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[79.53.109.127]) by smtp.gmail.com with ESMTPSA id k1-20020adff5c1000000b0020d07d90b71sm34830696wrp.66.2022.07.06.04.15.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Jul 2022 04:15:31 -0700 (PDT) From: "Fabio M. De Francesco" To: David Sterba , Chris Mason , Josef Bacik , Nick Terrell , linux-btrfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ira Weiny , Andrew Morton , Matthew Wilcox , Kees Cook , Sebastian Andrzej Siewior , "James E. J. Bottomley" , Helge Deller , John David Anglin , linux-parisc@vger.kernel.org Cc: "Fabio M. De Francesco" , Filipe Manana Subject: [PATCH v6 2/2] btrfs: Replace kmap() with kmap_local_page() in zstd.c Date: Wed, 6 Jul 2022 13:15:20 +0200 Message-Id: <20220706111520.12858-3-fmdefrancesco@gmail.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220706111520.12858-1-fmdefrancesco@gmail.com> References: <20220706111520.12858-1-fmdefrancesco@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org 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 zstd.c because in this file the mappings are per thread and are not visible in other contexts. In the meanwhile use plain page_address() on pages allocated with the GFP_NOFS flag instead of calling kmap*() on them (since they are always allocated from ZONE_NORMAL). Tested with xfstests on QEMU + KVM 32 bits VM with 4GB of RAM, booting a kernel with HIGHMEM64G enabled. Cc: Filipe Manana Suggested-by: Ira Weiny Signed-off-by: Fabio M. De Francesco --- fs/btrfs/zstd.c | 33 +++++++++++++-------------------- 1 file changed, 13 insertions(+), 20 deletions(-) diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c index 0fe31a6f6e68..35a0224d4eb7 100644 --- a/fs/btrfs/zstd.c +++ b/fs/btrfs/zstd.c @@ -403,7 +403,7 @@ 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 = kmap(in_page); + workspace->in_buf.src = kmap_local_page(in_page); workspace->in_buf.pos = 0; workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE); @@ -415,7 +415,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, goto out; } pages[nr_pages++] = out_page; - workspace->out_buf.dst = kmap(out_page); + workspace->out_buf.dst = page_address(out_page); workspace->out_buf.pos = 0; workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE); @@ -450,9 +450,7 @@ 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; goto out; } @@ -462,7 +460,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, goto out; } pages[nr_pages++] = out_page; - workspace->out_buf.dst = kmap(out_page); + workspace->out_buf.dst = page_address(out_page); workspace->out_buf.pos = 0; workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE); @@ -477,13 +475,12 @@ 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); + kunmap_local(workspace->in_buf.src); put_page(in_page); - start += PAGE_SIZE; len -= PAGE_SIZE; in_page = find_get_page(mapping, start >> PAGE_SHIFT); - workspace->in_buf.src = kmap(in_page); + workspace->in_buf.src = kmap_local_page(in_page); workspace->in_buf.pos = 0; workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE); } @@ -510,9 +507,7 @@ 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; goto out; } @@ -522,7 +517,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, goto out; } pages[nr_pages++] = out_page; - workspace->out_buf.dst = kmap(out_page); + workspace->out_buf.dst = page_address(out_page); workspace->out_buf.pos = 0; workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE); } @@ -537,13 +532,10 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, *total_out = tot_out; out: *out_pages = nr_pages; - /* Cleanup */ - if (in_page) { - kunmap(in_page); + if (workspace->in_buf.src) { + kunmap_local(workspace->in_buf.src); put_page(in_page); } - if (out_page) - kunmap(out_page); return ret; } @@ -567,7 +559,7 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) goto done; } - workspace->in_buf.src = kmap(pages_in[page_in_index]); + workspace->in_buf.src = kmap_local_page(pages_in[page_in_index]); workspace->in_buf.pos = 0; workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE); @@ -603,14 +595,15 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) break; if (workspace->in_buf.pos == workspace->in_buf.size) { - kunmap(pages_in[page_in_index++]); + kunmap_local(workspace->in_buf.src); + 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 = kmap(pages_in[page_in_index]); + workspace->in_buf.src = kmap_local_page(pages_in[page_in_index]); workspace->in_buf.pos = 0; workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE); } @@ -619,7 +612,7 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) zero_fill_bio(cb->orig_bio); done: if (workspace->in_buf.src) - kunmap(pages_in[page_in_index]); + kunmap_local(workspace->in_buf.src); return ret; }