Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2236 insertions, 0 deletions

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
new file mode 100644
index 000000000..3c210ac83
--- /dev/null
+++ b/fs/xfs/xfs_icache.c
@@ -0,0 +1,2236 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#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_trans.h"
+#include "xfs_trans_priv.h"
+#include "xfs_inode_item.h"
+#include "xfs_quota.h"
+#include "xfs_trace.h"
+#include "xfs_icache.h"
+#include "xfs_bmap_util.h"
+#include "xfs_dquot_item.h"
+#include "xfs_dquot.h"
+#include "xfs_reflink.h"
+#include "xfs_ialloc.h"
+#include "xfs_ag.h"
+#include "xfs_log_priv.h"
+
+#include <linux/iversion.h>
+
+/* Radix tree tags for incore inode tree. */
+
+/* inode is to be reclaimed */
+#define XFS_ICI_RECLAIM_TAG	0
+/* Inode has speculative preallocations (posteof or cow) to clean. */
+#define XFS_ICI_BLOCKGC_TAG	1
+
+/*
+ * The goal for walking incore inodes.  These can correspond with incore inode
+ * radix tree tags when convenient.  Avoid existing XFS_IWALK namespace.
+ */
+enum xfs_icwalk_goal {
+	/* Goals directly associated with tagged inodes. */
+	XFS_ICWALK_BLOCKGC	= XFS_ICI_BLOCKGC_TAG,
+	XFS_ICWALK_RECLAIM	= XFS_ICI_RECLAIM_TAG,
+};
+
+static int xfs_icwalk(struct xfs_mount *mp,
+		enum xfs_icwalk_goal goal, struct xfs_icwalk *icw);
+static int xfs_icwalk_ag(struct xfs_perag *pag,
+		enum xfs_icwalk_goal goal, struct xfs_icwalk *icw);
+
+/*
+ * Private inode cache walk flags for struct xfs_icwalk.  Must not
+ * coincide with XFS_ICWALK_FLAGS_VALID.
+ */
+
+/* Stop scanning after icw_scan_limit inodes. */
+#define XFS_ICWALK_FLAG_SCAN_LIMIT	(1U << 28)
+
+#define XFS_ICWALK_FLAG_RECLAIM_SICK	(1U << 27)
+#define XFS_ICWALK_FLAG_UNION		(1U << 26) /* union filter algorithm */
+
+#define XFS_ICWALK_PRIVATE_FLAGS	(XFS_ICWALK_FLAG_SCAN_LIMIT | \
+					 XFS_ICWALK_FLAG_RECLAIM_SICK | \
+					 XFS_ICWALK_FLAG_UNION)
+
+/*
+ * Allocate and initialise an xfs_inode.
+ */
+struct xfs_inode *
+xfs_inode_alloc(
+	struct xfs_mount	*mp,
+	xfs_ino_t		ino)
+{
+	struct xfs_inode	*ip;
+
+	/*
+	 * XXX: If this didn't occur in transactions, we could drop GFP_NOFAIL
+	 * and return NULL here on ENOMEM.
+	 */
+	ip = alloc_inode_sb(mp->m_super, xfs_inode_cache, GFP_KERNEL | __GFP_NOFAIL);
+
+	if (inode_init_always(mp->m_super, VFS_I(ip))) {
+		kmem_cache_free(xfs_inode_cache, ip);
+		return NULL;
+	}
+
+	/* VFS doesn't initialise i_mode or i_state! */
+	VFS_I(ip)->i_mode = 0;
+	VFS_I(ip)->i_state = 0;
+	mapping_set_large_folios(VFS_I(ip)->i_mapping);
+
+	XFS_STATS_INC(mp, vn_active);
+	ASSERT(atomic_read(&ip->i_pincount) == 0);
+	ASSERT(ip->i_ino == 0);
+
+	/* initialise the xfs inode */
+	ip->i_ino = ino;
+	ip->i_mount = mp;
+	memset(&ip->i_imap, 0, sizeof(struct xfs_imap));
+	ip->i_cowfp = NULL;
+	memset(&ip->i_af, 0, sizeof(ip->i_af));
+	ip->i_af.if_format = XFS_DINODE_FMT_EXTENTS;
+	memset(&ip->i_df, 0, sizeof(ip->i_df));
+	ip->i_flags = 0;
+	ip->i_delayed_blks = 0;
+	ip->i_diflags2 = mp->m_ino_geo.new_diflags2;
+	ip->i_nblocks = 0;
+	ip->i_forkoff = 0;
+	ip->i_sick = 0;
+	ip->i_checked = 0;
+	INIT_WORK(&ip->i_ioend_work, xfs_end_io);
+	INIT_LIST_HEAD(&ip->i_ioend_list);
+	spin_lock_init(&ip->i_ioend_lock);
+	ip->i_next_unlinked = NULLAGINO;
+	ip->i_prev_unlinked = 0;
+
+	return ip;
+}
+
+STATIC void
+xfs_inode_free_callback(
+	struct rcu_head		*head)
+{
+	struct inode		*inode = container_of(head, struct inode, i_rcu);
+	struct xfs_inode	*ip = XFS_I(inode);
+
+	switch (VFS_I(ip)->i_mode & S_IFMT) {
+	case S_IFREG:
+	case S_IFDIR:
+	case S_IFLNK:
+		xfs_idestroy_fork(&ip->i_df);
+		break;
+	}
+
+	xfs_ifork_zap_attr(ip);
+
+	if (ip->i_cowfp) {
+		xfs_idestroy_fork(ip->i_cowfp);
+		kmem_cache_free(xfs_ifork_cache, ip->i_cowfp);
+	}
+	if (ip->i_itemp) {
+		ASSERT(!test_bit(XFS_LI_IN_AIL,
+				 &ip->i_itemp->ili_item.li_flags));
+		xfs_inode_item_destroy(ip);
+		ip->i_itemp = NULL;
+	}
+
+	kmem_cache_free(xfs_inode_cache, ip);
+}
+
+static void
+__xfs_inode_free(
+	struct xfs_inode	*ip)
+{
+	/* asserts to verify all state is correct here */
+	ASSERT(atomic_read(&ip->i_pincount) == 0);
+	ASSERT(!ip->i_itemp || list_empty(&ip->i_itemp->ili_item.li_bio_list));
+	XFS_STATS_DEC(ip->i_mount, vn_active);
+
+	call_rcu(&VFS_I(ip)->i_rcu, xfs_inode_free_callback);
+}
+
+void
+xfs_inode_free(
+	struct xfs_inode	*ip)
+{
+	ASSERT(!xfs_iflags_test(ip, XFS_IFLUSHING));
+
+	/*
+	 * Because we use RCU freeing we need to ensure the inode always
+	 * appears to be reclaimed with an invalid inode number when in the
+	 * free state. The ip->i_flags_lock provides the barrier against lookup
+	 * races.
+	 */
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags = XFS_IRECLAIM;
+	ip->i_ino = 0;
+	spin_unlock(&ip->i_flags_lock);
+
+	__xfs_inode_free(ip);
+}
+
+/*
+ * Queue background inode reclaim work if there are reclaimable inodes and there
+ * isn't reclaim work already scheduled or in progress.
+ */
+static void
+xfs_reclaim_work_queue(
+	struct xfs_mount        *mp)
+{
+
+	rcu_read_lock();
+	if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
+		queue_delayed_work(mp->m_reclaim_workqueue, &mp->m_reclaim_work,
+			msecs_to_jiffies(xfs_syncd_centisecs / 6 * 10));
+	}
+	rcu_read_unlock();
+}
+
+/*
+ * Background scanning to trim preallocated space. This is queued based on the
+ * 'speculative_prealloc_lifetime' tunable (5m by default).
+ */
+static inline void
+xfs_blockgc_queue(
+	struct xfs_perag	*pag)
+{
+	struct xfs_mount	*mp = pag->pag_mount;
+
+	if (!xfs_is_blockgc_enabled(mp))
+		return;
+
+	rcu_read_lock();
+	if (radix_tree_tagged(&pag->pag_ici_root, XFS_ICI_BLOCKGC_TAG))
+		queue_delayed_work(pag->pag_mount->m_blockgc_wq,
+				   &pag->pag_blockgc_work,
+				   msecs_to_jiffies(xfs_blockgc_secs * 1000));
+	rcu_read_unlock();
+}
+
+/* Set a tag on both the AG incore inode tree and the AG radix tree. */
+static void
+xfs_perag_set_inode_tag(
+	struct xfs_perag	*pag,
+	xfs_agino_t		agino,
+	unsigned int		tag)
+{
+	struct xfs_mount	*mp = pag->pag_mount;
+	bool			was_tagged;
+
+	lockdep_assert_held(&pag->pag_ici_lock);
+
+	was_tagged = radix_tree_tagged(&pag->pag_ici_root, tag);
+	radix_tree_tag_set(&pag->pag_ici_root, agino, tag);
+
+	if (tag == XFS_ICI_RECLAIM_TAG)
+		pag->pag_ici_reclaimable++;
+
+	if (was_tagged)
+		return;
+
+	/* propagate the tag up into the perag radix tree */
+	spin_lock(&mp->m_perag_lock);
+	radix_tree_tag_set(&mp->m_perag_tree, pag->pag_agno, tag);
+	spin_unlock(&mp->m_perag_lock);
+
+	/* start background work */
+	switch (tag) {
+	case XFS_ICI_RECLAIM_TAG:
+		xfs_reclaim_work_queue(mp);
+		break;
+	case XFS_ICI_BLOCKGC_TAG:
+		xfs_blockgc_queue(pag);
+		break;
+	}
+
+	trace_xfs_perag_set_inode_tag(pag, _RET_IP_);
+}
+
+/* Clear a tag on both the AG incore inode tree and the AG radix tree. */
+static void
+xfs_perag_clear_inode_tag(
+	struct xfs_perag	*pag,
+	xfs_agino_t		agino,
+	unsigned int		tag)
+{
+	struct xfs_mount	*mp = pag->pag_mount;
+
+	lockdep_assert_held(&pag->pag_ici_lock);
+
+	/*
+	 * Reclaim can signal (with a null agino) that it cleared its own tag
+	 * by removing the inode from the radix tree.
