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Wed, 22 May 2024 00:16:52 +0200 Message-ID: <2b26245e-7602-4a00-b79a-eac481708ab3@gmx.com> Date: Wed, 22 May 2024 07:46:46 +0930 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 v5 3/5] btrfs: lock subpage ranges in one go for writepage_delalloc() To: Naohiro Aota , Qu Wenruo Cc: "linux-btrfs@vger.kernel.org" , Johannes Thumshirn , "josef@toxicpanda.com" References: <7oxv5xm6n4yg5r523pzm7hxql5pihrfylrducrsiwlk5k4jl7a@wxvlrl6w6cbu> <30371f39-18b1-4c3f-af31-b4927eab99a5@suse.com> Content-Language: en-US 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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:0azIaVDyMdFlrBPa84fHiHF3LRioIjprfrDFpeif4/9Md6WPPns WmbRkWI0y0lD8uwd6EGyNFBH4kb5iCatDTStV4UNjaMUqw796aOqsO369cXG34s78D67Y+H DohvtbwdxprR2GFGYW8KOT2yrvnSGDHEEVXMsEo14fzY+3+q9rPeankmEOIvhVAq8rn6k6L akjQU0EGpfYTutZhcRGqA== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:ejY7m/958kI=;Xd/BWD3nLQSol15xDw5Ii+/7wCV gMU1UeI95FuOT5L/K7xVcbTp3HRIXRix1i9/k/GeSH7+cAdm5ObiMlwJEvUnqUPb9AOwYFa9u y1N1fLbFUvltfzf1B7jZW1fYQ4Q3Sz7AlBzJfgLy3SEWwDGq5GnyVE9Ih+KJgcRL8ydWcqkeo cXTKtcGpQ2D2ViVp2+iVlV6id5aNcU+BZFHnS6IQCh9oslxUp9gQG5guyW/qseicc9SPr2Q1H x/KKy6FHbQ57I+7ET/2/l7YHcEwclqeF5ZRToUcrX+O4B089llX6OSK3aKl8B/0CDbvXkWmdV o7QyZ21FbyNFp5juaE2SSQus3fhuGG3Aq5VUq15ylmcqNfpMmuGT79q3qbnN64UDm9MG5HMdH byCduoH7UbThHBY3DRXEfbQcDqoJdjrp0UaFyPbKonPqkUSwLqM3a2FJk/JFIDWtCi8Q3rbmU 9z1XLY+6WhaTCrVAF8rE/ah2XblKAfZ7m2t934id20D+8kpFm9Tf81AQ5PilWvbXd3fyVoXGv /LaNdUS+lRi9ZazYkEEMPIELD1ac30lGcV3Vj4Sur4XNTQrt6EaAtzmXWxp6ZM8S6BXYqwMop hyVzjBWlWghhQf8JvVIWmtbHYR2zap0pUmrxb/SVzLiEL2GUobgoR2wakShTxomOV8mr40D9c Fzf8ptEceSuClVTQqwHOZJvtuKq7SIyc5AtgM7hsGzWqOCzl4ZxDClFZkoOxB36YK3WiRAKdz CdoX1QizEoU7Rrh5AzJspGR3FG4YehBfCtUn8ippJOOI2GoWOYWW6F5KqWAGxI9XOpJcyTQTG A6GyzSiHuYceHyGojryj2Knz2UoX92C9Kqc82NEeo0Dh0= =E5=9C=A8 2024/5/21 21:24, Naohiro Aota =E5=86=99=E9=81=93: > On Tue, May 21, 2024 at 06:15:32PM GMT, Qu Wenruo wrote: >> >> >> =E5=9C=A8 2024/5/21 17:41, Naohiro Aota =E5=86=99=E9=81=93: >> [...] >>> Same here. >>> >>>> while (delalloc_start < page_end) { >>>> delalloc_end =3D page_end; >>>> if (!find_lock_delalloc_range(&inode->vfs_inode, page, >>>> @@ -1240,15 +1249,68 @@ static noinline_for_stack int writepage_delal= loc(struct btrfs_inode *inode, >>>> delalloc_start =3D delalloc_end + 1; >>>> continue; >>>> } >>>> - >>>> - ret =3D btrfs_run_delalloc_range(inode, page, delalloc_start, >>>> - delalloc_end, wbc); >>>> - if (ret < 0) >>>> - return ret; >>>> - >>>> + btrfs_folio_set_writer_lock(fs_info, folio, delalloc_start, >>>> + min(delalloc_end, page_end) + 1 - >>>> + delalloc_start); >>>> + last_delalloc_end =3D delalloc_end; >>>> delalloc_start =3D delalloc_end + 1; >>>> } >>> >>> Can we bail out on the "if (!last_delalloc_end)" case? It would make t= he >>> following code simpler. >> >> Mind to explain it a little more? >> >> Did you mean something like this: >> >> while (delalloc_start < page_end) { >> /* lock all subpage delalloc range code */ >> } >> if (!last_delalloc_end) >> goto finish; >> while (delalloc_start < page_end) { >> /* run the delalloc ranges code* / >> } >> >> If so, I can definitely go that way. > > Yes, I meant that way. Apparently, "!last_delalloc_end" means it get no > delalloc region. So, we can just return 0 in that case without touching > "wbc->nr_to_write" as the current code does. > > BTW, is this actually an overlooked error case? Is it OK to progress in > __extent_writepage() even if we don't run run_delalloc_range() ? That's totally expected, and it would even be more common in fact. Consider a very ordinary case like this: 0 4K 8K 12K |/////////////|///////////////|/////////////| When running extent_writepage() for page 0, we run delalloc range for the whole [0, 12K) range, and created an OE for it. Then __extent_writepage_io() add page range [0, 4k) for bio. Then extent_writepage() for page 4K, find_lock_delalloc() would not find any range, as previous iteration at page 0 has already created OE for the whole [0, 12K) range. Although we would still run __extent_writepage_io() to add page range [4k, 8K) to the bio. The same for page 8K. Thanks, Qu