Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 1692 insertions, 0 deletions

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
new file mode 100644
index 000000000..e69a08ed7
--- /dev/null
+++ b/fs/xfs/xfs_icache.c
@@ -0,0 +1,1692 @@
+// 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_sb.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 <linux/iversion.h>
+
+/*
+ * 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 = kmem_cache_alloc(xfs_inode_zone, GFP_KERNEL | __GFP_NOFAIL);
+
+	if (inode_init_always(mp->m_super, VFS_I(ip))) {
+		kmem_cache_free(xfs_inode_zone, ip);
+		return NULL;
+	}
+
+	/* VFS doesn't initialise i_mode or i_state! */
+	VFS_I(ip)->i_mode = 0;
+	VFS_I(ip)->i_state = 0;
+
+	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_afp = NULL;
+	ip->i_cowfp = NULL;
+	memset(&ip->i_df, 0, sizeof(ip->i_df));
+	ip->i_flags = 0;
+	ip->i_delayed_blks = 0;
+	memset(&ip->i_d, 0, sizeof(ip->i_d));
+	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);
+
+	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;
+	}
+
+	if (ip->i_afp) {
+		xfs_idestroy_fork(ip->i_afp);
+		kmem_cache_free(xfs_ifork_zone, ip->i_afp);
+	}
+	if (ip->i_cowfp) {
+		xfs_idestroy_fork(ip->i_cowfp);
+		kmem_cache_free(xfs_ifork_zone, 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_zone, 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();
+}
+
+static void
+xfs_perag_set_reclaim_tag(
+	struct xfs_perag	*pag)
+{
+	struct xfs_mount	*mp = pag->pag_mount;
+
+	lockdep_assert_held(&pag->pag_ici_lock);
+	if (pag->pag_ici_reclaimable++)
+		return;
+
+	/* propagate the reclaim tag up into the perag radix tree */
+	spin_lock(&mp->m_perag_lock);
+	radix_tree_tag_set(&mp->m_perag_tree, pag->pag_agno,
+			   XFS_ICI_RECLAIM_TAG);
+	spin_unlock(&mp->m_perag_lock);
+
+	/* schedule periodic background inode reclaim */
+	xfs_reclaim_work_queue(mp);
+
+	trace_xfs_perag_set_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
+}
+
+static void
+xfs_perag_clear_reclaim_tag(
+	struct xfs_perag	*pag)
+{
+	struct xfs_mount	*mp = pag->pag_mount;
+
+	lockdep_assert_held(&pag->pag_ici_lock);
+	if (--pag->pag_ici_reclaimable)
+		return;
+
+	/* clear the reclaim tag from the perag radix tree */
+	spin_lock(&mp->m_perag_lock);
+	radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno,
+			     XFS_ICI_RECLAIM_TAG);
+	spin_unlock(&mp->m_perag_lock);
+	trace_xfs_perag_clear_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
+}
+
+
+/*
+ * 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.
+ */
+void
+xfs_inode_set_reclaim_tag(
+	struct xfs_inode	*ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_perag	*pag;
+
+	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);
+
+	radix_tree_tag_set(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, ip->i_ino),
+			   XFS_ICI_RECLAIM_TAG);
+	xfs_perag_set_reclaim_tag(pag);
+	__xfs_iflags_set(ip, XFS_IRECLAIMABLE);
+
+	spin_unlock(&ip->i_flags_lock);
+	spin_unlock(&pag->pag_ici_lock);
+	xfs_perag_put(pag);
+}
+
+STATIC void
+xfs_inode_clear_reclaim_tag(
+	struct xfs_perag	*pag,
+	xfs_ino_t		ino)
+{
+	radix_tree_tag_clear(&pag->pag_ici_root,
+			     XFS_INO_TO_AGINO(pag->pag_mount, ino),
+			     XFS_ICI_RECLAIM_TAG);
+	xfs_perag_clear_reclaim_tag(pag);
+}
+
+static void
+xfs_inew_wait(
+	struct xfs_inode	*ip)
+{
+	wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_INEW_BIT);
+	DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_INEW_BIT);
+
+	do {
+		prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
+		if (!xfs_iflags_test(ip, XFS_INEW))
+			break;
+		schedule();
+	} while (true);
+	finish_wait(wq, &wait.wq_entry);
+}
+
+/*
+ * 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;
+	return error;
+}
+
+/*
+ * 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_d.di_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;
+}
+
+/*
+ * 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) {
+		trace_xfs_iget_skip(ip);
+		XFS_STATS_INC(mp, xs_ig_frecycle);
+		error = -EAGAIN;
+		goto out_error;
+	}
+
+
+	/*
+	 * If we are racing with another cache hit that is currently
+	 * instantiating this inode or currently recycling it out of
+	 * reclaimabe state, wait for the initialisation to complete
+	 * before continuing.