+	 */
+	if (agino != NULLAGINO)
+		radix_tree_tag_clear(&pag->pag_ici_root, agino, tag);
+	else
+		ASSERT(tag == XFS_ICI_RECLAIM_TAG);
+
+	if (tag == XFS_ICI_RECLAIM_TAG)
+		pag->pag_ici_reclaimable--;
+
+	if (radix_tree_tagged(&pag->pag_ici_root, tag))
+		return;
+
+	/* clear the tag from the perag radix tree */
+	spin_lock(&mp->m_perag_lock);
+	radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno, tag);
+	spin_unlock(&mp->m_perag_lock);
+
+	trace_xfs_perag_clear_inode_tag(pag, _RET_IP_);
+}
+
+/*
+ * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
+ * part of the structure. This is made more complex by the fact we store
+ * information about the on-disk values in the VFS inode and so we can't just
+ * overwrite the values unconditionally. Hence we save the parameters we
+ * need to retain across reinitialisation, and rewrite them into the VFS inode
+ * after reinitialisation even if it fails.
+ */
+static int
+xfs_reinit_inode(
+	struct xfs_mount	*mp,
+	struct inode		*inode)
+{
+	int			error;
+	uint32_t		nlink = inode->i_nlink;
+	uint32_t		generation = inode->i_generation;
+	uint64_t		version = inode_peek_iversion(inode);
+	umode_t			mode = inode->i_mode;
+	dev_t			dev = inode->i_rdev;
+	kuid_t			uid = inode->i_uid;
+	kgid_t			gid = inode->i_gid;
+
+	error = inode_init_always(mp->m_super, inode);
+
+	set_nlink(inode, nlink);
+	inode->i_generation = generation;
+	inode_set_iversion_queried(inode, version);
+	inode->i_mode = mode;
+	inode->i_rdev = dev;
+	inode->i_uid = uid;
+	inode->i_gid = gid;
+	mapping_set_large_folios(inode->i_mapping);
+	return error;
+}
+
+/*
+ * Carefully nudge an inode whose VFS state has been torn down back into a
+ * usable state.  Drops the i_flags_lock and the rcu read lock.
+ */
+static int
+xfs_iget_recycle(
+	struct xfs_perag	*pag,
+	struct xfs_inode	*ip) __releases(&ip->i_flags_lock)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct inode		*inode = VFS_I(ip);
+	int			error;
+
+	trace_xfs_iget_recycle(ip);
+
+	if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
+		return -EAGAIN;
+
+	/*
+	 * We need to make it look like the inode is being reclaimed to prevent
+	 * the actual reclaim workers from stomping over us while we recycle
+	 * the inode.  We can't clear the radix tree tag yet as it requires
+	 * pag_ici_lock to be held exclusive.
+	 */
+	ip->i_flags |= XFS_IRECLAIM;
+
+	spin_unlock(&ip->i_flags_lock);
+	rcu_read_unlock();
+
+	ASSERT(!rwsem_is_locked(&inode->i_rwsem));
+	error = xfs_reinit_inode(mp, inode);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	if (error) {
+		/*
+		 * Re-initializing the inode failed, and we are in deep
+		 * trouble.  Try to re-add it to the reclaim list.
+		 */
+		rcu_read_lock();
+		spin_lock(&ip->i_flags_lock);
+		ip->i_flags &= ~(XFS_INEW | XFS_IRECLAIM);
+		ASSERT(ip->i_flags & XFS_IRECLAIMABLE);
+		spin_unlock(&ip->i_flags_lock);
+		rcu_read_unlock();
+
+		trace_xfs_iget_recycle_fail(ip);
+		return error;
+	}
+
+	spin_lock(&pag->pag_ici_lock);
+	spin_lock(&ip->i_flags_lock);
+
+	/*
+	 * Clear the per-lifetime state in the inode as we are now effectively
+	 * a new inode and need to return to the initial state before reuse
+	 * occurs.
+	 */
+	ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
+	ip->i_flags |= XFS_INEW;
+	xfs_perag_clear_inode_tag(pag, XFS_INO_TO_AGINO(mp, ip->i_ino),
+			XFS_ICI_RECLAIM_TAG);
+	inode->i_state = I_NEW;
+	spin_unlock(&ip->i_flags_lock);
+	spin_unlock(&pag->pag_ici_lock);
+
+	return 0;
+}
+
+/*
+ * If we are allocating a new inode, then check what was returned is
+ * actually a free, empty inode. If we are not allocating an inode,
+ * then check we didn't find a free inode.
+ *
+ * Returns:
+ *	0		if the inode free state matches the lookup context
+ *	-ENOENT		if the inode is free and we are not allocating
+ *	-EFSCORRUPTED	if there is any state mismatch at all
+ */
+static int
+xfs_iget_check_free_state(
+	struct xfs_inode	*ip,
+	int			flags)
+{
+	if (flags & XFS_IGET_CREATE) {
+		/* should be a free inode */
+		if (VFS_I(ip)->i_mode != 0) {
+			xfs_warn(ip->i_mount,
+"Corruption detected! Free inode 0x%llx not marked free! (mode 0x%x)",
+				ip->i_ino, VFS_I(ip)->i_mode);
+			return -EFSCORRUPTED;
+		}
+
+		if (ip->i_nblocks != 0) {
+			xfs_warn(ip->i_mount,
+"Corruption detected! Free inode 0x%llx has blocks allocated!",
+				ip->i_ino);
+			return -EFSCORRUPTED;
+		}
+		return 0;
+	}
+
+	/* should be an allocated inode */
+	if (VFS_I(ip)->i_mode == 0)
+		return -ENOENT;
+
+	return 0;
+}
+
+/* Make all pending inactivation work start immediately. */
+static bool
+xfs_inodegc_queue_all(
+	struct xfs_mount	*mp)
+{
+	struct xfs_inodegc	*gc;
+	int			cpu;
+	bool			ret = false;
+
+	for_each_cpu(cpu, &mp->m_inodegc_cpumask) {
+		gc = per_cpu_ptr(mp->m_inodegc, cpu);
+		if (!llist_empty(&gc->list)) {
+			mod_delayed_work_on(cpu, mp->m_inodegc_wq, &gc->work, 0);
+			ret = true;
+		}
+	}
+
+	return ret;
+}
+
+/* Wait for all queued work and collect errors */
+static int
+xfs_inodegc_wait_all(
+	struct xfs_mount	*mp)
+{
+	int			cpu;
+	int			error = 0;
+
+	flush_workqueue(mp->m_inodegc_wq);
+	for_each_cpu(cpu, &mp->m_inodegc_cpumask) {
+		struct xfs_inodegc	*gc;
+
+		gc = per_cpu_ptr(mp->m_inodegc, cpu);
+		if (gc->error && !error)
+			error = gc->error;
+		gc->error = 0;
+	}
+
+	return error;
+}
+
+/*
+ * Check the validity of the inode we just found it the cache
+ */
+static int
+xfs_iget_cache_hit(
+	struct xfs_perag	*pag,
+	struct xfs_inode	*ip,
+	xfs_ino_t		ino,
+	int			flags,
+	int			lock_flags) __releases(RCU)
+{
+	struct inode		*inode = VFS_I(ip);
+	struct xfs_mount	*mp = ip->i_mount;
+	int			error;
+
+	/*
+	 * check for re-use of an inode within an RCU grace period due to the
+	 * radix tree nodes not being updated yet. We monitor for this by
+	 * setting the inode number to zero before freeing the inode structure.
+	 * If the inode has been reallocated and set up, then the inode number
+	 * will not match, so check for that, too.
+	 */
+	spin_lock(&ip->i_flags_lock);
+	if (ip->i_ino != ino)
+		goto out_skip;
+
+	/*
+	 * If we are racing with another cache hit that is currently
+	 * instantiating this inode or currently recycling it out of
+	 * reclaimable state, wait for the initialisation to complete
+	 * before continuing.
+	 *
+	 * If we're racing with the inactivation worker we also want to wait.
+	 * If we're creating a new file, it's possible that the worker
+	 * previously marked the inode as free on disk but hasn't finished
+	 * updating the incore state yet.  The AGI buffer will be dirty and
+	 * locked to the icreate transaction, so a synchronous push of the
+	 * inodegc workers would result in deadlock.  For a regular iget, the
+	 * worker is running already, so we might as well wait.
+	 *
+	 * XXX(hch): eventually we should do something equivalent to
+	 *	     wait_on_inode to wait for these flags to be cleared
+	 *	     instead of polling for it.
+	 */
+	if (ip->i_flags & (XFS_INEW | XFS_IRECLAIM | XFS_INACTIVATING))
+		goto out_skip;
+
+	if (ip->i_flags & XFS_NEED_INACTIVE) {
+		/* Unlinked inodes cannot be re-grabbed. */
+		if (VFS_I(ip)->i_nlink == 0) {
+			error = -ENOENT;
+			goto out_error;
+		}
+		goto out_inodegc_flush;
+	}
+
+	/*
+	 * Check the inode free state is valid. This also detects lookup
+	 * racing with unlinks.
