Merge tag 'for-5.15-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "Last minute fixes for crash on 32bit architectures when compression is
  in use. It's a regression introduced in 5.15-rc and I'd really like
  not let this into the final release, fixes via stable trees would add
  unnecessary delay.

  The problem is on 32bit architectures with highmem enabled, the pages
  for compression may need to be kmapped, while the patches removed that
  as we don't use GFP_HIGHMEM allocations anymore. The pages that don't
  come from local allocation still may be from highmem. Despite being on
  32bit there's enough such ARM machines in use so it's not a marginal
  issue.

  I did full reverts of the patches one by one instead of a huge one.
  There's one exception for the "lzo" revert as there was an
  intermediate patch touching the same code to make it compatible with
  subpage. I can't revert that one too, so the revert in lzo.c is
  manual. Qu Wenruo has worked on that with me and verified the changes"

* tag 'for-5.15-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Revert "btrfs: compression: drop kmap/kunmap from lzo"
  Revert "btrfs: compression: drop kmap/kunmap from zlib"
  Revert "btrfs: compression: drop kmap/kunmap from zstd"
  Revert "btrfs: compression: drop kmap/kunmap from generic helpers"

1 files changed, 18 insertions, 9 deletions

diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 56dce9f00988..f06b68040352 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -399,7 +399,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 
 	/* map in the first page of input data */
 	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
-	workspace->in_buf.src = page_address(in_page);
+	workspace->in_buf.src = kmap(in_page);
 	workspace->in_buf.pos = 0;
 	workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 
@@ -411,7 +411,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 		goto out;
 	}
 	pages[nr_pages++] = out_page;
-	workspace->out_buf.dst = page_address(out_page);
+	workspace->out_buf.dst = kmap(out_page);
 	workspace->out_buf.pos = 0;
 	workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 
@@ -446,6 +446,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 		if (workspace->out_buf.pos == workspace->out_buf.size) {
 			tot_out += PAGE_SIZE;
 			max_out -= PAGE_SIZE;
+			kunmap(out_page);
 			if (nr_pages == nr_dest_pages) {
 				out_page = NULL;
 				ret = -E2BIG;
@@ -457,7 +458,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 				goto out;
 			}
 			pages[nr_pages++] = out_page;
-			workspace->out_buf.dst = page_address(out_page);
+			workspace->out_buf.dst = kmap(out_page);
 			workspace->out_buf.pos = 0;
 			workspace->out_buf.size = min_t(size_t, max_out,
 							PAGE_SIZE);
@@ -472,12 +473,13 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 		/* Check if we need more input */
 		if (workspace->in_buf.pos == workspace->in_buf.size) {
 			tot_in += PAGE_SIZE;
+			kunmap(in_page);
 			put_page(in_page);
 
 			start += PAGE_SIZE;
 			len -= PAGE_SIZE;
 			in_page = find_get_page(mapping, start >> PAGE_SHIFT);
-			workspace->in_buf.src = page_address(in_page);
+			workspace->in_buf.src = kmap(in_page);
 			workspace->in_buf.pos = 0;
 			workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 		}
@@ -504,6 +506,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 
 		tot_out += PAGE_SIZE;
 		max_out -= PAGE_SIZE;
+		kunmap(out_page);
 		if (nr_pages == nr_dest_pages) {
 			out_page = NULL;
 			ret = -E2BIG;
@@ -515,7 +518,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 			goto out;
 		}
 		pages[nr_pages++] = out_page;
-		workspace->out_buf.dst = page_address(out_page);
+		workspace->out_buf.dst = kmap(out_page);
 		workspace->out_buf.pos = 0;
 		workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 	}
@@ -531,8 +534,12 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 out:
 	*out_pages = nr_pages;
 	/* Cleanup */
-	if (in_page)
+	if (in_page) {
+		kunmap(in_page);
 		put_page(in_page);
+	}
+	if (out_page)
+		kunmap(out_page);
 	return ret;
 }
 
@@ -556,7 +563,7 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 		goto done;
 	}
 
-	workspace->in_buf.src = page_address(pages_in[page_in_index]);
+	workspace->in_buf.src = kmap(pages_in[page_in_index]);
 	workspace->in_buf.pos = 0;
 	workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 
@@ -592,14 +599,14 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 			break;
 
 		if (workspace->in_buf.pos == workspace->in_buf.size) {
-			page_in_index++;
+			kunmap(pages_in[page_in_index++]);
 			if (page_in_index >= total_pages_in) {
 				workspace->in_buf.src = NULL;
 				ret = -EIO;
 				goto done;
 			}
 			srclen -= PAGE_SIZE;
-			workspace->in_buf.src = page_address(pages_in[page_in_index]);
+			workspace->in_buf.src = kmap(pages_in[page_in_index]);
 			workspace->in_buf.pos = 0;
 			workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 		}
@@ -607,6 +614,8 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 	ret = 0;
 	zero_fill_bio(cb->orig_bio);
 done:
+	if (workspace->in_buf.src)
+		kunmap(pages_in[page_in_index]);
 	return ret;
 }