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A mirror of the official Linux kernel repository just in case
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e4d32142d1
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Kalesh Singh e4d32142d1 tracing: Fix tracefs mount options 
Commit 78ff640819 ("vfs: Convert tracefs to use the new mount API")
converted tracefs to use the new mount APIs caused mount options
(e.g. gid=<gid>) to not take effect.

The tracefs superblock can be updated from multiple paths:
    - on fs_initcall() to init_trace_printk_function_export()
    - from a work queue to initialize eventfs
      tracer_init_tracefs_work_func()
    - fsconfig() syscall to mount or remount of tracefs

The tracefs superblock root inode gets created early on in
init_trace_printk_function_export().

With the new mount API, tracefs effectively uses get_tree_single() instead
of the old API mount_single().

Previously, mount_single() ensured that the options are always applied to
the superblock root inode:
    (1) If the root inode didn't exist, call fill_super() to create it
        and apply the options.
    (2) If the root inode exists, call reconfigure_single() which
        effectively calls tracefs_apply_options() to parse and apply
        options to the subperblock's fs_info and inode and remount
        eventfs (if necessary)

On the other hand, get_tree_single() effectively calls vfs_get_super()
which:
    (3) If the root inode doesn't exists, calls fill_super() to create it
        and apply the options.
    (4) If the root inode already exists, updates the fs_context root
        with the superblock's root inode.

(4) above is always the case for tracefs mounts, since the super block's
root inode will already be created by init_trace_printk_function_export().

This means that the mount options get ignored:
    - Since it isn't applied to the superblock's root inode, it doesn't
      get inherited by the children.
    - Since eventfs is initialized from a separate work queue and
      before call to mount with the options, and it doesn't get remounted
      for mount.

Ensure that the mount options are applied to the super block and eventfs
is remounted to respect the mount options.

To understand this better, if fstab has the following:

 tracefs  /sys/kernel/tracing  tracefs   nosuid,nodev,noexec,gid=tracing 0  0

On boot up, permissions look like:

 # ls -l /sys/kernel/tracing/trace
 -rw-r----- 1 root root 0 Nov  1 08:37 /sys/kernel/tracing/trace

When it should look like:

 # ls -l /sys/kernel/tracing/trace
 -rw-r----- 1 root tracing 0 Nov  1 08:37 /sys/kernel/tracing/trace

Link: https://lore.kernel.org/r/536e99d3-345c-448b-adee-a21389d7ab4b@redhat.com/

Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Ali Zahraee <ahzahraee@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 78ff640819 ("vfs: Convert tracefs to use the new mount API")
Link: https://lore.kernel.org/20241030171928.4168869-2-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2024-11-01 08:38:14 -04:00
arch - Prevent a certain range of pages which get marked as hypervisor-only, to get 2024-10-27 09:01:36 -10:00
block block-6.12-20241026 2024-10-27 08:29:36 -10:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes the following issues: 2024-10-16 08:42:54 -07:00
Documentation Power management fixes for 6.12-rc5 2024-10-25 11:00:50 -07:00
drivers platform-drivers-x86 for v6.12-3 2024-10-27 08:40:33 -10:00
fs tracing: Fix tracefs mount options 2024-11-01 08:38:14 -04:00
include fuse fixes for 6.12-rc5 2024-10-25 11:41:18 -07:00
init cfi: fix conditions for HAVE_CFI_ICALL_NORMALIZE_INTEGERS 2024-10-13 22:23:13 +02:00
io_uring io_uring/rw: fix wrong NOWAIT check in io_rw_init_file() 2024-10-19 09:25:45 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel Fixes for function graph: 2024-10-27 08:56:22 -10:00
lib Probes fixes for v6.12-rc4(2): 2024-10-24 13:51:58 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm LoongArch: Set initial pte entry with PAGE_GLOBAL for kernel space 2024-10-21 22:11:19 +08:00
net BPF fixes: 2024-10-24 16:53:20 -07:00
rust Driver core fix for 6.12-rc3 2024-10-13 09:10:52 -07:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts kbuild: rust: add CONFIG_RUSTC_LLVM_VERSION 2024-10-13 22:22:28 +02:00
security ipe: fallback to platform keyring also if key in trusted keyring is rejected 2024-10-18 12:14:53 -07:00
sound ASoC: Fixes for v6.12 2024-10-24 07:57:39 +02:00
tools BPF fixes: 2024-10-24 16:53:20 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt ARM64: 2024-10-21 11:22:04 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap Including fixes from netfiler, xfrm and bluetooth. 2024-10-24 16:43:50 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: sort alphabetically by name 2024-10-09 12:47:19 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS gpio fixes for v6.12-rc5 2024-10-25 10:47:51 -07:00
Makefile Linux 6.12-rc5 2024-10-27 12:52:02 -10:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.