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[79.18.0.143]) by smtp.gmail.com with ESMTPSA id r20-20020a05600c35d400b0039c1396b495sm2593224wmq.9.2022.06.11.06.52.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 11 Jun 2022 06:52:07 -0700 (PDT) From: "Fabio M. De Francesco" To: Chris Mason , Josef Bacik , David Sterba , Nick Terrell , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Fabio M. De Francesco" , Filipe Manana , Ira Weiny Subject: [PATCH] btrfs: Replace kmap() with kmap_local_page() in zstd.c Date: Sat, 11 Jun 2022 15:52:03 +0200 Message-Id: <20220611135203.27992-1-fmdefrancesco@gmail.com> X-Mailer: git-send-email 2.36.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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; meanwhile refactor zstd_compress_pages() to comply with nested local mapping / unmapping ordering rules. Tested with xfstests on a QEMU + KVM 32 bits VM with 4GB of RAM and HIGHMEM64G enabled. Cc: Filipe Manana Suggested-by: Ira Weiny Signed-off-by: Fabio M. De Francesco --- Thanks to Ira Weiny for his invaluable help and persevering support. Thanks also to Filipe Manana for identifying a fundamental detail I had ove= rlooked: https://lore.kernel.org/lkml/20220611093411.GA3779054@falcondesktop/=20 tweed32:/usr/lib/xfstests # ./check -g compress FSTYP -- btrfs PLATFORM -- Linux/i686 tweed32 5.19.0-rc1-vanilla-debug+ #22 SMP PREEM= PT_DYNAMIC Sat Jun 11 14:31:39 CEST 2022 MKFS_OPTIONS -- /dev/loop1 MOUNT_OPTIONS -- /dev/loop1 /mnt/scratch btrfs/024 1s ... 0s btrfs/026 3s ... 3s btrfs/037 1s ... 1s btrfs/038 1s ... 0s btrfs/041 0s ... 1s btrfs/062 34s ... 35s btrfs/063 18s ... 18s btrfs/067 33s ... 32s btrfs/068 10s ... 10s btrfs/070 [not run] btrfs and this test needs 5 or more disks in SCRA= TCH_DEV_POOL btrfs/071 [not run] btrfs and this test needs 5 or more disks in SCRA= TCH_DEV_POOL btrfs/072 33s ... 33s btrfs/073 17s ... 15s btrfs/074 36s ... 32s btrfs/076 0s ... 0s btrfs/103 1s ... 1s btrfs/106 1s ... 1s btrfs/109 1s ... 0s btrfs/113 0s ... 1s btrfs/138 43s ... 46s btrfs/149 1s ... 1s btrfs/183 1s ... 1s btrfs/205 1s ... 1s btrfs/234 3s ... 3s btrfs/246 0s ... 0s btrfs/251 1s ... 1s Ran: btrfs/024 btrfs/026 btrfs/037 btrfs/038 btrfs/041 btrfs/062 btrfs/063 = btrfs/067 btrfs/068 btrfs/070 btrfs/071 btrfs/072 btrfs/073 btrfs/074 btrfs= /076 btrfs/103 btrfs/106 btrfs/109 btrfs/113 btrfs/138 btrfs/149 btrfs/183 = btrfs/205 btrfs/234 btrfs/246 btrfs/251 Not run: btrfs/070 btrfs/071 Passed all 26 tests fs/btrfs/zstd.c | 42 +++++++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 19 deletions(-) diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c index 0fe31a6f6e68..4d50eb3edce5 100644 --- a/fs/btrfs/zstd.c +++ b/fs/btrfs/zstd.c @@ -391,6 +391,8 @@ int zstd_compress_pages(struct list_head *ws, struct ad= dress_space *mapping, *out_pages =3D 0; *total_out =3D 0; *total_in =3D 0; + workspace->in_buf.src =3D NULL; + workspace->out_buf.dst =3D NULL; =20 /* Initialize the stream */ stream =3D zstd_init_cstream(¶ms, len, workspace->mem, @@ -403,7 +405,7 @@ int zstd_compress_pages(struct list_head *ws, struct ad= dress_space *mapping, =20 /* map in the first page of input data */ in_page =3D find_get_page(mapping, start >> PAGE_SHIFT); - workspace->in_buf.src =3D kmap(in_page); + workspace->in_buf.src =3D kmap_local_page(in_page); workspace->in_buf.pos =3D 0; workspace->in_buf.size =3D min_t(size_t, len, PAGE_SIZE); =20 @@ -415,7 +417,7 @@ int zstd_compress_pages(struct list_head *ws, struct ad= dress_space *mapping, goto out; } pages[nr_pages++] =3D out_page; - workspace->out_buf.dst =3D kmap(out_page); + workspace->out_buf.dst =3D kmap_local_page(out_page); workspace->out_buf.pos =3D 0; workspace->out_buf.size =3D