+	 */
+	error = xfs_iget_check_free_state(ip, flags);
+	if (error)
+		goto out_error;
+
+	/* Skip inodes that have no vfs state. */
+	if ((flags & XFS_IGET_INCORE) &&
+	    (ip->i_flags & XFS_IRECLAIMABLE))
+		goto out_skip;
+
+	/* The inode fits the selection criteria; process it. */
+	if (ip->i_flags & XFS_IRECLAIMABLE) {
+		/* Drops i_flags_lock and RCU read lock. */
+		error = xfs_iget_recycle(pag, ip);
+		if (error == -EAGAIN)
+			goto out_skip;
+		if (error)
+			return error;
+	} else {
+		/* If the VFS inode is being torn down, pause and try again. */
+		if (!igrab(inode))
+			goto out_skip;
+
+		/* We've got a live one. */
+		spin_unlock(&ip->i_flags_lock);
+		rcu_read_unlock();
+		trace_xfs_iget_hit(ip);
+	}
+
+	if (lock_flags != 0)
+		xfs_ilock(ip, lock_flags);
+
+	if (!(flags & XFS_IGET_INCORE))
+		xfs_iflags_clear(ip, XFS_ISTALE);
+	XFS_STATS_INC(mp, xs_ig_found);
+
+	return 0;
+
+out_skip:
+	trace_xfs_iget_skip(ip);
+	XFS_STATS_INC(mp, xs_ig_frecycle);
+	error = -EAGAIN;
+out_error:
+	spin_unlock(&ip->i_flags_lock);
+	rcu_read_unlock();
+	return error;
+
+out_inodegc_flush:
+	spin_unlock(&ip->i_flags_lock);
+	rcu_read_unlock();
+	/*
+	 * Do not wait for the workers, because the caller could hold an AGI
+	 * buffer lock.  We're just going to sleep in a loop anyway.
+	 */
+	if (xfs_is_inodegc_enabled(mp))
+		xfs_inodegc_queue_all(mp);
+	return -EAGAIN;
+}
+
+static int
+xfs_iget_cache_miss(
+	struct xfs_mount	*mp,
+	struct xfs_perag	*pag,
+	xfs_trans_t		*tp,
+	xfs_ino_t		ino,
+	struct xfs_inode	**ipp,
+	int			flags,
+	int			lock_flags)
+{
+	struct xfs_inode	*ip;
+	int			error;
+	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ino);
+	int			iflags;
+
+	ip = xfs_inode_alloc(mp, ino);
+	if (!ip)
+		return -ENOMEM;
+
+	error = xfs_imap(pag, tp, ip->i_ino, &ip->i_imap, flags);
+	if (error)
+		goto out_destroy;
+
+	/*
+	 * For version 5 superblocks, if we are initialising a new inode and we
+	 * are not utilising the XFS_FEAT_IKEEP inode cluster mode, we can
+	 * simply build the new inode core with a random generation number.
+	 *
+	 * For version 4 (and older) superblocks, log recovery is dependent on
+	 * the i_flushiter field being initialised from the current on-disk
+	 * value and hence we must also read the inode off disk even when
+	 * initializing new inodes.
+	 */
+	if (xfs_has_v3inodes(mp) &&
+	    (flags & XFS_IGET_CREATE) && !xfs_has_ikeep(mp)) {
+		VFS_I(ip)->i_generation = get_random_u32();
+	} else {
+		struct xfs_buf		*bp;
+
+		error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &bp);
+		if (error)
+			goto out_destroy;
+
+		error = xfs_inode_from_disk(ip,
+				xfs_buf_offset(bp, ip->i_imap.im_boffset));
+		if (!error)
+			xfs_buf_set_ref(bp, XFS_INO_REF);
+		xfs_trans_brelse(tp, bp);
+
+		if (error)
+			goto out_destroy;
+	}
+
+	trace_xfs_iget_miss(ip);
+
+	/*
+	 * Check the inode free state is valid. This also detects lookup
+	 * racing with unlinks.
+	 */
+	error = xfs_iget_check_free_state(ip, flags);
+	if (error)
+		goto out_destroy;
+
+	/*
+	 * Preload the radix tree so we can insert safely under the
+	 * write spinlock. Note that we cannot sleep inside the preload
+	 * region. Since we can be called from transaction context, don't
+	 * recurse into the file system.
+	 */
+	if (radix_tree_preload(GFP_NOFS)) {
+		error = -EAGAIN;
+		goto out_destroy;
+	}
+
+	/*
+	 * Because the inode hasn't been added to the radix-tree yet it can't
+	 * be found by another thread, so we can do the non-sleeping lock here.
+	 */
+	if (lock_flags) {
+		if (!xfs_ilock_nowait(ip, lock_flags))
+			BUG();
+	}
+
+	/*
+	 * These values must be set before inserting the inode into the radix
+	 * tree as the moment it is inserted a concurrent lookup (allowed by the
+	 * RCU locking mechanism) can find it and that lookup must see that this
+	 * is an inode currently under construction (i.e. that XFS_INEW is set).
+	 * The ip->i_flags_lock that protects the XFS_INEW flag forms the
+	 * memory barrier that ensures this detection works correctly at lookup
+	 * time.
+	 */
+	iflags = XFS_INEW;
+	if (flags & XFS_IGET_DONTCACHE)
+		d_mark_dontcache(VFS_I(ip));
+	ip->i_udquot = NULL;
+	ip->i_gdquot = NULL;
+	ip->i_pdquot = NULL;
+	xfs_iflags_set(ip, iflags);
+
+	/* insert the new inode */
+	spin_lock(&pag->pag_ici_lock);
+	error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
+	if (unlikely(error)) {
+		WARN_ON(error != -EEXIST);
+		XFS_STATS_INC(mp, xs_ig_dup);
+		error = -EAGAIN;
+		goto out_preload_end;
+	}
+	spin_unlock(&pag->pag_ici_lock);
+	radix_tree_preload_end();
+
+	*ipp = ip;
+	return 0;
+
+out_preload_end:
+	spin_unlock(&pag->pag_ici_lock);
+	radix_tree_preload_end();
+	if (lock_flags)
+		xfs_iunlock(ip, lock_flags);
+out_destroy:
+	__destroy_inode(VFS_I(ip));
+	xfs_inode_free(ip);
+	return error;
+}
+
+/*
+ * Look up an inode by number in the given file system.  The inode is looked up
+ * in the cache held in each AG.  If the inode is found in the cache, initialise
+ * the vfs inode if necessary.
+ *
+ * If it is not in core, read it in from the file system's device, add it to the
+ * cache and initialise the vfs inode.
+ *
+ * The inode is locked according to the value of the lock_flags parameter.
+ * Inode lookup is only done during metadata operations and not as part of the
+ * data IO path. Hence we only allow locking of the XFS_ILOCK during lookup.
+ */
+int
+xfs_iget(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	xfs_ino_t		ino,
+	uint			flags,
+	uint			lock_flags,
+	struct xfs_inode	**ipp)
+{
+	struct xfs_inode	*ip;
+	struct xfs_perag	*pag;
+	xfs_agino_t		agino;
+	int			error;
+
+	ASSERT((lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) == 0);
+
+	/* reject inode numbers outside existing AGs */
+	if (!ino || XFS_INO_TO_AGNO(mp, ino) >= mp->m_sb.sb_agcount)
+		return -EINVAL;
+
+	XFS_STATS_INC(mp, xs_ig_attempts);
+
+	/* get the perag structure and ensure that it's inode capable */
+	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
+	agino = XFS_INO_TO_AGINO(mp, ino);
+
+again:
+	error = 0;
+	rcu_read_lock();
+	ip = radix_tree_lookup(&pag->pag_ici_root, agino);
+
+	if (ip) {
+		error = xfs_iget_cache_hit(pag, ip, ino, flags, lock_flags);
+		if (error)
+			goto out_error_or_again;
+	} else {
+		rcu_read_unlock();
+		if (flags & XFS_IGET_INCORE) {
+			error = -ENODATA;
+			goto out_error_or_again;
+		}
+		XFS_STATS_INC(mp, xs_ig_missed);
+
+		error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip,
+							flags, lock_flags);
+		if (error)
+			goto out_error_or_again;
+	}
+	xfs_perag_put(pag);
+
+	*ipp = ip;
+
+	/*
+	 * If we have a real type for an on-disk inode, we can setup the inode
+	 * now.	 If it's a new inode being created, xfs_init_new_inode will
+	 * handle it.
+	 */
+	if (xfs_iflags_test(ip, XFS_INEW) && VFS_I(ip)->i_mode != 0)
+		xfs_setup_existing_inode(ip);
+	return 0;
+
+out_error_or_again:
+	if (!(flags & (XFS_IGET_INCORE | XFS_IGET_NORETRY)) &&
+	    error == -EAGAIN) {
+		delay(1);
+		goto again;
+	}
+	xfs_perag_put(pag);
+	return error;
+}
+
+/*
+ * Grab the inode for reclaim exclusively.
+ *
+ * We have found this inode via a lookup under RCU, so the inode may have
+ * already been freed, or it may be in the process of being recycled by
+ * xfs_iget(). In both cases, the inode will have XFS_IRECLAIM set. If the inode
+ * has been fully recycled by the time we get the i_flags_lock, XFS_IRECLAIMABLE
+ * will not be set. Hence we need to check for both these flag conditions to
+ * avoid inodes that are no longer reclaim candidates.
+ *
+ * Note: checking for other state flags here, under the i_flags_lock or not, is
+ * racy and should be avoided. Those races should be resolved only after we have
+ * ensured that we are able to reclaim this inode and the world can see that we
+ * are going to reclaim it.
