From: Darrick J. Wong <djwong@kernel.org>
Date: Wed, 29 May 2024 04:11:09 +0000 (-0700)
Subject: xfs: refactor realtime scrubbing context management
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=93b60bfff26c4e67d95055ce74919e3a45e86b7d;p=users%2Fhch%2Fmisc.git

xfs: refactor realtime scrubbing context management

Create a pair of helpers to deal with setting up the necessary incore
context to check metadata records against the realtime metadata.  Right
now this is limited to locking the realtime bitmap and summary inodes,
but as we add rmap and reflink to the realtime device this will grow to
include btree cursors.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---

diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index dba0cddcbab9..406d34f49cc8 100644
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -314,8 +314,10 @@ xchk_bmap_rt_iextent_xref(
 	struct xchk_bmap_info	*info,
 	struct xfs_bmbt_irec	*irec)
 {
+	xchk_rt_init(info->sc, &info->sc->sr, XCHK_RTLOCK_BITMAP_SHARED);
 	xchk_xref_is_used_rt_space(info->sc, irec->br_startblock,
 			irec->br_blockcount);
+	xchk_rt_unlock(info->sc, &info->sc->sr);
 }
 
 /* Cross-reference a single datadev extent record. */
diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
index 5053e6ed2f67..a3f836360840 100644
--- a/fs/xfs/scrub/common.c
+++ b/fs/xfs/scrub/common.c
@@ -684,6 +684,75 @@ xchk_ag_init(
 	return 0;
 }
 
+/*
+ * For scrubbing a realtime file, grab all the in-core resources we'll need to
+ * check the realtime metadata, which means taking the ILOCK of the realtime
+ * metadata inodes.  Callers must not join these inodes to the transaction
+ * with non-zero lockflags or concurrency problems will result.  The
+ * @rtlock_flags argument takes XCHK_RTLOCK_* flags because scrub has somewhat
+ * unusual locking requirements.
+ */
+void
+xchk_rt_init(
+	struct xfs_scrub	*sc,
+	struct xchk_rt		*sr,
+	unsigned int		rtlock_flags)
+{
+	ASSERT(!(rtlock_flags & ~XCHK_RTLOCK_ALL));
+	ASSERT(hweight32(rtlock_flags & (XCHK_RTLOCK_BITMAP |
+					 XCHK_RTLOCK_BITMAP_SHARED)) < 2);
+	ASSERT(hweight32(rtlock_flags & (XCHK_RTLOCK_SUMMARY |
+					 XCHK_RTLOCK_SUMMARY_SHARED)) < 2);
+
+	if (rtlock_flags & XCHK_RTLOCK_BITMAP)
+		xfs_ilock(sc->mp->m_rbmip, XFS_ILOCK_EXCL | XFS_ILOCK_RTBITMAP);
+	else if (rtlock_flags & XCHK_RTLOCK_BITMAP_SHARED)
+		xfs_ilock(sc->mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
+
+	if (rtlock_flags & XCHK_RTLOCK_SUMMARY)
+		xfs_ilock(sc->mp->m_rsumip, XFS_ILOCK_EXCL | XFS_ILOCK_RTSUM);
+	else if (rtlock_flags & XCHK_RTLOCK_SUMMARY_SHARED)
+		xfs_ilock(sc->mp->m_rsumip, XFS_ILOCK_SHARED | XFS_ILOCK_RTSUM);
+
+	sr->rtlock_flags = rtlock_flags;
+}
+
+/*
+ * Unlock the realtime metadata inodes.  This must be done /after/ committing
+ * (or cancelling) the scrub transaction.
+ */
+void
+xchk_rt_unlock(
+	struct xfs_scrub	*sc,
+	struct xchk_rt		*sr)
+{
+	if (!sr->rtlock_flags)
+		return;
+
+	if (sr->rtlock_flags & XCHK_RTLOCK_SUMMARY)
+		xfs_iunlock(sc->mp->m_rsumip, XFS_ILOCK_EXCL);
+	else if (sr->rtlock_flags & XCHK_RTLOCK_SUMMARY_SHARED)
+		xfs_iunlock(sc->mp->m_rsumip, XFS_ILOCK_SHARED);
+
+	if (sr->rtlock_flags & XCHK_RTLOCK_BITMAP)
+		xfs_iunlock(sc->mp->m_rbmip, XFS_ILOCK_EXCL);
+	else if (sr->rtlock_flags & XCHK_RTLOCK_BITMAP_SHARED)
+		xfs_iunlock(sc->mp->m_rbmip, XFS_ILOCK_SHARED);
+
+	sr->rtlock_flags = 0;
+}
+
+/* Drop only the shared rt bitmap lock. */
+void
+xchk_rt_unlock_rtbitmap(
+	struct xfs_scrub	*sc)
+{
+	ASSERT(sc->sr.rtlock_flags & XCHK_RTLOCK_BITMAP_SHARED);
+
+	xfs_iunlock(sc->mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
+	sc->sr.rtlock_flags &= ~XCHK_RTLOCK_BITMAP_SHARED;
+}
+
 /* Per-scrubber setup functions */
 
 void
diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
index 96fe6ef5f4dc..a5defe0defbd 100644
--- a/fs/xfs/scrub/common.h
+++ b/fs/xfs/scrub/common.h
@@ -129,6 +129,24 @@ xchk_ag_init_existing(
 	return error == -ENOENT ? -EFSCORRUPTED : error;
 }
 
