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-rw-r--r--fs/xfs/xfs_iwalk.c782
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diff --git a/fs/xfs/xfs_iwalk.c b/fs/xfs/xfs_iwalk.c
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+++ b/fs/xfs/xfs_iwalk.c
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+// 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_error.h"
+#include "xfs_trace.h"
+#include "xfs_icache.h"
+#include "xfs_health.h"
+#include "xfs_trans.h"
+#include "xfs_pwork.h"
+#include "xfs_ag.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
+ * -ECANCELED 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 {
+ /* parallel work control data; will be null if single threaded */
+ struct xfs_pwork pwork;
+
+ struct xfs_mount *mp;
+ struct xfs_trans *tp;
+ struct xfs_perag *pag;
+
+ /* Where do we start the traversal? */
+ xfs_ino_t startino;
+
+ /* What was the last inode number we saw when iterating the inobt? */
+ xfs_ino_t lastino;
+
+ /* 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;
+ xfs_inobt_walk_fn inobt_walk_fn;
+ void *data;
+
+ /*
+ * Make it look like the inodes up to startino are free so that
+ * bulkstat can start its inode iteration at the correct place without
+ * needing to special case everywhere.
+ */
+ unsigned int trim_start:1;
+
+ /* Skip empty inobt records? */
+ unsigned int skip_empty:1;
+
+ /* Drop the (hopefully empty) transaction when calling iwalk_fn. */
+ unsigned int drop_trans:1;
+};
+
+/*
+ * Loop over all clusters in a chunk for a given incore inode allocation btree
+ * record. Do a readahead if there are any allocated inodes in that cluster.
+ */
+STATIC void
+xfs_iwalk_ichunk_ra(
+ struct xfs_mount *mp,
+ struct xfs_perag *pag,
+ struct xfs_inobt_rec_incore *irec)
+{
+ struct xfs_ino_geometry *igeo = M_IGEO(mp);
+ xfs_agblock_t agbno;
+ struct blk_plug plug;
+ int i; /* inode chunk index */
+
+ agbno = XFS_AGINO_TO_AGBNO(mp, irec->ir_startino);
+
+ blk_start_plug(&plug);
+ for (i = 0; i < XFS_INODES_PER_CHUNK; i += igeo->inodes_per_cluster) {
+ xfs_inofree_t imask;
+
+ imask = xfs_inobt_maskn(i, igeo->inodes_per_cluster);
+ if (imask & ~irec->ir_free) {
+ xfs_btree_reada_bufs(mp, pag->pag_agno, agbno,
+ igeo->blocks_per_cluster,
+ &xfs_inode_buf_ops);
+ }
+ agbno += igeo->blocks_per_cluster;
+ }
+ blk_finish_plug(&plug);
+}
+
+/*
+ * Set the bits in @irec's free mask that correspond to the inodes before
+ * @agino so that we skip them. This is how we restart an inode walk that was
+ * interrupted in the middle of an inode record.
+ */
+STATIC void
+xfs_iwalk_adjust_start(
+ xfs_agino_t agino, /* starting inode of chunk */
+ struct xfs_inobt_rec_incore *irec) /* btree record */
+{
+ int idx; /* index into inode chunk */
+ int i;
+
+ idx = agino - irec->ir_startino;
+
+ /*
+ * We got a right chunk with some left inodes allocated at it. Grab
+ * the chunk record. Mark all the uninteresting inodes free because
+ * they're before our start point.
