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4356d575ef
Now that we provide a unique 64-bit mount ID interface in statx(2), we
can now provide a race-free way for name_to_handle_at(2) to provide a
file handle and corresponding mount without needing to worry about
racing with /proc/mountinfo parsing or having to open a file just to do
statx(2).
While this is not necessary if you are using AT_EMPTY_PATH and don't
care about an extra statx(2) call, users that pass full paths into
name_to_handle_at(2) need to know which mount the file handle comes from
(to make sure they don't try to open_by_handle_at a file handle from a
different filesystem) and switching to AT_EMPTY_PATH would require
allocating a file for every name_to_handle_at(2) call, turning
err = name_to_handle_at(-EBADF, "/foo/bar/baz", &handle, &mntid,
AT_HANDLE_MNT_ID_UNIQUE);
into
int fd = openat(-EBADF, "/foo/bar/baz", O_PATH | O_CLOEXEC);
err1 = name_to_handle_at(fd, "", &handle, &unused_mntid, AT_EMPTY_PATH);
err2 = statx(fd, "", AT_EMPTY_PATH, STATX_MNT_ID_UNIQUE, &statxbuf);
mntid = statxbuf.stx_mnt_id;
close(fd);
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Link: https://lore.kernel.org/r/20240828-exportfs-u64-mount-id-v3-2-10c2c4c16708@cyphar.com
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.