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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66765E77188 for ; Mon, 13 Jan 2025 02:49:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E82BA6B0085; Sun, 12 Jan 2025 21:49:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E32176B0088; Sun, 12 Jan 2025 21:49:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CFA2E6B0089; Sun, 12 Jan 2025 21:49:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id B07726B0085 for ; Sun, 12 Jan 2025 21:49:44 -0500 (EST) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id E93F0161A11 for ; Mon, 13 Jan 2025 02:49:43 +0000 (UTC) X-FDA: 83000898246.15.4959176 Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by imf07.hostedemail.com (Postfix) with ESMTP id 5E7F040002 for ; Mon, 13 Jan 2025 02:49:42 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=eywQMnqW; spf=pass (imf07.hostedemail.com: domain of djwong@kernel.org designates 147.75.193.91 as permitted sender) smtp.mailfrom=djwong@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1736736582; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=uB2P8jwpjOZiUozLsJujIIB3KhPPvxwxbJrCLVN9o0I=; b=7uJ4wk6mA9T08ZS6wcwTVrYbYYzDR09MijbtxEBLs0xBfu2fJaYS9zKnFrWyVULfIayK6Z NZ+Edh/GwKzSr+8e+oSoNEKS+Ynjw3eEwHNX9pVcrNscENBitj6rL3I+zPNntFAuxcr2IH XzQzZUCsQJYXV3c+W2LgpVMVDK+J4wQ= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1736736582; a=rsa-sha256; cv=none; b=Vcx3+x8hwaunE2OFUu3MCdOh9m+HfzAVUlcQsNFkt32iglUg52GOpof59puBcYlcPA02+e ZGJdkeqhD6XtmlMFUXs7Q7x9qjCBP/RhJQy0+7/plhmqMvyqp1u2Zi5F8XFk+yfQKP6p+I Ch04VyRdjoYq3TcGeSWfCY7L3dn0CA4= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=eywQMnqW; spf=pass (imf07.hostedemail.com: domain of djwong@kernel.org designates 147.75.193.91 as permitted sender) smtp.mailfrom=djwong@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 15FA5A40413; Mon, 13 Jan 2025 02:47:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E585BC4CEDF; Mon, 13 Jan 2025 02:49:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736736581; bh=lU2h4cDLMS/jwioVlby+F6n8EhqeYkZ/4QblEV9UZk8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eywQMnqWd/nIiMHxu4/+lbTQdRnw/YCCTi9N/MhD2f6CfUxDRBs9efHWijse6PJlW 2nvVjgE+CmtDe+iqoUUsmM6REhLzfJTvBJ0NfFh9lYvFo40mYhcQZ+WQ9W2gSnG2ba Pi3QA/Wj9g82TVIkyHTzCc8mtlTY8PzwyVFOBHkQMjCjLCw+/Fka2iDyxpxGgv2WRv WUK9mDeeY7h/KSW/WCE7kqUuInIv9b3PYYa2RN7JPYMIVJjDi2fescDM9VnKpdIApf J7HizeUFk+GRXPmF9gikOBeMsbLqdxZMgIL1AYylGW1pxcxDgRvWMLQq4Jl2agkt7O WmoXG0WRM2xTA== Date: Sun, 12 Jan 2025 18:49:40 -0800 From: "Darrick J. Wong" To: Alistair Popple Cc: akpm@linux-foundation.org, dan.j.williams@intel.com, linux-mm@kvack.org, alison.schofield@intel.com, lina@asahilina.net, zhang.lyra@gmail.com, gerald.schaefer@linux.ibm.com, vishal.l.verma@intel.com, dave.jiang@intel.com, logang@deltatee.com, bhelgaas@google.com, jack@suse.cz, jgg@ziepe.ca, catalin.marinas@arm.com, will@kernel.org, mpe@ellerman.id.au, npiggin@gmail.com, dave.hansen@linux.intel.com, ira.weiny@intel.com, willy@infradead.org, tytso@mit.edu, linmiaohe@huawei.com, david@redhat.com, peterx@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, jhubbard@nvidia.com, hch@lst.de, david@fromorbit.com, chenhuacai@kernel.org, kernel@xen0n.name, loongarch@lists.linux.dev