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| author | Mateusz Guzik <mjguzik@gmail.com> | 2024-06-25 17:18:06 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-06-27 18:31:20 +0200 |
| commit | 0ef625bba6fb2bc0c8ed2aab9524fdf423f67dd5 (patch) | |
| tree | dac526478b2be72640552a7ab9def6664ece9052 /fs/namespace.c | |
| parent | 27a2d0cb2f38c67b58285e6124b14f7fff3fd1a8 (diff) | |
| download | lwn-0ef625bba6fb2bc0c8ed2aab9524fdf423f67dd5.tar.gz lwn-0ef625bba6fb2bc0c8ed2aab9524fdf423f67dd5.zip | |
vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)
The newly used helper also checks for empty ("") paths.
NULL paths with any flag value other than AT_EMPTY_PATH go the usual
route and end up with -EFAULT to retain compatibility (Rust is abusing
calls of the sort to detect availability of statx).
This avoids path lookup code, lockref management, memory allocation and
in case of NULL path userspace memory access (which can be quite
expensive with SMAP on x86_64).
Benchmarked with statx(..., AT_EMPTY_PATH, ...) running on Sapphire
Rapids, with the "" path for the first two cases and NULL for the last
one.
Results in ops/s:
stock: 4231237
pre-check: 5944063 (+40%)
NULL path: 6601619 (+11%/+56%)
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240625151807.620812-1-mjguzik@gmail.com
Tested-by: Xi Ruoyao <xry111@xry111.site>
[brauner: use path_mounted() and other tweaks]
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 13 |
1 files changed, 0 insertions, 13 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 2b85d2f53df6..3aadd5361a18 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1846,19 +1846,6 @@ bool may_mount(void) return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); } -/** - * path_mounted - check whether path is mounted - * @path: path to check - * - * Determine whether @path refers to the root of a mount. - * - * Return: true if @path is the root of a mount, false if not. - */ -static inline bool path_mounted(const struct path *path) -{ - return path->mnt->mnt_root == path->dentry; -} - static void warn_mandlock(void) { pr_warn_once("=======================================================\n" |