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: Ira Weiny <ira.weiny@intel.com> Reviewed-by: David 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-04 18:40:07 -07:00 · 2021-05-04 18:40:07 -07:00 · d048b9c2a7
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@ -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);
 			}
 		}

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@ -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);
 	}

--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@ -646,17 +646,12 @@ again:
 		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 @@ again:
 	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 @@ again:
 		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);
--- a/fs/btrfs/reflink.c
+++ b/fs/btrfs/reflink.c
@ -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);
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@ -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 @@ next:
 	 * 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;
 }
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@ -631,7 +631,6 @@ int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 	size_t ret2;
 	unsigned long total_out = 0;
 	unsigned long pg_offset = 0;
-	char *kaddr;

 	stream = ZSTD_initDStream(
 			ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
@ -696,9 +695,7 @@ int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 	ret = 0;
 finish:
 	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;
 }