linux/include
Jann Horn bf6c571a80
fs: document semantics of kstat::{uid,gid} fields
The uid stored in struct kstat is logically a vfsuid; file systems
initialize it by converting a kuid (filesystem perspective) to a vfsuid
(mount perspective), then use vfsuid_into_kuid(), which essentially just
typecasts from vfsuid to kuid.

For now, just add a comment to note this mismatch between C type and
semantic type.

Below are some notes for anyone who wants to refactor this in the future.

There are probably two options to refactor this away:

1. Change the type of kstat::uid to vfsuid_t, and perform the conversion
   from vfsuid to userspace-uid in the VFS layer. This wouldn't change
   machine code, just be more semantically correct.
2. Change the semantics of kstat::uid to really be a kuid_t, and let the
   VFS layer take care of doing the translation from kuid to vfsuid that is
   currently done in filesystem code (or in generic_fillattr, on behalf of
   the filesystem code).

Option 2 is probably neater since it moves more logic into the generic VFS
layer, and this is something that is expected to work the same way in all
file systems?

The following coccinelle script:
```
virtual context

@@
struct kstat *stat;
@@
* stat->uid

@@
struct kstat *stat;
@@
* stat->gid

@@
struct kstat stat;
@@
* stat.uid

@@
struct kstat stat;
@@
* stat.gid
```
detects 43 field accesses to these uid/gid fields.

Signed-off-by: Jann Horn <jannh@google.com>
Link: https://patch.msgid.link/20260803-vfs-comment-stat-uid-v1-1-162d062b737c@google.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
2026-08-12 11:36:39 +02:00
..
acpi Driver core changes for 7.2-rc1 2026-06-15 12:41:17 +05:30
asm-generic mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
clocksource
crypto Networking changes for 7.2. 2026-06-17 08:17:00 +01:00
cxl cxl/region: Introduce devm_cxl_probe_mem() 2026-06-12 13:47:30 -07:00
drm drm fixes for 7.2-rc1 2026-06-26 17:03:48 -07:00
dt-bindings This is all clk driver updates. Mostly new SoC support for 2026-06-25 12:48:57 -07:00
hyperv
keys keys: Pin request_key_auth payload in instantiate paths 2026-06-15 15:19:13 +03:00
kunit linux_kselftest-kunit-7.2-rc1 2026-06-16 16:33:57 +05:30
kvm Merge branch kvm-arm64/vgic-v5-PPI-fixes into kvmarm-master/next 2026-06-12 09:08:31 +01:00
linux fs: document semantics of kstat::{uid,gid} fields 2026-08-12 11:36:39 +02:00
math-emu
media media: v4l2-fwnode: Fix subdev owner overwritten in v4l2_async_register_subdev_sensor() 2026-06-05 10:28:03 +03:00
memory
misc
net Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
pcmcia
ras
rdma RDMA v7.2 merge window 2026-06-18 08:16:21 -07:00
rv rv: Prevent task migration while handling per-CPU events 2026-06-03 12:33:25 +02:00
scsi
soc This is all clk driver updates. Mostly new SoC support for 2026-06-25 12:48:57 -07:00
sound ASoC: Fixes for v7.2 2026-06-26 07:33:15 +02:00
target
trace This adds support for manual client session reset in CephFS, allowing 2026-06-26 16:15:53 -07:00
uapi nstree: add/fix struct ns_id_req kernel-doc member fields 2026-07-31 10:09:12 +02:00
ufs Merge branch 7.1/scsi-fixes into 7.2/scsi-staging 2026-06-15 21:01:30 -04:00
vdso futex: Provide infrastructure to plug the non contended robust futex unlock race 2026-06-03 11:38:52 +02:00
video
xen xen: constify xsd_errors array 2026-06-08 09:00:06 +02:00
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