+/* Lock the rt bitmap in exclusive mode */
+#define XCHK_RTLOCK_BITMAP		(1U << 31)
+/* Lock the rt bitmap in shared mode */
+#define XCHK_RTLOCK_BITMAP_SHARED	(1U << 30)
+/* Lock the rt summary in exclusive mode */
+#define XCHK_RTLOCK_SUMMARY		(1U << 29)
+/* Lock the rt summary in shared mode */
+#define XCHK_RTLOCK_SUMMARY_SHARED	(1U << 28)
+
+#define XCHK_RTLOCK_ALL		(XCHK_RTLOCK_BITMAP | \
+				 XCHK_RTLOCK_BITMAP_SHARED | \
+				 XCHK_RTLOCK_SUMMARY | \
+				 XCHK_RTLOCK_SUMMARY_SHARED)
+
+void xchk_rt_init(struct xfs_scrub *sc, struct xchk_rt *sr,
+		unsigned int xchk_rtlock_flags);
+void xchk_rt_unlock(struct xfs_scrub *sc, struct xchk_rt *sr);
+void xchk_rt_unlock_rtbitmap(struct xfs_scrub *sc);
 int xchk_ag_read_headers(struct xfs_scrub *sc, xfs_agnumber_t agno,
 		struct xchk_ag *sa);
 void xchk_ag_btcur_free(struct xchk_ag *sa);
diff --git a/fs/xfs/scrub/rtbitmap.c b/fs/xfs/scrub/rtbitmap.c
index 46583517377f..83b3569807d6 100644
--- a/fs/xfs/scrub/rtbitmap.c
+++ b/fs/xfs/scrub/rtbitmap.c
@@ -53,7 +53,7 @@ xchk_setup_rtbitmap(
 	if (error)
 		return error;
 
-	xchk_ilock(sc, XFS_ILOCK_EXCL | XFS_ILOCK_RTBITMAP);
+	xchk_rt_init(sc, &sc->sr, XCHK_RTLOCK_BITMAP);
 
 	/*
 	 * Now that we've locked the rtbitmap, we can't race with growfsrt
@@ -217,13 +217,10 @@ xchk_xref_is_used_rt_space(
 
 	startext = xfs_rtb_to_rtx(sc->mp, rtbno);
 	endext = xfs_rtb_to_rtx(sc->mp, rtbno + len - 1);
-	xfs_ilock(sc->mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
 	error = xfs_rtalloc_extent_is_free(sc->mp, sc->tp, startext,
 			endext - startext + 1, &is_free);
 	if (!xchk_should_check_xref(sc, &error, NULL))
-		goto out_unlock;
+		return;
 	if (is_free)
 		xchk_ino_xref_set_corrupt(sc, sc->mp->m_rbmip->i_ino);
-out_unlock:
-	xfs_iunlock(sc->mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
 }
diff --git a/fs/xfs/scrub/rtsummary.c b/fs/xfs/scrub/rtsummary.c
index 3fee603f5244..c21d5c6220d4 100644
--- a/fs/xfs/scrub/rtsummary.c
+++ b/fs/xfs/scrub/rtsummary.c
@@ -80,14 +80,8 @@ xchk_setup_rtsummary(
 	if (error)
 		return error;
 
-	/*
-	 * Locking order requires us to take the rtbitmap first.  We must be
-	 * careful to unlock it ourselves when we are done with the rtbitmap
-	 * file since the scrub infrastructure won't do that for us.  Only
-	 * then we can lock the rtsummary inode.
-	 */
-	xfs_ilock(mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
-	xchk_ilock(sc, XFS_ILOCK_EXCL | XFS_ILOCK_RTSUM);
+	xchk_rt_init(sc, &sc->sr,
+			XCHK_RTLOCK_SUMMARY | XCHK_RTLOCK_BITMAP_SHARED);
 
 	/*
 	 * Now that we've locked the rtbitmap and rtsummary, we can't race with
@@ -366,6 +360,6 @@ out_rbm:
 	 * that order, so we're still protected against allocation activities
 	 * even if we continue on to the repair function.
 	 */
-	xfs_iunlock(mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
+	xchk_rt_unlock_rtbitmap(sc);
 	return error;
 }
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 04a7a5944837..00f545ea4458 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -225,6 +225,7 @@ xchk_teardown(
 			xfs_trans_cancel(sc->tp);
 		sc->tp = NULL;
 	}
+	xchk_rt_unlock(sc, &sc->sr);
 	if (sc->ip) {
 		if (sc->ilock_flags)
 			xchk_iunlock(sc, sc->ilock_flags);
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index ab143c7a531e..f8fc1d707b66 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -118,6 +118,12 @@ struct xchk_ag {
 	struct xfs_btree_cur	*refc_cur;
 };
 
+/* Inode lock state for the RT volume. */
+struct xchk_rt {
+	/* XCHK_RTLOCK_* lock state */
+	unsigned int		rtlock_flags;
+};
+
 struct xfs_scrub {
 	/* General scrub state. */
 	struct xfs_mount		*mp;
@@ -179,6 +185,9 @@ struct xfs_scrub {
 
 	/* State tracking for single-AG operations. */
 	struct xchk_ag			sa;
+
+	/* State tracking for realtime operations. */
+	struct xchk_rt			sr;
 };
 
 /* XCHK state flags grow up from zero, XREP state flags grown down from 2^31 */