*
+NOTE: If the destination is regular file, this option will also reduce the
+file size. Or it will only reduce the filesystem available space.
+Extra space will not be usable unless resized using 'btrfs filesystem resize'.
*-O|--features <feature1>[,<feature2>...]*::
A list of filesystem features turned on at mkfs time. Not all features are