xfs: implement online scrubbing of rtsummary infoscrub-rtsummary_2020-06-01

Finish the realtime summary scrubber by adding the functions we need to
compute a fresh copy of the rtsummary info and comparing it to the copy
on disk.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

6 files changed, 342 insertions, 28 deletions

diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
index 2e50d146105d..3324c88f6a08 100644
--- a/fs/xfs/scrub/common.h
+++ b/fs/xfs/scrub/common.h
@@ -96,10 +96,16 @@ int xchk_setup_symlink(struct xfs_scrub *sc,
 int xchk_setup_parent(struct xfs_scrub *sc,
 			   struct xfs_inode *ip);
 #ifdef CONFIG_XFS_RT
-int xchk_setup_rt(struct xfs_scrub *sc, struct xfs_inode *ip);
+int xchk_setup_rtbitmap(struct xfs_scrub *sc, struct xfs_inode *ip);
+int xchk_setup_rtsummary(struct xfs_scrub *sc, struct xfs_inode *ip);
 #else
 static inline int
-xchk_setup_rt(struct xfs_scrub *sc, struct xfs_inode *ip)
+xchk_setup_rtbitmap(struct xfs_scrub *sc, struct xfs_inode *ip)
+{
+	return -ENOENT;
+}
+static inline int
+xchk_setup_rtsummary(struct xfs_scrub *sc, struct xfs_inode *ip)
 {
 	return -ENOENT;
 }
diff --git a/fs/xfs/scrub/rtbitmap.c b/fs/xfs/scrub/rtbitmap.c
index 12c9c8fc6c70..fb58c25f35ac 100644
--- a/fs/xfs/scrub/rtbitmap.c
+++ b/fs/xfs/scrub/rtbitmap.c
@@ -19,13 +19,13 @@
 
 /* Set us up with the realtime metadata locked. */
 int
-xchk_setup_rt(
+xchk_setup_rtbitmap(
 	struct xfs_scrub	*sc,
 	struct xfs_inode	*ip)
 {
 	int			error;
 
-	error = xchk_setup_fs(sc, ip);
+	error = xchk_trans_alloc(sc, 0);
 	if (error)
 		return error;
 
diff --git a/fs/xfs/scrub/rtsummary.c b/fs/xfs/scrub/rtsummary.c
index 41c3634b8e2f..a70f6f0267bc 100644
--- a/fs/xfs/scrub/rtsummary.c
+++ b/fs/xfs/scrub/rtsummary.c
@@ -14,41 +14,312 @@
 #include "xfs_trans.h"
 #include "xfs_rtalloc.h"
 #include "xfs_inode.h"
+#include "xfs_bit.h"
+#include "xfs_bmap.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
+#include "scrub/trace.h"
+#include "scrub/xfile.h"
 
-/* Scrub the realtime summary. */
+/*
+ * Realtime Summary
+ * ================
+ *
+ * We check the realtime summary by scanning the realtime bitmap file to create
+ * a new summary file incore, and then we compare the computed version against
+ * the ondisk version.  We use the 'xfile' functionality to store this
+ * (potentially large) amount of data in pageable memory.
+ */
+
+struct xchk_rtsum_compute {
+	/* How far have we iterated through the rt extents? */
+	xfs_rtblock_t		rt_extent_nr;
+
+	/* How many free rt extents have we seen? */
+	xfs_rtblock_t		rt_free_nr;
+
+	/* block and bit offset of our current position in the rtbitmap. */
+	xfs_fileoff_t		off;
+	unsigned int		bit;
+
+	/* block and bit offset of the start of the most recent free rtext. */
+	xfs_fileoff_t		start_off;
+	unsigned int		start_bit;
+
+	/* Are we accumulating a free rtext? */
+	bool			in_extent;
+};
+
+/* Set us up to check the rtsummary file. */
 int
-xchk_rtsummary(
-	struct xfs_scrub	*sc)
+xchk_setup_rtsummary(
+	struct xfs_scrub	*sc,
+	struct xfs_inode	*ip)
 {
-	struct xfs_inode	*rsumip = sc->mp->m_rsumip;
-	struct xfs_inode	*old_ip = sc->ip;
-	uint			old_ilock_flags = sc->ilock_flags;
-	int			error = 0;
+	struct xfs_mount	*mp = sc->mp;
+	int			error;
 
