From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DAEE443DA38; Tue, 21 Jul 2026 22:01:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784671312; cv=none; b=FiG3AH0dKbcmmpUnzciuvsd60dhgplMpTj4Cp/GZuzSaEDw6iWSzyMB6A3aG0y3tbO9Puzt1eyyx/FLQOTOwwlmjUeRnP75PP6pbb7KjciT380WBXYPi0Sg5jeE8slU8ThUHpCBswAGI5HwkntyExpoNWeoT2ixks3pg5glmfsY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784671312; c=relaxed/simple; bh=cCiyTSRJLB+OriXGJwt76QjpT+qebmkKwM2YVYXVtaY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XK45mF/abwLeV13pYTESK0HaSIQZAhs1ps3SwRJ5D/ggRIQHipzHNK2rI1dgAe4Asn0SnwbzXVTyGiwUDUHKQLo1WPBHSu0C8RT6KsfADvT7I6e9A9BL0hYRkFfVT8/PTN2ZI3niZM5Go+XnlQOSMYT+VAZxngfd30GkqsAhI0M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=U9KDJ0kU; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="U9KDJ0kU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DA331F000E9; Tue, 21 Jul 2026 22:01:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784671310; bh=fVg5Ho8TWBP+sjeaLaMmqsagzAQEkaDs93bkhQOjYhM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=U9KDJ0kU7IPMZcCAv10rhMgWeZOII2Q9Gdk+M5c762kFC/iboC1HNIyAFNk6EbWt5 HFVmvcMg2GhKHeXAYyTGKBniAMUbfSZHLgjOLY6pQ1Q7z8dvf5NcxKEtN6Vv3VKJjp fYNYICW13G7+fG6EXKCJkcABsrDZYab9OQ2FXwrs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, hch@lst.de, "Darrick J. Wong" , Carlos Maiolino , Carlos Maiolino Subject: [PATCH 5.15 198/843] xfs: resample the data fork mapping after cycling ILOCK Date: Tue, 21 Jul 2026 17:17:13 +0200 Message-ID: <20260721152410.471115837@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Darrick J. Wong commit 2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7 upstream. xfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode, a data fork mapping, and a cow fork mapping. Unfortunately, these two helpers cycle the ILOCK to grab a transaction, which means that the mappings are stale as soon as we reacquire the ILOCK. Currently we refresh the cow fork mapping by re-calling xfs_find_trim_cow_extent, but we don't refresh the data fork mapping beforehand, which means that the xfs_bmap_trim_cow in that function queries the refcount btree about the wrong physical blocks and returns an inaccurate value in *shared. If *shared is now false, the directio write proceeds with a stale data fork mapping. Fix this by querying the data fork mapping if the sequence counter changes across the ILOCK cycle. Cc: hch@lst.de Cc: stable@vger.kernel.org # v4.11 Fixes: 3c68d44a2b49a0 ("xfs: allocate direct I/O COW blocks in iomap_begin") Signed-off-by: "Darrick J. Wong" Reviewed-by: Christoph Hellwig Reviewed-by: Carlos Maiolino Signed-off-by: Carlos Maiolino Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_reflink.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -386,6 +386,7 @@ xfs_reflink_fill_cow_hole( struct xfs_trans *tp; xfs_filblks_t resaligned; xfs_extlen_t resblks; + unsigned int seq_before = READ_ONCE(ip->i_df.if_seq); int nimaps; int error; bool found; @@ -404,6 +405,22 @@ xfs_reflink_fill_cow_hole( *lockmode = XFS_ILOCK_EXCL; + /* + * The data fork mapping may have changed while we dropped the ILOCK + * (a racing O_DIRECT writer under IOLOCK_SHARED can complete a full + * CoW cycle including xfs_reflink_end_cow(), which remaps this offset + * and drops the refcount of the old shared block). Re-read it so the + * shared-status recheck below and the caller's in-place iomap both + * operate on the current mapping rather than a stale physical block. + */ + if (seq_before != READ_ONCE(ip->i_df.if_seq)) { + nimaps = 1; + error = xfs_bmapi_read(ip, imap->br_startoff, + imap->br_blockcount, imap, &nimaps, 0); + if (error) + goto out_trans_cancel; + } + error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found); if (error || !*shared) goto out_trans_cancel; @@ -459,6 +476,8 @@ xfs_reflink_fill_delalloc( bool found; do { + unsigned int seq_before = READ_ONCE(ip->i_df.if_seq); + xfs_iunlock(ip, *lockmode); *lockmode = 0; @@ -469,6 +488,23 @@ xfs_reflink_fill_delalloc( *lockmode = XFS_ILOCK_EXCL; + /* + * The data fork mapping may have changed while we dropped the + * ILOCK (a racing O_DIRECT writer under IOLOCK_SHARED can + * complete a full CoW cycle including xfs_reflink_end_cow(), + * which remaps this offset and drops the refcount of the old + * shared block). Re-read it so the shared-status recheck + * below and the caller's in-place iomap both operate on the + * current mapping rather than a stale physical block. + */ + if (seq_before != READ_ONCE(ip->i_df.if_seq)) { + nimaps = 1; + error = xfs_bmapi_read(ip, imap->br_startoff, + imap->br_blockcount, imap, &nimaps, 0); + if (error) + goto out_trans_cancel; + } + error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found); if (error || !*shared)