On Tue, Oct 02, 2018 at 07:03:42PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > When we're reflinking between two files and the destination file range > is well beyond the destination file's EOF marker, zero any posteof > speculative preallocations in the destination file so that we don't > expose stale disk contents. The previous strategy of trying to clear > the preallocations does not work if the destination file has the > PREALLOC flag set but no delalloc blocks. > > Uncovered by shared/010. > > Reported-by: Zorro Lang <zlang@xxxxxxxxxx> > Bugzilla-id: https://bugzilla.kernel.org/show_bug.cgi?id=201259 > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > --- > fs/xfs/xfs_reflink.c | 34 ++++++++++++++++++++++++++-------- > 1 file changed, 26 insertions(+), 8 deletions(-) > > diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c > index 38f405415b88..c8e996a99a74 100644 > --- a/fs/xfs/xfs_reflink.c > +++ b/fs/xfs/xfs_reflink.c > @@ -1195,6 +1195,27 @@ xfs_iolock_two_inodes_and_break_layout( > return 0; > } > > +/* > + * If we're reflinking to a point past the destination file's EOF, we must > + * zero any speculative post-EOF preallocations that sit between the old EOF > + * and the destination file offset. > + */ > +static int > +xfs_reflink_zero_posteof( > + struct xfs_inode *ip, > + loff_t pos) > +{ > + loff_t isize = i_size_read(VFS_I(ip)); > + bool did_zeroing = false; > + > + if (pos <= isize) > + return 0; > + > + trace_xfs_zero_eof(ip, isize, pos - isize); > + return iomap_zero_range(VFS_I(ip), isize, pos - isize, &did_zeroing, > + &xfs_iomap_ops); iomap_zero_range() accepts NULL for the *did_zero param. Otherwise seems fine, barring Eric's question on whether we need additional checks.. Brian > +} > + > /* > * Link a range of blocks from one file to another. > */ > @@ -1257,15 +1278,12 @@ xfs_reflink_remap_range( > trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out); > > /* > - * Clear out post-eof preallocations because we don't have page cache > - * backing the delayed allocations and they'll never get freed on > - * their own. > + * Zero existing post-eof speculative preallocations in the destination > + * file. > */ > - if (xfs_can_free_eofblocks(dest, true)) { > - ret = xfs_free_eofblocks(dest); > - if (ret) > - goto out_unlock; > - } > + ret = xfs_reflink_zero_posteof(dest, pos_out); > + if (ret) > + goto out_unlock; > > /* Set flags and remap blocks. */ > ret = xfs_reflink_set_inode_flag(src, dest);
