From patchwork Wed Feb 8 14:53:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13133135 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6E3AC636D4 for ; Wed, 8 Feb 2023 14:53:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231562AbjBHOxt (ORCPT ); Wed, 8 Feb 2023 09:53:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60650 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231573AbjBHOxr (ORCPT ); Wed, 8 Feb 2023 09:53:47 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D04FAEFBE; Wed, 8 Feb 2023 06:53:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=5twZFLWxkhGrNUYEW65e76d9+Wc/N4CV9H47V5oY874=; b=jhLXZ5eOcYzyv9Lg+xvTxRJyod htyi0O7wkyJihprDroJwDFHYs9W2CcWo4Bs4BJHOjW9nuD0JUNpaFK5Wa61HKdQkPMSQCLgqkyg/M DV0Dnzg3tzPaqy0lbr+4FLoiA+i5arMxHxV8SW9J5hc9kLAkar0MCXj/KCk2QIbirelqMTDrVme0R A3URQMf7LwUPHnghYb3mTGC17gS+DN/dNrYNpJq8NeBmPVZYYyIzaz6Pz0nQ9H1PKke7jbWoVWrvx J4o/VqVfhlKIA+0WzL9koVRa5NLxuH5MvC09KZRtCGqBVSbjjKgZHfaSSwR5LK124VOts++i7+9Hw H0agG0oA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pPlpK-001HwR-SC; Wed, 08 Feb 2023 14:53:38 +0000 From: "Matthew Wilcox (Oracle)" To: linux-xfs@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" Subject: [PATCH 1/3] xfs: Remove xfs_filemap_map_pages() wrapper Date: Wed, 8 Feb 2023 14:53:33 +0000 Message-Id: <20230208145335.307287-2-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230208145335.307287-1-willy@infradead.org> References: <20230208145335.307287-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org XFS doesn't actually need to be holding the XFS_MMAPLOCK_SHARED to do this, any more than it needs the XFS_MMAPLOCK_SHARED for a read() that hits in the page cache. Signed-off-by: Matthew Wilcox (Oracle) --- fs/xfs/xfs_file.c | 17 +---------------- 1 file changed, 1 insertion(+), 16 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 705250f9f90a..528fc538b6b9 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -1388,25 +1388,10 @@ xfs_filemap_pfn_mkwrite( return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true); } -static vm_fault_t -xfs_filemap_map_pages( - struct vm_fault *vmf, - pgoff_t start_pgoff, - pgoff_t end_pgoff) -{ - struct inode *inode = file_inode(vmf->vma->vm_file); - vm_fault_t ret; - - xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED); - ret = filemap_map_pages(vmf, start_pgoff, end_pgoff); - xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED); - return ret; -} - static const struct vm_operations_struct xfs_file_vm_ops = { .fault = xfs_filemap_fault, .huge_fault = xfs_filemap_huge_fault, - .map_pages = xfs_filemap_map_pages, + .map_pages = filemap_map_pages, .page_mkwrite = xfs_filemap_page_mkwrite, .pfn_mkwrite = xfs_filemap_pfn_mkwrite, }; From patchwork Wed Feb 8 14:53:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13133134 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3715C636CC for ; Wed, 8 Feb 2023 14:53:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231577AbjBHOxr (ORCPT ); Wed, 8 Feb 2023 09:53:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230025AbjBHOxp (ORCPT ); Wed, 8 Feb 2023 09:53:45 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3B3093E0; Wed, 8 Feb 2023 06:53:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=TTM2LCEcKRo7ysqHQyalM6+7+sVXpuzC/6B32xfg/Y0=; b=IdUzCc3Zzpj0dk7Y3co7Xeb9Hu K1pFmhmbEWbghQC8l4HyI7WYZ5bqIPecSVLYqZtI3XGnLF59S92cQzcbCZzCarhz5TfeHsA6joJep e9oBXYOGl1W3+8N5ieshbvXsiS2dbNnWrTf5G4IOj2PUx7cHvVujcxiLbwQJmdNU0rp1yFtafGqG9 