From patchwork Mon Mar 27 17:45:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 13189764 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 1D026C77B60 for ; Mon, 27 Mar 2023 17:45:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229744AbjC0Rpf (ORCPT ); Mon, 27 Mar 2023 13:45:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229498AbjC0Rpb (ORCPT ); Mon, 27 Mar 2023 13:45:31 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A862519AD; Mon, 27 Mar 2023 10:45:25 -0700 (PDT) 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=fIu8B1m7y8UbXtnikmeJqrXTu7pczz9sY+BTw0TDSzU=; b=CKZEq1dbnw8YiG6UxQX5giGqXs b9qOE9hP4Zc+UTvy3UaWf9zFtTwqx+oPjlM6oYJZ+pjwcvBhQVO9urgYaxU378GSBu8PsOwkXiF2A P4w04/3X/Fk1dY8qO8rC5ABsCZ7tFnh7uVzkv62LsGUGSEU/ICt9/0nUVB4km/SkSgNgS4BL+TAzC I4/GoC4sgAfZcX7tK4aIIKfdPPPTJFpJSW94ooUXmGFjYrE5T3cpYJG7HES7h2QaDy3NFlDwcgp3O TsA8xaG1nVozZmC/WGOlhUKJiumhksvu+7CChPzNidOSqJ41toO1BytsA5c0/aUS1F1bhyv5WDQRu uZdUAbvA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pgquI-007bGU-9o; Mon, 27 Mar 2023 17:45:22 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-xfs@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 1/3] xfs: Remove xfs_filemap_map_pages() wrapper Date: Mon, 27 Mar 2023 18:45:13 +0100 Message-Id: <20230327174515.1811532-2-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230327174515.1811532-1-willy@infradead.org> References: <20230327174515.1811532-1-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. filemap_map_pages() cannot bring new folios into the page cache and the folio lock is taken during filemap_map_pages() which provides sufficient protection against a truncation or hole punch. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Dave Chinner --- 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 863289aaa441..aede746541f8 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -1389,25 +1389,10 @@ 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 Mon Mar 27 17:45:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 13189763 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 E88B3C77B6C for ; Mon, 27 Mar 2023 17:45:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230361AbjC0Rpf (ORCPT ); Mon, 27 Mar 2023 13:45:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230264AbjC0Rpb (ORCPT ); Mon, 27 Mar 2023 13:45:31 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5354B273B; Mon, 27 Mar 2023 10:45:28 -0700 (PDT) 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=GAyshjmKzZkCN3bMmDoTxHf/sR0cear/9s9hk1TbP0k=; b=lf+sGi73/ao9HbjaotBl2pVUzS pHH+wy60rrUFTqs+ErZYZmfjokJg2KXASQ+LmXKQy0XUSYzLIxvDDEwx6xSN7FNyAH+SsfFei0bID 3S6nHNMDJuUoZblr82s8LNGOzLzyA0XAt5qx092xMNkJQ2gKXS5prSE0iQ+2BOztSnlhDFZi+Lm+7 ONzWtkKoNSC9uFiMfvXkS/DOEgqJw3Kb4NovLp+d3T9dvyrz1fVXw0tVDxktZuOCskGIG4Ftv90UH a306skCf2SweTCGwfoQxnWcS0xKPlj/el+ecfNH3Xj8ZXE2+n+06FaOrPA7n1DHTk1OQ/va8IiawA asZPxL9g==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pgquI-007bGW-CW; Mon, 27 Mar 2023 17:45:22 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-xfs@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, David Howells Subject: [PATCH v2 2/3] afs: Split afs_pagecache_valid() out of afs_validate() Date: Mon, 27 Mar 2023 18:45:14 +0100 Message-Id: <20230327174515.1811532-3-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230327174515.1811532-1-willy@infradead.org> References: <20230327174515.1811532-1-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 Mon Mar 27 17:45:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 13189762 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 8B7BDC77B61 for ; Mon, 27 Mar 2023 17:45:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229498AbjC0Rpg (ORCPT ); Mon, 27 Mar 2023 13:45:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231820AbjC0Rpc (ORCPT ); Mon, 27 Mar 2023 13:45:32 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49280199E; Mon, 27 Mar 2023 10:45:31 -0700 (PDT) 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=sN2jldM9CY7aIkWwKeR1CK1+RammERB2ANKihvDELc4=; b=qZecYoGcykBbwmr7BQ73lsvQRL 7gZkBAEKJXtSnbFL1+kjXtQ9/BHx6ug9L2v458DCOq4fkXkxqUuFJ4CZ5M7L/GVgnHcLBQYhRBFC6 QWrfg+YCRq5wnEsDCbLZUN4kZSYirKyVwj0+KdtHTIXuD0om2HYLsfQhgcHrgVOgs5juAvishtQp0 VhctSXw8l3NyR8zrorbrBrgVMmqTFpSm2Bpvfy4H2Z4hLc7Jx5L4AmO8o6wcHhHgc8w7HvEUhJ24D 3Z9ZT4zFFIjhtTwiayCAFm1+6tWK5MycDRBzmsaxNAciKbdsiMxohtdQWGGc15DRYTUAP47SaXfGj Dspc/OhA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pgquI-007bGY-FT; Mon, 27 Mar 2023 17:45:22 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-xfs@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 3/3] mm: Hold the RCU read lock over calls to ->map_pages Date: Mon, 27 Mar 2023 18:45:15 +0100 Message-Id: <20230327174515.1811532-4-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230327174515.1811532-1-willy@infradead.org> References: <20230327174515.1811532-1-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 | 11 ++++++++--- 2 files changed, 10 insertions(+), 5 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 8071bb17abf2..a7edf6d714db 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4461,6 +4461,7 @@ static vm_fault_t do_fault_around(struct vm_fault *vmf) /* The page offset of vmf->address within the VMA. */ pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff; pgoff_t from_pte, to_pte; + vm_fault_t ret; /* The PTE offset of the start address, clamped to the VMA. */ from_pte = max(ALIGN_DOWN(pte_off, nr_pages), @@ -4476,9 +4477,13 @@ static vm_fault_t do_fault_around(struct vm_fault *vmf) return VM_FAULT_OOM; } - return vmf->vma->vm_ops->map_pages(vmf, - vmf->pgoff + from_pte - pte_off, - vmf->pgoff + to_pte - pte_off); + rcu_read_lock(); + ret = vmf->vma->vm_ops->map_pages(vmf, + vmf->pgoff + from_pte - pte_off, + vmf->pgoff + to_pte - pte_off); + rcu_read_unlock(); + + return ret; } /* Return true if we should do read fault-around, false otherwise */