On 06/08/2024 20:02, Darrick J. Wong wrote:
On Thu, Aug 01, 2024 at 04:30:50PM +0000, John Garry wrote:
From: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Add a new inode flag to require that all file data extent mappings must
be aligned (both the file offset range and the allocated space itself)
to the extent size hint. Having a separate COW extent size hint is no
longer allowed.
The goal here is to enable sysadmins and users to mandate that all space
mappings in a file must have a startoff/blockcount that are aligned to
(say) a 2MB alignment and that the startblock/blockcount will follow the
same alignment.
Allocated space will be aligned to start of the AG, and not necessarily
aligned with disk blocks. The upcoming atomic writes feature will rely and
forcealign and will also require allocated space will also be aligned to
disk blocks.
reflink will not be supported for forcealign yet, so disallow a mount under
this condition. This is because we have the limitation of pageache
writeback not knowing how to writeback an entire allocation unut, so
reject a mount with relink.
RT vol will not be supported for forcealign yet, so disallow a mount under
this condition. It will be possible to support RT vol and forcealign in
future. For this, the inode extsize must be a multiple of rtextsize - this
is enforced already in xfs_ioctl_setattr_check_extsize() and
xfs_inode_validate_extsize().
Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Co-developed-by: John Garry <john.g.garry@xxxxxxxxxx>
[jpg: many changes from orig, including forcealign inode verification
rework, ioctl setattr rework disallow reflink a forcealign inode,
disallow mount for forcealign + reflink or rt]
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
This patch looks ready to me but as I'm the original author I cannot add
a RVB tag. Someone else needs to add that -- frankly, John is the best
candidate because he grabbed my patch into his tree and actually
modified it to do what he wants, which means he's the most familiar with
it.
I thought my review would be implied since I noted how I appended it, above.
Anyway,
Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>
I am hoping that Dave and Christoph will give some formal ack/review
when they get a chance.
BTW, at what stage do we give XFS_SB_FEAT_RO_COMPAT_FORCEALIGN a more
proper value? So far it has the experimental dev value of 1 << 30, below.
Thanks!
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index e1bfee0c3b1a..95f5259c4255 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -352,6 +352,7 @@ xfs_sb_has_compat_feature(
#define XFS_SB_FEAT_RO_COMPAT_RMAPBT (1 << 1) /* reverse map btree */
#define XFS_SB_FEAT_RO_COMPAT_REFLINK (1 << 2) /* reflinked files */
#define XFS_SB_FEAT_RO_COMPAT_INOBTCNT (1 << 3) /* inobt block counts */
+#define XFS_SB_FEAT_RO_COMPAT_FORCEALIGN (1 << 30) /* aligned file data extents */
#define XFS_SB_FEAT_RO_COMPAT_ALL \
(XFS_SB_FEAT_RO_COMPAT_FINOBT | \
XFS_SB_FEAT_RO_COMPAT_RMAPBT | \
