Commit d048b9c2 authored by Ira Weiny's avatar Ira Weiny Committed by Linus Torvalds
Browse files

btrfs: use memzero_page() instead of open coded kmap pattern 

There are many places where kmap/memset/kunmap patterns occur.

Use the newly lifted memzero_page() to eliminate direct uses of kmap and
leverage the new core functions use of kmap_local_page().

The development of this patch was aided by the following coccinelle
script:

// <smpl>
// SPDX-License-Identifier: GPL-2.0-only
// Find kmap/memset/kunmap pattern and replace with memset*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:

//
// Then the memset pattern
//
@ memset_rule1 @
expression page, V, L, Off;
identifier ptr;
type VP;
@@

(
-VP ptr = kmap(page);
|
-ptr = kmap(page);
|
-VP ptr = kmap_atomic(page);
|
-ptr = kmap_atomic(page);
)
<+...
(
-memset(ptr, 0, L);
+memzero_page(page, 0, L);
|
-memset(ptr + Off, 0, L);
+memzero_page(page, Off, L);
|
-memset(ptr, V, L);
+memset_page(page, V, 0, L);
|
-memset(ptr + Off, V, L);
+memset_page(page, V, Off, L);
)
...+>
(
-kunmap(page);
|
-kunmap_atomic(ptr);
)

// Remove any pointers left unused
@
depends on memset_rule1
@
identifier memset_rule1.ptr;
type VP, VP1;
@@

-VP ptr;
	... when != ptr;
? VP1 ptr;

//
// Catch all
//
@ memset_rule2 @
expression page;
identifier ptr;
expression GenTo, GenSize, GenValue;
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 memset/memcpy
// The follow are catch alls which need to be evaluated by hand.
//
-memset(GenTo, 0, GenSize);
+memzero_pageExtra(page, GenTo, GenSize);
|
-memset(GenTo, GenValue, GenSize);
+memset_pageExtra(page, GenValue, GenTo, GenSize);
)
...+>
(
-kunmap(page);
|
-kunmap_atomic(ptr);
)

// Remove any pointers left unused
@
depends on memset_rule2
@
identifier memset_rule2.ptr;
type VP, VP1;
@@

-VP ptr;
	... when != ptr;
? VP1 ptr;

// </smpl>

Link: https://lkml.kernel.org/r/20210309212137.2610186-4-ira.weiny@intel.com


Signed-off-by: default avatarIra Weiny <ira.weiny@intel.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 28961998

fs/btrfs/compression.c

+1 −4
Original line number Diff line number Diff line
@@ -591,16 +591,13 @@ static noinline int add_ra_bio_pages(struct inode *inode, 
		free_extent_map(em);



		if (page->index == end_index) {

			char *userpage;

			size_t zero_offset = offset_in_page(isize);



			if (zero_offset) {

				int zeros;

				zeros = PAGE_SIZE - zero_offset;

				userpage = kmap_atomic(page);

				memset(userpage + zero_offset, 0, zeros);

				memzero_page(page, zero_offset, zeros);

				flush_dcache_page(page);

				kunmap_atomic(userpage);

			}

		}

fs/btrfs/extent_io.c

+4 −18
Original line number Diff line number Diff line
@@ -3421,15 +3421,12 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, 
	}



	if (page->index == last_byte >> PAGE_SHIFT) {

		char *userpage;

		size_t zero_offset = offset_in_page(last_byte);



		if (zero_offset) {

			iosize = PAGE_SIZE - zero_offset;

			userpage = kmap_atomic(page);

			memset(userpage + zero_offset, 0, iosize);

			memzero_page(page, zero_offset, iosize);

			flush_dcache_page(page);

			kunmap_atomic(userpage);

		}

	}

	begin_page_read(fs_info, page);
@@ -3438,14 +3435,11 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, 
		u64 disk_bytenr;



		if (cur >= last_byte) {

			char *userpage;

			struct extent_state *cached = NULL;



			iosize = PAGE_SIZE - pg_offset;

			userpage = kmap_atomic(page);

			memset(userpage + pg_offset, 0, iosize);

			memzero_page(page, pg_offset, iosize);

			flush_dcache_page(page);

			kunmap_atomic(userpage);

			set_extent_uptodate(tree, cur, cur + iosize - 1,

					    &cached, GFP_NOFS);

			unlock_extent_cached(tree, cur,
@@ -3528,13 +3522,10 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, 


		/* we've found a hole, just zero and go on */

		if (block_start == EXTENT_MAP_HOLE) {

			char *userpage;

			struct extent_state *cached = NULL;



			userpage = kmap_atomic(page);

			memset(userpage + pg_offset, 0, iosize);

			memzero_page(page, pg_offset, iosize);

			flush_dcache_page(page);

			kunmap_atomic(userpage);



			set_extent_uptodate(tree, cur, cur + iosize - 1,

					    &cached, GFP_NOFS);
@@ -3845,12 +3836,7 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, 
	}



	if (page->index == end_index) {

		char *userpage;



		userpage = kmap_atomic(page);

		memset(userpage + pg_offset, 0,

		       PAGE_SIZE - pg_offset);

		kunmap_atomic(userpage);

		memzero_page(page, pg_offset, PAGE_SIZE - pg_offset);

		flush_dcache_page(page);

