linux.git/samples/vfs, branch v6.18.21

samples: work around glibc redefining some of our defines wrong

2025-11-21T17:29:02+00:00

Apparently as of version 2.42, glibc headers define AT_RENAME_NOREPLACE
and some of the other flags for renameat2() and friends in .

Which would all be fine, except for inexplicable reasons glibc decided
to define them _differently_ from the kernel definitions, which then
makes some of our sample code that includes both kernel headers and user
space headers unhappy, because the compiler will (correctly) complain
about redefining things.

Now, mixing kernel headers and user space headers is always a somewhat
iffy proposition due to namespacing issues, but it's kind of inevitable
in our sample and selftest code.  And this is just glibc being stupid.

Those defines come from the kernel, glibc is exposing the kernel
interfaces, and glibc shouldn't make up some random new expressions for
these values.

It's not like glibc headers changed the actual result values, but they
arbitrarily just decided to use a different expression to describe those
values.  The kernel just does

    #define AT_RENAME_NOREPLACE  0x0001

while glibc does

    # define RENAME_NOREPLACE (1 << 0)
    # define AT_RENAME_NOREPLACE RENAME_NOREPLACE

instead.  Same value in the end, but very different macro definition.

For absolutely no reason.

This has since been fixed in the glibc development tree, so eventually
we'll end up with the canonical expressions and no clashes.  But in the
meantime the broken headers are in the glibc-2.42 release and have made
it out into distributions.

Do a minimal work-around to make the samples build cleanly by just
undefining the affected macros in between the user space header include
and the kernel header includes.

Signed-off-by: Linus Torvalds

samples/vfs: fix printf format string for size_t

2025-02-25T10:56:26+00:00

size_t needs a %z format string modifier instead of %l

samples/vfs/test-list-all-mounts.c:152:39: warning: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
  152 |                                         printf("mnt_uidmap[%lu]:\t%s\n", idx, idmap);
      |                                                            ~~~           ^~~
      |                                                            %zu
samples/vfs/test-list-all-mounts.c:161:39: warning: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
  161 |                                         printf("mnt_gidmap[%lu]:\t%s\n", idx, idmap);
      |                                                            ~~~           ^~~
      |                                                            %zu

Fixes: fa204a65f1b6 ("samples/vfs: add STATMOUNT_MNT_{G,U}IDMAP")
Signed-off-by: Arnd Bergmann 
Link: https://lore.kernel.org/r/20250224141406.1400864-1-arnd@kernel.org
Signed-off-by: Christian Brauner

samples/vfs: add STATMOUNT_MNT_{G,U}IDMAP

2025-02-12T11:12:27+00:00

Illustrate how to use STATMOUNT_MNT_{G,U}IDMAP.

Link: https://lore.kernel.org/r/20250204-work-mnt_idmap-statmount-v2-4-007720f39f2e@kernel.org
Reviewed-by: Jeff Layton 
Signed-off-by: Christian Brauner

samples/vfs: check whether flag was raised

2025-02-12T11:12:27+00:00

For string options the kernel will raise the corresponding flag only if
the string isn't empty. So check for the flag.

Link: https://lore.kernel.org/r/20250204-work-mnt_idmap-statmount-v2-3-007720f39f2e@kernel.org
Reviewed-by: Jeff Layton 
Signed-off-by: Christian Brauner

samples/vfs: fix build warnings

2025-01-20T12:14:21+00:00

Fix build warnings reported from linux-next.

Reported-by: Stephen Rothwell 
Link: https://lore.kernel.org/r/20250120192504.4a1965a0@canb.auug.org.au
Signed-off-by: Christian Brauner

samples/vfs: use shared header

2025-01-20T11:50:35+00:00

Share some infrastructure between sample programs and fix a build
failure that was reported.

Reported-by: Sasha Levin 
Link: https://lore.kernel.org/r/Z42UkSXx0MS9qZ9w@lappy
Link: https://qa-reports.linaro.org/lkft/sashal-linus-next/build/v6.13-rc7-511-g109a8e0fa9d6/testrun/26809210/suite/build/test/gcc-8-allyesconfig/log
Signed-off-by: Christian Brauner

samples/vfs/mountinfo: Use __u64 instead of uint64_t

2025-01-10T11:08:27+00:00

On 32-bit (e.g. arm32, m68k):

    samples/vfs/mountinfo.c: In function ‘dump_mountinfo’:
    samples/vfs/mountinfo.c:145:29: warning: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘uint64_t’ {aka ‘long long unsigned int’} [-Wformat=]
      145 |                 printf("0x%lx 0x%lx 0x%llx ", mnt_ns_id, mnt_id, buf->mnt_parent_id);
	  |                           ~~^                 ~~~~~~~~~
	  |                             |                 |
	  |                             long unsigned int uint64_t {aka long long unsigned int}
	  |                           %llx
    samples/vfs/mountinfo.c:145:35: warning: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘uint64_t’ {aka ‘long long unsigned int’} [-Wformat=]
      145 |                 printf("0x%lx 0x%lx 0x%llx ", mnt_ns_id, mnt_id, buf->mnt_parent_id);
	  |                                 ~~^                      ~~~~~~
	  |                                   |                      |
	  |                                   long unsigned int      uint64_t {aka long long unsigned int}
	  |                                 %llx

Just using "%llx" instead of "%lx" is not sufficient, as uint64_t is
"long unsigned int" on some 64-bit platforms like arm64.  Hence also
replace "uint64_t" by "__u64", which matches what most other samples
are already using.

Fixes: d95e49bf8bcdc7c1 ("samples: add a mountinfo program to demonstrate statmount()/listmount()")
Signed-off-by: Geert Uytterhoeven 
Link: https://lore.kernel.org/r/20250106134802.1019911-1-geert+renesas@glider.be
Reviewed-by: Jeff Layton 
Signed-off-by: Christian Brauner

samples: add test-list-all-mounts

2025-01-09T15:58:53+00:00

Add a sample program illustrating how to list all mounts in all mount
namespaces.

Link: https://lore.kernel.org/r/20241213-work-mount-rbtree-lockless-v3-10-6e3cdaf9b280@kernel.org
Reviewed-by: Jeff Layton 
Signed-off-by: Christian Brauner

samples: add a mountinfo program to demonstrate statmount()/listmount()

2025-01-09T15:58:50+00:00

Add a new "mountinfo" sample userland program that demonstrates how to
use statmount() and listmount() to get at the same info that
/proc/pid/mountinfo provides.

The output of the program tries to mimic the mountinfo procfile
contents. With the -p flag, it can be pointed at an arbitrary pid to
print out info about its mount namespace. With the -r flag it will
attempt to walk all of the namespaces under the pid's mount namespace
and dump out mount info from all of them.

Signed-off-by: Jeff Layton 
Link: https://lore.kernel.org/r/20241115-statmount-v2-1-cd29aeff9cbb@kernel.org
Signed-off-by: Christian Brauner

.gitignore: prefix local generated files with a slash

2021-05-01T15:43:35+00:00

The pattern prefixed with '/' matches files in the same directory,
but not ones in sub-directories.

Signed-off-by: Masahiro Yamada 
Acked-by: Miguel Ojeda 
Acked-by: Rob Herring 
Acked-by: Andra Paraschiv 
Acked-by: Greg Kroah-Hartman 
Acked-by: Gabriel Krisman Bertazi