Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 2595 insertions, 0 deletions

diff --git a/fs/inode.c b/fs/inode.c
new file mode 100644
index 000000000..ae1a6410b
--- /dev/null
+++ b/fs/inode.c
@@ -0,0 +1,2595 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * (C) 1997 Linus Torvalds
+ * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation)
+ */
+#include <linux/export.h>
+#include <linux/fs.h>
+#include <linux/filelock.h>
+#include <linux/mm.h>
+#include <linux/backing-dev.h>
+#include <linux/hash.h>
+#include <linux/swap.h>
+#include <linux/security.h>
+#include <linux/cdev.h>
+#include <linux/memblock.h>
+#include <linux/fsnotify.h>
+#include <linux/mount.h>
+#include <linux/posix_acl.h>
+#include <linux/buffer_head.h> /* for inode_has_buffers */
+#include <linux/ratelimit.h>
+#include <linux/list_lru.h>
+#include <linux/iversion.h>
+#include <trace/events/writeback.h>
+#include "internal.h"
+
+/*
+ * Inode locking rules:
+ *
+ * inode->i_lock protects:
+ *   inode->i_state, inode->i_hash, __iget(), inode->i_io_list
+ * Inode LRU list locks protect:
+ *   inode->i_sb->s_inode_lru, inode->i_lru
+ * inode->i_sb->s_inode_list_lock protects:
+ *   inode->i_sb->s_inodes, inode->i_sb_list
+ * bdi->wb.list_lock protects:
+ *   bdi->wb.b_{dirty,io,more_io,dirty_time}, inode->i_io_list
+ * inode_hash_lock protects:
+ *   inode_hashtable, inode->i_hash
+ *
+ * Lock ordering:
+ *
+ * inode->i_sb->s_inode_list_lock
+ *   inode->i_lock
+ *     Inode LRU list locks
+ *
+ * bdi->wb.list_lock
+ *   inode->i_lock
+ *
+ * inode_hash_lock
+ *   inode->i_sb->s_inode_list_lock
+ *   inode->i_lock
+ *
+ * iunique_lock
+ *   inode_hash_lock
+ */
+
+static unsigned int i_hash_mask __read_mostly;
+static unsigned int i_hash_shift __read_mostly;
+static struct hlist_head *inode_hashtable __read_mostly;
+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
+
+/*
+ * Empty aops. Can be used for the cases where the user does not
+ * define any of the address_space operations.
+ */
+const struct address_space_operations empty_aops = {
+};
+EXPORT_SYMBOL(empty_aops);
+
+static DEFINE_PER_CPU(unsigned long, nr_inodes);
+static DEFINE_PER_CPU(unsigned long, nr_unused);
+
+static struct kmem_cache *inode_cachep __read_mostly;
+
+static long get_nr_inodes(void)
+{
+	int i;
+	long sum = 0;
+	for_each_possible_cpu(i)
+		sum += per_cpu(nr_inodes, i);
+	return sum < 0 ? 0 : sum;
+}
+
+static inline long get_nr_inodes_unused(void)
+{
+	int i;
+	long sum = 0;
+	for_each_possible_cpu(i)
+		sum += per_cpu(nr_unused, i);
+	return sum < 0 ? 0 : sum;
+}
+
+long get_nr_dirty_inodes(void)
+{
+	/* not actually dirty inodes, but a wild approximation */
+	long nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
+	return nr_dirty > 0 ? nr_dirty : 0;
+}
+
+/*
+ * Handle nr_inode sysctl
+ */
+#ifdef CONFIG_SYSCTL
+/*
+ * Statistics gathering..
+ */
+static struct inodes_stat_t inodes_stat;
+
+static int proc_nr_inodes(struct ctl_table *table, int write, void *buffer,
+			  size_t *lenp, loff_t *ppos)
+{
+	inodes_stat.nr_inodes = get_nr_inodes();
+	inodes_stat.nr_unused = get_nr_inodes_unused();
+	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+}
+
+static struct ctl_table inodes_sysctls[] = {
+	{
+		.procname	= "inode-nr",
+		.data		= &inodes_stat,
+		.maxlen		= 2*sizeof(long),
+		.mode		= 0444,
+		.proc_handler	= proc_nr_inodes,
+	},
+	{
+		.procname	= "inode-state",
+		.data		= &inodes_stat,
+		.maxlen		= 7*sizeof(long),
+		.mode		= 0444,
+		.proc_handler	= proc_nr_inodes,
+	},
+	{ }
+};
+
+static int __init init_fs_inode_sysctls(void)
+{
+	register_sysctl_init("fs", inodes_sysctls);
+	return 0;
+}
+early_initcall(init_fs_inode_sysctls);
+#endif
+
+static int no_open(struct inode *inode, struct file *file)
+{
+	return -ENXIO;
+}
+
+/**
+ * inode_init_always - perform inode structure initialisation
+ * @sb: superblock inode belongs to
+ * @inode: inode to initialise
+ *
+ * These are initializations that need to be done on every inode
+ * allocation as the fields are not initialised by slab allocation.