ci4/6P1yNZ1uBrxEfeuo6ByOQUrd5I7c2pipHz/uWlY6zWnAldLGOwR2noGeyjl1y/xz9cA0xByhX V7fH8JaTWJGILwteEObitdanCl9gv1oqgfgSKNWxnAf1cjCbr/nihjaupG2qKmuHSC8BppP2t8Tjy /sfL/PGQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pPlpK-001HwT-Ut; Wed, 08 Feb 2023 14:53:38 +0000 From: "Matthew Wilcox (Oracle)" To: linux-xfs@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" Subject: [PATCH 2/3] afs: Split afs_pagecache_valid() out of afs_validate() Date: Wed, 8 Feb 2023 14:53:34 +0000 Message-Id: <20230208145335.307287-3-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230208145335.307287-1-willy@infradead.org> References: <20230208145335.307287-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org For the map_pages() method, we need a test that does not sleep. The page fault handler will continue to call the fault() method where we can sleep and do the full revalidation there. Signed-off-by: Matthew Wilcox (Oracle) Acked-by: David Howells Tested-by: David Howells --- fs/afs/file.c | 14 ++------------ fs/afs/inode.c | 27 +++++++++++++++++++-------- fs/afs/internal.h | 1 + 3 files changed, 22 insertions(+), 20 deletions(-) diff --git a/fs/afs/file.c b/fs/afs/file.c index 68d6d5dc608d..719b31374879 100644 --- a/fs/afs/file.c +++ b/fs/afs/file.c @@ -569,20 +569,10 @@ static void afs_vm_close(struct vm_area_struct *vma) 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 afs_file *af = vmf->vma->vm_file->private_data; - switch (afs_validate(vnode, af->key)) { - case 0: + if (afs_pagecache_valid(vnode)) return filemap_map_pages(vmf, start_pgoff, end_pgoff); - case -ENOMEM: - return VM_FAULT_OOM; - case -EINTR: - case -ERESTARTSYS: - return VM_FAULT_RETRY; - case -ESTALE: - default: - return VM_FAULT_SIGBUS; - } + return 0; } static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) diff --git a/fs/afs/inode.c b/fs/afs/inode.c index 0167e96e5198..b1bdffd5e888 100644 --- a/fs/afs/inode.c +++ b/fs/afs/inode.c @@ -667,6 +667,24 @@ bool afs_check_validity(struct afs_vnode *vnode) return false; } +/* + * Returns true if the pagecache is still valid. Does not sleep. + */ +bool afs_pagecache_valid(struct afs_vnode *vnode) +{ + if (unlikely(test_bit(AFS_VNODE_DELETED, &vnode->flags))) { + if (vnode->netfs.inode.i_nlink) + clear_nlink(&vnode->netfs.inode); + return true; + } + + if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags) && + afs_check_validity(vnode)) + return true; + + return false; +} + /* * validate a vnode/inode * - there are several things we need to check @@ -684,14 +702,7 @@ int afs_validate(struct afs_vnode *vnode, struct key *key) vnode->fid.vid, vnode->fid.vnode, vnode->flags, key_serial(key)); - if (unlikely(test_bit(AFS_VNODE_DELETED, &vnode->flags))) { - if (vnode->netfs.inode.i_nlink) - clear_nlink(&vnode->netfs.inode); - goto valid; - } - - if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags) && - afs_check_validity(vnode)) + if (afs_pagecache_valid(vnode)) goto valid; down_write(&vnode->validate_lock); diff --git a/fs/afs/internal.h b/fs/afs/internal.h index ad8523d0d038..5c95df6621f9 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -1171,6 +1171,7 @@ extern struct inode *afs_iget(struct afs_operation *, struct afs_vnode_param *); extern struct inode *afs_root_iget(struct super_block *, struct key *); extern bool afs_check_validity(struct afs_vnode *); extern int afs_validate(struct afs_vnode *, struct key *); +bool afs_pagecache_valid(struct afs_vnode *); extern int afs_getattr(struct mnt_idmap *idmap, const struct path *, struct