+ */
+ for (i = 0; i < idx; i++) {
+ if (XFS_INOBT_MASK(i) & ~irec->ir_free)
+ irec->ir_freecount++;
+ }
+
+ irec->ir_free |= xfs_inobt_maskn(0, idx);
+}
+
+/* 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;
+ struct xfs_perag *pag = iwag->pag;
+ xfs_ino_t ino;
+ unsigned int i, j;
+ int error;
+
+ for (i = 0; i < iwag->nr_recs; i++) {
+ struct xfs_inobt_rec_incore *irec = &iwag->recs[i];
+
+ trace_xfs_iwalk_ag_rec(mp, pag->pag_agno, irec);
+
+ if (xfs_pwork_want_abort(&iwag->pwork))
+ return 0;
+
+ if (iwag->inobt_walk_fn) {
+ error = iwag->inobt_walk_fn(mp, tp, pag->pag_agno, irec,
+ iwag->data);
+ if (error)
+ return error;
+ }
+
+ if (!iwag->iwalk_fn)
+ continue;
+
+ for (j = 0; j < XFS_INODES_PER_CHUNK; j++) {
+ if (xfs_pwork_want_abort(&iwag->pwork))
+ return 0;
+
+ /* 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, pag->pag_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_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;
+ struct xfs_perag *pag = iwag->pag;
+ struct xfs_inobt_rec_incore *irec;
+ int error;
+
+ /* Set up a fresh cursor and empty the inobt cache. */
+ iwag->nr_recs = 0;
+ error = xfs_inobt_cur(mp, tp, pag, 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 the
+ * caller doesn't have to deal with tearing down the cursor to walk the
+ * records.
+ */
+ error = xfs_inobt_lookup(*curpp, agino, XFS_LOOKUP_LE, has_more);
+ if (error)
+ return error;
+
+ /*
+ * If the LE lookup at @agino yields no records, jump ahead to the
+ * inobt cursor increment to see if there are more records to process.
+ */
+ if (!*has_more)
+ goto out_advance;
+
+ /* Get the record, should always work */
+ irec = &iwag->recs[iwag->nr_recs];
+ error = xfs_inobt_get_rec(*curpp, irec, has_more);
+ if (error)
+ return error;
+ if (XFS_IS_CORRUPT(mp, *has_more != 1))
+ return -EFSCORRUPTED;
+
+ iwag->lastino = XFS_AGINO_TO_INO(mp, pag->pag_agno,
+ irec->ir_startino + XFS_INODES_PER_CHUNK - 1);
+
+ /*
+ * If the LE lookup yielded an inobt record before the cursor position,
+ * skip it and see if there's another one after it.
+ */
+ if (irec->ir_startino + XFS_INODES_PER_CHUNK <= agino)
+ goto out_advance;
+
+ /*
+ * If agino fell in the middle of the inode record, make it look like
+ * the inodes up to agino are free so that we don't return them again.
+ */
+ if (iwag->trim_start)
+ xfs_iwalk_adjust_start(agino, irec);
+
+ /*
+ * 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.
+ */
+ iwag->nr_recs++;
+ ASSERT(iwag->nr_recs < iwag->sz_recs);
+
+out_advance:
+ 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,
+ struct xfs_btree_cur **curpp,
+ struct xfs_buf **agi_bpp,
+ int *has_more)
+{
+ struct xfs_mount *mp = iwag->mp;
+ struct xfs_inobt_rec_incore *irec;
+ xfs_agino_t next_agino;
+ int error;
+
+ next_agino = XFS_INO_TO_AGINO(mp, iwag->lastino) + 1;
+
+ ASSERT(iwag->nr_recs > 0);
+
+ /* Delete cursor but remember the last record we cached... */
+ xfs_iwalk_del_inobt(iwag->tp, curpp, agi_bpp, 0);
+ irec = &iwag->recs[iwag->nr_recs - 1];
+ ASSERT(next_agino >= irec->ir_startino + XFS_INODES_PER_CHUNK);
+
+ if (iwag->drop_trans) {
+ xfs_trans_cancel(iwag->tp);
+ iwag->tp = NULL;
+ }
+
+ error = xfs_iwalk_ag_recs(iwag);
+ if (error)
+ return error;
+
+ /* ...empty the cache... */
+ iwag->nr_recs = 0;
+
+ if (!has_more)