Subject: Re: [PATCH v6 07/26] fs/dax: Ensure all pages are idle prior to filesystem unmount Message-ID: <20250113024940.GW1306365@frogsfrogsfrogs> References: <704662ae360abeb777ed00efc6f8f232a79ae4ff.1736488799.git-series.apopple@nvidia.com> <20250110165019.GK6156@frogsfrogsfrogs> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 5E7F040002 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: hsxt3rryebjgwiwsekhhzbf6s6caitqn X-HE-Tag: 1736736582-93845 X-HE-Meta: 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 QLsYP6BR OC0r+a0OcH20+x7PKS1UKz7tAm5bpHXH9AIdiiwIrzxJsBk91bsjWAM8oXx2RMXqAt30ue7/pgaF2vptx4N6UhCykjYHI3mfrDc3a4HXJnOCmNj4t7P/EK7GLZrJn9zCLvqCYVf5GStbRcNWZam5dZT5+gLl3LNqcRuWi8cTJgWokI1WQCNbXHKISIpM0Iz75rW3q7JulHhRJiJfz+GdaJby3YdbZLU9VTDL2wNU72B613UAAbjtNJAr8ITVALifbbB/suLF5VntMwJl/jQnXIxsTKWfEt3BXYl67xfQkV1ewBqnBxa6rFoH5t+jmPaLybOveZgrniBJERrnfkz+nx80bancnCQCD2wRv X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jan 13, 2025 at 11:57:18AM +1100, Alistair Popple wrote: > On Fri, Jan 10, 2025 at 08:50:19AM -0800, Darrick J. Wong wrote: > > On Fri, Jan 10, 2025 at 05:00:35PM +1100, Alistair Popple wrote: > > > File systems call dax_break_mapping() prior to reallocating file > > > system blocks to ensure the page is not undergoing any DMA or other > > > accesses. Generally this is needed when a file is truncated to ensure > > > that if a block is reallocated nothing is writing to it. However > > > filesystems currently don't call this when an FS DAX inode is evicted. > > > > > > This can cause problems when the file system is unmounted as a page > > > can continue to be under going DMA or other remote access after > > > unmount. This means if the file system is remounted any truncate or > > > other operation which requires the underlying file system block to be > > > freed will not wait for the remote access to complete. Therefore a > > > busy block may be reallocated to a new file leading to corruption. > > > > > > Signed-off-by: Alistair Popple > > > > > > --- > > > > > > Changes for v5: > > > > > > - Don't wait for pages to be idle in non-DAX mappings > > > --- > > > fs/dax.c | 29 +++++++++++++++++++++++++++++ > > > fs/ext4/inode.c | 32 ++++++++++++++------------------ > > > fs/xfs/xfs_inode.c | 9 +++++++++ > > > fs/xfs/xfs_inode.h | 1 + > > > fs/xfs/xfs_super.c | 18 ++++++++++++++++++ > > > include/linux/dax.h | 2 ++ > > > 6 files changed, 73 insertions(+), 18 deletions(-) > > > > > > diff --git a/fs/dax.c b/fs/dax.c > > > index 7008a73..4e49cc4 100644 > > > --- a/fs/dax.c > > > +++ b/fs/dax.c > > > @@ -883,6 +883,14 @@ static int wait_page_idle(struct page *page, > > > TASK_INTERRUPTIBLE, 0, 0, cb(inode)); > > > } > > > > > > +static void wait_page_idle_uninterruptible(struct page *page, > > > + void (cb)(struct inode *), > > > + struct inode *inode) > > > +{ > > > + ___wait_var_event(page, page_ref_count(page) == 1, > > > + TASK_UNINTERRUPTIBLE, 0, 0, cb(inode)); > > > +} > > > + > > > /* > > > * Unmaps the inode and waits for any DMA to complete prior to deleting the > > > * DAX mapping entries for the range. > > > @@ -911,6 +919,27 @@ int dax_break_mapping(struct inode *inode, loff_t start, loff_t end, > > > } > > > EXPORT_SYMBOL_GPL(dax_break_mapping); > > > > > > +void dax_break_mapping_uninterruptible(struct inode *inode, > > > + void (cb)(struct inode *)) > > > +{ > > > + struct page *page; > > > + > > > + if (!dax_mapping(inode->i_mapping)) > > > + return; > > > + > > > + do { > > > + page = dax_layout_busy_page_range(inode->i_mapping, 0, > > > + LLONG_MAX); > > > + if (!page) > > > + break; > > > + > > > + wait_page_idle_uninterruptible(page, cb, inode); > > > + } while (true); > > > + > > > + dax_delete_mapping_range(inode->i_mapping, 0, LLONG_MAX); > > > +} > > > +EXPORT_SYMBOL_GPL(dax_break_mapping_uninterruptible); > > > + > > > /* > > > * Invalidate DAX entry if it is clean. > > > */ > > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > > > index ee8e83f..fa35161 100644 > > > --- a/fs/ext4/inode.c > > > +++ b/fs/ext4/inode.c > > > @@ -163,6 +163,18 @@ int ext4_inode_is_fast_symlink(struct inode *inode) > > > (inode->i_size < EXT4_N_BLOCKS * 4); > > > } > > > > > > +static void ext4_wait_dax_page(struct inode *inode) > > > +{ > > > + filemap_invalidate_unlock(inode->i_mapping); > > > + schedule(); > > > + filemap_invalidate_lock(inode->i_mapping); > > > +} > > > + > > > +int ext4_break_layouts(struct inode *inode) > > > +{ > > > + return dax_break_mapping_inode(inode, ext4_wait_dax_page); > > > +} > > > + > > > /* > > > * Called at the last iput() if i_nlink is zero. > > > */ > > > @@ -181,6 +193,8 @@ void ext4_evict_inode(struct inode *inode) > > > > > > trace_ext4_evict_inode(inode); > > > > > > + dax_break_mapping_uninterruptible(inode, ext4_wait_dax_page); > > > + > > > if (EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL) > > > ext4_evict_ea_inode(inode); > > > if (inode->i_nlink) { > > > @@ -3902,24 +3916,6 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset, > > > return ret; > > > } > > > > > > -static void ext4_wait_dax_page(struct inode *inode) > > > -{ > > > - filemap_invalidate_unlock(inode->i_mapping); > > > - schedule(); > > > - filemap_invalidate_lock(inode->i_mapping); > > > -} > > > - > > > -int ext4_break_layouts(struct inode *inode) > > > -{ > > > - struct page *page; > > > - int error; > > > - > > > - if (WARN_ON_ONCE(!rwsem_is_locked(&inode->i_mapping->invalidate_lock))) > > > - return -EINVAL; > > > - > > > - return dax_break_mapping_inode(inode, ext4_wait_dax_page); > > > -} > > > - > > > /* > > > * ext4_punch_hole: punches a hole in a file by releasing the blocks > > > * associated with the given offset and length > > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > > > index 4410b42..c7ec5ab 100644 > > > --- a/fs/xfs/xfs_inode.c > > > +++ b/fs/xfs/xfs_inode.c > > > @@ -2997,6 +2997,15 @@ xfs_break_dax_layouts( > > > return dax_break_mapping_inode(inode, xfs_wait_dax_page); > > > } > > > > > > +void > > > +xfs_break_dax_layouts_uninterruptible( > > > + struct inode *inode) > > > +{ > > > + xfs_assert_ilocked(XFS_I(inode), XFS_MMAPLOCK_EXCL); > > > + > > > + dax_break_mapping_uninterruptible(inode, xfs_wait_dax_page); > > > +} > > > + > > > int > > > xfs_break_layouts( > > > struct