xfs: create helpers to scan an allocation group

Add some helpers to enable us to lock an AG's headers, create btree
cursors for all btrees in that allocation group, and clean up
afterwards.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 179 insertions, 0 deletions

diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
index 709d4916fe04..cd6fada1b426 100644
--- a/fs/xfs/scrub/common.c
+++ b/fs/xfs/scrub/common.c
@@ -44,6 +44,7 @@
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/trace.h"
+#include "scrub/btree.h"
 
 /* Common code for the metadata scrubbers. */
 
@@ -237,6 +238,184 @@ xfs_scrub_set_incomplete(
 	trace_xfs_scrub_incomplete(sc, __return_address);
 }
 
+/*
+ * AG scrubbing
+ *
+ * These helpers facilitate locking an allocation group's header
+ * buffers, setting up cursors for all btrees that are present, and
+ * cleaning everything up once we're through.
+ */
+
+/*
+ * Grab all the headers for an AG.
+ *
+ * The headers should be released by xfs_scrub_ag_free, but as a fail
+ * safe we attach all the buffers we grab to the scrub transaction so
+ * they'll all be freed when we cancel it.
+ */
+int
+xfs_scrub_ag_read_headers(
+	struct xfs_scrub_context	*sc,
+	xfs_agnumber_t			agno,
+	struct xfs_buf			**agi,
+	struct xfs_buf			**agf,
+	struct xfs_buf			**agfl)
+{
+	struct xfs_mount		*mp = sc->mp;
+	int				error;
+
+	error = xfs_ialloc_read_agi(mp, sc->tp, agno, agi);
+	if (error)
+		goto out;
+
+	error = xfs_alloc_read_agf(mp, sc->tp, agno, 0, agf);
+	if (error)
+		goto out;
+	if (!*agf) {
+		error = -ENOMEM;
+		goto out;
+	}
+
+	error = xfs_alloc_read_agfl(mp, sc->tp, agno, agfl);
+	if (error)
+		goto out;
+
+out:
+	return error;
+}
+
+/* Release all the AG btree cursors. */
+void
+xfs_scrub_ag_btcur_free(
+	struct xfs_scrub_ag		*sa)
+{
+	if (sa->refc_cur)
+		xfs_btree_del_cursor(sa->refc_cur, XFS_BTREE_ERROR);
+	if (sa->rmap_cur)
+		xfs_btree_del_cursor(sa->rmap_cur, XFS_BTREE_ERROR);
+	if (sa->fino_cur)
+		xfs_btree_del_cursor(sa->fino_cur, XFS_BTREE_ERROR);
+	if (sa->ino_cur)
+		xfs_btree_del_cursor(sa->ino_cur, XFS_BTREE_ERROR);
+	if (sa->cnt_cur)
+		xfs_btree_del_cursor(sa->cnt_cur, XFS_BTREE_ERROR);
+	if (sa->bno_cur)
+		xfs_btree_del_cursor(sa->bno_cur, XFS_BTREE_ERROR);
+
+	sa->refc_cur = NULL;
+	sa->rmap_cur = NULL;
+	sa->fino_cur = NULL;
+	sa->ino_cur = NULL;
+	sa->bno_cur = NULL;
+	sa->cnt_cur = NULL;
+}
+
+/* Initialize all the btree cursors for an AG. */
+int
+xfs_scrub_ag_btcur_init(
+	struct xfs_scrub_context	*sc,
+	struct xfs_scrub_ag		*sa)
+{
+	struct xfs_mount		*mp = sc->mp;
+	xfs_agnumber_t			agno = sa->agno;
+
+	if (sa->agf_bp) {
+		/* Set up a bnobt cursor for cross-referencing. */
+		sa->bno_cur = xfs_allocbt_init_cursor(mp, sc->tp, sa->agf_bp,
+				agno, XFS_BTNUM_BNO);
+		if (!sa->bno_cur)
+			goto err;
+
+		/* Set up a cntbt cursor for cross-referencing. */
+		sa->cnt_cur = xfs_allocbt_init_cursor(mp, sc->tp, sa->agf_bp,
+				agno, XFS_BTNUM_CNT);
+		if (!sa->cnt_cur)
+			goto err;
+	}
+
+	/* Set up a inobt cursor for cross-referencing. */
+	if (sa->agi_bp) {
+		sa->ino_cur = xfs_inobt_init_cursor(mp, sc->tp, sa->agi_bp,
+					agno, XFS_BTNUM_INO);
+		if (!sa->ino_cur)
+			goto err;
+	}
+
+	/* Set up a finobt cursor for cross-referencing. */
+	if (sa->agi_bp && xfs_sb_version_hasfinobt(&mp->m_sb)) {
+		sa->fino_cur = xfs_inobt_init_cursor(mp, sc->tp, sa->agi_bp,
+				agno, XFS_BTNUM_FINO);
+		if (!sa->fino_cur)
+			goto err;
+	}
+
+	/* Set up a rmapbt cursor for cross-referencing. */
+	if (sa->agf_bp && xfs_sb_version_hasrmapbt(&mp->m_sb)) {
+		sa->rmap_cur = xfs_rmapbt_init_cursor(mp, sc->tp, sa->agf_bp,
+				agno);
+		if (!sa->rmap_cur)
+			goto err;
+	}
+
+	/* Set up a refcountbt cursor for cross-referencing. */
+	if (sa->agf_bp && xfs_sb_version_hasreflink(&mp->m_sb)) {
+		sa->refc_cur = xfs_refcountbt_init_cursor(mp, sc->tp,
+				sa->agf_bp, agno, NULL);
+		if (!sa->refc_cur)
+			goto err;
+	}
+
+	return 0;
+err:
+	return -ENOMEM;
+}
+
+/* Release the AG header context and btree cursors. */
+void
+xfs_scrub_ag_free(
+	struct xfs_scrub_context	*sc,
+	struct xfs_scrub_ag		*sa)
+{
+	xfs_scrub_ag_btcur_free(sa);
+	if (sa->agfl_bp) {
+		xfs_trans_brelse(sc->tp, sa->agfl_bp);
+		sa->agfl_bp = NULL;
+	}
+	if (sa->agf_bp) {
+		xfs_trans_brelse(sc->tp, sa->agf_bp);
+		sa->agf_bp = NULL;
+	}
+	if (sa->agi_bp) {
+		xfs_trans_brelse(sc->tp, sa->agi_bp);
+		sa->agi_bp = NULL;
+	}
+	sa->agno = NULLAGNUMBER;
+}
+
+/*
+ * For scrub, grab the AGI and the AGF headers, in that order.  Locking
+ * order requires us to get the AGI before the AGF.  We use the
+ * transaction to avoid deadlocking on crosslinked metadata buffers;
+ * either the caller passes one in (bmap scrub) or we have to create a
+ * transaction ourselves.
+ */
+int
+xfs_scrub_ag_init(
+	struct xfs_scrub_context	*sc,
+	xfs_agnumber_t			agno,
+	struct xfs_scrub_ag		*sa)
+{
+	int				error;
+
+	sa->agno = agno;
+	error = xfs_scrub_ag_read_headers(sc, agno, &sa->agi_bp,
+			&sa->agf_bp, &sa->agfl_bp);
+	if (error)
+		return error;
+
+	return xfs_scrub_ag_btcur_init(sc, sa);
+}
+
 /* Per-scrubber setup functions */
 
 /* Set us up with a transaction and an empty context. */