diff options
| author | Chandan Rajendra <chandan@linux.vnet.ibm.com> | 2015-10-14 23:09:37 +0530 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2015-11-02 09:35:04 +0100 |
| commit | c11e36a29e84b7dc142f4dad8d02902f4f7ae158 (patch) | |
| tree | 08877d380af1bfc58d3c4678a69c7fc3529e2f1e /Documentation/mkfs.btrfs.asciidoc | |
| parent | cd12def348a1d55fdc1c680f3ed9c393f77ab407 (diff) | |
Btrfs-progs: Do not force mixed block group creation unless '-M' option is specified
When creating small Btrfs filesystem instances (i.e. filesystem size <= 1GiB),
mkfs.btrfs fails if both sectorsize and nodesize are specified on the command
line and sectorsize != nodesize, since mixed block groups involves both data
and metadata blocks sharing the same block group. This is an incorrect behavior
when '-M' option isn't specified on the command line.
This commit makes optional the creation of mixed block groups i.e. Mixed block
groups are created only when -M option is specified on the command line.
Since we now allow small filesystem instances with sectorsize != nodesize to
be created, we can end up in the following situation,
[root@localhost ~]# mkfs.btrfs -f -n 65536 /dev/loop0
btrfs-progs v3.19-rc2-405-g976307c
See http://btrfs.wiki.kernel.org for more information.
Performing full device TRIM (512.00MiB) ...
Label: (null)
UUID: 49fab72e-0c8b-466b-a3ca-d1bfe56475f0
Node size: 65536
Sector size: 4096
Filesystem size: 512.00MiB
Block group profiles:
Data: single 8.00MiB
Metadata: DUP 40.00MiB
System: DUP 12.00MiB
SSD detected: no
Incompat features: extref, skinny-metadata
Number of devices: 1
Devices:
ID SIZE PATH
1 512.00MiB /dev/loop0
[root@localhost ~]# mount /dev/loop0 /mnt/
mount: mount /dev/loop0 on /mnt failed: No space left on device
The ENOSPC occurs during the creation of the UUID tree. This is because of
things like large metadata block size, DUP mode used for metadata and global
reservation consuming space. Also, large nodesize does not make sense on small
filesystems, hence this should not be an issue.
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'Documentation/mkfs.btrfs.asciidoc')
| -rw-r--r-- | Documentation/mkfs.btrfs.asciidoc | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/Documentation/mkfs.btrfs.asciidoc b/Documentation/mkfs.btrfs.asciidoc index a9aa3cb4..5789762a 100644 --- a/Documentation/mkfs.btrfs.asciidoc +++ b/Documentation/mkfs.btrfs.asciidoc @@ -133,9 +133,42 @@ UNIT As default the unit is the byte, however it is possible to append a suffix to the arguments like 'k' for KBytes, 'm' for MBytes... +NOTES +----- +Since mixed block group creation is optional, we allow small +filesystem instances with differing values for sectorsize and nodesize +to be created and could end up in the following situation, + + [root@localhost ~]# mkfs.btrfs -f -n 65536 /dev/loop0 + btrfs-progs v3.19-rc2-405-g976307c + See http://btrfs.wiki.kernel.org for more information. + + Performing full device TRIM (512.00MiB) ... + Label: (null) + UUID: 49fab72e-0c8b-466b-a3ca-d1bfe56475f0 + Node size: 65536 + Sector size: 4096 + Filesystem size: 512.00MiB + Block group profiles: + Data: single 8.00MiB + Metadata: DUP 40.00MiB + System: DUP 12.00MiB + SSD detected: no + Incompat features: extref, skinny-metadata + Number of devices: 1 + Devices: + ID SIZE PATH + 1 512.00MiB /dev/loop0 + [root@localhost ~]# mount /dev/loop0 /mnt/ + mount: mount /dev/loop0 on /mnt failed: No space left on device + +The ENOSPC occurs during the creation of the UUID tree. This is +because of things like large metadata block size, DUP mode used for +metadata and global reservation consuming space. + AVAILABILITY ------------ -*btrfs* is part of btrfs-progs. +*mkfs.btrfs* is part of btrfs-progs. Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for further details. |