inode *inode, > > > diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h > > > index c4f03f6..613797a 100644 > > > --- a/fs/xfs/xfs_inode.h > > > +++ b/fs/xfs/xfs_inode.h > > > @@ -594,6 +594,7 @@ xfs_itruncate_extents( > > > } > > > > > > int xfs_break_dax_layouts(struct inode *inode); > > > +void xfs_break_dax_layouts_uninterruptible(struct inode *inode); > > > int xfs_break_layouts(struct inode *inode, uint *iolock, > > > enum layout_break_reason reason); > > > > > > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c > > > index 8524b9d..73ec060 100644 > > > --- a/fs/xfs/xfs_super.c > > > +++ b/fs/xfs/xfs_super.c > > > @@ -751,6 +751,23 @@ xfs_fs_drop_inode( > > > return generic_drop_inode(inode); > > > } > > > > > > +STATIC void > > > +xfs_fs_evict_inode( > > > + struct inode *inode) > > > +{ > > > + struct xfs_inode *ip = XFS_I(inode); > > > + uint iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL; > > > + > > > + if (IS_DAX(inode)) { > > > + xfs_ilock(ip, iolock); > > > + xfs_break_dax_layouts_uninterruptible(inode); > > > + xfs_iunlock(ip, iolock); > > > > If we're evicting the inode, why is it necessary to take i_rwsem and the > > mmap invalidation lock? Shouldn't the evicting thread be the only one > > with access to this inode? > > Hmm, good point. I think you're right. I can easily stop taking > XFS_IOLOCK_EXCL. Not taking XFS_MMAPLOCK_EXCL is slightly more difficult because > xfs_wait_dax_page() expects it to be taken. Do you think it is worth creating a > separate callback (xfs_wait_dax_page_unlocked()?) specifically for this path or > would you be happy with a comment explaining why we take the XFS_MMAPLOCK_EXCL > lock here? There shouldn't be any other threads removing "pages" from i_mapping during eviction, right? If so, I think you can just call schedule() directly from dax_break_mapping_uninterruptble. (dax mappings aren't allowed supposed to persist beyond unmount / eviction, just like regular pagecache, right??) --D > - Alistair > > > --D > > > > > + } > > > + > > > + truncate_inode_pages_final(&inode->i_data); > > > + clear_inode(inode); > > > +} > > > + > > > static void > > > xfs_mount_free( > > > struct xfs_mount *mp) > > > @@ -1189,6 +1206,7 @@ static const struct super_operations xfs_super_operations = { > > > .destroy_inode = xfs_fs_destroy_inode, > > > .dirty_inode = xfs_fs_dirty_inode, > > > .drop_inode = xfs_fs_drop_inode, > > > + .evict_inode = xfs_fs_evict_inode, > > > .put_super = xfs_fs_put_super, > > > .sync_fs = xfs_fs_sync_fs, > > > .freeze_fs = xfs_fs_freeze, > > > diff --git a/include/linux/dax.h b/include/linux/dax.h > > > index ef9e02c..7c3773f 100644 > > > --- a/include/linux/dax.h > > > +++ b/include/linux/dax.h > > > @@ -274,6 +274,8 @@ static inline int __must_check dax_break_mapping_inode(struct inode *inode, > > > { > > > return dax_break_mapping(inode, 0, LLONG_MAX, cb); > > > } > > > +void dax_break_mapping_uninterruptible(struct inode *inode, > > > + void (cb)(struct inode *)); > > > int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff, > > > struct inode *dest, loff_t destoff, > > > loff_t len, bool *is_same, > > > -- > > > git-series 0.9.1 > > > >