diff options
| author | Paul Dagnelie <[email protected]> | 2020-05-07 09:36:33 -0700 |
|---|---|---|
| committer | GitHub <[email protected]> | 2020-05-07 09:36:33 -0700 |
| commit | 108a454a4604df6ea3be817f3cf076726df2c67a (patch) | |
| tree | f7f71af839cae02d5ed74b318bcfb5b280602b72 /include/libzfs.h | |
| parent | a36bad17596e5cbc472a0d1fecb200a6b2e3530d (diff) | |
Add support for boot environment data to be stored in the label
Modern bootloaders leverage data stored in the root filesystem to
enable some of their powerful features. GRUB specifically has a grubenv
file which can store large amounts of configuration data that can be
read and written at boot time and during normal operation. This allows
sysadmins to configure useful features like automated failover after
failed boot attempts. Unfortunately, due to the Copy-on-Write nature
of ZFS, the standard behavior of these tools cannot handle writing to
ZFS files safely at boot time. We need an alternative way to store
data that allows the bootloader to make changes to the data.
This work is very similar to work that was done on Illumos to enable
similar functionality in the FreeBSD bootloader. This patch is different
in that the data being stored is a raw grubenv file; this file can store
arbitrary variables and values, and the scripting provided by grub is
powerful enough that special structures are not required to implement
advanced behavior.
We repurpose the second padding area in each label to store the grubenv
file, protected by an embedded checksum. We add two ioctls to get and
set this data, and libzfs_core and libzfs functions to access them more
easily. There are no direct command line interfaces to these functions;
these will be added directly to the bootloader utilities.
Reviewed-by: Pavel Zakharov <[email protected]>
Reviewed-by: Matthew Ahrens <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Paul Dagnelie <[email protected]>
Closes #10009
Diffstat (limited to 'include/libzfs.h')
| -rw-r--r-- | include/libzfs.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/libzfs.h b/include/libzfs.h index c4f08882e..dd013ad0c 100644 --- a/include/libzfs.h +++ b/include/libzfs.h @@ -862,6 +862,8 @@ extern int zpool_in_use(libzfs_handle_t *, int, pool_state_t *, char **, * Label manipulation. */ extern int zpool_clear_label(int); +extern int zpool_set_bootenv(zpool_handle_t *, const char *); +extern int zpool_get_bootenv(zpool_handle_t *, char *, size_t, off_t); /* * Management interfaces for SMB ACL files |