+	 *
+	 * 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)) {
+		trace_xfs_iget_skip(ip);
+		XFS_STATS_INC(mp, xs_ig_frecycle);
+		error = -EAGAIN;
+		goto out_error;
+	}
+
+	/*
+	 * 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;
+
+	/*
+	 * If IRECLAIMABLE is set, we've torn down the VFS inode already.
+	 * Need to carefully get it back into useable state.
+	 */
+	if (ip->i_flags & XFS_IRECLAIMABLE) {
+		trace_xfs_iget_reclaim(ip);
+
+		if (flags & XFS_IGET_INCORE) {
+			error = -EAGAIN;
+			goto out_error;
+		}
+
+		/*
+		 * We need to set XFS_IRECLAIM to prevent xfs_reclaim_inode
+		 * from stomping over us while we recycle the inode.  We can't
+		 * clear the radix tree reclaimable 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);
+		if (error) {
+			bool wake;
+			/*
+			 * 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);
+			wake = !!__xfs_iflags_test(ip, XFS_INEW);
+			ip->i_flags &= ~(XFS_INEW | XFS_IRECLAIM);
+			if (wake)
+				wake_up_bit(&ip->i_flags, __XFS_INEW_BIT);
+			ASSERT(ip->i_flags & XFS_IRECLAIMABLE);
+			trace_xfs_iget_reclaim_fail(ip);
+			goto out_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_inode_clear_reclaim_tag(pag, ip->i_ino);
+		inode->i_state = I_NEW;
+		ip->i_sick = 0;
+		ip->i_checked = 0;
+
+		spin_unlock(&ip->i_flags_lock);
+		spin_unlock(&pag->pag_ici_lock);
+	} else {
+		/* If the VFS inode is being torn down, pause and try again. */
+		if (!igrab(inode)) {
+			trace_xfs_iget_skip(ip);
+			error = -EAGAIN;
+			goto out_error;
+		}
+
+		/* 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_error:
+	spin_unlock(&ip->i_flags_lock);
+	rcu_read_unlock();
+	return error;
+}
+
+
+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(mp, 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_MOUNT_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 di_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_sb_version_has_v3inode(&mp->m_sb) &&
+	    (flags & XFS_IGET_CREATE) && !(mp->m_flags & XFS_MOUNT_IKEEP)) {
+		VFS_I(ip)->i_generation = prandom_u32();
+	} else {
+		struct xfs_dinode	*dip;
+		struct xfs_buf		*bp;
+
+		error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &bp, 0);
+		if (error)
+			goto out_destroy;
+
+		error = xfs_inode_from_disk(ip, dip);
+		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_ialloc 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) && error == -EAGAIN) {
+		delay(1);
+		goto again;
+	}
+	xfs_perag_put(pag);
+	return error;
+}
+
+/*
+ * "Is this a cached inode that's also allocated?"
+ *
+ * Look up an inode by number in the given file system.  If the inode is
+ * in cache and isn't in purgatory, return 1 if the inode is allocated
+ * and 0 if it is not.  For all other cases (not in cache, being torn
+ * down, etc.), return a negative error code.
+ *
+ * The caller has to prevent inode allocation and freeing activity,
+ * presumably by locking the AGI buffer.   This is to ensure that an
+ * inode cannot transition from allocated to freed until the caller is
+ * ready to allow that.  If the inode is in an intermediate state (new,
+ * reclaimable, or being reclaimed), -EAGAIN will be returned; if the
+ * inode is not in the cache, -ENOENT will be returned.  The caller must
+ * deal with these scenarios appropriately.
