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authorIra Weiny <ira.weiny@intel.com>2021-02-10 09:22:19 +0300
committerDavid Sterba <dsterba@suse.com>2021-02-26 14:45:15 +0300
commit3590ec58991bcf0f3512c4353a786079a6619758 (patch)
tree91d4c140aea719e47510ab7820170f963088d974 /fs/btrfs/zlib.c
parentca18f6ea012bf30236b76c3480ac2c97131b6f8f (diff)
downloadlinux-3590ec58991bcf0f3512c4353a786079a6619758.tar.xz
btrfs: use memcpy_[to|from]_page() and kmap_local_page()
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: // <smpl> // 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; // <smpl> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/zlib.c')
-rw-r--r--fs/btrfs/zlib.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 05615a1099db..d524acf7b3e5 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -432,9 +432,8 @@ int zlib_decompress(struct list_head *ws, unsigned char *data_in,
PAGE_SIZE - (buf_offset % PAGE_SIZE));
bytes = min(bytes, bytes_left);
- kaddr = kmap_atomic(dest_page);
- memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
- kunmap_atomic(kaddr);
+ memcpy_to_page(dest_page, pg_offset,
+ workspace->buf + buf_offset, bytes);
pg_offset += bytes;
bytes_left -= bytes;