+ *
+ * Return true if we grabbed it, false otherwise.
+ */
+static bool
+xfs_reclaim_igrab(
+	struct xfs_inode	*ip,
+	struct xfs_icwalk	*icw)
+{
+	ASSERT(rcu_read_lock_held());
+
+	spin_lock(&ip->i_flags_lock);
+	if (!__xfs_iflags_test(ip, XFS_IRECLAIMABLE) ||
+	    __xfs_iflags_test(ip, XFS_IRECLAIM)) {
+		/* not a reclaim candidate. */
+		spin_unlock(&ip->i_flags_lock);
+		return false;
+	}
+
+	/* Don't reclaim a sick inode unless the caller asked for it. */
+	if (ip->i_sick &&
+	    (!icw || !(icw->icw_flags & XFS_ICWALK_FLAG_RECLAIM_SICK))) {
+		spin_unlock(&ip->i_flags_lock);
+		return false;
+	}
+
+	__xfs_iflags_set(ip, XFS_IRECLAIM);
+	spin_unlock(&ip->i_flags_lock);
+	return true;
+}
+
+/*
+ * Inode reclaim is non-blocking, so the default action if progress cannot be
+ * made is to "requeue" the inode for reclaim by unlocking it and clearing the
+ * XFS_IRECLAIM flag.  If we are in a shutdown state, we don't care about
+ * blocking anymore and hence we can wait for the inode to be able to reclaim
+ * it.
+ *
+ * We do no IO here - if callers require inodes to be cleaned they must push the
+ * AIL first to trigger writeback of dirty inodes.  This enables writeback to be
+ * done in the background in a non-blocking manner, and enables memory reclaim
+ * to make progress without blocking.
+ */
+static void
+xfs_reclaim_inode(
+	struct xfs_inode	*ip,
+	struct xfs_perag	*pag)
+{
+	xfs_ino_t		ino = ip->i_ino; /* for radix_tree_delete */
+
+	if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
+		goto out;
+	if (xfs_iflags_test_and_set(ip, XFS_IFLUSHING))
+		goto out_iunlock;
+
+	/*
+	 * Check for log shutdown because aborting the inode can move the log
+	 * tail and corrupt in memory state. This is fine if the log is shut
+	 * down, but if the log is still active and only the mount is shut down
+	 * then the in-memory log tail movement caused by the abort can be
+	 * incorrectly propagated to disk.
+	 */
+	if (xlog_is_shutdown(ip->i_mount->m_log)) {
+		xfs_iunpin_wait(ip);
+		xfs_iflush_shutdown_abort(ip);
+		goto reclaim;
+	}
+	if (xfs_ipincount(ip))
+		goto out_clear_flush;
+	if (!xfs_inode_clean(ip))
+		goto out_clear_flush;
+
+	xfs_iflags_clear(ip, XFS_IFLUSHING);
+reclaim:
+	trace_xfs_inode_reclaiming(ip);
+
+	/*
+	 * Because we use RCU freeing we need to ensure the inode always appears
+	 * to be reclaimed with an invalid inode number when in the free state.
+	 * We do this as early as possible under the ILOCK so that
+	 * xfs_iflush_cluster() and xfs_ifree_cluster() can be guaranteed to
+	 * detect races with us here. By doing this, we guarantee that once
+	 * xfs_iflush_cluster() or xfs_ifree_cluster() has locked XFS_ILOCK that
+	 * it will see either a valid inode that will serialise correctly, or it
+	 * will see an invalid inode that it can skip.
+	 */
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags = XFS_IRECLAIM;
+	ip->i_ino = 0;
+	ip->i_sick = 0;
+	ip->i_checked = 0;
+	spin_unlock(&ip->i_flags_lock);
+
+	ASSERT(!ip->i_itemp || ip->i_itemp->ili_item.li_buf == NULL);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+	XFS_STATS_INC(ip->i_mount, xs_ig_reclaims);
+	/*
+	 * Remove the inode from the per-AG radix tree.
+	 *
+	 * Because radix_tree_delete won't complain even if the item was never
+	 * added to the tree assert that it's been there before to catch
+	 * problems with the inode life time early on.
+	 */
+	spin_lock(&pag->pag_ici_lock);
+	if (!radix_tree_delete(&pag->pag_ici_root,
+				XFS_INO_TO_AGINO(ip->i_mount, ino)))
+		ASSERT(0);
+	xfs_perag_clear_inode_tag(pag, NULLAGINO, XFS_ICI_RECLAIM_TAG);
+	spin_unlock(&pag->pag_ici_lock);
+
+	/*
+	 * Here we do an (almost) spurious inode lock in order to coordinate
+	 * with inode cache radix tree lookups.  This is because the lookup
+	 * can reference the inodes in the cache without taking references.
+	 *
+	 * We make that OK here by ensuring that we wait until the inode is
+	 * unlocked after the lookup before we go ahead and free it.
+	 */
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	ASSERT(!ip->i_udquot && !ip->i_gdquot && !ip->i_pdquot);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	ASSERT(xfs_inode_clean(ip));
+
+	__xfs_inode_free(ip);
+	return;
+
+out_clear_flush:
+	xfs_iflags_clear(ip, XFS_IFLUSHING);
+out_iunlock:
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+out:
+	xfs_iflags_clear(ip, XFS_IRECLAIM);
+}
+
+/* Reclaim sick inodes if we're unmounting or the fs went down. */
+static inline bool
+xfs_want_reclaim_sick(
+	struct xfs_mount	*mp)
+{
+	return xfs_is_unmounting(mp) || xfs_has_norecovery(mp) ||
+	       xfs_is_shutdown(mp);
+}
+
+void
+xfs_reclaim_inodes(
+	struct xfs_mount	*mp)
+{
+	struct xfs_icwalk	icw = {
+		.icw_flags	= 0,
+	};
+
+	if (xfs_want_reclaim_sick(mp))
+		icw.icw_flags |= XFS_ICWALK_FLAG_RECLAIM_SICK;
+
+	while (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
+		xfs_ail_push_all_sync(mp->m_ail);
+		xfs_icwalk(mp, XFS_ICWALK_RECLAIM, &icw);
+	}
+}
+
+/*
+ * The shrinker infrastructure determines how many inodes we should scan for
+ * reclaim. We want as many clean inodes ready to reclaim as possible, so we
+ * push the AIL here. We also want to proactively free up memory if we can to
+ * minimise the amount of work memory reclaim has to do so we kick the
+ * background reclaim if it isn't already scheduled.
+ */
+long
+xfs_reclaim_inodes_nr(
+	struct xfs_mount	*mp,
+	unsigned long		nr_to_scan)
+{
+	struct xfs_icwalk	icw = {
+		.icw_flags	= XFS_ICWALK_FLAG_SCAN_LIMIT,
+		.icw_scan_limit	= min_t(unsigned long, LONG_MAX, nr_to_scan),
+	};
+
+	if (xfs_want_reclaim_sick(mp))
+		icw.icw_flags |= XFS_ICWALK_FLAG_RECLAIM_SICK;
+
+	/* kick background reclaimer and push the AIL */
+	xfs_reclaim_work_queue(mp);
+	xfs_ail_push_all(mp->m_ail);
+
+	xfs_icwalk(mp, XFS_ICWALK_RECLAIM, &icw);
+	return 0;
+}
+
+/*
+ * Return the number of reclaimable inodes in the filesystem for
+ * the shrinker to determine how much to reclaim.
+ */
+long
+xfs_reclaim_inodes_count(
+	struct xfs_mount	*mp)
+{
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		ag = 0;
+	long			reclaimable = 0;
+
+	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
+		ag = pag->pag_agno + 1;
+		reclaimable += pag->pag_ici_reclaimable;
+		xfs_perag_put(pag);
+	}
+	return reclaimable;
+}
+
+STATIC bool
+xfs_icwalk_match_id(
+	struct xfs_inode	*ip,
+	struct xfs_icwalk	*icw)
+{
+	if ((icw->icw_flags & XFS_ICWALK_FLAG_UID) &&
+	    !uid_eq(VFS_I(ip)->i_uid, icw->icw_uid))
+		return false;
+
+	if ((icw->icw_flags & XFS_ICWALK_FLAG_GID) &&
+	    !gid_eq(VFS_I(ip)->i_gid, icw->icw_gid))
+		return false;
+
+	if ((icw->icw_flags & XFS_ICWALK_FLAG_PRID) &&
+	    ip->i_projid != icw->icw_prid)
+		return false;
+
+	return true;
+}
+
+/*
+ * A union-based inode filtering algorithm. Process the inode if any of the
+ * criteria match. This is for global/internal scans only.
+ */
+STATIC bool
+xfs_icwalk_match_id_union(
+	struct xfs_inode	*ip,
+	struct xfs_icwalk	*icw)
+{
+	if ((icw->icw_flags & XFS_ICWALK_FLAG_UID) &&
+	    uid_eq(VFS_I(ip)->i_uid, icw->icw_uid))
+		return true;
+
+	if ((icw->icw_flags & XFS_ICWALK_FLAG_GID) &&
+	    gid_eq(VFS_I(ip)->i_gid, icw->icw_gid))
+		return true;
+
+	if ((icw->icw_flags & XFS_ICWALK_FLAG_PRID) &&
+	    ip->i_projid == icw->icw_prid)
+		return true;
+
+	return false;
+}
+
+/*
+ * Is this inode @ip eligible for eof/cow block reclamation, given some
+ * filtering parameters @icw?  The inode is eligible if @icw is null or
+ * if the predicate functions match.
