From 56ee254d23c59fd48fb6f192d79858f60cfe2bf6 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Wed, 27 Oct 2021 10:42:27 +0200 Subject: Revert "btrfs: compression: drop kmap/kunmap from zstd" This reverts commit bbaf9715f3f5b5ff0de71da91fcc34ee9c198ed8. 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. Example stacktrace with ZSTD on a 32bit ARM machine: Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = c4159ed3 [00000000] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 210 Comm: kworker/u2:3 Not tainted 5.14.0-rc79+ #12 Hardware name: Allwinner sun4i/sun5i Families Workqueue: btrfs-delalloc btrfs_work_helper PC is at mmiocpy+0x48/0x330 LR is at ZSTD_compressStream_generic+0x15c/0x28c (mmiocpy) from [] (ZSTD_compressStream_generic+0x15c/0x28c) (ZSTD_compressStream_generic) from [] (ZSTD_compressStream+0x64/0xa0) (ZSTD_compressStream) from [] (zstd_compress_pages+0x170/0x488) (zstd_compress_pages) from [] (btrfs_compress_pages+0x124/0x12c) (btrfs_compress_pages) from [] (compress_file_range+0x3c0/0x834) (compress_file_range) from [] (async_cow_start+0x10/0x28) (async_cow_start) from [] (btrfs_work_helper+0x100/0x230) (btrfs_work_helper) from [] (process_one_work+0x1b4/0x418) (process_one_work) from [] (worker_thread+0x44/0x524) (worker_thread) from [] (kthread+0x180/0x1b0) (kthread) from [] Link: https://lore.kernel.org/all/CAJCQCtT+OuemovPO7GZk8Y8=qtOObr0XTDp8jh4OHD6y84AFxw@mail.gmail.com/ Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=214839 Signed-off-by: David Sterba --- fs/btrfs/zstd.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) (limited to 'fs/btrfs/zstd.c') 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; } -- cgit v1.2.3