From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:38818 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754239AbdJSOXP (ORCPT ); Thu, 19 Oct 2017 10:23:15 -0400 From: Christoph Hellwig Subject: [PATCH 05/16] xfs: update i_size after unwritten conversion in dio completion Date: Thu, 19 Oct 2017 16:22:48 +0200 Message-Id: <20171019142259.20082-6-hch@lst.de> In-Reply-To: <20171019142259.20082-1-hch@lst.de> References: <20171019142259.20082-1-hch@lst.de> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: stable@vger.kernel.org Cc: linux-xfs@vger.kernel.org, Eryu Guan , "Darrick J . Wong" From: Eryu Guan commit ee70daaba82d70766d0723b743d9fdeb3b06102a upstream. Since commit d531d91d6990 ("xfs: always use unwritten extents for direct I/O writes"), we start allocating unwritten extents for all direct writes to allow appending aio in XFS. But for dio writes that could extend file size we update the in-core inode size first, then convert the unwritten extents to real allocations at dio completion time in xfs_dio_write_end_io(). Thus a racing direct read could see the new i_size and find the unwritten extents first and read zeros instead of actual data, if the direct writer also takes a shared iolock. Fix it by updating the in-core inode size after the unwritten extent conversion. To do this, introduce a new boolean argument to xfs_iomap_write_unwritten() to tell if we want to update in-core i_size or not. Suggested-by: Brian Foster Reviewed-by: Brian Foster Signed-off-by: Eryu Guan Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong [hch: backported to the old direct I/O code before Linux 4.10] Signed-off-by: Christoph Hellwig --- fs/xfs/xfs_aops.c | 25 +++++++++++++++++-------- fs/xfs/xfs_iomap.c | 7 +++++-- fs/xfs/xfs_iomap.h | 2 +- fs/xfs/xfs_pnfs.c | 2 +- 4 files changed, 24 insertions(+), 12 deletions(-) diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index d23889e0bedc..2b9d7c5800ee 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -335,7 +335,8 @@ xfs_end_io( error = xfs_reflink_end_cow(ip, offset, size); break; case XFS_IO_UNWRITTEN: - error = xfs_iomap_write_unwritten(ip, offset, size); + /* writeback should never update isize */ + error = xfs_iomap_write_unwritten(ip, offset, size, false); break; default: ASSERT(!xfs_ioend_is_append(ioend) || ioend->io_append_trans); @@ -1532,6 +1533,21 @@ xfs_end_io_direct_write( return 0; } + if (flags & XFS_DIO_FLAG_COW) + error = xfs_reflink_end_cow(ip, offset, size); + + /* + * Unwritten conversion updates the in-core isize after extent + * conversion but before updating the on-disk size. Updating isize any + * earlier allows a racing dio read to find unwritten extents before + * they are converted. + */ + if (flags & XFS_DIO_FLAG_UNWRITTEN) { + trace_xfs_end_io_direct_write_unwritten(ip, offset, size); + + return xfs_iomap_write_unwritten(ip, offset, size, true); + } + /* * We need to update the in-core inode size here so that we don't end up * with the on-disk inode size being outside the in-core inode size. We @@ -1548,13 +1564,6 @@ xfs_end_io_direct_write( i_size_write(inode, offset + size); spin_unlock(&ip->i_flags_lock); - if (flags & XFS_DIO_FLAG_COW) - error = xfs_reflink_end_cow(ip, offset, size); - if (flags & XFS_DIO_FLAG_UNWRITTEN) { - trace_xfs_end_io_direct_write_unwritten(ip, offset, size); - - error = xfs_iomap_write_unwritten(ip, offset, size); - } if (flags & XFS_DIO_FLAG_APPEND) { trace_xfs_end_io_direct_write_append(ip, offset, size); diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 65740d1cbd92..f286f63c430c 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -836,7 +836,8 @@ int xfs_iomap_write_unwritten( xfs_inode_t *ip, xfs_off_t offset, - xfs_off_t count) + xfs_off_t count, + bool update_isize) { xfs_mount_t *mp = ip->i_mount; xfs_fileoff_t offset_fsb; @@ -847,6 +848,7 @@ xfs_iomap_write_unwritten( xfs_trans_t *tp; xfs_bmbt_irec_t imap; struct xfs_defer_ops dfops; + struct inode *inode = VFS_I(ip); xfs_fsize_t i_size; uint resblks; int error; @@ -906,7 +908,8 @@ xfs_iomap_write_unwritten( i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb); if (i_size > offset + count) i_size = offset + count; - + if (update_isize && i_size > i_size_read(inode)) + i_size_write(inode, i_size); i_size = xfs_new_eof(ip, i_size); if (i_size) { ip->i_d.di_size = i_size; diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h index 6d45cf01fcff..d71703af5c76 100644 --- a/fs/xfs/xfs_iomap.h +++ b/fs/xfs/xfs_iomap.h @@ -27,7 +27,7 @@ int xfs_iomap_write_direct(struct xfs_inode *, xfs_off_t, size_t, struct xfs_bmbt_irec *, int); int xfs_iomap_write_allocate(struct xfs_inode *, int, xfs_off_t, struct xfs_bmbt_irec *); -int xfs_iomap_write_unwritten(struct xfs_inode *, xfs_off_t, xfs_off_t); +int xfs_iomap_write_unwritten(struct xfs_inode *, xfs_off_t, xfs_off_t, bool); void xfs_bmbt_to_iomap(struct xfs_inode *, struct iomap *, struct xfs_bmbt_irec *); diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c index 93a7aafa56d6..cecd37569ddb 100644 --- a/fs/xfs/xfs_pnfs.c +++ b/fs/xfs/xfs_pnfs.c @@ -279,7 +279,7 @@ xfs_fs_commit_blocks( (end - 1) >> PAGE_SHIFT); WARN_ON_ONCE(error); - error = xfs_iomap_write_unwritten(ip, start, length); + error = xfs_iomap_write_unwritten(ip, start, length, false); if (error) goto out_drop_iolock; } -- 2.14.2