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Wed, 08 Apr 2026 12:44:38 -0700 (PDT) X-Received: by 2002:a05:622a:558b:b0:509:3098:819a with SMTP id d75a77b69052e-50dc22dd2a7mr10871821cf.44.1775677478076; Wed, 08 Apr 2026 12:44:38 -0700 (PDT) Received: from [192.168.129.206] ([216.158.158.246]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50d4b1a3fc7sm215560781cf.5.2026.04.08.12.44.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Apr 2026 12:44:37 -0700 (PDT) Message-ID: <9631d652-fd3a-45ac-b8a3-b632b26f6fa5@columbia.edu> Date: Wed, 8 Apr 2026 15:44:37 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v4 2/3] iomap: use BIO_COMPLETE_IN_TASK for dropbehind writeback To: Matthew Wilcox Cc: Jens Axboe , Christian Brauner , "Darrick J. Wong" , Carlos Maiolino , Alexander Viro , Jan Kara , Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20260325-blk-dontcache-v4-0-c4b56db43f64@columbia.edu> <20260325-blk-dontcache-v4-2-c4b56db43f64@columbia.edu> Content-Language: en-US From: Tal Zussman In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: XMjLC-rGGWxzyE0bP0h8cNE-jSkxbq1v X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDA4MDE4NCBTYWx0ZWRfX0yDfog+LDeDg GR5+AosVQrjTdwJZSKXx33aUipLi/yp0i7Uj/KQfD7Mf/BJ3GzXLLhd3oZxdZnAkLxgxu6kJapx ervWD6eMeuYZwdppnFoum4Cbpl3mGLQ/zILedRdFbyDi4dNKhYLlp7G20mISf0F9OXzrs+CD5ku 2FZgC/nsResOYq8/PyKw25ai9cAzKAV/BRrSqCEbMEmB3vzx5JITUmBpCD37+Rsmth/AKa/hoar Rf4k2kqCET3j62rY2eMtIwUk5vgLI90if79lao59e1vZJFs6EbjRM19nm60dT+Hl9WEDjK1oxXM Rin6HI/8+sqnW+6Mmnja8+UtuvT1JKvOOZqR0AKbxrhp/IZfOtT1ZN1J0bFPaA5rsX3dpnjqvPR 9G5O0YLttv862pAZqLR7rVPhTkF00qlkK50MrMZvu50rcPR4WE9X0YdV1nqNNJ7x9NqTZ4Hc2vA HtXgVdwvFWUuvsdvGhg== X-Authority-Analysis: v=2.4 cv=QPRYgALL c=1 sm=1 tr=0 ts=69d6b027 cx=c_pps a=mPf7EqFMSY9/WdsSgAYMbA==:117 a=mD05b5UW6KhLIDvowZ5dSQ==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=x7bEGLp0ZPQA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=79PYxaXUQd1wl-QFWJnA:22 a=X-nALmS6JCAzqVr0gswA:9 a=QEXdDO2ut3YA:10 a=dawVfQjAaf238kedN5IG:22 X-Proofpoint-ORIG-GUID: XMjLC-rGGWxzyE0bP0h8cNE-jSkxbq1v X-Proofpoint-Virus-Version: vendor=nai engine=6800 definitions=11753 signatures=596818 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 suspectscore=0 bulkscore=10 malwarescore=0 phishscore=0 priorityscore=1501 clxscore=1015 spamscore=0 impostorscore=10 lowpriorityscore=10 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604080184 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 0389DA0009 X-Stat-Signature: qorxc3t6y1ffusnu8k373e7c3ut5iohr X-Rspam-User: X-HE-Tag: 1775677480-815902 X-HE-Meta: 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 5Eimf/T8 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/25/26 4:21 PM, Matthew Wilcox wrote: > On Wed, Mar 25, 2026 at 02:43:01PM -0400, Tal Zussman wrote: >> Set BIO_COMPLETE_IN_TASK on iomap writeback bios when >> IOMAP_IOEND_DONTCACHE is set. This ensures that bi_end_io runs in task >> context, where folio_end_dropbehind() can safely invalidate folios. >> >> With the bio layer now handling task-context deferral generically, XFS >> no longer needs to route DONTCACHE ioends through its completion >> workqueue for page cache invalidation. Remove the DONTCACHE check from >> xfs_ioend_needs_wq_completion(). >> >> Signed-off-by: Tal Zussman >> --- >> fs/iomap/ioend.c | 2 ++ >> fs/xfs/xfs_aops.c | 4 ---- >> 2 files changed, 2 insertions(+), 4 deletions(-) >> >> diff --git a/fs/iomap/ioend.c b/fs/iomap/ioend.c >> index e4d57cb969f1..6b8375d11cc0 100644 >> --- a/fs/iomap/ioend.c >> +++ b/fs/iomap/ioend.c >> @@ -113,6 +113,8 @@ static struct iomap_ioend *iomap_alloc_ioend(struct iomap_writepage_ctx *wpc, >> GFP_NOFS, &iomap_ioend_bioset); >> bio->bi_iter.bi_sector = iomap_sector(&wpc->iomap, pos); >> bio->bi_write_hint = wpc->inode->i_write_hint; >> + if (ioend_flags & IOMAP_IOEND_DONTCACHE) >> + bio_set_flag(bio, BIO_COMPLETE_IN_TASK); >> wbc_init_bio(wpc->wbc, bio); >> wpc->nr_folios = 0; >> return iomap_init_ioend(wpc->inode, bio, pos, ioend_flags); > > Can't we delete IOMAP_IOEND_DONTCACHE, and just do: > > if (folio_test_dropbehind(folio)) > bio_set_flag(&ioend->io_bio, BIO_COMPLETE_IN_TASK); > > It'd need to move down a few lines in iomap_add_to_ioend() to after > bio_add_folio() succeeds. > Actually, looking into it more, IOMAP_IOEND_DONTCACHE is used as part of IOMAP_IOEND_NOMERGE_FLAGS. I think deleting it while maintaining the no-merge behavior would be uglier than leaving it in.