+ */
+static bool
+xfs_icwalk_match(
+	struct xfs_inode	*ip,
+	struct xfs_icwalk	*icw)
+{
+	bool			match;
+
+	if (!icw)
+		return true;
+
+	if (icw->icw_flags & XFS_ICWALK_FLAG_UNION)
+		match = xfs_icwalk_match_id_union(ip, icw);
+	else
+		match = xfs_icwalk_match_id(ip, icw);
+	if (!match)
+		return false;
+
+	/* skip the inode if the file size is too small */
+	if ((icw->icw_flags & XFS_ICWALK_FLAG_MINFILESIZE) &&
+	    XFS_ISIZE(ip) < icw->icw_min_file_size)
+		return false;
+
+	return true;
+}
+
+/*
+ * This is a fast pass over the inode cache to try to get reclaim moving on as
+ * many inodes as possible in a short period of time. It kicks itself every few
+ * seconds, as well as being kicked by the inode cache shrinker when memory
+ * goes low.
+ */
+void
+xfs_reclaim_worker(
+	struct work_struct *work)
+{
+	struct xfs_mount *mp = container_of(to_delayed_work(work),
+					struct xfs_mount, m_reclaim_work);
+
+	xfs_icwalk(mp, XFS_ICWALK_RECLAIM, NULL);
+	xfs_reclaim_work_queue(mp);
+}
+
+STATIC int
+xfs_inode_free_eofblocks(
+	struct xfs_inode	*ip,
+	struct xfs_icwalk	*icw,
+	unsigned int		*lockflags)
+{
+	bool			wait;
+
+	wait = icw && (icw->icw_flags & XFS_ICWALK_FLAG_SYNC);
+
+	if (!xfs_iflags_test(ip, XFS_IEOFBLOCKS))
+		return 0;
+
+	/*
+	 * If the mapping is dirty the operation can block and wait for some
+	 * time. Unless we are waiting, skip it.
+	 */
+	if (!wait && mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_DIRTY))
+		return 0;
+
+	if (!xfs_icwalk_match(ip, icw))
+		return 0;
+
+	/*
+	 * If the caller is waiting, return -EAGAIN to keep the background
+	 * scanner moving and revisit the inode in a subsequent pass.
+	 */
+	if (!xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
+		if (wait)
+			return -EAGAIN;
+		return 0;
+	}
+	*lockflags |= XFS_IOLOCK_EXCL;
+
+	if (xfs_can_free_eofblocks(ip, false))
+		return xfs_free_eofblocks(ip);
+
+	/* inode could be preallocated or append-only */
+	trace_xfs_inode_free_eofblocks_invalid(ip);
+	xfs_inode_clear_eofblocks_tag(ip);
+	return 0;
+}
+
+static void
+xfs_blockgc_set_iflag(
+	struct xfs_inode	*ip,
+	unsigned long		iflag)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_perag	*pag;
+
+	ASSERT((iflag & ~(XFS_IEOFBLOCKS | XFS_ICOWBLOCKS)) == 0);
+
+	/*
+	 * Don't bother locking the AG and looking up in the radix trees
+	 * if we already know that we have the tag set.
+	 */
+	if (ip->i_flags & iflag)
+		return;
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags |= iflag;
+	spin_unlock(&ip->i_flags_lock);
+
+	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
+	spin_lock(&pag->pag_ici_lock);
+
+	xfs_perag_set_inode_tag(pag, XFS_INO_TO_AGINO(mp, ip->i_ino),
+			XFS_ICI_BLOCKGC_TAG);
+
+	spin_unlock(&pag->pag_ici_lock);
+	xfs_perag_put(pag);
+}
+
+void
+xfs_inode_set_eofblocks_tag(
+	xfs_inode_t	*ip)
+{
+	trace_xfs_inode_set_eofblocks_tag(ip);
+	return xfs_blockgc_set_iflag(ip, XFS_IEOFBLOCKS);
+}
+
+static void
+xfs_blockgc_clear_iflag(
+	struct xfs_inode	*ip,
+	unsigned long		iflag)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_perag	*pag;
+	bool			clear_tag;
+
+	ASSERT((iflag & ~(XFS_IEOFBLOCKS | XFS_ICOWBLOCKS)) == 0);
+
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags &= ~iflag;
+	clear_tag = (ip->i_flags & (XFS_IEOFBLOCKS | XFS_ICOWBLOCKS)) == 0;
+	spin_unlock(&ip->i_flags_lock);
+
+	if (!clear_tag)
+		return;
+
+	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
+	spin_lock(&pag->pag_ici_lock);
+
+	xfs_perag_clear_inode_tag(pag, XFS_INO_TO_AGINO(mp, ip->i_ino),
+			XFS_ICI_BLOCKGC_TAG);
+
+	spin_unlock(&pag->pag_ici_lock);
+	xfs_perag_put(pag);
+}
+
+void
+xfs_inode_clear_eofblocks_tag(
+	xfs_inode_t	*ip)
+{
+	trace_xfs_inode_clear_eofblocks_tag(ip);
+	return xfs_blockgc_clear_iflag(ip, XFS_IEOFBLOCKS);
+}
+
+/*
+ * Set ourselves up to free CoW blocks from this file.  If it's already clean
+ * then we can bail out quickly, but otherwise we must back off if the file
+ * is undergoing some kind of write.
+ */
+static bool
+xfs_prep_free_cowblocks(
+	struct xfs_inode	*ip)
+{
+	/*
+	 * Just clear the tag if we have an empty cow fork or none at all. It's
+	 * possible the inode was fully unshared since it was originally tagged.
+	 */
+	if (!xfs_inode_has_cow_data(ip)) {
+		trace_xfs_inode_free_cowblocks_invalid(ip);
+		xfs_inode_clear_cowblocks_tag(ip);
+		return false;
+	}
+
+	/*
+	 * If the mapping is dirty or under writeback we cannot touch the
+	 * CoW fork.  Leave it alone if we're in the midst of a directio.
+	 */
+	if ((VFS_I(ip)->i_state & I_DIRTY_PAGES) ||
+	    mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_DIRTY) ||
+	    mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_WRITEBACK) ||
+	    atomic_read(&VFS_I(ip)->i_dio_count))
+		return false;
+
+	return true;
+}
+
+/*
+ * Automatic CoW Reservation Freeing
+ *
+ * These functions automatically garbage collect leftover CoW reservations
+ * that were made on behalf of a cowextsize hint when we start to run out
+ * of quota or when the reservations sit around for too long.  If the file
+ * has dirty pages or is undergoing writeback, its CoW reservations will
+ * be retained.
+ *
+ * The actual garbage collection piggybacks off the same code that runs
+ * the speculative EOF preallocation garbage collector.
+ */
+STATIC int
+xfs_inode_free_cowblocks(
+	struct xfs_inode	*ip,
+	struct xfs_icwalk	*icw,
+	unsigned int		*lockflags)
+{
+	bool			wait;
+	int			ret = 0;
+
+	wait = icw && (icw->icw_flags & XFS_ICWALK_FLAG_SYNC);
+
+	if (!xfs_iflags_test(ip, XFS_ICOWBLOCKS))
+		return 0;
+
+	if (!xfs_prep_free_cowblocks(ip))
+		return 0;
+
+	if (!xfs_icwalk_match(ip, icw))
+		return 0;
+
+	/*
+	 * If the caller is waiting, return -EAGAIN to keep the background
+	 * scanner moving and revisit the inode in a subsequent pass.
+	 */
+	if (!(*lockflags & XFS_IOLOCK_EXCL) &&
+	    !xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
+		if (wait)
+			return -EAGAIN;
+		return 0;
+	}
+	*lockflags |= XFS_IOLOCK_EXCL;
+
+	if (!xfs_ilock_nowait(ip, XFS_MMAPLOCK_EXCL)) {
+		if (wait)
+			return -EAGAIN;
+		return 0;
+	}
+	*lockflags |= XFS_MMAPLOCK_EXCL;
+
+	/*
+	 * Check again, nobody else should be able to dirty blocks or change
+	 * the reflink iflag now that we have the first two locks held.
+	 */
+	if (xfs_prep_free_cowblocks(ip))
+		ret = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, false);
+	return ret;
+}
+
+void
+xfs_inode_set_cowblocks_tag(
+	xfs_inode_t	*ip)
+{
+	trace_xfs_inode_set_cowblocks_tag(ip);
+	return xfs_blockgc_set_iflag(ip, XFS_ICOWBLOCKS);
+}
+
+void
+xfs_inode_clear_cowblocks_tag(
+	xfs_inode_t	*ip)
+{
+	trace_xfs_inode_clear_cowblocks_tag(ip);
+	return xfs_blockgc_clear_iflag(ip, XFS_ICOWBLOCKS);
+}
+
+/* Disable post-EOF and CoW block auto-reclamation. */
+void
+xfs_blockgc_stop(
+	struct xfs_mount	*mp)
+{
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		agno;
+
+	if (!xfs_clear_blockgc_enabled(mp))
+		return;
+
+	for_each_perag(mp, agno, pag)
+		cancel_delayed_work_sync(&pag->pag_blockgc_work);
+	trace_xfs_blockgc_stop(mp, __return_address);
+}
+
+/* Enable post-EOF and CoW block auto-reclamation. */
+void
+xfs_blockgc_start(
+	struct xfs_mount	*mp)
+{
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		agno;
+
+	if (xfs_set_blockgc_enabled(mp))
+		return;
+
+	trace_xfs_blockgc_start(mp, __return_address);
+	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+		xfs_blockgc_queue(pag);
+}
+
+/* Don't try to run block gc on an inode that's in any of these states. */
+#define XFS_BLOCKGC_NOGRAB_IFLAGS	(XFS_INEW | \
+					 XFS_NEED_INACTIVE | \
+					 XFS_INACTIVATING | \
+					 XFS_IRECLAIMABLE | \
+					 XFS_IRECLAIM)
+/*
+ * Decide if the given @ip is eligible for garbage collection of speculative
+ * preallocations, and grab it if so.  Returns true if it's ready to go or
+ * false if we should just ignore it.
