mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-11 12:28:41 +08:00
8b70deb8ca
kmap() has been deprecated in favor of kmap_local_page(). Therefore, replace kmap() with kmap_local_page() in fs/ecryptfs. There are two main problems with kmap(): (1) It comes with an overhead as the mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap’s pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. The tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Obviously, thread locality implies that the kernel virtual addresses returned by kmap_local_page() are only valid in the context of the callers (i.e., they cannot be handed to other threads). The use of kmap_local_page() in fs/ecryptfs does not break the above-mentioned assumption, so it is allowed and preferred. Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Suggested-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: "Fabio M. De Francesco" <fmdefrancesco@gmail.com> Message-Id: <20230426172223.8896-2-fmdefrancesco@gmail.com> Signed-off-by: Christian Brauner <brauner@kernel.org> |
||
|---|---|---|
| .. | ||
| crypto.c | ||
| debug.c | ||
| dentry.c | ||
| ecryptfs_kernel.h | ||
| file.c | ||
| inode.c | ||
| Kconfig | ||
| keystore.c | ||
| kthread.c | ||
| main.c | ||
| Makefile | ||
| messaging.c | ||
| miscdev.c | ||
| mmap.c | ||
| read_write.c | ||
| super.c | ||