--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2021-2024 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#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_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_inode.h"
+#include "xfs_btree.h"
+#include "xfs_ialloc.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_ag.h"
+#include "xfs_error.h"
+#include "xfs_bit.h"
+#include "xfs_icache.h"
+#include "scrub/scrub.h"
+#include "scrub/iscan.h"
+#include "scrub/common.h"
+#include "scrub/trace.h"
+
+/*
+ * Live File Scan
+ * ==============
+ *
+ * Live file scans walk every inode in a live filesystem. This is more or
+ * less like a regular iwalk, except that when we're advancing the scan cursor,
+ * we must ensure that inodes cannot be added or deleted anywhere between the
+ * old cursor value and the new cursor value. If we're advancing the cursor
+ * by one inode, the caller must hold that inode; if we're finding the next
+ * inode to scan, we must grab the AGI and hold it until we've updated the
+ * scan cursor.
+ *
+ * Callers are expected to use this code to scan all files in the filesystem to
+ * construct a new metadata index of some kind. The scan races against other
+ * live updates, which means there must be a provision to update the new index
+ * when updates are made to inodes that already been scanned. The iscan lock
+ * can be used in live update hook code to stop the scan and protect this data
+ * structure.
+ *
+ * To keep the new index up to date with other metadata updates being made to
+ * the live filesystem, it is assumed that the caller will add hooks as needed
+ * to be notified when a metadata update occurs. The inode scanner must tell
+ * the hook code when an inode has been visited with xchk_iscan_mark_visit.
+ * Hook functions can use xchk_iscan_want_live_update to decide if the
+ * scanner's observations must be updated.
+ */
+
+/*
+ * Set *cursor to the next allocated inode after whatever it's set to now.
+ * If there are no more inodes in this AG, cursor is set to NULLAGINO.
+ */
+STATIC int
+xchk_iscan_find_next(
+ struct xchk_iscan *iscan,
+ struct xfs_buf *agi_bp,
+ struct xfs_perag *pag,
+ xfs_agino_t *cursor)
+{
+ struct xfs_scrub *sc = iscan->sc;
+ struct xfs_inobt_rec_incore rec;
+ struct xfs_btree_cur *cur;
+ struct xfs_mount *mp = sc->mp;
+ struct xfs_trans *tp = sc->tp;
+ xfs_agnumber_t agno = pag->pag_agno;
+ xfs_agino_t lastino = NULLAGINO;
+ xfs_agino_t first, last;
+ xfs_agino_t agino = *cursor;
+ int has_rec;
+ int error;
+
+ /* If the cursor is beyond the end of this AG, move to the next one. */
+ xfs_agino_range(mp, agno, &first, &last);
+ if (agino > last) {
+ *cursor = NULLAGINO;
+ return 0;
+ }
+
+ /*
+ * Look up the inode chunk for the current cursor position. If there
+ * is no chunk here, we want the next one.
+ */
+ cur = xfs_inobt_init_cursor(pag, tp, agi_bp, XFS_BTNUM_INO);
+ error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &has_rec);
+ if (!error && !has_rec)
+ error = xfs_btree_increment(cur, 0, &has_rec);
+ for (; !error; error = xfs_btree_increment(cur, 0, &has_rec)) {
+ xfs_inofree_t allocmask;
+
+ /*
+ * If we've run out of inobt records in this AG, move the
+ * cursor on to the next AG and exit. The caller can try
+ * again with the next AG.
+ */
+ if (!has_rec) {
+ *cursor = NULLAGINO;
+ break;
+ }
+
+ error = xfs_inobt_get_rec(cur, &rec, &has_rec);
+ if (error)
+ break;
+ if (!has_rec) {
+ error = -EFSCORRUPTED;
+ break;
+ }
+
+ /* Make sure that we always move forward. */
+ if (lastino != NULLAGINO &&
+ XFS_IS_CORRUPT(mp, lastino >= rec.ir_startino)) {
+ error = -EFSCORRUPTED;
+ break;
+ }
+ lastino = rec.ir_startino + XFS_INODES_PER_CHUNK - 1;
+
+ /*
+ * If this record only covers inodes that come before the
+ * cursor, advance to the next record.
+ */
+ if (rec.ir_startino + XFS_INODES_PER_CHUNK <= agino)
+ continue;
+
+ /*
+ * If the incoming lookup put us in the middle of an inobt
+ * record, mark it and the previous inodes "free" so that the
+ * search for allocated inodes will start at the cursor.
+ * We don't care about ir_freecount here.
+ */
+ if (agino >= rec.ir_startino)
+ rec.ir_free |= xfs_inobt_maskn(0,
+ agino + 1 - rec.ir_startino);
+
+ /*
+ * If there are allocated inodes in this chunk, find them
+ * and update the scan cursor.
+ */
+ allocmask = ~rec.ir_free;
+ if (hweight64(allocmask) > 0) {
+ int next = xfs_lowbit64(allocmask);
+
+ ASSERT(next >= 0);
+ *cursor = rec.ir_startino + next;
+ break;
+ }
+ }
+
+ xfs_btree_del_cursor(cur, error);
+ return error;
+}
+
+/*
+ * Advance both the scan and the visited cursors.
+ *
+ * The inumber address space for a given filesystem is sparse, which means that
+ * the scan cursor can jump a long ways in a single iter() call. There are no
+ * inodes in these sparse areas, so we must move the visited cursor forward at
+ * the same time so that the scan user can receive live updates for inodes that
+ * may get created once we release the AGI buffer.
+ */
+static inline void
+xchk_iscan_move_cursor(
+ struct xchk_iscan *iscan,
+ xfs_agnumber_t agno,
+ xfs_agino_t agino)
+{
+ struct xfs_scrub *sc = iscan->sc;
+ struct xfs_mount *mp = sc->mp;
+
+ mutex_lock(&iscan->lock);
+ iscan->cursor_ino = XFS_AGINO_TO_INO(mp, agno, agino);
+ iscan->__visited_ino = iscan->cursor_ino - 1;
+ trace_xchk_iscan_move_cursor(iscan);
+ mutex_unlock(&iscan->lock);
+}
+
+/*
+ * Prepare to return agno/agino to the iscan caller by moving the lastino
+ * cursor to the previous inode. Do this while we still hold the AGI so that
+ * no other threads can create or delete inodes in this AG.
+ */
+static inline void
+xchk_iscan_finish(
+ struct xchk_iscan *iscan)
+{
+ mutex_lock(&iscan->lock);
+ iscan->cursor_ino = NULLFSINO;
+
+ /* All live updates will be applied from now on */
+ iscan->__visited_ino = NULLFSINO;
+
+ mutex_unlock(&iscan->lock);
+}
+
+/*
+ * Advance ino to the next inode that the inobt thinks is allocated, being
+ * careful to jump to the next AG if we've reached the right end of this AG's
+ * inode btree. Advancing ino effectively means that we've pushed the inode
+ * scan forward, so set the iscan cursor to (ino - 1) so that our live update
+ * predicates will track inode allocations in that part of the inode number
+ * key space once we release the AGI buffer.
+ *
+ * Returns 1 if there's a new inode to examine, 0 if we've run out of inodes,
+ * -ECANCELED if the live scan aborted, or the usual negative errno.
+ */
+STATIC int
+xchk_iscan_advance(
+ struct xchk_iscan *iscan,
+ struct xfs_perag **pagp,
+ struct xfs_buf **agi_bpp)
+{
+ struct xfs_scrub *sc = iscan->sc;
+ struct xfs_mount *mp = sc->mp;
+ struct xfs_buf *agi_bp;
+ struct xfs_perag *pag;
+ xfs_agnumber_t agno;
+ xfs_agino_t agino;
+ int ret;
+
+ ASSERT(iscan->cursor_ino >= iscan->__visited_ino);
+
+ do {
+ if (xchk_iscan_aborted(iscan))
+ return -ECANCELED;
+
+ agno = XFS_INO_TO_AGNO(mp, iscan->cursor_ino);
+ pag = xfs_perag_get(mp, agno);
+ if (!pag)
+ return -ECANCELED;
+
+ ret = xfs_ialloc_read_agi(pag, sc->tp, &agi_bp);
+ if (ret)
+ goto out_pag;
+
+ agino = XFS_INO_TO_AGINO(mp, iscan->cursor_ino);
+ ret = xchk_iscan_find_next(iscan, agi_bp, pag, &agino);
+ if (ret)
+ goto out_buf;
+
+ if (agino != NULLAGINO) {
+ /*
+ * Found the next inode in this AG, so return it along
+ * with the AGI buffer and the perag structure to
+ * ensure it cannot go away.
+ */
+ xchk_iscan_move_cursor(iscan, agno, agino);
+ *agi_bpp = agi_bp;
+ *pagp = pag;
+ return 1;
+ }
+
+ /*
+ * Did not find any more inodes in this AG, move on to the next
+ * AG.
+ */
+ xchk_iscan_move_cursor(iscan, ++agno, 0);
+ xfs_trans_brelse(sc->tp, agi_bp);
+ xfs_perag_put(pag);
+
+ trace_xchk_iscan_advance_ag(iscan);
+ } while (agno < mp->m_sb.sb_agcount);
+
+ xchk_iscan_finish(iscan);
+ return 0;
+
+out_buf:
+ xfs_trans_brelse(sc->tp, agi_bp);
+out_pag:
+ xfs_perag_put(pag);
+ return ret;
+}
+
+/*
+ * Grabbing the inode failed, so we need to back up the scan and ask the caller
+ * to try to _advance the scan again. Returns -EBUSY if we've run out of retry
+ * opportunities, -ECANCELED if the process has a fatal signal pending, or
+ * -EAGAIN if we should try again.
+ */
+STATIC int
+xchk_iscan_iget_retry(
+ struct xchk_iscan *iscan,
+ bool wait)
+{
+ ASSERT(iscan->cursor_ino == iscan->__visited_ino + 1);
+
+ if (!iscan->iget_timeout ||
+ time_is_before_jiffies(iscan->__iget_deadline))
+ return -EBUSY;
+
+ if (wait) {
+ unsigned long relax;
+
+ /*
+ * Sleep for a period of time to let the rest of the system
+ * catch up. If we return early, someone sent a kill signal to
+ * the calling process.
+ */
+ relax = msecs_to_jiffies(iscan->iget_retry_delay);
+ trace_xchk_iscan_iget_retry_wait(iscan);
+
+ if (schedule_timeout_killable(relax) ||
+ xchk_iscan_aborted(iscan))
+ return -ECANCELED;
+ }
+
+ iscan->cursor_ino--;
+ return -EAGAIN;
+}
+
+/*
+ * Grab an inode as part of an inode scan. While scanning this inode, the
+ * caller must ensure that no other threads can modify the inode until a call
+ * to xchk_iscan_visit succeeds.
+ *
+ * Returns 0 and an incore inode; -EAGAIN if the caller should call again
+ * xchk_iscan_advance; -EBUSY if we couldn't grab an inode; -ECANCELED if
+ * there's a fatal signal pending; or some other negative errno.
+ */
+STATIC int
+xchk_iscan_iget(
+ struct xchk_iscan *iscan,
+ struct xfs_perag *pag,
+ struct xfs_buf *agi_bp,
+ struct xfs_inode **ipp)
+{
+ struct xfs_scrub *sc = iscan->sc;
+ struct xfs_mount *mp = sc->mp;
+ int error;
+
+ error = xfs_iget(sc->mp, sc->tp, iscan->cursor_ino, XFS_IGET_NORETRY,
+ 0, ipp);
+ xfs_trans_brelse(sc->tp, agi_bp);
+ xfs_perag_put(pag);
+
+ trace_xchk_iscan_iget(iscan, error);
+
+ if (error == -ENOENT || error == -EAGAIN) {
+ /*
+ * It's possible that this inode has lost all of its links but
+ * hasn't yet been inactivated. If we don't have a transaction
+ * or it's not writable, flush the inodegc workers and wait.
+ */
+ xfs_inodegc_flush(mp);
+ return xchk_iscan_iget_retry(iscan, true);
+ }
+
+ if (error == -EINVAL) {
+ /*
+ * We thought the inode was allocated, but the inode btree
+ * lookup failed, which means that it was freed since the last
+ * time we advanced the cursor. Back up and try again. This
+ * should never happen since still hold the AGI buffer from the
+ * inobt check, but we need to be careful about infinite loops.
+ */
+ return xchk_iscan_iget_retry(iscan, false);
+ }
+
+ return error;
+}
+
+/*
+ * Advance the inode scan cursor to the next allocated inode and return the
+ * incore inode structure associated with it.
+ *
+ * Returns 1 if there's a new inode to examine, 0 if we've run out of inodes,
+ * -ECANCELED if the live scan aborted, -EBUSY if the incore inode could not be
+ * grabbed, or the usual negative errno.
+ *
+ * If the function returns -EBUSY and the caller can handle skipping an inode,
+ * it may call this function again to continue the scan with the next allocated
+ * inode.
+ */
+int
+xchk_iscan_iter(
+ struct xchk_iscan *iscan,
+ struct xfs_inode **ipp)
+{
+ struct xfs_scrub *sc = iscan->sc;
+ int ret;
+
+ if (iscan->iget_timeout)
+ iscan->__iget_deadline = jiffies +
+ msecs_to_jiffies(iscan->iget_timeout);
+
+ do {
+ struct xfs_buf *agi_bp = NULL;
+ struct xfs_perag *pag = NULL;
+
+ ret = xchk_iscan_advance(iscan, &pag, &agi_bp);
+ if (ret != 1)
+ return ret;
+
+ if (xchk_iscan_aborted(iscan)) {
+ xfs_trans_brelse(sc->tp, agi_bp);
+ xfs_perag_put(pag);
+ ret = -ECANCELED;
+ break;
+ }
+
+ ret = xchk_iscan_iget(iscan, pag, agi_bp, ipp);
+ } while (ret == -EAGAIN);
+
+ if (!ret)
+ return 1;
+
+ return ret;
+}
+
+
+/* Mark this inode scan finished and release resources. */
+void
+xchk_iscan_teardown(
+ struct xchk_iscan *iscan)
+{
+ xchk_iscan_finish(iscan);
+ mutex_destroy(&iscan->lock);
+}
+
+/*
+ * Set ourselves up to start an inode scan. If the @iget_timeout and
+ * @iget_retry_delay parameters are set, the scan will try to iget each inode
+ * for @iget_timeout milliseconds. If an iget call indicates that the inode is
+ * waiting to be inactivated, the CPU will relax for @iget_retry_delay
+ * milliseconds after pushing the inactivation workers.
+ */
+void
+xchk_iscan_start(
+ struct xfs_scrub *sc,
+ unsigned int iget_timeout,
+ unsigned int iget_retry_delay,
+ struct xchk_iscan *iscan)
+{
+ iscan->sc = sc;
+ clear_bit(XCHK_ISCAN_OPSTATE_ABORTED, &iscan->__opstate);
+ iscan->iget_timeout = iget_timeout;
+ iscan->iget_retry_delay = iget_retry_delay;
+ iscan->__visited_ino = 0;
+ iscan->cursor_ino = 0;
+ mutex_init(&iscan->lock);
+
+ trace_xchk_iscan_start(iscan);
+}
+
+/*
+ * Mark this inode as having been visited. Callers must hold a sufficiently
+ * exclusive lock on the inode to prevent concurrent modifications.
+ */
+void
+xchk_iscan_mark_visited(
+ struct xchk_iscan *iscan,
+ struct xfs_inode *ip)
+{
+ mutex_lock(&iscan->lock);
+ iscan->__visited_ino = ip->i_ino;
+ trace_xchk_iscan_visit(iscan);
+ mutex_unlock(&iscan->lock);
+}
+
+/*
+ * Do we need a live update for this inode? This is true if the scanner thread
+ * has visited this inode and the scan hasn't been aborted due to errors.
+ * Callers must hold a sufficiently exclusive lock on the inode to prevent
+ * scanners from reading any inode metadata.