+ */
+static bool
+xfs_blockgc_igrab(
+	struct xfs_inode	*ip)
+{
+	struct inode		*inode = VFS_I(ip);
+
+	ASSERT(rcu_read_lock_held());
+
+	/* Check for stale RCU freed inode */
+	spin_lock(&ip->i_flags_lock);
+	if (!ip->i_ino)
+		goto out_unlock_noent;
+
+	if (ip->i_flags & XFS_BLOCKGC_NOGRAB_IFLAGS)
+		goto out_unlock_noent;
+	spin_unlock(&ip->i_flags_lock);
+
+	/* nothing to sync during shutdown */
+	if (xfs_is_shutdown(ip->i_mount))
+		return false;
+
+	/* If we can't grab the inode, it must on it's way to reclaim. */
+	if (!igrab(inode))
+		return false;
+
+	/* inode is valid */
+	return true;
+
+out_unlock_noent:
+	spin_unlock(&ip->i_flags_lock);
+	return false;
+}
+
+/* Scan one incore inode for block preallocations that we can remove. */
+static int
+xfs_blockgc_scan_inode(
+	struct xfs_inode	*ip,
+	struct xfs_icwalk	*icw)
+{
+	unsigned int		lockflags = 0;
+	int			error;
+
+	error = xfs_inode_free_eofblocks(ip, icw, &lockflags);
+	if (error)
+		goto unlock;
+
+	error = xfs_inode_free_cowblocks(ip, icw, &lockflags);
+unlock:
+	if (lockflags)
+		xfs_iunlock(ip, lockflags);
+	xfs_irele(ip);
+	return error;
+}
+
+/* Background worker that trims preallocated space. */
+void
+xfs_blockgc_worker(
+	struct work_struct	*work)
+{
+	struct xfs_perag	*pag = container_of(to_delayed_work(work),
+					struct xfs_perag, pag_blockgc_work);
+	struct xfs_mount	*mp = pag->pag_mount;
+	int			error;
+
+	trace_xfs_blockgc_worker(mp, __return_address);
+
+	error = xfs_icwalk_ag(pag, XFS_ICWALK_BLOCKGC, NULL);
+	if (error)
+		xfs_info(mp, "AG %u preallocation gc worker failed, err=%d",
+				pag->pag_agno, error);
+	xfs_blockgc_queue(pag);
+}
+
+/*
+ * Try to free space in the filesystem by purging inactive inodes, eofblocks
+ * and cowblocks.
+ */
+int
+xfs_blockgc_free_space(
+	struct xfs_mount	*mp,
+	struct xfs_icwalk	*icw)
+{
+	int			error;
+
+	trace_xfs_blockgc_free_space(mp, icw, _RET_IP_);
+
+	error = xfs_icwalk(mp, XFS_ICWALK_BLOCKGC, icw);
+	if (error)
+		return error;
+
+	return xfs_inodegc_flush(mp);
+}
+
+/*
+ * Reclaim all the free space that we can by scheduling the background blockgc
+ * and inodegc workers immediately and waiting for them all to clear.
+ */
+int
+xfs_blockgc_flush_all(
+	struct xfs_mount	*mp)
+{
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		agno;
+
+	trace_xfs_blockgc_flush_all(mp, __return_address);
+
+	/*
+	 * For each blockgc worker, move its queue time up to now.  If it
+	 * wasn't queued, it will not be requeued.  Then flush whatever's
+	 * left.
+	 */
+	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+		mod_delayed_work(pag->pag_mount->m_blockgc_wq,
+				&pag->pag_blockgc_work, 0);
+
+	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+		flush_delayed_work(&pag->pag_blockgc_work);
+
+	return xfs_inodegc_flush(mp);
+}
+
+/*
+ * Run cow/eofblocks scans on the supplied dquots.  We don't know exactly which
+ * quota caused an allocation failure, so we make a best effort by including
+ * each quota under low free space conditions (less than 1% free space) in the
+ * scan.
+ *
+ * Callers must not hold any inode's ILOCK.  If requesting a synchronous scan
+ * (XFS_ICWALK_FLAG_SYNC), the caller also must not hold any inode's IOLOCK or
+ * MMAPLOCK.
+ */
+int
+xfs_blockgc_free_dquots(
+	struct xfs_mount	*mp,
+	struct xfs_dquot	*udqp,
+	struct xfs_dquot	*gdqp,
+	struct xfs_dquot	*pdqp,
+	unsigned int		iwalk_flags)
+{
+	struct xfs_icwalk	icw = {0};
+	bool			do_work = false;
+
+	if (!udqp && !gdqp && !pdqp)
+		return 0;
+
+	/*
+	 * Run a scan to free blocks using the union filter to cover all
+	 * applicable quotas in a single scan.
+	 */
+	icw.icw_flags = XFS_ICWALK_FLAG_UNION | iwalk_flags;
+
+	if (XFS_IS_UQUOTA_ENFORCED(mp) && udqp && xfs_dquot_lowsp(udqp)) {
+		icw.icw_uid = make_kuid(mp->m_super->s_user_ns, udqp->q_id);
+		icw.icw_flags |= XFS_ICWALK_FLAG_UID;
+		do_work = true;
+	}
+
+	if (XFS_IS_UQUOTA_ENFORCED(mp) && gdqp && xfs_dquot_lowsp(gdqp)) {
+		icw.icw_gid = make_kgid(mp->m_super->s_user_ns, gdqp->q_id);
+		icw.icw_flags |= XFS_ICWALK_FLAG_GID;
+		do_work = true;
+	}
+
+	if (XFS_IS_PQUOTA_ENFORCED(mp) && pdqp && xfs_dquot_lowsp(pdqp)) {
+		icw.icw_prid = pdqp->q_id;
+		icw.icw_flags |= XFS_ICWALK_FLAG_PRID;
+		do_work = true;
+	}
+
+	if (!do_work)
+		return 0;
+
+	return xfs_blockgc_free_space(mp, &icw);
+}
+
+/* Run cow/eofblocks scans on the quotas attached to the inode. */
+int
+xfs_blockgc_free_quota(
+	struct xfs_inode	*ip,
+	unsigned int		iwalk_flags)
+{
+	return xfs_blockgc_free_dquots(ip->i_mount,
+			xfs_inode_dquot(ip, XFS_DQTYPE_USER),
+			xfs_inode_dquot(ip, XFS_DQTYPE_GROUP),
+			xfs_inode_dquot(ip, XFS_DQTYPE_PROJ), iwalk_flags);
+}
+
+/* XFS Inode Cache Walking Code */
+
+/*
+ * The inode lookup is done in batches to keep the amount of lock traffic and
+ * radix tree lookups to a minimum. The batch size is a trade off between
+ * lookup reduction and stack usage. This is in the reclaim path, so we can't
+ * be too greedy.
+ */
+#define XFS_LOOKUP_BATCH	32
+
+
+/*
+ * Decide if we want to grab this inode in anticipation of doing work towards
+ * the goal.
+ */
+static inline bool
+xfs_icwalk_igrab(
+	enum xfs_icwalk_goal	goal,
+	struct xfs_inode	*ip,
+	struct xfs_icwalk	*icw)
+{
+	switch (goal) {
+	case XFS_ICWALK_BLOCKGC:
+		return xfs_blockgc_igrab(ip);
+	case XFS_ICWALK_RECLAIM:
+		return xfs_reclaim_igrab(ip, icw);
+	default:
+		return false;
+	}
+}
+
+/*
+ * Process an inode.  Each processing function must handle any state changes
+ * made by the icwalk igrab function.  Return -EAGAIN to skip an inode.
+ */
+static inline int
+xfs_icwalk_process_inode(
+	enum xfs_icwalk_goal	goal,
+	struct xfs_inode	*ip,
+	struct xfs_perag	*pag,
+	struct xfs_icwalk	*icw)
+{
+	int			error = 0;
+
+	switch (goal) {
+	case XFS_ICWALK_BLOCKGC:
+		error = xfs_blockgc_scan_inode(ip, icw);
+		break;
+	case XFS_ICWALK_RECLAIM:
+		xfs_reclaim_inode(ip, pag);
+		break;
+	}
+	return error;
+}
+
+/*
+ * For a given per-AG structure @pag and a goal, grab qualifying inodes and
+ * process them in some manner.
+ */
+static int
+xfs_icwalk_ag(
+	struct xfs_perag	*pag,
+	enum xfs_icwalk_goal	goal,
+	struct xfs_icwalk	*icw)
+{
+	struct xfs_mount	*mp = pag->pag_mount;
+	uint32_t		first_index;
+	int			last_error = 0;
+	int			skipped;
+	bool			done;
+	int			nr_found;
+
+restart:
+	done = false;
+	skipped = 0;
+	if (goal == XFS_ICWALK_RECLAIM)
+		first_index = READ_ONCE(pag->pag_ici_reclaim_cursor);
+	else
+		first_index = 0;
+	nr_found = 0;
+	do {
+		struct xfs_inode *batch[XFS_LOOKUP_BATCH];
+		int		error = 0;
+		int		i;
+
+		rcu_read_lock();
+
+		nr_found = radix_tree_gang_lookup_tag(&pag->pag_ici_root,
+				(void **) batch, first_index,
+				XFS_LOOKUP_BATCH, goal);
+		if (!nr_found) {
+			done = true;
+			rcu_read_unlock();
+			break;
+		}
+
+		/*
+		 * Grab the inodes before we drop the lock. if we found
+		 * nothing, nr == 0 and the loop will be skipped.