+ */
+int inode_init_always(struct super_block *sb, struct inode *inode)
+{
+	static const struct inode_operations empty_iops;
+	static const struct file_operations no_open_fops = {.open = no_open};
+	struct address_space *const mapping = &inode->i_data;
+
+	inode->i_sb = sb;
+	inode->i_blkbits = sb->s_blocksize_bits;
+	inode->i_flags = 0;
+	atomic64_set(&inode->i_sequence, 0);
+	atomic_set(&inode->i_count, 1);
+	inode->i_op = &empty_iops;
+	inode->i_fop = &no_open_fops;
+	inode->i_ino = 0;
+	inode->__i_nlink = 1;
+	inode->i_opflags = 0;
+	if (sb->s_xattr)
+		inode->i_opflags |= IOP_XATTR;
+	i_uid_write(inode, 0);
+	i_gid_write(inode, 0);
+	atomic_set(&inode->i_writecount, 0);
+	inode->i_size = 0;
+	inode->i_write_hint = WRITE_LIFE_NOT_SET;
+	inode->i_blocks = 0;
+	inode->i_bytes = 0;
+	inode->i_generation = 0;
+	inode->i_pipe = NULL;
+	inode->i_cdev = NULL;
+	inode->i_link = NULL;
+	inode->i_dir_seq = 0;
+	inode->i_rdev = 0;
+	inode->dirtied_when = 0;
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+	inode->i_wb_frn_winner = 0;
+	inode->i_wb_frn_avg_time = 0;
+	inode->i_wb_frn_history = 0;
+#endif
+
+	spin_lock_init(&inode->i_lock);
+	lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
+
+	init_rwsem(&inode->i_rwsem);
+	lockdep_set_class(&inode->i_rwsem, &sb->s_type->i_mutex_key);
+
+	atomic_set(&inode->i_dio_count, 0);
+
+	mapping->a_ops = &empty_aops;
+	mapping->host = inode;
+	mapping->flags = 0;
+	mapping->wb_err = 0;
+	atomic_set(&mapping->i_mmap_writable, 0);
+#ifdef CONFIG_READ_ONLY_THP_FOR_FS
+	atomic_set(&mapping->nr_thps, 0);
+#endif
+	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
+	mapping->private_data = NULL;
+	mapping->writeback_index = 0;
+	init_rwsem(&mapping->invalidate_lock);
+	lockdep_set_class_and_name(&mapping->invalidate_lock,
+				   &sb->s_type->invalidate_lock_key,
+				   "mapping.invalidate_lock");
+	if (sb->s_iflags & SB_I_STABLE_WRITES)
+		mapping_set_stable_writes(mapping);
+	inode->i_private = NULL;
+	inode->i_mapping = mapping;
+	INIT_HLIST_HEAD(&inode->i_dentry);	/* buggered by rcu freeing */
+#ifdef CONFIG_FS_POSIX_ACL
+	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
+#endif
+
+#ifdef CONFIG_FSNOTIFY
+	inode->i_fsnotify_mask = 0;
+#endif
+	inode->i_flctx = NULL;
+
+	if (unlikely(security_inode_alloc(inode)))
+		return -ENOMEM;
+	this_cpu_inc(nr_inodes);
+
+	return 0;
+}
+EXPORT_SYMBOL(inode_init_always);
+
+void free_inode_nonrcu(struct inode *inode)
+{
+	kmem_cache_free(inode_cachep, inode);
+}
+EXPORT_SYMBOL(free_inode_nonrcu);
+
+static void i_callback(struct rcu_head *head)
+{
+	struct inode *inode = container_of(head, struct inode, i_rcu);
+	if (inode->free_inode)
+		inode->free_inode(inode);
+	else
+		free_inode_nonrcu(inode);
+}
+
+static struct inode *alloc_inode(struct super_block *sb)
+{
+	const struct super_operations *ops = sb->s_op;
+	struct inode *inode;
+
+	if (ops->alloc_inode)
+		inode = ops->alloc_inode(sb);
+	else
+		inode = alloc_inode_sb(sb, inode_cachep, GFP_KERNEL);
+
+	if (!inode)
+		return NULL;
+
+	if (unlikely(inode_init_always(sb, inode))) {
+		if (ops->destroy_inode) {
+			ops->destroy_inode(inode);
+			if (!ops->free_inode)
+				return NULL;
+		}
+		inode->free_inode = ops->free_inode;
+		i_callback(&inode->i_rcu);
+		return NULL;
+	}
+
+	return inode;
+}
+
+void __destroy_inode(struct inode *inode)
+{
+	BUG_ON(inode_has_buffers(inode));
