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Date: Fri, 10 Jan 2020 11:29:36 -0800 From: ira.weiny@...el.com To: linux-kernel@...r.kernel.org Cc: Ira Weiny <ira.weiny@...el.com>, Alexander Viro <viro@...iv.linux.org.uk>, "Darrick J. Wong" <darrick.wong@...cle.com>, Dan Williams <dan.j.williams@...el.com>, Dave Chinner <david@...morbit.com>, Christoph Hellwig <hch@....de>, "Theodore Y. Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org Subject: [RFC PATCH V2 06/12] fs/xfs: Check if the inode supports DAX under lock From: Ira Weiny <ira.weiny@...el.com> One of the checks for an inode supporting DAX is if the inode is reflinked. During a non-DAX to DAX mode change we could race with the file being reflinked and end up with a reflinked file being in DAX mode. Prevent this race by checking for DAX support under the MMAP_LOCK. Signed-off-by: Ira Weiny <ira.weiny@...el.com> --- fs/xfs/xfs_ioctl.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index b5e00b67c297..bc3654fe3b5d 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -1180,10 +1180,6 @@ xfs_ioctl_setattr_dax_invalidate( *join_flags = 0; - if ((fa->fsx_xflags & FS_XFLAG_DAX) == FS_XFLAG_DAX && - !xfs_inode_supports_dax(ip)) - return -EINVAL; - /* If the DAX state is not changing, we have nothing to do here. */ if ((fa->fsx_xflags & FS_XFLAG_DAX) && (ip->i_d.di_flags2 & XFS_DIFLAG2_DAX)) @@ -1197,6 +1193,13 @@ xfs_ioctl_setattr_dax_invalidate( /* lock, flush and invalidate mapping in preparation for flag change */ xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); + + if ((fa->fsx_xflags & FS_XFLAG_DAX) == FS_XFLAG_DAX && + !xfs_inode_supports_dax(ip)) { + error = -EINVAL; + goto out_unlock; + } + error = filemap_write_and_wait(inode->i_mapping); if (error) goto out_unlock; -- 2.21.0
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