+		 */
+		for (i = 0; i < nr_found; i++) {
+			struct xfs_inode *ip = batch[i];
+
+			if (done || !xfs_icwalk_igrab(goal, ip, icw))
+				batch[i] = NULL;
+
+			/*
+			 * Update the index for the next lookup. Catch
+			 * overflows into the next AG range which can occur if
+			 * we have inodes in the last block of the AG and we
+			 * are currently pointing to the last inode.
+			 *
+			 * Because we may see inodes that are from the wrong AG
+			 * due to RCU freeing and reallocation, only update the
+			 * index if it lies in this AG. It was a race that lead
+			 * us to see this inode, so another lookup from the
+			 * same index will not find it again.
+			 */
+			if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag->pag_agno)
+				continue;
+			first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
+			if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
+				done = true;
+		}
+
+		/* unlock now we've grabbed the inodes. */
+		rcu_read_unlock();
+
+		for (i = 0; i < nr_found; i++) {
+			if (!batch[i])
+				continue;
+			error = xfs_icwalk_process_inode(goal, batch[i], pag,
+					icw);
+			if (error == -EAGAIN) {
+				skipped++;
+				continue;
+			}
+			if (error && last_error != -EFSCORRUPTED)
+				last_error = error;
+		}
+
+		/* bail out if the filesystem is corrupted.  */
+		if (error == -EFSCORRUPTED)
+			break;
+
+		cond_resched();
+
+		if (icw && (icw->icw_flags & XFS_ICWALK_FLAG_SCAN_LIMIT)) {
+			icw->icw_scan_limit -= XFS_LOOKUP_BATCH;
+			if (icw->icw_scan_limit <= 0)
+				break;
+		}
+	} while (nr_found && !done);
+
+	if (goal == XFS_ICWALK_RECLAIM) {
+		if (done)
+			first_index = 0;
+		WRITE_ONCE(pag->pag_ici_reclaim_cursor, first_index);
+	}
+
+	if (skipped) {
+		delay(1);
+		goto restart;
+	}
+	return last_error;
+}
+
+/* Walk all incore inodes to achieve a given goal. */
+static int
+xfs_icwalk(
+	struct xfs_mount	*mp,
+	enum xfs_icwalk_goal	goal,
+	struct xfs_icwalk	*icw)
+{
+	struct xfs_perag	*pag;
+	int			error = 0;
+	int			last_error = 0;
+	xfs_agnumber_t		agno;
+
+	for_each_perag_tag(mp, agno, pag, goal) {
+		error = xfs_icwalk_ag(pag, goal, icw);
+		if (error) {
+			last_error = error;
+			if (error == -EFSCORRUPTED) {
+				xfs_perag_rele(pag);
+				break;
+			}
+		}
+	}
+	return last_error;
+	BUILD_BUG_ON(XFS_ICWALK_PRIVATE_FLAGS & XFS_ICWALK_FLAGS_VALID);
+}
+
+#ifdef DEBUG
+static void
+xfs_check_delalloc(
+	struct xfs_inode	*ip,
+	int			whichfork)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_bmbt_irec	got;
+	struct xfs_iext_cursor	icur;
+
+	if (!ifp || !xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got))
+		return;
+	do {
+		if (isnullstartblock(got.br_startblock)) {
+			xfs_warn(ip->i_mount,
+	"ino %llx %s fork has delalloc extent at [0x%llx:0x%llx]",
+				ip->i_ino,
+				whichfork == XFS_DATA_FORK ? "data" : "cow",
+				got.br_startoff, got.br_blockcount);
+		}
+	} while (xfs_iext_next_extent(ifp, &icur, &got));
+}
+#else
+#define xfs_check_delalloc(ip, whichfork)	do { } while (0)
+#endif
+
+/* Schedule the inode for reclaim. */
+static void
+xfs_inodegc_set_reclaimable(
+	struct xfs_inode	*ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_perag	*pag;
+
+	if (!xfs_is_shutdown(mp) && ip->i_delayed_blks) {
+		xfs_check_delalloc(ip, XFS_DATA_FORK);
+		xfs_check_delalloc(ip, XFS_COW_FORK);
+		ASSERT(0);
+	}
+
+	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
+	spin_lock(&pag->pag_ici_lock);
+	spin_lock(&ip->i_flags_lock);
+
+	trace_xfs_inode_set_reclaimable(ip);
+	ip->i_flags &= ~(XFS_NEED_INACTIVE | XFS_INACTIVATING);
+	ip->i_flags |= XFS_IRECLAIMABLE;
+	xfs_perag_set_inode_tag(pag, XFS_INO_TO_AGINO(mp, ip->i_ino),
+			XFS_ICI_RECLAIM_TAG);
+
+	spin_unlock(&ip->i_flags_lock);
+	spin_unlock(&pag->pag_ici_lock);
+	xfs_perag_put(pag);
+}
+
+/*
+ * Free all speculative preallocations and possibly even the inode itself.
+ * This is the last chance to make changes to an otherwise unreferenced file
+ * before incore reclamation happens.
+ */
+static int
+xfs_inodegc_inactivate(
+	struct xfs_inode	*ip)
+{
+	int			error;
+
+	trace_xfs_inode_inactivating(ip);
+	error = xfs_inactive(ip);
+	xfs_inodegc_set_reclaimable(ip);
+	return error;
+
+}
+
+void
+xfs_inodegc_worker(
+	struct work_struct	*work)
+{
+	struct xfs_inodegc	*gc = container_of(to_delayed_work(work),
+						struct xfs_inodegc, work);
+	struct llist_node	*node = llist_del_all(&gc->list);
+	struct xfs_inode	*ip, *n;
+	struct xfs_mount	*mp = gc->mp;
+	unsigned int		nofs_flag;
+
+	/*
+	 * Clear the cpu mask bit and ensure that we have seen the latest
+	 * update of the gc structure associated with this CPU. This matches
+	 * with the release semantics used when setting the cpumask bit in
+	 * xfs_inodegc_queue.
+	 */
+	cpumask_clear_cpu(gc->cpu, &mp->m_inodegc_cpumask);
+	smp_mb__after_atomic();
+
+	WRITE_ONCE(gc->items, 0);
+
+	if (!node)
+		return;
+
+	/*
+	 * We can allocate memory here while doing writeback on behalf of
+	 * memory reclaim.  To avoid memory allocation deadlocks set the
+	 * task-wide nofs context for the following operations.
+	 */
+	nofs_flag = memalloc_nofs_save();
+
+	ip = llist_entry(node, struct xfs_inode, i_gclist);
+	trace_xfs_inodegc_worker(mp, READ_ONCE(gc->shrinker_hits));
+
+	WRITE_ONCE(gc->shrinker_hits, 0);
+	llist_for_each_entry_safe(ip, n, node, i_gclist) {
+		int	error;
+
+		xfs_iflags_set(ip, XFS_INACTIVATING);
+		error = xfs_inodegc_inactivate(ip);
+		if (error && !gc->error)
+			gc->error = error;
+	}
+
+	memalloc_nofs_restore(nofs_flag);
+}
+
+/*
+ * Expedite all pending inodegc work to run immediately. This does not wait for
+ * completion of the work.
+ */
+void
+xfs_inodegc_push(
+	struct xfs_mount	*mp)
+{
+	if (!xfs_is_inodegc_enabled(mp))
+		return;
+	trace_xfs_inodegc_push(mp, __return_address);
+	xfs_inodegc_queue_all(mp);
+}
+
+/*
+ * Force all currently queued inode inactivation work to run immediately and
+ * wait for the work to finish.
+ */
+int
+xfs_inodegc_flush(
+	struct xfs_mount	*mp)
+{
+	xfs_inodegc_push(mp);
+	trace_xfs_inodegc_flush(mp, __return_address);
+	return xfs_inodegc_wait_all(mp);
+}
+
+/*
+ * Flush all the pending work and then disable the inode inactivation background
+ * workers and wait for them to stop.  Caller must hold sb->s_umount to
+ * coordinate changes in the inodegc_enabled state.
+ */
+void
+xfs_inodegc_stop(
+	struct xfs_mount	*mp)
+{
+	bool			rerun;
+
+	if (!xfs_clear_inodegc_enabled(mp))
+		return;
+
+	/*
+	 * Drain all pending inodegc work, including inodes that could be
+	 * queued by racing xfs_inodegc_queue or xfs_inodegc_shrinker_scan
+	 * threads that sample the inodegc state just prior to us clearing it.
+	 * The inodegc flag state prevents new threads from queuing more
+	 * inodes, so we queue pending work items and flush the workqueue until
+	 * all inodegc lists are empty.  IOWs, we cannot use drain_workqueue
+	 * here because it does not allow other unserialized mechanisms to
+	 * reschedule inodegc work while this draining is in progress.
+	 */
+	xfs_inodegc_queue_all(mp);
+	do {
+		flush_workqueue(mp->m_inodegc_wq);
+		rerun = xfs_inodegc_queue_all(mp);
+	} while (rerun);
+
+	trace_xfs_inodegc_stop(mp, __return_address);
+}
+
+/*
+ * Enable the inode inactivation background workers and schedule deferred inode
+ * inactivation work if there is any.  Caller must hold sb->s_umount to
+ * coordinate changes in the inodegc_enabled state.
