On Mon, Jun 08, 2020 at 07:05:37PM -0400, Sasha Levin wrote: > From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx> > > [ Upstream commit a5949d3faedf492fa7863b914da408047ab46eb0 ] > > When writing to a delalloc region in the data fork, commit the new > allocations (of the da reservation) as unwritten so that the mappings > are only marked written once writeback completes successfully. This > fixes the problem of stale data exposure if the system goes down during > targeted writeback of a specific region of a file, as tested by > generic/042. > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> Err, this doesn't have a Fixes: tag attached to it. Does it pass fstests? Because it doesn't look like you've pulled in "xfs: don't fail unwritten extent conversion on writeback due to edquot", which is needed to avoid regressing fstests... ...waitaminute, that whole series lacks Fixes: tags because it wasn't considered a good enough candidate for automatic backport. Ummm, does the autosel fstests driver turn on quotas? ;) --D > --- > fs/xfs/libxfs/xfs_bmap.c | 29 +++++++++++++++++------------ > 1 file changed, 17 insertions(+), 12 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c > index fda13cd7add0..f8fe83c9348d 100644 > --- a/fs/xfs/libxfs/xfs_bmap.c > +++ b/fs/xfs/libxfs/xfs_bmap.c > @@ -4193,17 +4193,7 @@ xfs_bmapi_allocate( > bma->got.br_blockcount = bma->length; > bma->got.br_state = XFS_EXT_NORM; > > - /* > - * In the data fork, a wasdelay extent has been initialized, so > - * shouldn't be flagged as unwritten. > - * > - * For the cow fork, however, we convert delalloc reservations > - * (extents allocated for speculative preallocation) to > - * allocated unwritten extents, and only convert the unwritten > - * extents to real extents when we're about to write the data. > - */ > - if ((!bma->wasdel || (bma->flags & XFS_BMAPI_COWFORK)) && > - (bma->flags & XFS_BMAPI_PREALLOC)) > + if (bma->flags & XFS_BMAPI_PREALLOC) > bma->got.br_state = XFS_EXT_UNWRITTEN; > > if (bma->wasdel) > @@ -4611,8 +4601,23 @@ xfs_bmapi_convert_delalloc( > bma.offset = bma.got.br_startoff; > bma.length = max_t(xfs_filblks_t, bma.got.br_blockcount, MAXEXTLEN); > bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork); > + > + /* > + * When we're converting the delalloc reservations backing dirty pages > + * in the page cache, we must be careful about how we create the new > + * extents: > + * > + * New CoW fork extents are created unwritten, turned into real extents > + * when we're about to write the data to disk, and mapped into the data > + * fork after the write finishes. End of story. > + * > + * New data fork extents must be mapped in as unwritten and converted > + * to real extents after the write succeeds to avoid exposing stale > + * disk contents if we crash. > + */ > + bma.flags = XFS_BMAPI_PREALLOC; > if (whichfork == XFS_COW_FORK) > - bma.flags = XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC; > + bma.flags |= XFS_BMAPI_COWFORK; > > if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev)) > bma.prev.br_startoff = NULLFILEOFF; > -- > 2.25.1 >
