[PATCH 05/22] xfs: scrub in-memory metadata buffers

Darrick J. Wong
2017-07-21T04:39:03Z

From: Darrick J. Wong <darrick.wong@oracle.com>

Call the verifier function for all in-memory metadata buffers, looking
for memory corruption either due to bad memory or coding bugs.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/Makefile | 1
fs/xfs/libxfs/xfs_fs.h | 3 +
fs/xfs/scrub/common.c | 4 +
fs/xfs/scrub/common.h | 2 +
fs/xfs/scrub/metabufs.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_trace.h | 3 +
6 files changed, 188 insertions(+), 2 deletions(-)
create mode 100644 fs/xfs/scrub/metabufs.c

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 4e04da9..67cf4ac 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -142,5 +142,6 @@ ifeq ($(CONFIG_XFS_ONLINE_SCRUB),y)
xfs-y += $(addprefix scrub/, \
btree.o \
common.o \
+ metabufs.o \
)
endif
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index aeccc99..9fb3c65 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -482,7 +482,8 @@ struct xfs_scrub_metadata {
* Metadata types and flags for scrub operation.
*/
#define XFS_SCRUB_TYPE_TEST 0 /* dummy to test ioctl */
-#define XFS_SCRUB_TYPE_MAX 0
+#define XFS_SCRUB_TYPE_METABUFS 1 /* in-core metadata buffers */
+#define XFS_SCRUB_TYPE_MAX 1

/* i: repair this metadata */
#define XFS_SCRUB_FLAG_REPAIR (1 << 0)
diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
index 331aa14..e06131f 100644
--- a/fs/xfs/scrub/common.c
+++ b/fs/xfs/scrub/common.c
@@ -610,6 +610,10 @@ static const struct xfs_scrub_meta_fns meta_scrub_fns[] = {
.setup = xfs_scrub_setup_fs,
.scrub = xfs_scrub_dummy,
},
+ { /* in-memory metadata buffers */
+ .setup = xfs_scrub_setup_metabufs,
+ .scrub = xfs_scrub_metabufs,
+ },
};

/* Dispatch metadata scrubbing. */
diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
index 15baccb..5f0818c 100644
--- a/fs/xfs/scrub/common.h
+++ b/fs/xfs/scrub/common.h
@@ -198,12 +198,14 @@ int xfs_scrub_ag_btcur_init(struct xfs_scrub_context *sc,

#define SETUP_FN(name) int name(struct xfs_scrub_context *sc, struct xfs_inode *ip)
SETUP_FN(xfs_scrub_setup_fs);
+SETUP_FN(xfs_scrub_setup_metabufs);
#undef SETUP_FN

/* Metadata scrubbers */

#define SCRUB_FN(name) int name(struct xfs_scrub_context *sc)
SCRUB_FN(xfs_scrub_dummy);
+SCRUB_FN(xfs_scrub_metabufs);
#undef SCRUB_FN