 	/*
-	 * We ILOCK'd the rt bitmap ip in the setup routine, now lock the
-	 * rt summary ip in compliance with the rt inode locking rules.
-	 *
-	 * Since we switch sc->ip to rsumip we have to save the old ilock
-	 * flags so that we don't mix up the inode state that @sc tracks.
+	 * Create an xfile to construct a new rtsummary file.  The xfile allows
+	 * us to avoid pinning kernel memory for this purpose.
 	 */
-	sc->ip = rsumip;
+	sc->xfile = xfile_create("rtsummary", mp->m_rsumsize);
+	if (IS_ERR(sc->xfile))
+		return PTR_ERR(sc->xfile);
+
+	error = xchk_trans_alloc(sc, 0);
+	if (error)
+		return error;
+
+	/* Allocate a memory buffer for the summary comparison. */
+	sc->buf = kmem_alloc_large(sc->mp->m_sb.sb_blocksize, KM_MAYFAIL);
+	if (!sc->buf)
+		return -ENOMEM;
+
+	/*
+	 * 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.
+	 */
+	xfs_ilock(mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
+
+	/* ...and then we can lock the rtsummary inode. */
 	sc->ilock_flags = XFS_ILOCK_EXCL | XFS_ILOCK_RTSUM;
+	sc->ip = sc->mp->m_rsumip;
 	xfs_ilock(sc->ip, sc->ilock_flags);
 
