Commit 0ef625bba6fb ("vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)") added support for passing in NULL when AT_EMPTY_PATH is given, improving performance when statx is used for fetching stat informantion from a given fd, which is especially important for 32-bit platforms. This commit also improved the performance when an empty string is given by short-circuiting the handling of such paths.
This series is based on the commits in the Linus’ tree. Comparing to the original patches, the helper vfs_empty_path() is moved to stat.c from linux/fs.h, because get_user() is only available in fs.h since v5.7, where commit 80fbaf1c3f29 ('rcuwait: Add @State argument to rcuwait_wait_event()') added linux/sched/signal.h to rcuwait.h, and uaccess.h finally got its way to fs.h along the path uaccess.h -> sched/task.h -> sched/signal.h -> rcuwait.h -> percpu-rwsem.h -> fs.h. uaccess.h cannot be directly included in fs.h before v5.7, where commit df23e2be3d24 ('acpi: Remove header dependency') removed proc_fs.h from acpi/acpi_bus.h, preventing arch/x86/boot/compressed/cmdline.c from indirectly including fs.h. Otherwise, the function set_fs() defined in asm/uaccess.h will get into cmdline.c, which contains another set_fs(), resulting conflicting function definations. There is no users of vfs_empty_path() except stat.c, and as a result, putting it in stat.c is acceptable.
The existing vfs_statx_fd(), which is removed since v5.10, is utilized to implement short-circuit handling of NULL and "" paths, instead of introducing vfs_statx_path(), simplifying the implementation.
Tested-by: Xi Ruoyao xry111@xry111.site Signed-off-by: Miao Wang shankerwangmiao@gmail.com --- Christian Brauner (2): fs: new helper vfs_empty_path() stat: use vfs_empty_path() helper
Christoph Hellwig (2): fs: implement vfs_stat and vfs_lstat in terms of vfs_fstatat fs: move vfs_fstatat out of line
Linus Torvalds (1): vfs: mostly undo glibc turning 'fstat()' into 'fstatat(AT_EMPTY_PATH)'
Mateusz Guzik (1): vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)
fs/stat.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++----- include/linux/fs.h | 26 ++++++++++-------------- 2 files changed, 63 insertions(+), 21 deletions(-) --- base-commit: 661f109c057497c8baf507a2562ceb9f9fb3cbc2 change-id: 20240918-statx-stable-linux-5-4-y-a79d4268600d
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