+ *
+ * This is a specialized use case for the online scrubber; if you're
+ * reading this, you probably want xfs_iget.
+ */
+int
+xfs_icache_inode_is_allocated(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	xfs_ino_t		ino,
+	bool			*inuse)
+{
+	struct xfs_inode	*ip;
+	int			error;
+
+	error = xfs_iget(mp, tp, ino, XFS_IGET_INCORE, 0, &ip);
+	if (error)
+		return error;
+
+	*inuse = !!(VFS_I(ip)->i_mode);
+	xfs_irele(ip);
+	return 0;
+}
+
+/*
+ * 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 the given @ip is eligible to be a part of the inode walk, and
+ * grab it if so.  Returns true if it's ready to go or false if we should just
+ * ignore it.
+ */
+STATIC bool
+xfs_inode_walk_ag_grab(
+	struct xfs_inode	*ip,
+	int			flags)
+{
+	struct inode		*inode = VFS_I(ip);
+	bool			newinos = !!(flags & XFS_INODE_WALK_INEW_WAIT);
+
+	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;
+
+	/* avoid new or reclaimable inodes. Leave for reclaim code to flush */
+	if ((!newinos && __xfs_iflags_test(ip, XFS_INEW)) ||
+	    __xfs_iflags_test(ip, XFS_IRECLAIMABLE | XFS_IRECLAIM))
+		goto out_unlock_noent;
+	spin_unlock(&ip->i_flags_lock);
+
+	/* nothing to sync during shutdown */
+	if (XFS_FORCED_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;
+}
+
+/*
+ * For a given per-AG structure @pag, grab, @execute, and rele all incore
+ * inodes with the given radix tree @tag.
+ */
+STATIC int
+xfs_inode_walk_ag(
+	struct xfs_perag	*pag,
+	int			iter_flags,
+	int			(*execute)(struct xfs_inode *ip, void *args),
+	void			*args,
+	int			tag)
+{
+	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;
+	first_index = 0;
+	nr_found = 0;
+	do {
+		struct xfs_inode *batch[XFS_LOOKUP_BATCH];
+		int		error = 0;
+		int		i;
+
+		rcu_read_lock();
+
+		if (tag == XFS_ICI_NO_TAG)
+			nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
+					(void **)batch, first_index,
+					XFS_LOOKUP_BATCH);
+		else
+			nr_found = radix_tree_gang_lookup_tag(
+					&pag->pag_ici_root,
+					(void **) batch, first_index,
+					XFS_LOOKUP_BATCH, tag);
+
+		if (!nr_found) {
+			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_inode_walk_ag_grab(ip, iter_flags))
+				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;
+			if ((iter_flags & XFS_INODE_WALK_INEW_WAIT) &&
+			    xfs_iflags_test(batch[i], XFS_INEW))
+				xfs_inew_wait(batch[i]);
+			error = execute(batch[i], args);
+			xfs_irele(batch[i]);
+			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();
+
+	} while (nr_found && !done);
+
+	if (skipped) {
+		delay(1);
+		goto restart;
+	}
+	return last_error;
+}
+
+/* Fetch the next (possibly tagged) per-AG structure. */
+static inline struct xfs_perag *
+xfs_inode_walk_get_perag(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	int			tag)
+{
+	if (tag == XFS_ICI_NO_TAG)
+		return xfs_perag_get(mp, agno);
+	return xfs_perag_get_tag(mp, agno, tag);
+}
+
+/*
+ * Call the @execute function on all incore inodes matching the radix tree
+ * @tag.
+ */
+int
+xfs_inode_walk(
+	struct xfs_mount	*mp,
+	int			iter_flags,
+	int			(*execute)(struct xfs_inode *ip, void *args),
+	void			*args,
+	int			tag)
+{
+	struct xfs_perag	*pag;
+	int			error = 0;
+	int			last_error = 0;
+	xfs_agnumber_t		ag;
+
+	ag = 0;
+	while ((pag = xfs_inode_walk_get_perag(mp, ag, tag))) {
+		ag = pag->pag_agno + 1;
+		error = xfs_inode_walk_ag(pag, iter_flags, execute, args, tag);
+		xfs_perag_put(pag);
+		if (error) {
+			last_error = error;
+			if (error == -EFSCORRUPTED)
+				break;
+		}
+	}
+	return last_error;
+}
+
+/*
+ * Background scanning to trim post-EOF preallocated space. This is queued
+ * based on the 'speculative_prealloc_lifetime' tunable (5m by default).
