On Mon, Jun 08, 2020 at 07:05:37PM -0400, Sasha Levin wrote:
From: "Darrick J. Wong" darrick.wong@oracle.com
[ 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@oracle.com Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Brian Foster bfoster@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org
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