From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9602CFEA83D for ; Wed, 25 Mar 2026 09:47:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=d27maMT+gaVBX+I8KOk4v9fQBs+qrT50oEtm7+Gc3S4=; b=DChLKfmXzENU78Ai1VCYD7t/41 g/MtTKEkhVPUUmnQOM7ajeHJp+c86mUC2CB+i+w7dftHLjHz9mWAJLbkG9XPdDXO15VwkoWOy+n1S vILOljimx4tWP37xWooIqcockXeWKQBmpG4NaqaKkIN8Tu5CKGxhchn6phWlk7JhBRy4ECx6P+ScO czYpso3Ac/xiQOC9INM0pI64ADaJ6SyY7o42fO0peAyeWRoC2/7FXMVK6qBbf3RF7GrYu2AUmycUM TUtA2OZ5ziA75m7LEHFTtyAWtgG1gMvxuFkJe2E/NtPrQB0QUSJn9uuQSCf4AA+sy0g9pSTTWeOsN zqk8D0/A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5Kpr-000000034XO-3dMo; Wed, 25 Mar 2026 09:47:35 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5Kpo-000000034Wo-37xc; Wed, 25 Mar 2026 09:47:33 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 5B0374417E; Wed, 25 Mar 2026 09:47:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44F83C2BC9E; Wed, 25 Mar 2026 09:47:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774432051; bh=vUFrcOFz84OveU1pgKHoD1qwpdPZX9ciji33h3siGaE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=h7rjxRys800WY0i8LFUswSR3PcQtVI+WfcvFbM55iwz1ZH6sEQagzhf2LyOreVOSW R1lGyQTKbfLllWJzdn5W8eaoKRVYpL0edcGcr6SCeDfoN1NRmrSZOCLjsPkGst2Vue whTAV+F4IJb7xm4J+qcGoX5SFmIZFB+fhBwrR2605pUGNgx0fg/E3JSQRqS9sFkabZ CtbaFD/j2jHu/4k19QPOkOOINFcC55JlaP/BKzrZDZAQkiiAvQh9vim4ubQ9CkIKj9 xhp7ke2Xf5zs7lnOYxqAky/AVcczwO5PeQU9qs8vfUKFRe22DcZ0GFLqD7cqpncinF 7/z8KNyW3nyVA== Message-ID: <2bf17da7-fb46-4503-8de9-9368a73d8487@kernel.org> Date: Wed, 25 Mar 2026 10:47:21 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 10/21] fs: afs: restore mmap_prepare implementation Content-Language: en-US To: "Lorenzo Stoakes (Oracle)" , Andrew Morton Cc: Jonathan Corbet , Clemens Ladisch , Arnd Bergmann , Greg Kroah-Hartman , "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Alexander Shishkin , Maxime Coquelin , Alexandre Torgue , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Bodo Stroesser , "Martin K . Petersen" , David Howells , Marc Dionne , Alexander Viro , Christian Brauner , Jan Kara , David Hildenbrand , "Liam R . Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-mtd@lists.infradead.org, linux-staging@lists.linux.dev, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Ryan Roberts References: From: "Vlastimil Babka (SUSE)" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260325_024732_835914_26C67ABB X-CRM114-Status: GOOD ( 31.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 3/20/26 23:39, Lorenzo Stoakes (Oracle) wrote: > Commit 9d5403b1036c ("fs: convert most other generic_file_*mmap() users to > .mmap_prepare()") updated AFS to use the mmap_prepare callback in favour > of the deprecated mmap callback. > > However, it did not account for the fact that mmap_prepare is called > pre-merge, and may then be merged, nor that mmap_prepare can fail to map > due to an out of memory error. > > This change was therefore since reverted. > > Both of those are cases in which we should not be incrementing a reference > count. > > With the newly added vm_ops->mapped callback available, we can simply > defer this operation to that callback which is only invoked once the > mapping is successfully in place (but not yet visible to userspace as the > mmap and VMA write locks are held). > > This allows us to once again reimplement the .mmap_prepare implementation > for this file system. > > Therefore add afs_mapped() to implement this callback for AFS, and remove > the code doing so in afs_mmap_prepare(). > > Also update afs_vm_open(), afs_vm_close() and afs_vm_map_pages() to be > consistent in how the vnode is accessed. > > Signed-off-by: Lorenzo Stoakes (Oracle) Yep that should take care of that reference count problem. Acked-by: Vlastimil Babka (SUSE) > --- > fs/afs/file.c | 42 +++++++++++++++++++++++++++++------------- > 1 file changed, 29 insertions(+), 13 deletions(-) > > diff --git a/fs/afs/file.c b/fs/afs/file.c > index 74d04af51ff4..85696ac984cc 100644 > --- a/fs/afs/file.c > +++ b/fs/afs/file.c > @@ -19,7 +19,7 @@ > #include > #include "internal.h" > > -static int afs_file_mmap(struct file *file, struct vm_area_struct *vma); > +static int afs_file_mmap_prepare(struct vm_area_desc *desc); > > static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter); > static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos, > @@ -28,6 +28,8 @@ static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos, > static void afs_vm_open(struct vm_area_struct *area); > static void afs_vm_close(struct vm_area_struct *area); > static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff); > +static int afs_mapped(unsigned long start, unsigned long end, pgoff_t pgoff, > + const struct file *file, void **vm_private_data); > > const struct file_operations afs_file_operations = { > .open = afs_open, > @@ -35,7 +37,7 @@ const struct file_operations afs_file_operations = { > .llseek = generic_file_llseek, > .read_iter = afs_file_read_iter, > .write_iter = netfs_file_write_iter, > - .mmap = afs_file_mmap, > + .mmap_prepare = afs_file_mmap_prepare, > .splice_read = afs_file_splice_read, > .splice_write = iter_file_splice_write, > .fsync = afs_fsync, > @@ -61,6 +63,7 @@ const struct address_space_operations afs_file_aops = { > }; > > static const struct vm_operations_struct afs_vm_ops = { > + .mapped = afs_mapped, > .open = afs_vm_open, > .close = afs_vm_close, > .fault = filemap_fault, > @@ -492,34 +495,47 @@ static void afs_drop_open_mmap(struct afs_vnode *vnode) > /* > * Handle setting up a memory mapping on an AFS file. > */ > -static int afs_file_mmap(struct file *file, struct vm_area_struct *vma) > +static int afs_file_mmap_prepare(struct vm_area_desc *desc) > { > - struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); > int ret; > > - afs_add_open_mmap(vnode); > + ret = generic_file_mmap_prepare(desc); > + if (ret) > + return ret; > > - ret = generic_file_mmap(file, vma); > - if (ret == 0) > - vma->vm_ops = &afs_vm_ops; > - else > - afs_drop_open_mmap(vnode); > + desc->vm_ops = &afs_vm_ops; > return ret; > } > > +static int afs_mapped(unsigned long start, unsigned long end, pgoff_t pgoff, > + const struct file *file, void **vm_private_data) > +{ > + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); > + > + afs_add_open_mmap(vnode); > + return 0; > +} > + > static void afs_vm_open(struct vm_area_struct *vma) > { > - afs_add_open_mmap(AFS_FS_I(file_inode(vma->vm_file))); > + struct file *file = vma->vm_file; > + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); > + > + afs_add_open_mmap(vnode); > } > > static void afs_vm_close(struct vm_area_struct *vma) > { > - afs_drop_open_mmap(AFS_FS_I(file_inode(vma->vm_file))); > + struct file *file = vma->vm_file; > + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); > + > + afs_drop_open_mmap(vnode); > } > > static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff) > { > - struct afs_vnode *vnode = AFS_FS_I(file_inode(vmf->vma->vm_file)); > + struct file *file = vmf->vma->vm_file; > + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); > > if (afs_check_validity(vnode)) > return filemap_map_pages(vmf, start_pgoff, end_pgoff); > -- > 2.53.0