Background ========== Linus suggested printing full path for file instead of printing the components as '%pd'. Typically, there is no need for printk specifiers to take any real locks (ie mount_lock or rename_lock). So I introduce a new helper d_path_fast which is similar to d_path except it doesn't take any seqlock/spinlock. This series is based on Al Viro's d_path cleanup patches [1] which lifted the inner lockless loop into a new helper. [1] https://lkml.org/lkml/2021/5/18/1260 Test ==== The cases I tested: 1. print '%pD' with full path of ext4 file 2. mount a ext4 filesystem upon a ext4 filesystem, and print the file with '%pD' 3. all test_print selftests, including the new '%14pD' '%-14pD' 4. kasnprintf Changelog ========= v4: - don't support spec.precision anymore for '%pD' - add Rasmus's patch into this series v3: - implement new d_path_unsafe to use [buf, end] instead of stack space for filling bytes (by Matthew) - add new test cases for '%pD' - drop patch "hmcdrv: remove the redundant directory path" before removing rfc. v2: - implement new d_path_fast based on Al Viro's patches - add check_pointer check (by Petr) - change the max full path size to 256 in stack space v1: https://lkml.org/lkml/2021/5/8/122 Jia He (4): fs: introduce helper d_path_unsafe() lib/vsprintf.c: make '%pD' print full path for file lib/test_printf.c: split write-beyond-buffer check in two lib/test_printf.c: add test cases for '%pD' Documentation/core-api/printk-formats.rst | 5 +- fs/d_path.c | 83 ++++++++++++++++++++++- include/linux/dcache.h | 1 + lib/test_printf.c | 31 ++++++++- lib/vsprintf.c | 37 ++++++++-- 5 files changed, 148 insertions(+), 9 deletions(-) -- 2.17.1