+ return 0;
+
+ if (iwag->drop_trans) {
+ error = xfs_trans_alloc_empty(mp, &iwag->tp);
+ if (error)
+ return error;
+ }
+
+ /* ...and recreate the cursor just past where we left off. */
+ error = xfs_inobt_cur(mp, iwag->tp, iwag->pag, XFS_BTNUM_INO, curpp,
+ agi_bpp);
+ if (error)
+ return error;
+
+ return xfs_inobt_lookup(*curpp, next_agino, 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_perag *pag = iwag->pag;
+ struct xfs_buf *agi_bp = NULL;
+ struct xfs_btree_cur *cur = NULL;
+ xfs_agino_t agino;
+ int has_more;
+ int error = 0;
+
+ /* Set up our cursor at the right place in the inode btree. */
+ ASSERT(pag->pag_agno == XFS_INO_TO_AGNO(mp, iwag->startino));
+ agino = XFS_INO_TO_AGINO(mp, iwag->startino);
+ error = xfs_iwalk_ag_start(iwag, agino, &cur, &agi_bp, &has_more);
+
+ while (!error && has_more) {
+ struct xfs_inobt_rec_incore *irec;
+ xfs_ino_t rec_fsino;
+
+ cond_resched();
+ if (xfs_pwork_want_abort(&iwag->pwork))
+ goto out;
+
+ /* Fetch the inobt record. */
+ irec = &iwag->recs[iwag->nr_recs];
+ error = xfs_inobt_get_rec(cur, irec, &has_more);
+ if (error || !has_more)
+ break;
+
+ /* Make sure that we always move forward. */
+ rec_fsino = XFS_AGINO_TO_INO(mp, pag->pag_agno, irec->ir_startino);
+ if (iwag->lastino != NULLFSINO &&
+ XFS_IS_CORRUPT(mp, iwag->lastino >= rec_fsino)) {
+ error = -EFSCORRUPTED;
+ goto out;
+ }
+ iwag->lastino = rec_fsino + XFS_INODES_PER_CHUNK - 1;
+
+ /* No allocated inodes in this chunk; skip it. */
+ if (iwag->skip_empty && 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.
+ */
+ if (iwag->iwalk_fn)
+ xfs_iwalk_ichunk_ra(mp, pag, 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, &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, &cur, &agi_bp, &has_more);
+
+out:
+ xfs_iwalk_del_inobt(iwag->tp, &cur, &agi_bp, error);
+ return error;
+}
+
+/*
+ * We experimentally determined that the reduction in ioctl call overhead
+ * diminishes when userspace asks for more than 2048 inodes, so we'll cap
+ * prefetch at this point.
+ */
+#define IWALK_MAX_INODE_PREFETCH (2048U)
+
+/*
+ * 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. Set the maximum if @inodes == 0.
+ */
+static inline unsigned int
+xfs_iwalk_prefetch(
+ unsigned int inodes)
+{
+ unsigned int inobt_records;
+
+ /*
+ * If the caller didn't tell us the number of inodes they wanted,
+ * assume the maximum prefetch possible for best performance.
+ * Otherwise, cap prefetch at that maximum so that we don't start an
+ * absurd amount of prefetch.
+ */
+ if (inodes == 0)
+ inodes = IWALK_MAX_INODE_PREFETCH;
+ inodes = min(inodes, IWALK_MAX_INODE_PREFETCH);
+
+ /* Round the inode count up to a full chunk. */
+ inodes = round_up(inodes, XFS_INODES_PER_CHUNK);
+
+ /*
+ * In order to convert the number of inodes to prefetch into an
+ * estimate of the number of inobt records to cache, we require a
+ * conversion factor that reflects our expectations of the average
+ * loading factor of an inode chunk. Based on data gathered, most
+ * (but not all) filesystems manage to keep the inode chunks totally
+ * full, so we'll underestimate slightly so that our readahead will
+ * still deliver the performance we want on aging filesystems:
+ *
+ * inobt = inodes / (INODES_PER_CHUNK * (4 / 5));
+ *
+ * The funny math is to avoid integer division.
