[1/3] xfs_scrub: automatic downgrades to dry-run mode in service mode

Commit Message

Darrick J. Wong July 2, 2024, 1:09 a.m. UTC

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

When service mode is enabled, xfs_scrub is being run within the context
of a systemd service.  The service description language doesn't have any
particularly good constructs for adding in a '-n' argument if the
filesystem is readonly, which means that xfs_scrub is passed a path, and
needs to switch to dry-run mode on its own if the fs is mounted
readonly or the kernel doesn't support repairs.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 scrub/phase1.c |   13 +++++++++++++
 scrub/repair.c |   33 +++++++++++++++++++++++++++++++++
 scrub/repair.h |    2 ++
 3 files changed, 48 insertions(+)

Comments

Christoph Hellwig July 2, 2024, 5:43 a.m. UTC | #1

Looks good:

Reviewed-by: Christoph Hellwig <[e-mail]>

Patch

diff --git a/scrub/phase1.c b/scrub/phase1.c
index 516d929d6268..095c045915a7 100644
--- a/scrub/phase1.c
+++ b/scrub/phase1.c
@@ -216,6 +216,19 @@  _("Kernel metadata scrubbing facility is not available."));
 		return ECANCELED;
 	}
 
+	/*
+	 * Normally, callers are required to pass -n if the provided path is a
+	 * readonly filesystem or the kernel wasn't built with online repair
+	 * enabled.  However, systemd services are not scripts and cannot
+	 * determine either of these conditions programmatically.  Change the
+	 * behavior to dry-run mode if either condition is detected.
+	 */
+	if (repair_want_service_downgrade(ctx)) {
+		str_info(ctx, ctx->mntpoint,
+_("Filesystem cannot be repaired in service mode, downgrading to dry-run mode."));
+		ctx->mode = SCRUB_MODE_DRY_RUN;
+	}
+
 	/* Do we need kernel-assisted metadata repair? */
 	if (ctx->mode != SCRUB_MODE_DRY_RUN && !can_repair(ctx)) {
 		str_error(ctx, ctx->mntpoint,
diff --git a/scrub/repair.c b/scrub/repair.c
index 19f5c9052aff..2883f98af4ab 100644
--- a/scrub/repair.c
+++ b/scrub/repair.c
@@ -45,6 +45,39 @@  static const unsigned int repair_deps[XFS_SCRUB_TYPE_NR] = {
 };
 #undef DEP
 
+/*
+ * Decide if we want an automatic downgrade to dry-run mode.  This is only
+ * for service mode, where we are fed a path and have to figure out if the fs
+ * is repairable or not.
+ */
+bool
+repair_want_service_downgrade(
+	struct scrub_ctx		*ctx)
+{
+	struct xfs_scrub_metadata	meta = {
+		.sm_type		= XFS_SCRUB_TYPE_PROBE,
+		.sm_flags		= XFS_SCRUB_IFLAG_REPAIR,
+	};
+	int				error;
+
+	if (ctx->mode == SCRUB_MODE_DRY_RUN)
+		return false;
+	if (!is_service)
+		return false;
+	if (debug_tweak_on("XFS_SCRUB_NO_KERNEL"))
+		return false;
+
+	error = -xfrog_scrub_metadata(&ctx->mnt, &meta);
+	switch (error) {
+	case EROFS:
+	case ENOTRECOVERABLE:
+	case EOPNOTSUPP:
+		return true;
+	}
+
+	return false;
+}
+
 /* Repair some metadata. */
 static int
 xfs_repair_metadata(
diff --git a/scrub/repair.h b/scrub/repair.h
index a685e90374cb..411a379f6faa 100644
--- a/scrub/repair.h
+++ b/scrub/repair.h
@@ -102,4 +102,6 @@  repair_item_completely(
 	return repair_item(ctx, sri, XRM_FINAL_WARNING | XRM_NOPROGRESS);
 }
 
+bool repair_want_service_downgrade(struct scrub_ctx *ctx);
+
 #endif /* XFS_SCRUB_REPAIR_H_ */