From 718e58551aecf7a63aa643ec0668a0374eee9de0 Mon Sep 17 00:00:00 2001 From: "Fabio M. De Francesco" Date: Mon, 27 Jun 2022 18:33:05 +0200 Subject: [PATCH] btrfs: zlib: replace kmap() with kmap_local_page() in zlib_compress_pages() The use of kmap() is being deprecated in favor of kmap_local_page(). With kmap_local_page(), the mapping is per thread, CPU local and not globally visible. Therefore, use kmap_local_page() / kunmap_local() in zlib_compress_pages() because in this function the mappings are per thread and are not visible in other contexts. Furthermore, drop the mappings of "out_page" which is allocated within zlib_compress_pages() with alloc_page(GFP_NOFS) and use page_address(). Tested with xfstests on a QEMU + KVM 32-bits VM with 4GB of RAM booting a kernel with HIGHMEM64G enabled. This patch passes 26/26 tests of group "compress". CC: Qu Wenruo Suggested-by: Ira Weiny Reviewed-by: Ira Weiny Signed-off-by: Fabio M. De Francesco Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/zlib.c | 32 +++++++++++++------------------- 1 file changed, 13 insertions(+), 19 deletions(-) diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c index 767a0c6..82a43ac 100644 --- a/fs/btrfs/zlib.c +++ b/fs/btrfs/zlib.c @@ -97,7 +97,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, { struct workspace *workspace = list_entry(ws, struct workspace, list); int ret; - char *data_in; + char *data_in = NULL; char *cpage_out; int nr_pages = 0; struct page *in_page = NULL; @@ -126,7 +126,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, ret = -ENOMEM; goto out; } - cpage_out = kmap(out_page); + cpage_out = page_address(out_page); pages[0] = out_page; nr_pages = 1; @@ -148,26 +148,26 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, int i; for (i = 0; i < in_buf_pages; i++) { - if (in_page) { - kunmap(in_page); + if (data_in) { + kunmap_local(data_in); put_page(in_page); } in_page = find_get_page(mapping, start >> PAGE_SHIFT); - data_in = kmap(in_page); + data_in = kmap_local_page(in_page); memcpy(workspace->buf + i * PAGE_SIZE, data_in, PAGE_SIZE); start += PAGE_SIZE; } workspace->strm.next_in = workspace->buf; } else { - if (in_page) { - kunmap(in_page); + if (data_in) { + kunmap_local(data_in); put_page(in_page); } in_page = find_get_page(mapping, start >> PAGE_SHIFT); - data_in = kmap(in_page); + data_in = kmap_local_page(in_page); start += PAGE_SIZE; workspace->strm.next_in = data_in; } @@ -196,9 +196,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, * the stream end if required */ if (workspace->strm.avail_out == 0) { - kunmap(out_page); if (nr_pages == nr_dest_pages) { - out_page = NULL; ret = -E2BIG; goto out; } @@ -207,7 +205,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, ret = -ENOMEM; goto out; } - cpage_out = kmap(out_page); + cpage_out = page_address(out_page); pages[nr_pages] = out_page; nr_pages++; workspace->strm.avail_out = PAGE_SIZE; @@ -234,9 +232,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, goto out; } else if (workspace->strm.avail_out == 0) { /* get another page for the stream end */ - kunmap(out_page); if (nr_pages == nr_dest_pages) { - out_page = NULL; ret = -E2BIG; goto out; } @@ -245,7 +241,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, ret = -ENOMEM; goto out; } - cpage_out = kmap(out_page); + cpage_out = page_address(out_page); pages[nr_pages] = out_page; nr_pages++; workspace->strm.avail_out = PAGE_SIZE; @@ -264,13 +260,11 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, *total_in = workspace->strm.total_in; out: *out_pages = nr_pages; - if (out_page) - kunmap(out_page); - - if (in_page) { - kunmap(in_page); + if (data_in) { + kunmap_local(data_in); put_page(in_page); } + return ret; } -- 2.7.4