+ */
+ inobt_records = (inodes * 5) / (4 * XFS_INODES_PER_CHUNK);
+
+ /*
+ * Allocate enough space to prefetch at least two inobt records so that
+ * we can cache both the record where the iwalk started and the next
+ * record. This simplifies the AG inode walk loop setup code.
+ */
+ return max(inobt_records, 2U);
+}
+
+/*
+ * 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,
+ unsigned int flags,
+ 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),
+ .trim_start = 1,
+ .skip_empty = 1,
+ .pwork = XFS_PWORK_SINGLE_THREADED,
+ .lastino = NULLFSINO,
+ };
+ struct xfs_perag *pag;
+ xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, startino);
+ int error;
+
+ ASSERT(agno < mp->m_sb.sb_agcount);
+ ASSERT(!(flags & ~XFS_IWALK_FLAGS_ALL));
+
+ error = xfs_iwalk_alloc(&iwag);
+ if (error)
+ return error;
+
+ for_each_perag_from(mp, agno, pag) {
+ iwag.pag = pag;
+ error = xfs_iwalk_ag(&iwag);
+ if (error)
+ break;
+ iwag.startino = XFS_AGINO_TO_INO(mp, agno + 1, 0);
+ if (flags & XFS_INOBT_WALK_SAME_AG)
+ break;
+ iwag.pag = NULL;
+ }
+
+ if (iwag.pag)
+ xfs_perag_put(pag);
+ xfs_iwalk_free(&iwag);
+ return error;
+}
+
+/* Run per-thread iwalk work. */
+static int
+xfs_iwalk_ag_work(
+ struct xfs_mount *mp,
+ struct xfs_pwork *pwork)
+{
+ struct xfs_iwalk_ag *iwag;
+ int error = 0;
+
+ iwag = container_of(pwork, struct xfs_iwalk_ag, pwork);
+ if (xfs_pwork_want_abort(pwork))
+ goto out;
+
+ error = xfs_iwalk_alloc(iwag);
+ if (error)
+ goto out;
+ /*
+ * Grab an empty transaction so that we can use its recursive buffer
+ * locking abilities to detect cycles in the inobt without deadlocking.
+ */
+ error = xfs_trans_alloc_empty(mp, &iwag->tp);
+ if (error)
+ goto out;
+ iwag->drop_trans = 1;
+
+ error = xfs_iwalk_ag(iwag);
+ if (iwag->tp)
+ xfs_trans_cancel(iwag->tp);
+ xfs_iwalk_free(iwag);
+out:
+ xfs_perag_put(iwag->pag);
+ kmem_free(iwag);
+ return error;
+}
+
+/*
+ * Walk all the inodes in the filesystem using multiple threads to process each
+ * AG.
+ */
+int
+xfs_iwalk_threaded(
+ struct xfs_mount *mp,
+ xfs_ino_t startino,
+ unsigned int flags,
+ xfs_iwalk_fn iwalk_fn,
+ unsigned int inode_records,
+ bool polled,
+ void *data)
+{
+ struct xfs_pwork_ctl pctl;
+ struct xfs_perag *pag;
+ xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, startino);
+ int error;
+
+ ASSERT(agno < mp->m_sb.sb_agcount);
+ ASSERT(!(flags & ~XFS_IWALK_FLAGS_ALL));
+
+ error = xfs_pwork_init(mp, &pctl, xfs_iwalk_ag_work, "xfs_iwalk");
+ if (error)
+ return error;
+
+ for_each_perag_from(mp, agno, pag) {
+ struct xfs_iwalk_ag *iwag;
+
+ if (xfs_pwork_ctl_want_abort(&pctl))
+ break;
+
+ iwag = kmem_zalloc(sizeof(struct xfs_iwalk_ag), 0);
+ iwag->mp = mp;
+
+ /*
+ * perag is being handed off to async work, so take another
+ * reference for the async work to release.