+ */
+void
+xfs_queue_eofblocks(
+	struct xfs_mount *mp)
+{
+	rcu_read_lock();
+	if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_EOFBLOCKS_TAG))
+		queue_delayed_work(mp->m_eofblocks_workqueue,
+				   &mp->m_eofblocks_work,
+				   msecs_to_jiffies(xfs_eofb_secs * 1000));
+	rcu_read_unlock();
+}
+
+void
+xfs_eofblocks_worker(
+	struct work_struct *work)
+{
+	struct xfs_mount *mp = container_of(to_delayed_work(work),
+				struct xfs_mount, m_eofblocks_work);
+
+	if (!sb_start_write_trylock(mp->m_super))
+		return;
+	xfs_icache_free_eofblocks(mp, NULL);
+	sb_end_write(mp->m_super);
+
+	xfs_queue_eofblocks(mp);
+}
+
+/*
+ * Background scanning to trim preallocated CoW space. This is queued
+ * based on the 'speculative_cow_prealloc_lifetime' tunable (5m by default).
+ * (We'll just piggyback on the post-EOF prealloc space workqueue.)
+ */
+void
+xfs_queue_cowblocks(
+	struct xfs_mount *mp)
+{
+	rcu_read_lock();
+	if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_COWBLOCKS_TAG))
+		queue_delayed_work(mp->m_eofblocks_workqueue,
+				   &mp->m_cowblocks_work,
+				   msecs_to_jiffies(xfs_cowb_secs * 1000));
+	rcu_read_unlock();
+}
+
+void
+xfs_cowblocks_worker(
+	struct work_struct *work)
+{
+	struct xfs_mount *mp = container_of(to_delayed_work(work),
+				struct xfs_mount, m_cowblocks_work);
+
+	if (!sb_start_write_trylock(mp->m_super))
+		return;
+	xfs_icache_free_cowblocks(mp, NULL);
+	sb_end_write(mp->m_super);
+
+	xfs_queue_cowblocks(mp);
+}
+
+/*
+ * 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_inode_grab(
+	struct xfs_inode	*ip)
+{
+	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;
+	}
+	__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;
+
+	if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+		xfs_iunpin_wait(ip);
+		xfs_iflush_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:
+
+	/*
+	 * 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;
+	spin_unlock(&ip->i_flags_lock);
+
+	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_reclaim_tag(pag);
+	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);
+	xfs_qm_dqdetach(ip);
+	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);
+}
+
+/*
+ * Walk the AGs and reclaim the inodes in them. Even if the filesystem is
+ * corrupted, we still want to try to reclaim all the inodes. If we don't,
+ * then a shut down during filesystem unmount reclaim walk leak all the
+ * unreclaimed inodes.
+ *
+ * Returns non-zero if any AGs or inodes were skipped in the reclaim pass
+ * so that callers that want to block until all dirty inodes are written back
+ * and reclaimed can sanely loop.