min_t(size_t, max_out, PAGE_SIZE); =20 @@ -450,9 +452,9 @@ int zstd_compress_pages(struct list_head *ws, struct ad= dress_space *mapping, if (workspace->out_buf.pos =3D=3D workspace->out_buf.size) { tot_out +=3D PAGE_SIZE; max_out -=3D PAGE_SIZE; - kunmap(out_page); + kunmap_local(workspace->out_buf.dst); if (nr_pages =3D=3D nr_dest_pages) { - out_page =3D NULL; + workspace->out_buf.dst =3D NULL; ret =3D -E2BIG; goto out; } @@ -462,7 +464,7 @@ int zstd_compress_pages(struct list_head *ws, struct ad= dress_space *mapping, goto out; } pages[nr_pages++] =3D out_page; - workspace->out_buf.dst =3D kmap(out_page); + workspace->out_buf.dst =3D kmap_local_page(out_page); workspace->out_buf.pos =3D 0; workspace->out_buf.size =3D min_t(size_t, max_out, PAGE_SIZE); @@ -477,15 +479,16 @@ int zstd_compress_pages(struct list_head *ws, struct = address_space *mapping, /* Check if we need more input */ if (workspace->in_buf.pos =3D=3D workspace->in_buf.size) { tot_in +=3D PAGE_SIZE; - kunmap(in_page); + kunmap_local(workspace->out_buf.dst); + kunmap_local((void *)workspace->in_buf.src); put_page(in_page); - start +=3D PAGE_SIZE; len -=3D PAGE_SIZE; in_page =3D find_get_page(mapping, start >> PAGE_SHIFT); - workspace->in_buf.src =3D kmap(in_page); + workspace->in_buf.src =3D kmap_local_page(in_page); workspace->in_buf.pos =3D 0; workspace->in_buf.size =3D min_t(size_t, len, PAGE_SIZE); + workspace->out_buf.dst =3D kmap_local_page(out_page); } } while (1) { @@ -510,9 +513,9 @@ int zstd_compress_pages(struct list_head *ws, struct ad= dress_space *mapping, =20 tot_out +=3D PAGE_SIZE; max_out -=3D PAGE_SIZE; - kunmap(out_page); + kunmap_local(workspace->out_buf.dst); if (nr_pages =3D=3D nr_dest_pages) { - out_page =3D NULL; + workspace->out_buf.dst =3D NULL; ret =3D -E2BIG; goto out; } @@ -522,7 +525,7 @@ int zstd_compress_pages(struct list_head *ws, struct ad= dress_space *mapping, goto out; } pages[nr_pages++] =3D out_page; - workspace->out_buf.dst =3D kmap(out_page); + workspace->out_buf.dst =3D kmap_local_page(out_page); workspace->out_buf.pos =3D 0; workspace->out_buf.size =3D min_t(size_t, max_out, PAGE_SIZE); } @@ -538,12 +541,12 @@ int zstd_compress_pages(struct list_head *ws, struct = address_space *mapping, out: *out_pages =3D nr_pages; /* Cleanup */ - if (in_page) { - kunmap(in_page); + if (workspace->out_buf.dst) + kunmap_local(workspace->out_buf.dst); + if (workspace->in_buf.src) { + kunmap_local((void *)workspace->in_buf.src); put_page(in_page); } - if (out_page) - kunmap(out_page); return ret; } =20 @@ -567,7 +570,7 @@ int zstd_decompress_bio(struct list_head *ws, struct co= mpressed_bio *cb) goto done; } =20 - workspace->in_buf.src =3D kmap(pages_in[page_in_index]); + workspace->in_buf.src =3D kmap_local_page(pages_in[page_in_index]); workspace->in_buf.pos =3D 0; workspace->in_buf.size =3D min_t(size_t, srclen, PAGE_SIZE); =20 @@ -603,14 +606,15 @@ int zstd_decompress_bio(struct list_head *ws, struct = compressed_bio *cb) break; =20 if (workspace->in_buf.pos =3D=3D workspace->in_buf.size) { - kunmap(pages_in[page_in_index++]); + kunmap_local((void *)workspace->in_buf.src); + page_in_index++; if (page_in_index >=3D total_pages_in) { workspace->in_buf.src =3D NULL; ret =3D -EIO; goto done; } srclen -=3D PAGE_SIZE; - workspace->in_buf.src =3D kmap(pages_in[page_in_index]); + workspace->in_buf.src =3D kmap_local_page(pages_in[page_in_index]); workspace->in_buf.pos =3D 0; workspace->in_buf.size =3D min_t(size_t, srclen, PAGE_SIZE); } @@ -619,7 +623,7 @@ int zstd_decompress_bio(struct list_head *ws, struct co= mpressed_bio *cb) zero_fill_bio(cb->orig_bio); done: if (workspace->in_buf.src) - kunmap(pages_in[page_in_index]); + kunmap_local((void *)workspace->in_buf.src); return ret; } =20 --=20 2.36.1