+	return 0;
+}
+
+/* Update the summary file to reflect the free extent that we've accumulated. */
+STATIC int
+xchk_rtsum_record_free(
+	struct xfs_scrub	*sc,
+	struct xchk_rtsum_compute *state)
+{
+	struct xfs_mount	*mp = sc->mp;
+	loff_t			pos;
+	uint64_t		len;
+	unsigned int		offs;
+	unsigned int		log;
+	unsigned int		bitsperblock = mp->m_sb.sb_blocksize * NBBY;
+	xfs_suminfo_t		v = 0;
+	int			error;
+
+	/* Compute the relevant location in the rtsum file. */
+	len = (state->off - state->start_off) * bitsperblock +
+	      (state->bit - state->start_bit);
+	log = XFS_RTBLOCKLOG(len);
+	offs = XFS_SUMOFFS(mp, log, state->start_off);
+
+	/* Read current rtsummary contents. */
+	pos = sizeof(xfs_suminfo_t) * offs;
+	error = xfile_io(sc->xfile, XFILE_IO_READ, &pos, &v,
+			sizeof(xfs_suminfo_t));
+	if (error)
+		return error;
+
+	/* Bump the summary count... */
+	v++;
+	pos = sizeof(xfs_suminfo_t) * offs;
+	trace_xchk_rtsum_record_free(mp,
+			state->start_off * bitsperblock + state->start_bit,
+			state->off * bitsperblock + state->bit - 1,
+			len, log, offs, v);
+
+	/* ...and write it back. */
+	error = xfile_io(sc->xfile, XFILE_IO_WRITE, &pos, &v,
+			sizeof(xfs_suminfo_t));
+	if (error)
+		return error;
+
+	state->in_extent = false;
+	return 0;
+}
+
+static inline bool
+xchk_rtsum_isset(
+	xfs_rtword_t	*words,
+	unsigned int	bit)
+{
+	return words[bit / (sizeof(*words) * NBBY)] &
+			(1ULL << (bit % (sizeof(*words) * NBBY)));
+}
+
+/* Walk a single rtbitmap block looking for changes in the free status. */
+STATIC int
+xchk_rtsum_process_bmblock(
+	struct xfs_scrub	*sc,
+	xfs_fileoff_t		block_off,
+	struct xchk_rtsum_compute *state)
+{
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_buf		*bp;
+	xfs_rtword_t		*words;
+	unsigned int		bitsperblock = mp->m_sb.sb_blocksize * NBBY;
+	int			error = 0;
+
+	if (xchk_should_terminate(sc, &error))
+		return error;
+
+	error = xfs_rtbuf_get(mp, sc->tp, block_off, 0, &bp);
+	if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, block_off,
+				&error))
+		return error;
+
+	state->off = block_off;
+	words = (xfs_rtword_t *)bp->b_addr;
+	for (state->bit = 0;
+	     state->bit < bitsperblock &&
+	     state->rt_extent_nr < mp->m_sb.sb_rextents;
+	     state->bit++, state->rt_extent_nr++) {
+		if (xchk_rtsum_isset(words, state->bit)) {
+			state->rt_free_nr++;
+			if (!state->in_extent) {
+				state->start_off = block_off;
+				state->start_bit = state->bit;
+				state->in_extent = true;
+			}
+		} else if (state->in_extent) {
+			error = xchk_rtsum_record_free(sc, state);
+			if (error)
+				goto out_relse;
+		}
+	}
+
+out_relse:
+	xfs_trans_brelse(sc->tp, bp);
+	return error;
+}
+
+/*
+ * Compute the realtime summary from the realtime bitmap.  This is a kernel
+ * port of the defunct process_rtbitmap function in xfs_repair.
+ */
+STATIC int
+xchk_rtsum_compute(
+	struct xfs_scrub	*sc)
+{
+	struct xchk_rtsum_compute state = { 0 };
+	struct xfs_mount	*mp = sc->mp;
+	unsigned long long	rtbmp_bytes;
+	xfs_fileoff_t		off = 0;
+	xfs_fileoff_t		end_off;
+	int			error;
+
+	rtbmp_bytes = howmany_64(mp->m_sb.sb_rextents, NBBY);
+	end_off = howmany_64(rtbmp_bytes, mp->m_sb.sb_blocksize);
+
+	/* If the bitmap size doesn't match the computed size, bail. */
+	if (roundup_64(rtbmp_bytes, mp->m_sb.sb_blocksize) !=
+			mp->m_rbmip->i_d.di_size)
+		return -EFSCORRUPTED;
+
+	for (off = 0; off < end_off; off++) {
+		error = xchk_rtsum_process_bmblock(sc, off, &state);
+		if (error)
+			return error;
+		if (state.rt_extent_nr == mp->m_sb.sb_rextents)
+			break;
+	}
+	if (state.in_extent) {
+		error = xchk_rtsum_record_free(sc, &state);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+/* Compare the rtsummary file against the one we computed. */
+STATIC int
+xchk_rtsum_compare(
+	struct xfs_scrub	*sc)
+{
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_buf		*bp;
+	struct xfs_bmbt_irec	map;
+	xfs_rtblock_t		off;
+	loff_t			pos;
+	int			nmap;
+	int			error = 0;
+
+	for (off = 0, pos = 0;
+	     pos < mp->m_rsumsize;
+	     pos += mp->m_sb.sb_blocksize, off++) {
+		loff_t		ppos = pos;
+		size_t		count;
+
+		if (xchk_should_terminate(sc, &error) ||
+		    (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
+			break;
+
+		/* Make sure we have a written extent. */
+		nmap = 1;
+		error = xfs_bmapi_read(mp->m_rsumip, off, 1, &map, &nmap,
+				XFS_DATA_FORK);
+		if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, off, &error))
+			break;
+
+		if (nmap != 1 || !xfs_bmap_is_real_extent(&map)) {
+			xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, off);
+			break;
+		}
+
+		/* Read a block's worth of ondisk rtsummary file. */
+		error = xfs_rtbuf_get(mp, sc->tp, off, 1, &bp);
+		if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, off, &error))
+			break;
+
+		/* Read a block's worth of computed rtsummary file. */
+		count = min_t(loff_t, mp->m_rsumsize - pos,
+				mp->m_sb.sb_blocksize);
+		error = xfile_io(sc->xfile, XFILE_IO_READ, &ppos, sc->buf,
+				count);
+		if (error) {
+			xfs_trans_brelse(sc->tp, bp);
+			break;
+		}
+
+		if (memcmp(bp->b_addr, sc->buf, count) != 0)
+			xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, off);
+
+		xfs_trans_brelse(sc->tp, bp);
+	}
+
+	return error;
+}
+
+/* Scrub the realtime summary. */
+int
+xchk_rtsummary(
+	struct xfs_scrub	*sc)
+{
+	struct xfs_mount	*mp = sc->mp;
+	int			error = 0;
+
 	/* Invoke the fork scrubber. */
 	error = xchk_metadata_inode_forks(sc);
 	if (error || (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
-		goto out;
-
-	/* XXX: implement this some day */
-	xchk_set_incomplete(sc);
-out:
-	/* Switch back to the rtbitmap inode and lock flags. */
-	xfs_iunlock(sc->ip, sc->ilock_flags);
-	sc->ilock_flags = old_ilock_flags;
-	sc->ip = old_ip;
+		goto out_rbm;
+
+	/* Construct the new summary file from the rtbitmap. */
+	error = xchk_rtsum_compute(sc);
+	if (error == -EFSCORRUPTED) {
+		/*
+		 * EFSCORRUPTED means the rtbitmap is corrupt, which is an xref
+		 * error since we're checking the summary file.
+		 */
+		xchk_ino_xref_set_corrupt(sc, mp->m_rbmip->i_ino);
+		error = 0;
+		goto out_rbm;
+	}
+
+	/* Does the computed summary file match the actual rtsummary file? */
+	error = xchk_rtsum_compare(sc);
+
+out_rbm:
+	/* Unlock the rtbitmap since we're done with it. */
+	xfs_iunlock(mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
 	return error;
 }
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index bcc3bf8ea813..6aaae5d39072 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -177,6 +177,10 @@ xchk_teardown(
 		mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock);
 		sc->flags &= ~XCHK_HAS_QUOTAOFFLOCK;
 	}
+	if (sc->xfile) {
+		fput(sc->xfile);
+		sc->xfile = NULL;
+	}
 	if (sc->buf) {
 		kmem_free(sc->buf);
 		sc->buf = NULL;
@@ -306,14 +310,14 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
 	},
 	[XFS_SCRUB_TYPE_RTBITMAP] = {	/* realtime bitmap */
 		.type	= ST_FS,
-		.setup	= xchk_setup_rt,
+		.setup	= xchk_setup_rtbitmap,
 		.scrub	= xchk_rtbitmap,
 		.has	= xfs_sb_version_hasrealtime,
 		.repair	= xrep_notsupported,
 	},
 	[XFS_SCRUB_TYPE_RTSUM] = {	/* realtime summary */
 		.type	= ST_FS,
-		.setup	= xchk_setup_rt,
+		.setup	= xchk_setup_rtsummary,
 		.scrub	= xchk_rtsummary,
 		.has	= xfs_sb_version_hasrealtime,
 		.repair	= xrep_notsupported,
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index ad1ceb44a628..6577ad22151d 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -61,6 +61,7 @@ struct xfs_scrub {
 	struct xfs_trans		*tp;
 	struct xfs_inode		*ip;
 	void				*buf;
+	struct file			*xfile;
 	uint				ilock_flags;
 