#endif /* __XFS_REPAIR_COMMON_H__ */
diff --git a/fs/xfs/scrub/metabufs.c b/fs/xfs/scrub/metabufs.c
new file mode 100644
index 0000000..63faaa6
--- /dev/null
+++ b/fs/xfs/scrub/metabufs.c
@@ -0,0 +1,177 @@
+/*
+ * Copyright (C) 2017 Oracle. All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_btree.h"
+#include "xfs_bit.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_trace.h"
+#include "xfs_sb.h"
+#include "scrub/common.h"
+
+/* We only iterate buffers one by one, so we don't need any setup. */
+int
+xfs_scrub_setup_metabufs(
+ struct xfs_scrub_context *sc,
+ struct xfs_inode *ip)
+{
+ return 0;
+}
+
+#define XFS_SCRUB_METABUFS_TOO_MANY_RETRIES 10
+struct xfs_scrub_metabufs_info {
+ struct xfs_scrub_context *sc;
+ unsigned int retries;
+};
+
+/* In-memory buffer corruption. */
+
+#define XFS_SCRUB_BUF_OP_ERROR_GOTO(label) \
+ XFS_SCRUB_OP_ERROR_GOTO(smi->sc, \
+ xfs_daddr_to_agno(smi->sc->mp, bp->b_bn), \
+ xfs_daddr_to_agbno(smi->sc->mp, bp->b_bn), "buf", \
+ &error, label)
+STATIC int
+xfs_scrub_metabufs_scrub_buf(
+ struct xfs_scrub_metabufs_info *smi,
+ struct xfs_buf *bp)
+{
+ int olderror;
+ int error = 0;
+
+ /*
+ * We hold the rcu lock during the rhashtable walk, so we can't risk
+ * having the log forced due to a stale buffer by xfs_buf_lock.
+ */
+ if (bp->b_flags & XBF_STALE)
+ return 0;
+
+ atomic_inc(&bp->b_hold);
+ if (!xfs_buf_trylock(bp)) {
+ if (smi->retries > XFS_SCRUB_METABUFS_TOO_MANY_RETRIES) {
+ /* We've retried too many times, do what we can. */
+ XFS_SCRUB_INCOMPLETE(smi->sc, "metabufs", true);
+ error = 0;
+ } else {
+ /* Restart the metabuf scrub from the start. */
+ smi->retries++;
+ error = -EAGAIN;
+ }
+ goto out_dec;
+ }
+
+ /* Skip this buffer if it's stale, unread, or has no verifiers. */
+ if ((bp->b_flags & XBF_STALE) ||
+ !(bp->b_flags & XBF_DONE) ||
+ !bp->b_ops)
+ goto out_unlock;
+
+ /*
+ * Run the verifiers to see if the in-memory buffer is bitrotting or
+ * otherwise corrupt. If the buffer doesn't have a log item then
+ * it's clean, so call the read verifier. However, if the buffer
+ * has a log item, it is probably dirty. Checksums will be written
+ * when the buffer is about to go out to disk, so call the write
+ * verifier to check the structure.
+ */
+ olderror = bp->b_error;
+ if (bp->b_fspriv)
+ bp->b_ops->verify_write(bp);
+ else
+ bp->b_ops->verify_read(bp);
+ error = bp->b_error;
+ bp->b_error = olderror;
+
+ /* Mark any corruption errors we might find. */
+ XFS_SCRUB_BUF_OP_ERROR_GOTO(out_unlock);
+
+out_unlock:
+ xfs_buf_unlock(bp);
+out_dec:
+ atomic_dec(&bp->b_hold);
+ return error;
+}
+#undef XFS_SCRUB_BUF_OP_ERROR_GOTO
+
+/* Walk the buffer rhashtable and dispatch buffer checking. */
+STATIC int
+xfs_scrub_metabufs_walk_rhash(
+ struct xfs_scrub_metabufs_info *smi,
+ struct rhashtable_iter *iter)
+{
+ struct xfs_buf *bp;
+ int error = 0;
+
+ do {
+ if (xfs_scrub_should_terminate(&error))
+ break;
+
+ bp = rhashtable_walk_next(iter);
+ if (IS_ERR(bp))
+ return PTR_ERR(bp);
+ else if (bp == NULL)
+ return 0;
+
+ error = xfs_scrub_metabufs_scrub_buf(smi, bp);
+ } while (error != 0);
+
+ return error;
+}
+
+/* Try to walk the buffers in this AG in order to scrub them. */
+int
+xfs_scrub_metabufs(
+ struct xfs_scrub_context *sc)
+{
+ struct xfs_scrub_metabufs_info smi;
+ struct rhashtable_iter iter;
+ struct xfs_perag *pag;
+ int error;
+
+ smi.sc = sc;
+ smi.retries = 0;
+ pag = xfs_perag_get(sc->mp, sc->sm->sm_agno);
+ rhashtable_walk_enter(&pag->pag_buf_hash, &iter);
+
+ while (1) {
+ if (xfs_scrub_should_terminate(&error))
+ break;
+
+ error = rhashtable_walk_start(&iter);
+ if (!error) {
+ error = xfs_scrub_metabufs_walk_rhash(&smi, &iter);
+ rhashtable_walk_stop(&iter);
+ }
+
+ if (error != -EAGAIN)
+ break;
+ cond_resched();
+ }
+
+ rhashtable_walk_exit(&iter);
+ xfs_perag_put(pag);
+ return error;
+}
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index d4de29b..036e65c 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -3312,7 +3312,8 @@ DEFINE_GETFSMAP_EVENT(xfs_getfsmap_mapping);

/* scrub */
#define XFS_SCRUB_TYPE_DESC \
- { XFS_SCRUB_TYPE_TEST, "dummy" }
+ { XFS_SCRUB_TYPE_TEST, "dummy" }, \
+ { XFS_SCRUB_TYPE_METABUFS, "metabufs" }
DECLARE_EVENT_CLASS(xfs_scrub_class,
TP_PROTO(struct xfs_inode *ip, struct xfs_scrub_metadata *sm,
int error),