path: root/Documentation/btrfs-filesystem.asciidoc
diff options
authorFilipe Manana <>2015-07-16 16:47:13 +0100
committerDavid Sterba <>2015-08-31 19:25:03 +0200
commita57606e815f3e1c4fe66c61ce3c6e3621ea522e9 (patch)
treec080653dec7deef76a04045c57ee170a8b091aae /Documentation/btrfs-filesystem.asciidoc
parent9dbee1a6802896a6443896bfe407ab4062dff4f9 (diff)
Btrfs-progs: add feature to get mininum size for resizing a fs/device
Currently there is not way for a user to know what is the minimum size a device of a btrfs filesystem can be resized to. Sometimes the value of total allocated space (sum of all allocated chunks/device extents), which can be parsed from 'btrfs filesystem show' and 'btrfs filesystem usage', works as the minimum size, but sometimes it does not, namely when device extents have to relocated to holes (unallocated space) within the new size of the device (the total allocated space sum). This change adds the ability to reliably compute such minimum value and extents 'btrfs filesystem resize' with the following syntax to get such value: btrfs filesystem resize [devid:]get_min_size Signed-off-by: Filipe Manana <> Signed-off-by: David Sterba <>
Diffstat (limited to 'Documentation/btrfs-filesystem.asciidoc')
1 files changed, 3 insertions, 1 deletions
diff --git a/Documentation/btrfs-filesystem.asciidoc b/Documentation/btrfs-filesystem.asciidoc
index 31cd51be..2b34242d 100644
--- a/Documentation/btrfs-filesystem.asciidoc
+++ b/Documentation/btrfs-filesystem.asciidoc
@@ -93,7 +93,7 @@ If a newlabel optional argument is passed, the label is changed.
NOTE: the maximum allowable length shall be less than 256 chars
// Some wording are extracted by the resize2fs man page
-*resize* [<devid>:][+/-]<size>[kKmMgGtTpPeE]|[<devid>:]max <path>::
+*resize* [<devid>:][+/-]<size>[kKmMgGtTpPeE]|[<devid>:]max|[<devid>:]get_min_size <path>::
Resize a mounted filesystem identified by directory <path>. A particular device
can be resized by specifying a <devid>.
@@ -113,6 +113,8 @@ KiB, MiB, GiB, TiB, PiB, or EiB, respectively. Case does not matter.
If \'max' is passed, the filesystem will occupy all available space on the
device devid.
+If \'get_min_size' is passed, return the minimum size the device can be
+shrunk to, without performing any resize operation.
The resize command does not manipulate the size of underlying
partition. If you wish to enlarge/reduce a filesystem, you must make sure you