Re: [PATCH V2] xfs: do not allow reflinking inodes with the dax flag set
From: Darrick J. Wong <hidden>
Date: 2021-01-08 01:33:08
On Thu, Jan 07, 2021 at 03:36:34PM -0600, Eric Sandeen wrote:
Today, xfs_reflink_remap_prep() will reject inodes which are in the CPU direct access state, i.e. IS_DAX() is true. However, it is possible to have inodes with the XFS_DIFLAG2_DAX set, but which are not activated as dax, due to the flag being set after the inode was loaded. To avoid confusion and make the lack of dax+reflink crystal clear for the user, reject reflink requests for both IS_DAX and XFS_DIFLAG2_DAX inodes unless DAX mode is impossible due to mounting with -o dax=never.
I thought we were allowing arbitrary combinations of DAX & REFLINK inode flags now, since we're now officially ok with "you set the inode flag but you don't get cpu direct access because $reasons"? --D
quoted hunk ↗ jump to hunk
Signed-off-by: Eric Sandeen <redacted> --- V2: Allow reflinking dax-flagged inodes in "mount -o dax=never" modediff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 6fa05fb78189..e238a5b7b722 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c@@ -1308,6 +1308,15 @@ xfs_reflink_remap_prep( if (IS_DAX(inode_in) || IS_DAX(inode_out)) goto out_unlock; + /* + * Until we have dax+reflink, don't allow reflinking dax-flagged + * inodes unless we are in dax=never mode. + */ + if (!(mp->m_flags & XFS_MOUNT_DAX_NEVER) && + (src->i_d.di_flags2 & XFS_DIFLAG2_DAX || + dest->i_d.di_flags2 & XFS_DIFLAG2_DAX)) + goto out_unlock; + ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out, len, remap_flags); if (ret || *len == 0)