From: Ira Weiny
There are many places where the pattern kmap/memcpy/kunmap occurs.
This pattern was lifted to the core common functions
memcpy_[to|from]_page().
Use these new functions to reduce the code, eliminate direct uses of
kmap, and leverage the new core functions use of kmap_local_page().
Also, there is 1 place where a kmap/memcpy is followed by an
optional memset. Here we leave the kmap open coded to avoid remapping
the page but use kmap_local_page() directly.
Development of this patch was aided by the coccinelle script:
//
// SPDX-License-Identifier: GPL-2.0-only
// Find kmap/memcpy/kunmap pattern and replace with memcpy*page calls
//
// NOTE: Offsets and other expressions may be more complex than what the script
// will automatically generate. Therefore a catchall rule is provided to find
// the pattern which then must be evaluated by hand.
//
// Confidence: Low
// Copyright: (C) 2021 Intel Corporation
// URL: http://coccinelle.lip6.fr/
// Comments:
// Options:
//
// simple memcpy version
//
@ memcpy_rule1 @
expression page, T, F, B, Off;
identifier ptr;
type VP;
@@
(
-VP ptr = kmap(page);
|
-ptr = kmap(page);
|
-VP ptr = kmap_atomic(page);
|
-ptr = kmap_atomic(page);
)
<+...
(
-memcpy(ptr + Off, F, B);
+memcpy_to_page(page, Off, F, B);
|
-memcpy(ptr, F, B);
+memcpy_to_page(page, 0, F, B);
|
-memcpy(T, ptr + Off, B);
+memcpy_from_page(T, page, Off, B);
|
-memcpy(T, ptr, B);
+memcpy_from_page(T, page, 0, B);
)
...+>
(
-kunmap(page);
|
-kunmap_atomic(ptr);
)
// Remove any pointers left unused
@
depends on memcpy_rule1
@
identifier memcpy_rule1.ptr;
type VP, VP1;
@@
-VP ptr;
... when != ptr;
? VP1 ptr;
//
// Some callers kmap without a temp pointer
//
@ memcpy_rule2 @
expression page, T, Off, F, B;
@@
<+...
(
-memcpy(kmap(page) + Off, F, B);
+memcpy_to_page(page, Off, F, B);
|
-memcpy(kmap(page), F, B);
+memcpy_to_page(page, 0, F, B);
|
-memcpy(T, kmap(page) + Off, B);
+memcpy_from_page(T, page, Off, B);
|
-memcpy(T, kmap(page), B);
+memcpy_from_page(T, page, 0, B);
)
...+>
-kunmap(page);
// No need for the ptr variable removal
//
// Catch all
//
@ memcpy_rule3 @
expression page;
expression GenTo, GenFrom, GenSize;
identifier ptr;
type VP;
@@
(
-VP ptr = kmap(page);
|
-ptr = kmap(page);
|
-VP ptr = kmap_atomic(page);
|
-ptr = kmap_atomic(page);
)
<+...
(
//
// Some call sites have complex expressions within the memcpy
// match a catch all to be evaluated by hand.
//
-memcpy(GenTo, GenFrom, GenSize);
+memcpy_to_pageExtra(page, GenTo, GenFrom, GenSize);
+memcpy_from_pageExtra(GenTo, page, GenFrom, GenSize);
)
...+>
(
-kunmap(page);
|
-kunmap_atomic(ptr);
)
// Remove any pointers left unused
@
depends on memcpy_rule3
@
identifier memcpy_rule3.ptr;
type VP, VP1;
@@
-VP ptr;
... when != ptr;
? VP1 ptr;
//
Signed-off-by: Ira Weiny
---
Changes from v1:
Update commit message per David
https://lore.kernel.org/lkml/20210209151442.gu1...@suse.cz/
---
fs/btrfs/compression.c | 6 ++
fs/btrfs/lzo.c | 4 ++--
fs/btrfs/reflink.c | 6 +-
fs/btrfs/send.c| 7 ++-
fs/btrfs/zlib.c| 5 ++---
fs/btrfs/zstd.c| 6 ++
6 files changed, 11 insertions(+), 23 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 5ae3fa0386b7..047b632b4139 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -1231,7 +1231,6 @@ int btrfs_decompress_buf2page(const char *buf, unsigned
long buf_start,
unsigned long prev_start_byte;
unsigned long working_bytes = total_out - buf_start;
unsigned long bytes;
- char *kaddr;
struct bio_vec bvec = bio_iter_iovec(bio, bio->bi_iter);
/*
@@ -1262,9 +1261,8 @@ int btrfs_decompress_buf2page(const char *buf, unsigned
long buf_start,
PAGE_SIZE - (buf_offset % PAGE_SIZE));
bytes = min(bytes, working_bytes);
- kaddr = kmap_atomic(bvec.bv_page);
- memcpy(kaddr + bvec.bv_offset, buf + buf_offset, bytes);
- kunmap_atomic(kaddr);
+ memcpy_to_page(bvec.bv_page, bvec.bv_offset, buf + buf_offset,
+ bytes);
flush_dcache_page(bvec.bv_page);
buf_offset += bytes;
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index aa9cd11f4b78..9084a950dc09 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -467,7 +467,7 @@ int lzo_decompress(struct list_head *ws, unsigned char
*data_in,
destlen = min_t(unsigned long, destlen, PAGE_SIZE);
bytes = min_t(unsigned long, destlen, out_len - start_byte);
- kaddr = kmap_atomic(dest_page);
+ kaddr = kmap_local_page(dest_page);
memcpy(kaddr, workspace->buf + start_byte, bytes);
/*
@@ -477,7 +477,7 @@ int lzo_decompress(struct list_head *ws, unsigned char
*data_in,
*/
if (bytes < destlen)
memset(kaddr+bytes, 0, destlen-bytes);
-
