2077006d47
When I expanded uidgid mappings I intended for a struct uid_gid_map to fit into a single cacheline on x86 as they tend to be pretty performance sensitive (idmapped mounts etc). But a 4 byte hole was added that brought it over 64 bytes. Fix that by adding the static extent array and the extent counter into a substruct. C's type punning for unions guarantees that we can access ->nr_extents even if the last written to member wasn't within the same object. This is also what we rely on in struct_group() and friends. This of course relies on non-strict aliasing which we don't do. 99) If the member used to read the contents of a union object is not the same as the member last used to store a value in the object, the appropriate part of the object representation of the value is reinterpreted as an object representation in the new type as described in 6.2.6 (a process sometimes called "type punning"). Link: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2310.pdf Link: https://lore.kernel.org/r/20240910-work-uid_gid_map-v1-1-e6bc761363ed@kernel.org Reviewed-by: Jeff Layton <jlayton@kernel.org> 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.