Let's clarify from where we take idmapping of each type:
- caller
- filesystem
- mount
Cc: Jonathan Corbet <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Alexander Mikhalitsyn <[email protected]>
---
Documentation/filesystems/idmappings.rst | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/Documentation/filesystems/idmappings.rst b/Documentation/filesystems/idmappings.rst
index ad6d21640576..c20382f8bbb0 100644
--- a/Documentation/filesystems/idmappings.rst
+++ b/Documentation/filesystems/idmappings.rst
@@ -373,6 +373,12 @@ kernel maps the caller's userspace id down into a kernel id according to the
caller's idmapping and then maps that kernel id up according to the
filesystem's idmapping.
+From the implementation point it's worth mentioning how idmappings are represented.
+All idmappings are taken from the corresponding user namespace.
+ - caller's idmapping (usually taken from ``current_user_ns()``)
+ - filesystem's idmapping (``sb->s_user_ns``)
+ - mount's idmapping (``mnt_idmap(vfsmnt)``)
+
Let's see some examples with caller/filesystem idmapping but without mount
idmappings. This will exhibit some problems we can hit. After that we will
revisit/reconsider these examples, this time using mount idmappings, to see how
--
2.34.1
Hi Alexander,
kernel test robot noticed the following build warnings:
[auto build test WARNING on vfs-idmapping/for-next]
[also build test WARNING on linus/master v6.4-rc7 next-20230623]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Alexander-Mikhalitsyn/docs-filesystems-idmappings-clarify-from-where-idmappings-are-taken/20230621-180345
base: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping.git for-next
patch link: https://lore.kernel.org/r/20230621095905.31346-1-aleksandr.mikhalitsyn%40canonical.com
patch subject: [PATCH] docs: filesystems: idmappings: clarify from where idmappings are taken
reproduce: (https://download.01.org/0day-ci/archive/20230625/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All warnings (new ones prefixed by >>):
>> Documentation/filesystems/idmappings.rst:378: WARNING: Unexpected indentation.
vim +378 Documentation/filesystems/idmappings.rst
375
376 From the implementation point it's worth mentioning how idmappings are represented.
377 All idmappings are taken from the corresponding user namespace.
> 378 - caller's idmapping (usually taken from ``current_user_ns()``)
379 - filesystem's idmapping (``sb->s_user_ns``)
380 - mount's idmapping (``mnt_idmap(vfsmnt)``)
381
--
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https://github.com/intel/lkp-tests/wiki