+ */
+void
+xfs_inodegc_start(
+	struct xfs_mount	*mp)
+{
+	if (xfs_set_inodegc_enabled(mp))
+		return;
+
+	trace_xfs_inodegc_start(mp, __return_address);
+	xfs_inodegc_queue_all(mp);
+}
+
+#ifdef CONFIG_XFS_RT
+static inline bool
+xfs_inodegc_want_queue_rt_file(
+	struct xfs_inode	*ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+
+	if (!XFS_IS_REALTIME_INODE(ip))
+		return false;
+
+	if (__percpu_counter_compare(&mp->m_frextents,
+				mp->m_low_rtexts[XFS_LOWSP_5_PCNT],
+				XFS_FDBLOCKS_BATCH) < 0)
+		return true;
+
+	return false;
+}
+#else
+# define xfs_inodegc_want_queue_rt_file(ip)	(false)
+#endif /* CONFIG_XFS_RT */
+
+/*
+ * Schedule the inactivation worker when:
+ *
+ *  - We've accumulated more than one inode cluster buffer's worth of inodes.
+ *  - There is less than 5% free space left.
+ *  - Any of the quotas for this inode are near an enforcement limit.
+ */
+static inline bool
+xfs_inodegc_want_queue_work(
+	struct xfs_inode	*ip,
+	unsigned int		items)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+
+	if (items > mp->m_ino_geo.inodes_per_cluster)
+		return true;
+
+	if (__percpu_counter_compare(&mp->m_fdblocks,
+				mp->m_low_space[XFS_LOWSP_5_PCNT],
+				XFS_FDBLOCKS_BATCH) < 0)
+		return true;
+
+	if (xfs_inodegc_want_queue_rt_file(ip))
+		return true;
+
+	if (xfs_inode_near_dquot_enforcement(ip, XFS_DQTYPE_USER))
+		return true;
+
+	if (xfs_inode_near_dquot_enforcement(ip, XFS_DQTYPE_GROUP))
+		return true;
+
+	if (xfs_inode_near_dquot_enforcement(ip, XFS_DQTYPE_PROJ))
+		return true;
+
+	return false;
+}
+
+/*
+ * Upper bound on the number of inodes in each AG that can be queued for
+ * inactivation at any given time, to avoid monopolizing the workqueue.
+ */
+#define XFS_INODEGC_MAX_BACKLOG		(4 * XFS_INODES_PER_CHUNK)
+
+/*
+ * Make the frontend wait for inactivations when:
+ *
+ *  - Memory shrinkers queued the inactivation worker and it hasn't finished.
+ *  - The queue depth exceeds the maximum allowable percpu backlog.
+ *
+ * Note: If the current thread is running a transaction, we don't ever want to
+ * wait for other transactions because that could introduce a deadlock.
+ */
+static inline bool
+xfs_inodegc_want_flush_work(
+	struct xfs_inode	*ip,
+	unsigned int		items,
+	unsigned int		shrinker_hits)
+{
+	if (current->journal_info)
+		return false;
+
+	if (shrinker_hits > 0)
+		return true;
+
+	if (items > XFS_INODEGC_MAX_BACKLOG)
+		return true;
+
+	return false;
+}
+
+/*
+ * Queue a background inactivation worker if there are inodes that need to be
+ * inactivated and higher level xfs code hasn't disabled the background
+ * workers.
+ */
+static void
+xfs_inodegc_queue(
+	struct xfs_inode	*ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_inodegc	*gc;
+	int			items;
+	unsigned int		shrinker_hits;
+	unsigned int		cpu_nr;
+	unsigned long		queue_delay = 1;
+
+	trace_xfs_inode_set_need_inactive(ip);
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags |= XFS_NEED_INACTIVE;
+	spin_unlock(&ip->i_flags_lock);
+
+	cpu_nr = get_cpu();
+	gc = this_cpu_ptr(mp->m_inodegc);
+	llist_add(&ip->i_gclist, &gc->list);
+	items = READ_ONCE(gc->items);
+	WRITE_ONCE(gc->items, items + 1);
+	shrinker_hits = READ_ONCE(gc->shrinker_hits);
+
+	/*
+	 * Ensure the list add is always seen by anyone who finds the cpumask
+	 * bit set. This effectively gives the cpumask bit set operation
+	 * release ordering semantics.
+	 */
+	smp_mb__before_atomic();
+	if (!cpumask_test_cpu(cpu_nr, &mp->m_inodegc_cpumask))
+		cpumask_test_and_set_cpu(cpu_nr, &mp->m_inodegc_cpumask);
+
+	/*
+	 * We queue the work while holding the current CPU so that the work
+	 * is scheduled to run on this CPU.
+	 */
+	if (!xfs_is_inodegc_enabled(mp)) {
+		put_cpu();
+		return;
+	}
+
+	if (xfs_inodegc_want_queue_work(ip, items))
+		queue_delay = 0;
+
+	trace_xfs_inodegc_queue(mp, __return_address);
+	mod_delayed_work_on(current_cpu(), mp->m_inodegc_wq, &gc->work,
+			queue_delay);
+	put_cpu();
+
+	if (xfs_inodegc_want_flush_work(ip, items, shrinker_hits)) {
+		trace_xfs_inodegc_throttle(mp, __return_address);
+		flush_delayed_work(&gc->work);
+	}
+}
+
+/*
+ * We set the inode flag atomically with the radix tree tag.  Once we get tag
+ * lookups on the radix tree, this inode flag can go away.
+ *
+ * We always use background reclaim here because even if the inode is clean, it
+ * still may be under IO and hence we have wait for IO completion to occur
+ * before we can reclaim the inode. The background reclaim path handles this
+ * more efficiently than we can here, so simply let background reclaim tear down
+ * all inodes.
+ */
+void
+xfs_inode_mark_reclaimable(
+	struct xfs_inode	*ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	bool			need_inactive;
+
+	XFS_STATS_INC(mp, vn_reclaim);
+
+	/*
+	 * We should never get here with any of the reclaim flags already set.
+	 */
+	ASSERT_ALWAYS(!xfs_iflags_test(ip, XFS_ALL_IRECLAIM_FLAGS));
+
+	need_inactive = xfs_inode_needs_inactive(ip);
+	if (need_inactive) {
+		xfs_inodegc_queue(ip);
+		return;
+	}
+
+	/* Going straight to reclaim, so drop the dquots. */
+	xfs_qm_dqdetach(ip);
+	xfs_inodegc_set_reclaimable(ip);
+}
+
+/*
+ * Register a phony shrinker so that we can run background inodegc sooner when
+ * there's memory pressure.  Inactivation does not itself free any memory but
+ * it does make inodes reclaimable, which eventually frees memory.
+ *
+ * The count function, seek value, and batch value are crafted to trigger the
+ * scan function during the second round of scanning.  Hopefully this means
+ * that we reclaimed enough memory that initiating metadata transactions won't
+ * make things worse.
+ */
+#define XFS_INODEGC_SHRINKER_COUNT	(1UL << DEF_PRIORITY)
+#define XFS_INODEGC_SHRINKER_BATCH	((XFS_INODEGC_SHRINKER_COUNT / 2) + 1)
+
+static unsigned long
+xfs_inodegc_shrinker_count(
+	struct shrinker		*shrink,
+	struct shrink_control	*sc)
+{
+	struct xfs_mount	*mp = container_of(shrink, struct xfs_mount,
+						   m_inodegc_shrinker);
+	struct xfs_inodegc	*gc;
+	int			cpu;
+
+	if (!xfs_is_inodegc_enabled(mp))
+		return 0;
+
+	for_each_cpu(cpu, &mp->m_inodegc_cpumask) {
+		gc = per_cpu_ptr(mp->m_inodegc, cpu);
+		if (!llist_empty(&gc->list))
+			return XFS_INODEGC_SHRINKER_COUNT;
+	}
+
+	return 0;
+}
+
+static unsigned long
+xfs_inodegc_shrinker_scan(
+	struct shrinker		*shrink,
+	struct shrink_control	*sc)
+{
+	struct xfs_mount	*mp = container_of(shrink, struct xfs_mount,
+						   m_inodegc_shrinker);
+	struct xfs_inodegc	*gc;
+	int			cpu;
+	bool			no_items = true;
+
+	if (!xfs_is_inodegc_enabled(mp))
+		return SHRINK_STOP;
+
+	trace_xfs_inodegc_shrinker_scan(mp, sc, __return_address);
+
+	for_each_cpu(cpu, &mp->m_inodegc_cpumask) {
+		gc = per_cpu_ptr(mp->m_inodegc, cpu);
+		if (!llist_empty(&gc->list)) {
+			unsigned int	h = READ_ONCE(gc->shrinker_hits);
+
+			WRITE_ONCE(gc->shrinker_hits, h + 1);
+			mod_delayed_work_on(cpu, mp->m_inodegc_wq, &gc->work, 0);
+			no_items = false;
+		}
+	}
+
+	/*
+	 * If there are no inodes to inactivate, we don't want the shrinker
+	 * to think there's deferred work to call us back about.
+	 */
+	if (no_items)
+		return LONG_MAX;
+
+	return SHRINK_STOP;
+}
+
+/* Register a shrinker so we can accelerate inodegc and throttle queuing. */
+int
+xfs_inodegc_register_shrinker(
+	struct xfs_mount	*mp)
+{
+	struct shrinker		*shrink = &mp->m_inodegc_shrinker;
+
+	shrink->count_objects = xfs_inodegc_shrinker_count;
+	shrink->scan_objects = xfs_inodegc_shrinker_scan;
+	shrink->seeks = 0;
+	shrink->flags = SHRINKER_NONSLAB;
+	shrink->batch = XFS_INODEGC_SHRINKER_BATCH;
+
+	return register_shrinker(shrink, "xfs-inodegc:%s", mp->m_super->s_id);
+}