From: David Sterba <dsterba@suse.com>

Date: Wed, 27 Oct 2021 10:44:21 +0200

Subject: [PATCH 132/132] Revert "btrfs: compression: drop kmap/kunmap from

 lzo"

Git-commit: ccaa66c8dd277ac02f96914168bb7177f7ea8117

Patch-mainline: 5.15

References: bsc#1193852

This reverts commit 8c945d32e60427cbc0859cf7045bbe6196bb03d8.

The kmaps in compression code are still needed and cause crashes on

32bit machines (ARM, x86). Reproducible eg. by running fstest btrfs/004

with enabled LZO or ZSTD compression.

The revert does not apply cleanly due to changes in a6e66e6f8c1b

("btrfs: rework lzo_decompress_bio() to make it subpage compatible")

that reworked the page iteration so the revert is done to be equivalent

to the original code.

Link: https://lore.kernel.org/all/CAJCQCtT+OuemovPO7GZk8Y8=qtOObr0XTDp8jh4OHD6y84AFxw@mail.gmail.com/

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=214839

Tested-by: Qu Wenruo <wqu@suse.com>

Signed-off-by: Qu Wenruo <wqu@suse.com>

Signed-off-by: David Sterba <dsterba@suse.com>

---

 fs/btrfs/lzo.c | 36 +++++++++++++++++++++++++-----------

 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c

index c25dfd1a8a54..3dbe6eb5fda7 100644

--- a/fs/btrfs/lzo.c

+++ b/fs/btrfs/lzo.c

@@ -141,7 +141,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,

 	*total_in = 0;

 	in_page = find_get_page(mapping, start >> PAGE_SHIFT);

-	data_in = page_address(in_page);

+	data_in = kmap(in_page);

 	/*

 	 * store the size of all chunks of compressed data in

@@ -152,7 +152,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,

 		ret = -ENOMEM;

 		goto out;

 	}

-	cpage_out = page_address(out_page);

+	cpage_out = kmap(out_page);

 	out_offset = LZO_LEN;

 	tot_out = LZO_LEN;

 	pages[0] = out_page;

@@ -210,6 +210,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,

 				if (out_len == 0 && tot_in >= len)

 					break;

+				kunmap(out_page);

 				if (nr_pages == nr_dest_pages) {

 					out_page = NULL;

 					ret = -E2BIG;

@@ -221,7 +222,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,

 					ret = -ENOMEM;

 					goto out;

 				}

-				cpage_out = page_address(out_page);

+				cpage_out = kmap(out_page);

 				pages[nr_pages++] = out_page;

 				pg_bytes_left = PAGE_SIZE;

@@ -243,11 +244,12 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,

 			break;

 		bytes_left = len - tot_in;

+		kunmap(in_page);

 		put_page(in_page);

 		start += PAGE_SIZE;

 		in_page = find_get_page(mapping, start >> PAGE_SHIFT);

-		data_in = page_address(in_page);

+		data_in = kmap(in_page);

 		in_len = min(bytes_left, PAGE_SIZE);

 	}

@@ -257,17 +259,22 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,

 	}

 	/* store the size of all chunks of compressed data */

-	sizes_ptr = page_address(pages[0]);

+	sizes_ptr = kmap_local_page(pages[0]);

 	write_compress_length(sizes_ptr, tot_out);

+	kunmap_local(sizes_ptr);

 	ret = 0;

 	*total_out = tot_out;

 	*total_in = tot_in;

 out:

 	*out_pages = nr_pages;

+	if (out_page)

+		kunmap(out_page);

-	if (in_page)

+	if (in_page) {

+		kunmap(in_page);

 		put_page(in_page);

+	}

 	return ret;

 }

@@ -283,6 +290,7 @@ static void copy_compressed_segment(struct compressed_bio *cb,

 	u32 orig_in = *cur_in;

 	while (*cur_in < orig_in + len) {

+		char *kaddr;

 		struct page *cur_page;

 		u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),

 					  orig_in + len - *cur_in);

@@ -290,9 +298,11 @@ static void copy_compressed_segment(struct compressed_bio *cb,

 		ASSERT(copy_len);

 		cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE];

+		kaddr = kmap(cur_page);

 		memcpy(dest + *cur_in - orig_in,

-			page_address(cur_page) + offset_in_page(*cur_in),

+			kaddr + offset_in_page(*cur_in),

 			copy_len);

+		kunmap(cur_page);

 		*cur_in += copy_len;

 	}

@@ -303,6 +313,7 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)

 	struct workspace *workspace = list_entry(ws, struct workspace, list);

 	const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);

 	const u32 sectorsize = fs_info->sectorsize;

+	char *kaddr;

 	int ret;

 	/* Compressed data length, can be unaligned */

 	u32 len_in;

@@ -311,7 +322,9 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)

 	/* Bytes decompressed so far */

 	u32 cur_out = 0;

-	len_in = read_compress_length(page_address(cb->compressed_pages[0]));

+	kaddr = kmap(cb->compressed_pages[0]);

+	len_in = read_compress_length(kaddr);

+	kunmap(cb->compressed_pages[0]);

 	cur_in += LZO_LEN;

 	/*

@@ -344,9 +357,9 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)

 		ASSERT(cur_in / sectorsize ==

 		       (cur_in + LZO_LEN - 1) / sectorsize);

 		cur_page = cb->compressed_pages[cur_in / PAGE_SIZE];

+		kaddr = kmap(cur_page);

 		ASSERT(cur_page);

-		seg_len = read_compress_length(page_address(cur_page) +

-					       offset_in_page(cur_in));

+		seg_len = read_compress_length(kaddr + offset_in_page(cur_in));

 		cur_in += LZO_LEN;

 		/* Copy the compressed segment payload into workspace */

@@ -431,7 +444,7 @@ 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 = page_address(dest_page);

+	kaddr = kmap_local_page(dest_page);

 	memcpy(kaddr, workspace->buf + start_byte, bytes);

 	/*

@@ -441,6 +454,7 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in,

 	 */

 	if (bytes < destlen)

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

+	kunmap_local(kaddr);

 out:

 	return ret;

 }

-- 

2.33.0