	}

fs/btrfs/inode.c

+10 −23
Original line number Diff line number Diff line
@@ -646,17 +646,12 @@ static noinline int compress_file_range(struct async_chunk *async_chunk) 
		if (!ret) {

			unsigned long offset = offset_in_page(total_compressed);

			struct page *page = pages[nr_pages - 1];

			char *kaddr;



			/* zero the tail end of the last page, we might be

			 * sending it down to disk

			 */

			if (offset) {

				kaddr = kmap_atomic(page);

				memset(kaddr + offset, 0,

				       PAGE_SIZE - offset);

				kunmap_atomic(kaddr);

			}

			if (offset)

				memzero_page(page, offset, PAGE_SIZE - offset);

			will_compress = 1;

		}

	}
@@ -4833,7 +4828,6 @@ int btrfs_truncate_block(struct btrfs_inode *inode, loff_t from, loff_t len, 
	struct btrfs_ordered_extent *ordered;

	struct extent_state *cached_state = NULL;

	struct extent_changeset *data_reserved = NULL;

	char *kaddr;

	bool only_release_metadata = false;

	u32 blocksize = fs_info->sectorsize;

	pgoff_t index = from >> PAGE_SHIFT;
@@ -4925,15 +4919,13 @@ int btrfs_truncate_block(struct btrfs_inode *inode, loff_t from, loff_t len, 
	if (offset != blocksize) {

		if (!len)

			len = blocksize - offset;

		kaddr = kmap(page);

		if (front)

			memset(kaddr + (block_start - page_offset(page)),

				0, offset);

			memzero_page(page, (block_start - page_offset(page)),

				     offset);

		else

			memset(kaddr + (block_start - page_offset(page)) +  offset,

				0, len);

			memzero_page(page, (block_start - page_offset(page)) + offset,

				     len);

		flush_dcache_page(page);

		kunmap(page);

	}

	ClearPageChecked(page);

	set_page_dirty(page);
@@ -6832,11 +6824,9 @@ static noinline int uncompress_inline(struct btrfs_path *path, 
	 * cover that region here.

	 */



	if (max_size + pg_offset < PAGE_SIZE) {

		char *map = kmap(page);

		memset(map + pg_offset + max_size, 0, PAGE_SIZE - max_size - pg_offset);

		kunmap(page);

	}

	if (max_size + pg_offset < PAGE_SIZE)

		memzero_page(page,  pg_offset + max_size,

			     PAGE_SIZE - max_size - pg_offset);

	kfree(tmp);

	return ret;

}
@@ -8506,7 +8496,6 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) 
	struct btrfs_ordered_extent *ordered;

	struct extent_state *cached_state = NULL;

	struct extent_changeset *data_reserved = NULL;

	char *kaddr;

	unsigned long zero_start;

	loff_t size;

	vm_fault_t ret;
@@ -8620,10 +8609,8 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) 
		zero_start = PAGE_SIZE;



	if (zero_start != PAGE_SIZE) {

		kaddr = kmap(page);

		memset(kaddr + zero_start, 0, PAGE_SIZE - zero_start);

		memzero_page(page, zero_start, PAGE_SIZE - zero_start);

		flush_dcache_page(page);

		kunmap(page);

	}

	ClearPageChecked(page);

	set_page_dirty(page);

fs/btrfs/reflink.c

+1 −5
Original line number Diff line number Diff line
@@ -129,12 +129,8 @@ static int copy_inline_to_page(struct btrfs_inode *inode, 
	 * So what's in the range [500, 4095] corresponds to zeroes.

	 */

	if (datal < block_size) {

		char *map;



		map = kmap(page);

		memset(map + datal, 0, block_size - datal);

		memzero_page(page, datal, block_size - datal);

		flush_dcache_page(page);

		kunmap(page);

	}



	SetPageUptodate(page);

fs/btrfs/zlib.c

+1 −4
Original line number Diff line number Diff line
@@ -375,7 +375,6 @@ int zlib_decompress(struct list_head *ws, unsigned char *data_in, 
	unsigned long bytes_left;

	unsigned long total_out = 0;

	unsigned long pg_offset = 0;

	char *kaddr;



	destlen = min_t(unsigned long, destlen, PAGE_SIZE);

	bytes_left = destlen;
@@ -455,9 +454,7 @@ int zlib_decompress(struct list_head *ws, unsigned char *data_in, 
	 * end of the inline extent (destlen) to the end of the page

	 */

	if (pg_offset < destlen) {

		kaddr = kmap_atomic(dest_page);

		memset(kaddr + pg_offset, 0, destlen - pg_offset);

		kunmap_atomic(kaddr);

		memzero_page(dest_page, pg_offset, destlen - pg_offset);

	}

	return ret;

}