 	/* See the XCHK/XREP state flags below. */
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index 3449d01e459f..2965c30ff319 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -651,6 +651,38 @@ TRACE_EVENT(xchk_fscounters_within_range,
 		  __entry->old_value)
 )
 
+TRACE_EVENT(xchk_rtsum_record_free,
+	TP_PROTO(struct xfs_mount *mp, xfs_rtblock_t start, xfs_rtblock_t end,
+		 uint64_t len, unsigned int log, loff_t pos, xfs_suminfo_t v),
+	TP_ARGS(mp, start, end, len, log, pos, v),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(xfs_rtblock_t, start)
+		__field(xfs_rtblock_t, end)
+		__field(unsigned long long, len)
+		__field(unsigned int, log)
+		__field(loff_t, pos)
+		__field(xfs_suminfo_t, v)
+	),
+	TP_fast_assign(
+		__entry->dev = mp->m_super->s_dev;
+		__entry->start = start;
+		__entry->end = end;
+		__entry->len = len;
+		__entry->log = log;
+		__entry->pos = pos;
+		__entry->v = v;
+	),
+	TP_printk("dev %d:%d start %llu end %llu len %llu log %u pos %lld v %u",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->start,
+		  __entry->end,
+		  __entry->len,
+		  __entry->log,
+		  __entry->pos,
+		  __entry->v)
+)
+
 /* repair tracepoints */
 #if IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR)