--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2019 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_btree.h"
+#include "xfs_ialloc.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_iwalk.h"
+#include "xfs_itable.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_icache.h"
+#include "xfs_health.h"
+#include "xfs_trans.h"
+
+/*
+ * Walking Inodes in the Filesystem
+ * ================================
+ *
+ * This iterator function walks a subset of filesystem inodes in increasing
+ * order from @startino until there are no more inodes. For each allocated
+ * inode it finds, it calls a walk function with the relevant inode number and
+ * a pointer to caller-provided data. The walk function can return the usual
+ * negative error code to stop the iteration; 0 to continue the iteration; or
+ * XFS_IWALK_ABORT to stop the iteration. This return value is returned to the
+ * caller.
+ *
+ * Internally, we allow the walk function to do anything, which means that we
+ * cannot maintain the inobt cursor or our lock on the AGI buffer. We
+ * therefore cache the inobt records in kernel memory and only call the walk
+ * function when our memory buffer is full. @nr_recs is the number of records
+ * that we've cached, and @sz_recs is the size of our cache.
+ *
+ * It is the responsibility of the walk function to ensure it accesses
+ * allocated inodes, as the inobt records may be stale by the time they are
+ * acted upon.
+ */
+
+struct xfs_iwalk_ag {
+ struct xfs_mount *mp;
+ struct xfs_trans *tp;
+
+ /* Where do we start the traversal? */
+ xfs_ino_t startino;
+
+ /* Array of inobt records we cache. */
+ struct xfs_inobt_rec_incore *recs;
+
+ /* Number of entries allocated for the @recs array. */
+ unsigned int sz_recs;
+
+ /* Number of entries in the @recs array that are in use. */
+ unsigned int nr_recs;
+
+ /* Inode walk function and data pointer. */
+ xfs_iwalk_fn iwalk_fn;
+ void *data;
+};
+
+/* Allocate memory for a walk. */
+STATIC int
+xfs_iwalk_alloc(
+ struct xfs_iwalk_ag *iwag)
+{
+ size_t size;
+
+ ASSERT(iwag->recs == NULL);
+ iwag->nr_recs = 0;
+
+ /* Allocate a prefetch buffer for inobt records. */
+ size = iwag->sz_recs * sizeof(struct xfs_inobt_rec_incore);
+ iwag->recs = kmem_alloc(size, KM_MAYFAIL);
+ if (iwag->recs == NULL)
+ return -ENOMEM;
+
+ return 0;
+}
+
+/* Free memory we allocated for a walk. */
+STATIC void
+xfs_iwalk_free(
+ struct xfs_iwalk_ag *iwag)
+{
+ kmem_free(iwag->recs);
+ iwag->recs = NULL;
+}
+
+/* For each inuse inode in each cached inobt record, call our function. */
+STATIC int
+xfs_iwalk_ag_recs(
+ struct xfs_iwalk_ag *iwag)
+{
+ struct xfs_mount *mp = iwag->mp;
+ struct xfs_trans *tp = iwag->tp;
+ xfs_ino_t ino;
+ unsigned int i, j;
+ xfs_agnumber_t agno;
+ int error;
+
+ agno = XFS_INO_TO_AGNO(mp, iwag->startino);
+ for (i = 0; i < iwag->nr_recs; i++) {
+ struct xfs_inobt_rec_incore *irec = &iwag->recs[i];
+
+ trace_xfs_iwalk_ag_rec(mp, agno, irec);
+
+ for (j = 0; j < XFS_INODES_PER_CHUNK; j++) {
+ /* Skip if this inode is free */
+ if (XFS_INOBT_MASK(j) & irec->ir_free)
+ continue;
+
+ /* Otherwise call our function. */
+ ino = XFS_AGINO_TO_INO(mp, agno, irec->ir_startino + j);
+ error = iwag->iwalk_fn(mp, tp, ino, iwag->data);
+ if (error)
+ return error;
+ }
+ }
+
+ return 0;
+}
+
+/* Delete cursor and let go of AGI. */
+static inline void
+xfs_iwalk_del_inobt(
+ struct xfs_trans *tp,
+ struct xfs_btree_cur **curpp,
+ struct xfs_buf **agi_bpp,
+ int error)
+{
+ if (*curpp) {
+ xfs_btree_del_cursor(*curpp, error);
+ *curpp = NULL;
+ }
+ if (*agi_bpp) {
+ xfs_trans_brelse(tp, *agi_bpp);
+ *agi_bpp = NULL;
+ }
+}
+
+/*
+ * Set ourselves up for walking inobt records starting from a given point in
+ * the filesystem.
+ *
+ * If caller passed in a nonzero start inode number, load the record from the
+ * inobt and make the record look like all the inodes before agino are free so
+ * that we skip them, and then move the cursor to the next inobt record. This
+ * is how we support starting an iwalk in the middle of an inode chunk.
+ *
+ * If the caller passed in a start number of zero, move the cursor to the first
+ * inobt record.
+ *
+ * The caller is responsible for cleaning up the cursor and buffer pointer
+ * regardless of the error status.
+ */
+STATIC int
+xfs_iwalk_ag_start(
+ struct xfs_iwalk_ag *iwag,
+ xfs_agnumber_t agno,
+ xfs_agino_t agino,
+ struct xfs_btree_cur **curpp,
+ struct xfs_buf **agi_bpp,
+ int *has_more)
+{
+ struct xfs_mount *mp = iwag->mp;
+ struct xfs_trans *tp = iwag->tp;
+ int icount;
+ int error;
+
+ /* Set up a fresh cursor and empty the inobt cache. */
+ iwag->nr_recs = 0;
+ error = xfs_inobt_cur(mp, tp, agno, XFS_BTNUM_INO, curpp, agi_bpp);
+ if (error)
+ return error;
+
+ /* Starting at the beginning of the AG? That's easy! */
+ if (agino == 0)
+ return xfs_inobt_lookup(*curpp, 0, XFS_LOOKUP_GE, has_more);
+
+ /*
+ * Otherwise, we have to grab the inobt record where we left off, stuff
+ * the record into our cache, and then see if there are more records.
+ * We require a lookup cache of at least two elements so that we don't
+ * have to deal with tearing down the cursor to walk the records.
+ */
+ error = xfs_bulkstat_grab_ichunk(*curpp, agino - 1, &icount,
+ &iwag->recs[iwag->nr_recs]);
+ if (error)
+ return error;
+ if (icount)
+ iwag->nr_recs++;
+
+ /*
+ * The prefetch calculation is supposed to give us a large enough inobt
+ * record cache that grab_ichunk can stage a partial first record and
+ * the loop body can cache a record without having to check for cache
+ * space until after it reads an inobt record.
+ */
+ ASSERT(iwag->nr_recs < iwag->sz_recs);
+
+ return xfs_btree_increment(*curpp, 0, has_more);
+}
+
+/*
+ * The inobt record cache is full, so preserve the inobt cursor state and
+ * run callbacks on the cached inobt records. When we're done, restore the
+ * cursor state to wherever the cursor would have been had the cache not been
+ * full (and therefore we could've just incremented the cursor) if *@has_more
+ * is true. On exit, *@has_more will indicate whether or not the caller should
+ * try for more inode records.
+ */
+STATIC int
+xfs_iwalk_run_callbacks(
+ struct xfs_iwalk_ag *iwag,
+ xfs_agnumber_t agno,
+ struct xfs_btree_cur **curpp,
+ struct xfs_buf **agi_bpp,
+ int *has_more)
+{
+ struct xfs_mount *mp = iwag->mp;
+ struct xfs_trans *tp = iwag->tp;
+ struct xfs_inobt_rec_incore *irec;
+ xfs_agino_t restart;
+ int error;
+
+ ASSERT(iwag->nr_recs > 0);
+
+ /* Delete cursor but remember the last record we cached... */
+ xfs_iwalk_del_inobt(tp, curpp, agi_bpp, 0);
+ irec = &iwag->recs[iwag->nr_recs - 1];
+ restart = irec->ir_startino + XFS_INODES_PER_CHUNK - 1;
+
+ error = xfs_iwalk_ag_recs(iwag);
+ if (error)
+ return error;
+
+ /* ...empty the cache... */
+ iwag->nr_recs = 0;
+
+ if (!has_more)
+ return 0;
+
+ /* ...and recreate the cursor just past where we left off. */
+ error = xfs_inobt_cur(mp, tp, agno, XFS_BTNUM_INO, curpp, agi_bpp);
+ if (error)
+ return error;
+
+ return xfs_inobt_lookup(*curpp, restart, XFS_LOOKUP_GE, has_more);
+}
+
+/* Walk all inodes in a single AG, from @iwag->startino to the end of the AG. */
+STATIC int
+xfs_iwalk_ag(
+ struct xfs_iwalk_ag *iwag)
+{
+ struct xfs_mount *mp = iwag->mp;
+ struct xfs_trans *tp = iwag->tp;
+ struct xfs_buf *agi_bp = NULL;
+ struct xfs_btree_cur *cur = NULL;
+ xfs_agnumber_t agno;
+ xfs_agino_t agino;
+ int has_more;
+ int error = 0;
+
+ /* Set up our cursor at the right place in the inode btree. */
+ agno = XFS_INO_TO_AGNO(mp, iwag->startino);
+ agino = XFS_INO_TO_AGINO(mp, iwag->startino);
+ error = xfs_iwalk_ag_start(iwag, agno, agino, &cur, &agi_bp, &has_more);
+
+ while (!error && has_more) {
+ struct xfs_inobt_rec_incore *irec;
+
+ cond_resched();
+
+ /* Fetch the inobt record. */
+ irec = &iwag->recs[iwag->nr_recs];
+ error = xfs_inobt_get_rec(cur, irec, &has_more);
+ if (error || !has_more)
+ break;
+
+ /* No allocated inodes in this chunk; skip it. */
+ if (irec->ir_freecount == irec->ir_count) {
+ error = xfs_btree_increment(cur, 0, &has_more);
+ if (error)
+ break;
+ continue;
+ }
+
+ /*
+ * Start readahead for this inode chunk in anticipation of
+ * walking the inodes.
+ */
+ xfs_bulkstat_ichunk_ra(mp, agno, irec);
+
+ /*
+ * If there's space in the buffer for more records, increment
+ * the btree cursor and grab more.
+ */
+ if (++iwag->nr_recs < iwag->sz_recs) {
+ error = xfs_btree_increment(cur, 0, &has_more);
+ if (error || !has_more)
+ break;
+ continue;
+ }
+
+ /*
+ * Otherwise, we need to save cursor state and run the callback
+ * function on the cached records. The run_callbacks function
+ * is supposed to return a cursor pointing to the record where
+ * we would be if we had been able to increment like above.
+ */
+ ASSERT(has_more);
+ error = xfs_iwalk_run_callbacks(iwag, agno, &cur, &agi_bp,
+ &has_more);
+ }
+
+ if (iwag->nr_recs == 0 || error)
+ goto out;
+
+ /* Walk the unprocessed records in the cache. */
+ error = xfs_iwalk_run_callbacks(iwag, agno, &cur, &agi_bp, &has_more);
+
+out:
+ xfs_iwalk_del_inobt(tp, &cur, &agi_bp, error);
+ return error;
+}
+
+/*
+ * Given the number of inodes to prefetch, set the number of inobt records that
+ * we cache in memory, which controls the number of inodes we try to read
+ * ahead.
+ */
+static inline unsigned int
+xfs_iwalk_prefetch(
+ unsigned int inode_records)
+{
+ return PAGE_SIZE * 4 / sizeof(struct xfs_inobt_rec_incore);
+}
+
+/*
+ * Walk all inodes in the filesystem starting from @startino. The @iwalk_fn
+ * will be called for each allocated inode, being passed the inode's number and
+ * @data. @max_prefetch controls how many inobt records' worth of inodes we
+ * try to readahead.
+ */
+int
+xfs_iwalk(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ xfs_ino_t startino,
+ xfs_iwalk_fn iwalk_fn,
+ unsigned int inode_records,
+ void *data)
+{
+ struct xfs_iwalk_ag iwag = {
+ .mp = mp,
+ .tp = tp,
+ .iwalk_fn = iwalk_fn,
+ .data = data,
+ .startino = startino,
+ .sz_recs = xfs_iwalk_prefetch(inode_records),
+ };
+ xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, startino);
+ int error;
+
+ ASSERT(agno < mp->m_sb.sb_agcount);
+
+ error = xfs_iwalk_alloc(&iwag);
+ if (error)
+ return error;
+
+ for (; agno < mp->m_sb.sb_agcount; agno++) {
+ error = xfs_iwalk_ag(&iwag);
+ if (error)
+ break;
+ iwag.startino = XFS_AGINO_TO_INO(mp, agno + 1, 0);
+ }
+
+ xfs_iwalk_free(&iwag);
+ return error;
+}
projects / openwrt / staging / blogic.git / commitdiff