+ */
+static void
+xfs_reclaim_inodes_ag(
+	struct xfs_mount	*mp,
+	int			*nr_to_scan)
+{
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		ag = 0;
+
+	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
+		unsigned long	first_index = 0;
+		int		done = 0;
+		int		nr_found = 0;
+
+		ag = pag->pag_agno + 1;
+
+		first_index = READ_ONCE(pag->pag_ici_reclaim_cursor);
+		do {
+			struct xfs_inode *batch[XFS_LOOKUP_BATCH];
+			int	i;
+
+			rcu_read_lock();
+			nr_found = radix_tree_gang_lookup_tag(
+					&pag->pag_ici_root,
+					(void **)batch, first_index,
+					XFS_LOOKUP_BATCH,
+					XFS_ICI_RECLAIM_TAG);
+			if (!nr_found) {
+				done = 1;
+				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_reclaim_inode_grab(ip))
+					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 = 1;
+			}
+
+			/* unlock now we've grabbed the inodes. */
+			rcu_read_unlock();
+
+			for (i = 0; i < nr_found; i++) {
+				if (batch[i])
+					xfs_reclaim_inode(batch[i], pag);
+			}
+
+			*nr_to_scan -= XFS_LOOKUP_BATCH;
+			cond_resched();
+		} while (nr_found && !done && *nr_to_scan > 0);
+
+		if (done)
+			first_index = 0;
+		WRITE_ONCE(pag->pag_ici_reclaim_cursor, first_index);
+		xfs_perag_put(pag);
+	}
+}
+
+void
+xfs_reclaim_inodes(
+	struct xfs_mount	*mp)
+{
+	int		nr_to_scan = INT_MAX;
+
+	while (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
+		xfs_ail_push_all_sync(mp->m_ail);
+		xfs_reclaim_inodes_ag(mp, &nr_to_scan);
+	}
+}
+
+/*
+ * 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,
+	int			nr_to_scan)
+{
+	/* kick background reclaimer and push the AIL */
+	xfs_reclaim_work_queue(mp);
+	xfs_ail_push_all(mp->m_ail);
+
+	xfs_reclaim_inodes_ag(mp, &nr_to_scan);
+	return 0;
+}
+
+/*
+ * Return the number of reclaimable inodes in the filesystem for
+ * the shrinker to determine how much to reclaim.
+ */
+int
+xfs_reclaim_inodes_count(
+	struct xfs_mount	*mp)
+{
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		ag = 0;
+	int			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_inode_match_id(
+	struct xfs_inode	*ip,
+	struct xfs_eofblocks	*eofb)
+{
+	if ((eofb->eof_flags & XFS_EOF_FLAGS_UID) &&
+	    !uid_eq(VFS_I(ip)->i_uid, eofb->eof_uid))
+		return false;
+
+	if ((eofb->eof_flags & XFS_EOF_FLAGS_GID) &&
+	    !gid_eq(VFS_I(ip)->i_gid, eofb->eof_gid))
+		return false;
+
+	if ((eofb->eof_flags & XFS_EOF_FLAGS_PRID) &&
+	    ip->i_d.di_projid != eofb->eof_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_inode_match_id_union(
+	struct xfs_inode	*ip,
+	struct xfs_eofblocks	*eofb)
+{
+	if ((eofb->eof_flags & XFS_EOF_FLAGS_UID) &&
+	    uid_eq(VFS_I(ip)->i_uid, eofb->eof_uid))
+		return true;
+
+	if ((eofb->eof_flags & XFS_EOF_FLAGS_GID) &&
+	    gid_eq(VFS_I(ip)->i_gid, eofb->eof_gid))
+		return true;
+
+	if ((eofb->eof_flags & XFS_EOF_FLAGS_PRID) &&
+	    ip->i_d.di_projid == eofb->eof_prid)
+		return true;
+
+	return false;
+}
+
+/*
+ * Is this inode @ip eligible for eof/cow block reclamation, given some
+ * filtering parameters @eofb?  The inode is eligible if @eofb is null or
+ * if the predicate functions match.
+ */
+static bool
+xfs_inode_matches_eofb(
+	struct xfs_inode	*ip,
+	struct xfs_eofblocks	*eofb)
+{
+	bool			match;
+
+	if (!eofb)
+		return true;
+
+	if (eofb->eof_flags & XFS_EOF_FLAGS_UNION)
+		match = xfs_inode_match_id_union(ip, eofb);
+	else
+		match = xfs_inode_match_id(ip, eofb);
+	if (!match)
+		return false;
+
+	/* skip the inode if the file size is too small */
+	if ((eofb->eof_flags & XFS_EOF_FLAGS_MINFILESIZE) &&
+	    XFS_ISIZE(ip) < eofb->eof_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);
+	int		nr_to_scan = INT_MAX;
+
+	xfs_reclaim_inodes_ag(mp, &nr_to_scan);
+	xfs_reclaim_work_queue(mp);
+}
+
+STATIC int
+xfs_inode_free_eofblocks(
+	struct xfs_inode	*ip,
+	void			*args)
+{
+	struct xfs_eofblocks	*eofb = args;
+	bool			wait;
+	int			ret;
+
+	wait = eofb && (eofb->eof_flags & XFS_EOF_FLAGS_SYNC);
+
+	if (!xfs_can_free_eofblocks(ip, false)) {
+		/* inode could be preallocated or append-only */
+		trace_xfs_inode_free_eofblocks_invalid(ip);
+		xfs_inode_clear_eofblocks_tag(ip);
+		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_inode_matches_eofb(ip, eofb))
+		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;
+	}
+
+	ret = xfs_free_eofblocks(ip);
+	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+
+	return ret;
+}
+
+int
+xfs_icache_free_eofblocks(
+	struct xfs_mount	*mp,
+	struct xfs_eofblocks	*eofb)
+{
+	return xfs_inode_walk(mp, 0, xfs_inode_free_eofblocks, eofb,
+			XFS_ICI_EOFBLOCKS_TAG);
+}
+
+/*
+ * Run eofblocks scans on the quotas applicable to the inode. For inodes with
+ * multiple quotas, we don't know exactly which quota caused an allocation
+ * failure. We make a best effort by including each quota under low free space
+ * conditions (less than 1% free space) in the scan.