+ */
+bool
+xchk_iscan_want_live_update(
+ struct xchk_iscan *iscan,
+ xfs_ino_t ino)
+{
+ bool ret;
+
+ if (xchk_iscan_aborted(iscan))
+ return false;
+
+ mutex_lock(&iscan->lock);
+ trace_xchk_iscan_want_live_update(iscan, ino);
+ ret = iscan->__visited_ino >= ino;
+ mutex_unlock(&iscan->lock);
+
+ return ret;
+}
#include <linux/tracepoint.h>
#include "xfs_bit.h"
+struct xfs_scrub;
struct xfile;
struct xfarray;
struct xfarray_sortinfo;
struct xchk_dqiter;
+struct xchk_iscan;
/*
* ftrace's __print_symbolic requires that all enum values be wrapped in the
);
#endif /* CONFIG_XFS_RT */
+DECLARE_EVENT_CLASS(xchk_iscan_class,
+ TP_PROTO(struct xchk_iscan *iscan),
+ TP_ARGS(iscan),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(xfs_ino_t, cursor)
+ __field(xfs_ino_t, visited)
+ ),
+ TP_fast_assign(
+ __entry->dev = iscan->sc->mp->m_super->s_dev;
+ __entry->cursor = iscan->cursor_ino;
+ __entry->visited = iscan->__visited_ino;
+ ),
+ TP_printk("dev %d:%d iscan cursor 0x%llx visited 0x%llx",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->cursor,
+ __entry->visited)
+)
+#define DEFINE_ISCAN_EVENT(name) \
+DEFINE_EVENT(xchk_iscan_class, name, \
+ TP_PROTO(struct xchk_iscan *iscan), \
+ TP_ARGS(iscan))
+DEFINE_ISCAN_EVENT(xchk_iscan_move_cursor);
+DEFINE_ISCAN_EVENT(xchk_iscan_visit);
+DEFINE_ISCAN_EVENT(xchk_iscan_advance_ag);
+DEFINE_ISCAN_EVENT(xchk_iscan_start);
+
+DECLARE_EVENT_CLASS(xchk_iscan_ino_class,
+ TP_PROTO(struct xchk_iscan *iscan, xfs_ino_t ino),
+ TP_ARGS(iscan, ino),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(xfs_ino_t, cursor)
+ __field(xfs_ino_t, visited)
+ __field(xfs_ino_t, ino)
+ ),
+ TP_fast_assign(
+ __entry->dev = iscan->sc->mp->m_super->s_dev;
+ __entry->cursor = iscan->cursor_ino;
+ __entry->visited = iscan->__visited_ino;
+ __entry->ino = ino;
+ ),
+ TP_printk("dev %d:%d iscan cursor 0x%llx visited 0x%llx ino 0x%llx",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->cursor,
+ __entry->visited,
+ __entry->ino)
+)
+#define DEFINE_ISCAN_INO_EVENT(name) \
+DEFINE_EVENT(xchk_iscan_ino_class, name, \
+ TP_PROTO(struct xchk_iscan *iscan, xfs_ino_t ino), \
+ TP_ARGS(iscan, ino))
+DEFINE_ISCAN_INO_EVENT(xchk_iscan_want_live_update);
+
+TRACE_EVENT(xchk_iscan_iget,
+ TP_PROTO(struct xchk_iscan *iscan, int error),
+ TP_ARGS(iscan, error),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(xfs_ino_t, cursor)
+ __field(xfs_ino_t, visited)
+ __field(int, error)
+ ),
+ TP_fast_assign(
+ __entry->dev = iscan->sc->mp->m_super->s_dev;
+ __entry->cursor = iscan->cursor_ino;
+ __entry->visited = iscan->__visited_ino;
+ __entry->error = error;
+ ),
+ TP_printk("dev %d:%d iscan cursor 0x%llx visited 0x%llx error %d",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->cursor,
+ __entry->visited,
+ __entry->error)
+);
+
+TRACE_EVENT(xchk_iscan_iget_retry_wait,
+ TP_PROTO(struct xchk_iscan *iscan),
+ TP_ARGS(iscan),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(xfs_ino_t, cursor)
+ __field(xfs_ino_t, visited)
+ __field(unsigned int, retry_delay)
+ __field(unsigned long, remaining)
+ __field(unsigned int, iget_timeout)
+ ),
+ TP_fast_assign(
+ __entry->dev = iscan->sc->mp->m_super->s_dev;
+ __entry->cursor = iscan->cursor_ino;
+ __entry->visited = iscan->__visited_ino;
+ __entry->retry_delay = iscan->iget_retry_delay;
+ __entry->remaining = jiffies_to_msecs(iscan->__iget_deadline - jiffies);
+ __entry->iget_timeout = iscan->iget_timeout;
+ ),
+ TP_printk("dev %d:%d iscan cursor 0x%llx visited 0x%llx remaining %lu timeout %u delay %u",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->cursor,
+ __entry->visited,
+ __entry->remaining,
+ __entry->iget_timeout,
+ __entry->retry_delay)
+);
+
/* repair tracepoints */
#if IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR)
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