[40/41] mkfs: validate CoW extent size hint when rtinherit is set

Commit Message

Darrick J. Wong Dec. 30, 2022, 10:20 p.m. UTC

From: Darrick J. Wong <[e-mail]>

Extent size hints exist to nudge the behavior of the file data block
allocator towards trying to make aligned allocations.  Therefore, it
doesn't make sense to allow a hint that isn't a multiple of the
fundamental allocation unit for a given file.

This means that if the sysadmin is formatting with rtinherit set on the
root dir, validate_cowextsize_hint needs to check the hint value on a
simulated realtime file to make sure that it's correct.  This hasn't
been necessary in the past since one cannot have a CoW hint without a
reflink filesystem, and we previously didn't allow rt reflink
filesystems.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 mkfs/xfs_mkfs.c |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

Patch

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index eebcade7d1a..dcce3d0136e 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -2669,6 +2669,26 @@  _("illegal CoW extent size hint %lld, must be less than %u.\n"),
 				min(XFS_MAX_BMBT_EXTLEN, mp->m_sb.sb_agblocks / 2));
 		usage();
 	}
+
+	/*
+	 * If the value is to be passed on to realtime files, revalidate with
+	 * a realtime file so that we know the hint and flag that get passed on
+	 * to realtime files will be correct.
+	 */
+	if (!(cli->fsx.fsx_xflags & FS_XFLAG_RTINHERIT))
+		return;
+
+	fa = libxfs_inode_validate_cowextsize(mp, cli->fsx.fsx_cowextsize,
+			S_IFREG, XFS_DIFLAG_REALTIME, flags2);
+
+	if (fa) {
+		fprintf(stderr,
+_("illegal CoW extent size hint %lld, must be less than %u and a multiple of %u. %p\n"),
+				(long long)cli->fsx.fsx_cowextsize,
+				min(XFS_MAX_BMBT_EXTLEN, mp->m_sb.sb_agblocks / 2),
+				mp->m_sb.sb_rextsize, fa);
+		usage();
+	}
 }
 
 /* Complain if this filesystem is not a supported configuration. */