kstat *, u32, unsigned int); extern int afs_setattr(struct mnt_idmap *idmap, struct dentry *, struct iattr *); From patchwork Wed Feb 8 14:53:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13133136 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 683F9C636D7 for ; Wed, 8 Feb 2023 14:53:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231573AbjBHOxw (ORCPT ); Wed, 8 Feb 2023 09:53:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231566AbjBHOxv (ORCPT ); Wed, 8 Feb 2023 09:53:51 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0A0872BD; Wed, 8 Feb 2023 06:53:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=HdngZPvdXKZlg8aWQlwaqgB89GRwI5fL2TphFM1bPZg=; b=mIOoo7xcGsiBchVCgVhbLA4GaO maepzfffPhFBJh1ZKAHeGTvMELGTvkEl1c5Pd5Ozj2+WhTRZx5zJhWSjhMJuicBsK3oVsqPUYMhir uhf0TZjF4cHNOgF+dXtJ10FaVGNsWhu0m47+EYSn3La4I863Krw849ee81FyoWUx3PJAUiIHGTEx4 t3Jhl1tgNZhpQvFDRvqar4cn/H8ZeaFrvvVzrNlGj97rXB3vggM1iZ+jaPHHIv5QuHYkSemgA2mQN SGpnygNsMm2kdC4RlP/rI5FyFdlvpYKAB2nQNKgD9zG2/T9PP+JHqyc7/ih3F9IQX2KMX6ueG+rhe QO25gZLw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pPlpL-001HwV-1L; Wed, 08 Feb 2023 14:53:39 +0000 From: "Matthew Wilcox (Oracle)" To: linux-xfs@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" Subject: [PATCH 3/3] mm: Hold the RCU read lock over calls to ->map_pages Date: Wed, 8 Feb 2023 14:53:35 +0000 Message-Id: <20230208145335.307287-4-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230208145335.307287-1-willy@infradead.org> References: <20230208145335.307287-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org Prevent filesystems from doing things which sleep in their map_pages method. This is in preparation for a pagefault path protected only by RCU. Signed-off-by: Matthew Wilcox (Oracle) --- Documentation/filesystems/locking.rst | 4 ++-- mm/memory.c | 7 ++++++- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index 922886fefb7f..8a80390446ba 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -645,7 +645,7 @@ ops mmap_lock PageLocked(page) open: yes close: yes fault: yes can return with page locked -map_pages: yes +map_pages: read page_mkwrite: yes can return with page locked pfn_mkwrite: yes access: yes @@ -661,7 +661,7 @@ locked. The VM will unlock the page. ->map_pages() is called when VM asks to map easy accessible pages. Filesystem should find and map pages associated with offsets from "start_pgoff" -till "end_pgoff". ->map_pages() is called with page table locked and must +till "end_pgoff". ->map_pages() is called with the RCU lock held and must not block. If it's not possible to reach a page without blocking, filesystem should skip it. Filesystem should use set_pte_range() to setup page table entry. Pointer to entry associated with the page is passed in diff --git a/mm/memory.c b/mm/memory.c index f1cf47b7e3bb..77577a1d09ac 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4442,6 +4442,7 @@ static vm_fault_t do_fault_around(struct vm_fault *vmf) unsigned long address = vmf->address, nr_pages, mask; pgoff_t start_pgoff = vmf->pgoff; pgoff_t end_pgoff; + vm_fault_t ret; int off; nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT; @@ -4467,7 +4468,11 @@ static vm_fault_t do_fault_around(struct vm_fault *vmf) return VM_FAULT_OOM; } - return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff); + rcu_read_lock(); + ret = vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff); + rcu_read_unlock(); + + return ret; } /* Return true if we should do read fault-around, false otherwise */