+ */
+ atomic_inc(&pag->pag_ref);
+ iwag->pag = pag;
+ iwag->iwalk_fn = iwalk_fn;
+ iwag->data = data;
+ iwag->startino = startino;
+ iwag->sz_recs = xfs_iwalk_prefetch(inode_records);
+ iwag->lastino = NULLFSINO;
+ xfs_pwork_queue(&pctl, &iwag->pwork);
+ startino = XFS_AGINO_TO_INO(mp, pag->pag_agno + 1, 0);
+ if (flags & XFS_INOBT_WALK_SAME_AG)
+ break;
+ }
+ if (pag)
+ xfs_perag_put(pag);
+ if (polled)
+ xfs_pwork_poll(&pctl);
+ return xfs_pwork_destroy(&pctl);
+}
+
+/*
+ * Allow callers to cache up to a page's worth of inobt records. This reflects
+ * the existing inumbers prefetching behavior. Since the inobt walk does not
+ * itself do anything with the inobt records, we can set a fairly high limit
+ * here.
+ */
+#define MAX_INOBT_WALK_PREFETCH \
+ (PAGE_SIZE / sizeof(struct xfs_inobt_rec_incore))
+
+/*
+ * Given the number of records that the user wanted, set the number of inobt
+ * records that we buffer in memory. Set the maximum if @inobt_records == 0.
+ */
+static inline unsigned int
+xfs_inobt_walk_prefetch(
+ unsigned int inobt_records)
+{
+ /*
+ * If the caller didn't tell us the number of inobt records they
+ * wanted, assume the maximum prefetch possible for best performance.
+ */
+ if (inobt_records == 0)
+ inobt_records = MAX_INOBT_WALK_PREFETCH;
+
+ /*
+ * Allocate enough space to prefetch at least two inobt records so that
+ * we can cache both the record where the iwalk started and the next
+ * record. This simplifies the AG inode walk loop setup code.
+ */
+ inobt_records = max(inobt_records, 2U);
+
+ /*
+ * Cap prefetch at that maximum so that we don't use an absurd amount
+ * of memory.
+ */
+ return min_t(unsigned int, inobt_records, MAX_INOBT_WALK_PREFETCH);
+}
+
+/*
+ * Walk all inode btree records in the filesystem starting from @startino. The
+ * @inobt_walk_fn will be called for each btree record, being passed the incore
+ * record and @data. @max_prefetch controls how many inobt records we try to
+ * cache ahead of time.
+ */
+int
+xfs_inobt_walk(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ xfs_ino_t startino,
+ unsigned int flags,
+ xfs_inobt_walk_fn inobt_walk_fn,
+ unsigned int inobt_records,
+ void *data)
+{
+ struct xfs_iwalk_ag iwag = {
+ .mp = mp,
+ .tp = tp,
+ .inobt_walk_fn = inobt_walk_fn,
+ .data = data,
+ .startino = startino,
+ .sz_recs = xfs_inobt_walk_prefetch(inobt_records),
+ .pwork = XFS_PWORK_SINGLE_THREADED,
+ .lastino = NULLFSINO,
+ };
+ struct xfs_perag *pag;
+ xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, startino);
+ int error;
+
+ ASSERT(agno < mp->m_sb.sb_agcount);
+ ASSERT(!(flags & ~XFS_INOBT_WALK_FLAGS_ALL));
+
+ error = xfs_iwalk_alloc(&iwag);
+ if (error)
+ return error;
+
+ for_each_perag_from(mp, agno, pag) {
+ iwag.pag = pag;
+ error = xfs_iwalk_ag(&iwag);
+ if (error)
+ break;
+ iwag.startino = XFS_AGINO_TO_INO(mp, pag->pag_agno + 1, 0);
+ if (flags & XFS_INOBT_WALK_SAME_AG)
+ break;
+ iwag.pag = NULL;
+ }
+
+ if (iwag.pag)
+ xfs_perag_put(pag);
+ xfs_iwalk_free(&iwag);
+ return error;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-10 02:07:29 +0000