WSL2-Linux-Kernel/fs/hfsplus
Fabio M. De Francesco 6c3014a67a hfsplus: convert kmap() to kmap_local_page() in bnode.c
kmap() is being deprecated in favor of kmap_local_page().

Two main problems with kmap(): (1) It comes with an overhead as 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.  Furthermore,
the tasks can be preempted and, when they are scheduled to run again, the
kernel virtual addresses are restored and still valid.

Since its use in bnode.c is safe everywhere, it should be preferred.

Therefore, replace kmap() with kmap_local_page() in bnode.c.  Where
possible, use the suited standard helpers (memzero_page(), memcpy_page())
instead of open coding kmap_local_page() plus memset() or memcpy().

Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with
HIGHMEM64GB enabled.

Link: https://lkml.kernel.org/r/20220809203105.26183-3-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-09-11 21:55:04 -07:00
..
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile hfsplus: drop ACL support 2018-08-22 10:52:50 -07:00
attributes.c hfsplus: fix crash and filesystem corruption when deleting files 2020-04-10 15:36:20 -07:00
bfind.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bitmap.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bnode.c hfsplus: convert kmap() to kmap_local_page() in bnode.c 2022-09-11 21:55:04 -07:00
brec.c hfsplus: fix BUG on bnode parent update 2018-10-31 08:54:13 -07:00
btree.c hfsplus: unmap the page in the "fail_page" label 2022-09-11 21:55:04 -07:00
catalog.c hfsplus: prevent btree data loss on ENOSPC 2018-10-31 08:54:13 -07:00
dir.c hfsplus: convert to fileattr 2021-04-12 15:04:29 +02:00
extents.c hfsplus: Call hfsplus_write_begin() and generic_write_end() directly 2022-05-08 14:45:56 -04:00
hfsplus_fs.h fs/hfsplus: Use the enum req_op and blk_opf_t types 2022-07-14 12:14:32 -06:00
hfsplus_raw.h hfsplus: use struct_group_attr() for memcpy() region 2022-01-20 08:52:54 +02:00
inode.c fs: Change try_to_free_buffers() to take a folio 2022-05-09 23:12:34 -04:00
ioctl.c hfsplus: convert to fileattr 2021-04-12 15:04:29 +02:00
options.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
part_tbl.c fs/hfsplus: Use the enum req_op and blk_opf_t types 2022-07-14 12:14:32 -06:00
super.c fs/hfsplus: Use the enum req_op and blk_opf_t types 2022-07-14 12:14:32 -06:00
tables.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
unicode.c treewide: Remove uninitialized_var() usage 2020-07-16 12:35:15 -07:00
wrapper.c fs/hfsplus: Use the enum req_op and blk_opf_t types 2022-07-14 12:14:32 -06:00
xattr.c hfsplus: use struct_group_attr() for memcpy() region 2022-01-20 08:52:54 +02:00
xattr.h hfsplus: drop ACL support 2018-08-22 10:52:50 -07:00
xattr_security.c acl: handle idmapped mounts 2021-01-24 14:27:17 +01:00
xattr_trusted.c acl: handle idmapped mounts 2021-01-24 14:27:17 +01:00
xattr_user.c acl: handle idmapped mounts 2021-01-24 14:27:17 +01:00