+ */
+static int
+__xfs_inode_free_quota_eofblocks(
+	struct xfs_inode	*ip,
+	int			(*execute)(struct xfs_mount *mp,
+					   struct xfs_eofblocks	*eofb))
+{
+	int scan = 0;
+	struct xfs_eofblocks eofb = {0};
+	struct xfs_dquot *dq;
+
+	/*
+	 * Run a sync scan to increase effectiveness and use the union filter to
+	 * cover all applicable quotas in a single scan.
+	 */
+	eofb.eof_flags = XFS_EOF_FLAGS_UNION|XFS_EOF_FLAGS_SYNC;
+
+	if (XFS_IS_UQUOTA_ENFORCED(ip->i_mount)) {
+		dq = xfs_inode_dquot(ip, XFS_DQTYPE_USER);
+		if (dq && xfs_dquot_lowsp(dq)) {
+			eofb.eof_uid = VFS_I(ip)->i_uid;
+			eofb.eof_flags |= XFS_EOF_FLAGS_UID;
+			scan = 1;
+		}
+	}
+
+	if (XFS_IS_GQUOTA_ENFORCED(ip->i_mount)) {
+		dq = xfs_inode_dquot(ip, XFS_DQTYPE_GROUP);
+		if (dq && xfs_dquot_lowsp(dq)) {
+			eofb.eof_gid = VFS_I(ip)->i_gid;
+			eofb.eof_flags |= XFS_EOF_FLAGS_GID;
+			scan = 1;
+		}
+	}
+
+	if (scan)
+		execute(ip->i_mount, &eofb);
+
+	return scan;
+}
+
+int
+xfs_inode_free_quota_eofblocks(
+	struct xfs_inode *ip)
+{
+	return __xfs_inode_free_quota_eofblocks(ip, xfs_icache_free_eofblocks);
+}
+
+static inline unsigned long
+xfs_iflag_for_tag(
+	int		tag)
+{
+	switch (tag) {
+	case XFS_ICI_EOFBLOCKS_TAG:
+		return XFS_IEOFBLOCKS;
+	case XFS_ICI_COWBLOCKS_TAG:
+		return XFS_ICOWBLOCKS;
+	default:
+		ASSERT(0);
+		return 0;
+	}
+}
+
+static void
+__xfs_inode_set_blocks_tag(
+	xfs_inode_t	*ip,
+	void		(*execute)(struct xfs_mount *mp),
+	void		(*set_tp)(struct xfs_mount *mp, xfs_agnumber_t agno,
+				  int error, unsigned long caller_ip),
+	int		tag)
+{
+	struct xfs_mount *mp = ip->i_mount;
+	struct xfs_perag *pag;
+	int tagged;
+
+	/*
+	 * 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 & xfs_iflag_for_tag(tag))
+		return;
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags |= xfs_iflag_for_tag(tag);
+	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);
+
+	tagged = radix_tree_tagged(&pag->pag_ici_root, tag);
+	radix_tree_tag_set(&pag->pag_ici_root,
+			   XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino), tag);
+	if (!tagged) {
+		/* propagate the eofblocks tag up into the perag radix tree */
+		spin_lock(&ip->i_mount->m_perag_lock);
+		radix_tree_tag_set(&ip->i_mount->m_perag_tree,
+				   XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
+				   tag);
+		spin_unlock(&ip->i_mount->m_perag_lock);
+
+		/* kick off background trimming */
+		execute(ip->i_mount);
+
+		set_tp(ip->i_mount, pag->pag_agno, -1, _RET_IP_);
+	}
+
+	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_inode_set_blocks_tag(ip, xfs_queue_eofblocks,
+			trace_xfs_perag_set_eofblocks,
+			XFS_ICI_EOFBLOCKS_TAG);
+}
+
+static void
+__xfs_inode_clear_blocks_tag(
