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Sat, 10 Feb 2024 10:39:51 +0100 Message-ID: <91eda445-e58c-4fab-ae49-a10951edfa8d@gmx.com> Date: Sat, 10 Feb 2024 20:09:47 +1030 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 10/16] btrfs: remove non-standard extent handling in __extent_writepage_io Content-Language: en-US To: Christoph Hellwig , Chris Mason , Josef Bacik , David Sterba Cc: linux-btrfs@vger.kernel.org References: <20230531060505.468704-1-hch@lst.de> <20230531060505.468704-11-hch@lst.de> From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00iVQUJDToH pgAKCRDCPZHzoSX+qNKACACkjDLzCvcFuDlgqCiS4ajHAo6twGra3uGgY2klo3S4JespWifr BLPPak74oOShqNZ8yWzB1Bkz1u93Ifx3c3H0r2vLWrImoP5eQdymVqMWmDAq+sV1Koyt8gXQ XPD2jQCrfR9nUuV1F3Z4Lgo+6I5LjuXBVEayFdz/VYK63+YLEAlSowCF72Lkz06TmaI0XMyj jgRNGM2MRgfxbprCcsgUypaDfmhY2nrhIzPUICURfp9t/65+/PLlV4nYs+DtSwPyNjkPX72+ LdyIdY+BqS8cZbPG5spCyJIlZonADojLDYQq4QnufARU51zyVjzTXMg5gAttDZwTH+8LbNI4 mm2YzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00ibgUJDToHvwAK CRDCPZHzoSX+qK6vB/9yyZlsS+ijtsvwYDjGA2WhVhN07Xa5SBBvGCAycyGGzSMkOJcOtUUf tD+ADyrLbLuVSfRN1ke738UojphwkSFj4t9scG5A+U8GgOZtrlYOsY2+cG3R5vjoXUgXMP37 INfWh0KbJodf0G48xouesn08cbfUdlphSMXujCA8y5TcNyRuNv2q5Nizl8sKhUZzh4BascoK DChBuznBsucCTAGrwPgG4/ul6HnWE8DipMKvkV9ob1xJS2W4WJRPp6QdVrBWJ9cCdtpR6GbL iQi22uZXoSPv/0oUrGU+U5X4IvdnvT+8viPzszL5wXswJZfqfy8tmHM85yjObVdIG6AlnrrD In-Reply-To: <20230531060505.468704-11-hch@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:QFCRvcFstv7hnbQC2G2ioQntwrbSty7oZcKIVVqMdPS83NDYQai NwX/E8E8YzFidgqykqHmtHf6dzVanrCCKvzwYe95c8cbdwtbASNnJYe6+c+4K5tF/f7YPlR 1JogL4fn8AU25lXG6ANmMDp+c/PWeren4oOIiQa+/ffKKK9dJok4mBINJ9xeKhJPIgMcivU FiEbhy6oh0AuPCAq3xANA== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:I2ffT+guAn8=;3XwIetITirvwem5MQ/0Leh6kiOw 1Io31ZxiAY6uxa6zX2jkbwztRZ6CmcmP/kh0SHqU9TMxY7tYMTpCvjuqZ51heqxRvR3EyS7vE fSR8Lvj79GNDeonVh2XP0oCefB2LVeAuZEs1w9abqnQkeKHXz8yifOXgniugC6H3tJe5QkOc1 rssB9DR1VmbvTX4y4hcChVo8bYQMKsx+POZzSvoahGdhoPWWAYZdivwQDZPOBJ2QRr/tQaFnn I7autgRWxXBIjojge7kpNY4XmiGdYOyILDGxC1yhxuIw6bTSEMZa4N4alqi07LpwhKyPIKyRr Gl/25Xw5Nut9JjdN8lVMxD//TiCijrjx1mE5UZJM9XOujq2sWwojblkYI+oabp582XUMDnABd yf905Kt95KExZJ4gxtRz02WFmEr4jStBD0uCmIfgXXoI8L1bCAZb0PqYWLyTOPsEkN22TLtcX B5U1Lt8bxYGrnaPZXpgsbpLVt2HRm/rAHuiipr2w6StEexOA7FLt5bfrQ93xvrEgAanv+wNe7 XBOAOCnMbwWY0H8DHKAI7LluBYdm8YTfIOMxn0OAeBW9i4XwpYa5kW1ODkf8/T45ddyQc3VGR QRzyhPIMcaRxmGNpNm27TU8Vry9hi416GuyQFKKYGkTcPX8RrwgiZWBk1RJTLKQ59olYGRqIh Ha8l5W1oP4ZPZOddWobMyP6Xby0Vpb642Rd0ALM026uUFFyO6YnsgQDuCmHIbIMeuK6rsoxc2 flnJhy5EFeJ9NKns85GNz1mGmTGnQH+dVT+I8Z3qLSDnbCKkyeAEcS8mPjfDE3GCcxQLVj8q2 O7DMSA22wciy/6mwkm3jnywXjI2nW1eAklLJ2lcAeCn4E= On 2023/5/31 15:34, Christoph