+	xfs_inode_t	*ip,
+	void		(*clear_tp)(struct xfs_mount *mp, xfs_agnumber_t agno,
+				    int error, unsigned long caller_ip),
+	int		tag)
+{
+	struct xfs_mount *mp = ip->i_mount;
+	struct xfs_perag *pag;
+
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags &= ~xfs_iflag_for_tag(tag);
+	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);
+
+	radix_tree_tag_clear(&pag->pag_ici_root,
+			     XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino), tag);
+	if (!radix_tree_tagged(&pag->pag_ici_root, tag)) {
+		/* clear the eofblocks tag from the perag radix tree */
+		spin_lock(&ip->i_mount->m_perag_lock);
+		radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
+				     XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
+				     tag);
+		spin_unlock(&ip->i_mount->m_perag_lock);
+		clear_tp(ip->i_mount, pag->pag_agno, -1, _RET_IP_);
+	}
+
+	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_inode_clear_blocks_tag(ip,
+			trace_xfs_perag_clear_eofblocks, XFS_ICI_EOFBLOCKS_TAG);
+}
+
+/*
+ * 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,
+	void			*args)
+{
+	struct xfs_eofblocks	*eofb = args;
+	int			ret = 0;
+
+	if (!xfs_prep_free_cowblocks(ip))
+		return 0;
+
+	if (!xfs_inode_matches_eofb(ip, eofb))
+		return 0;
+
+	/* Free the CoW blocks */
+	xfs_ilock(ip, XFS_IOLOCK_EXCL);
+	xfs_ilock(ip, 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);
+
+	xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
+	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+
+	return ret;
+}
+
+int
+xfs_icache_free_cowblocks(
+	struct xfs_mount	*mp,
+	struct xfs_eofblocks	*eofb)
+{
+	return xfs_inode_walk(mp, 0, xfs_inode_free_cowblocks, eofb,
+			XFS_ICI_COWBLOCKS_TAG);
+}
+
+int
+xfs_inode_free_quota_cowblocks(
+	struct xfs_inode *ip)
+{
+	return __xfs_inode_free_quota_eofblocks(ip, xfs_icache_free_cowblocks);
+}
+
+void
+xfs_inode_set_cowblocks_tag(
+	xfs_inode_t	*ip)
+{
+	trace_xfs_inode_set_cowblocks_tag(ip);
+	return __xfs_inode_set_blocks_tag(ip, xfs_queue_cowblocks,
+			trace_xfs_perag_set_cowblocks,
+			XFS_ICI_COWBLOCKS_TAG);
+}
+
+void
+xfs_inode_clear_cowblocks_tag(
+	xfs_inode_t	*ip)
+{
+	trace_xfs_inode_clear_cowblocks_tag(ip);
+	return __xfs_inode_clear_blocks_tag(ip,
+			trace_xfs_perag_clear_cowblocks, XFS_ICI_COWBLOCKS_TAG);
+}
+
+/* Disable post-EOF and CoW block auto-reclamation. */
+void
+xfs_stop_block_reaping(
+	struct xfs_mount	*mp)
+{
+	cancel_delayed_work_sync(&mp->m_eofblocks_work);
+	cancel_delayed_work_sync(&mp->m_cowblocks_work);
+}
+
+/* Enable post-EOF and CoW block auto-reclamation. */
+void
+xfs_start_block_reaping(
+	struct xfs_mount	*mp)
+{
+	xfs_queue_eofblocks(mp);
+	xfs_queue_cowblocks(mp);
+}