Hellwig wrote: > __extent_writepage_io is never called for compressed or inline extents, > or holes. Remove the not quite working code for them and replace it wit= h > asserts that these cases don't happen. > > Signed-off-by: Christoph Hellwig It's a little too late, but this patch is causing crashing for subpage. > --- > fs/btrfs/extent_io.c | 23 +++++------------------ > 1 file changed, 5 insertions(+), 18 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 09a9973c27ccfb..a2e1dbd9b92309 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -1361,7 +1361,6 @@ static noinline_for_stack int __extent_writepage_i= o(struct btrfs_inode *inode, > struct extent_map *em; > int ret =3D 0; > int nr =3D 0; > - bool compressed; > > ret =3D btrfs_writepage_cow_fixup(page); > if (ret) { > @@ -1419,10 +1418,14 @@ static noinline_for_stack int __extent_writepage= _io(struct btrfs_inode *inode, > ASSERT(cur < end); > ASSERT(IS_ALIGNED(em->start, fs_info->sectorsize)); > ASSERT(IS_ALIGNED(em->len, fs_info->sectorsize)); > + > block_start =3D em->block_start; > - compressed =3D test_bit(EXTENT_FLAG_COMPRESSED, &em->flags); > disk_bytenr =3D em->block_start + extent_offset; > > + ASSERT(!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)); > + ASSERT(block_start !=3D EXTENT_MAP_HOLE); For subpage cases, __extent_writepage_io() can be triggered to write only a subset of the page, from extent_write_locked_range(). In that case, if we have submitted the target range, since our @len is to the end of the page, we can hit a hole. In that case, this ASSERT() would be triggered. And even worse, if CONFIG_BTRFS_ASSERT() is not enabled, we can do wrong writeback using the wrong disk_bytenr. So at least we need to skip the hole ranges for subpage. And thankfully the remaining two cases are impossible for subpage. Thanks, Qu > + ASSERT(block_start !=3D EXTENT_MAP_INLINE); > + > /* > * Note that em_end from extent_map_end() and dirty_range_end from > * find_next_dirty_byte() are all exclusive > @@ -1431,22 +1434,6 @@ static noinline_for_stack int __extent_writepage_= io(struct btrfs_inode *inode, > free_extent_map(em); > em =3D NULL; > > - /* > - * compressed and inline extents are written through other > - * paths in the FS > - */ > - if (compressed || block_start =3D=3D EXTENT_MAP_HOLE || > - block_start =3D=3D EXTENT_MAP_INLINE) { > - if (compressed) > - nr++; > - else > - btrfs_writepage_endio_finish_ordered(inode, > - page, cur, cur + iosize - 1, true); > - btrfs_page_clear_dirty(fs_info, page, cur, iosize); > - cur +=3D iosize; > - continue; > - } > - > btrfs_set_range_writeback(inode, cur, cur + iosize - 1); > if (!PageWriteback(page)) { > btrfs_err(inode->root->fs_info,