+	inode_detach_wb(inode);
+	security_inode_free(inode);
+	fsnotify_inode_delete(inode);
+	locks_free_lock_context(inode);
+	if (!inode->i_nlink) {
+		WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);
+		atomic_long_dec(&inode->i_sb->s_remove_count);
+	}
+
+#ifdef CONFIG_FS_POSIX_ACL
+	if (inode->i_acl && !is_uncached_acl(inode->i_acl))
+		posix_acl_release(inode->i_acl);
+	if (inode->i_default_acl && !is_uncached_acl(inode->i_default_acl))
+		posix_acl_release(inode->i_default_acl);
+#endif
+	this_cpu_dec(nr_inodes);
+}
+EXPORT_SYMBOL(__destroy_inode);
+
+static void destroy_inode(struct inode *inode)
+{
+	const struct super_operations *ops = inode->i_sb->s_op;
+
+	BUG_ON(!list_empty(&inode->i_lru));
+	__destroy_inode(inode);
+	if (ops->destroy_inode) {
+		ops->destroy_inode(inode);
+		if (!ops->free_inode)
+			return;
+	}
+	inode->free_inode = ops->free_inode;
+	call_rcu(&inode->i_rcu, i_callback);
+}
+
+/**
+ * drop_nlink - directly drop an inode's link count
+ * @inode: inode
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink.  In cases
+ * where we are attempting to track writes to the
+ * filesystem, a decrement to zero means an imminent
+ * write when the file is truncated and actually unlinked
+ * on the filesystem.
+ */
+void drop_nlink(struct inode *inode)
+{
+	WARN_ON(inode->i_nlink == 0);
+	inode->__i_nlink--;
+	if (!inode->i_nlink)
+		atomic_long_inc(&inode->i_sb->s_remove_count);
+}
+EXPORT_SYMBOL(drop_nlink);
+
+/**
+ * clear_nlink - directly zero an inode's link count
+ * @inode: inode
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink.  See
+ * drop_nlink() for why we care about i_nlink hitting zero.
+ */
+void clear_nlink(struct inode *inode)
+{
+	if (inode->i_nlink) {
+		inode->__i_nlink = 0;
+		atomic_long_inc(&inode->i_sb->s_remove_count);
+	}
+}
+EXPORT_SYMBOL(clear_nlink);
+
+/**
+ * set_nlink - directly set an inode's link count
+ * @inode: inode
+ * @nlink: new nlink (should be non-zero)
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink.
+ */
+void set_nlink(struct inode *inode, unsigned int nlink)
+{
+	if (!nlink) {
+		clear_nlink(inode);
+	} else {
+		/* Yes, some filesystems do change nlink from zero to one */
+		if (inode->i_nlink == 0)
+			atomic_long_dec(&inode->i_sb->s_remove_count);
+
+		inode->__i_nlink = nlink;
+	}
+}
+EXPORT_SYMBOL(set_nlink);
+
+/**
+ * inc_nlink - directly increment an inode's link count
+ * @inode: inode
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink.  Currently,
+ * it is only here for parity with dec_nlink().
+ */
+void inc_nlink(struct inode *inode)
+{
+	if (unlikely(inode->i_nlink == 0)) {
+		WARN_ON(!(inode->i_state & I_LINKABLE));
+		atomic_long_dec(&inode->i_sb->s_remove_count);
+	}
+
+	inode->__i_nlink++;
+}
+EXPORT_SYMBOL(inc_nlink);
+
+static void __address_space_init_once(struct address_space *mapping)
+{
+	xa_init_flags(&mapping->i_pages, XA_FLAGS_LOCK_IRQ | XA_FLAGS_ACCOUNT);
+	init_rwsem(&mapping->i_mmap_rwsem);
+	INIT_LIST_HEAD(&mapping->private_list);
+	spin_lock_init(&mapping->private_lock);
+	mapping->i_mmap = RB_ROOT_CACHED;
+}
+
+void address_space_init_once(struct address_space *mapping)
+{
+	memset(mapping, 0, sizeof(*mapping));
+	__address_space_init_once(mapping);
+}
+EXPORT_SYMBOL(address_space_init_once);
+
+/*
+ * These are initializations that only need to be done
+ * once, because the fields are idempotent across use
+ * of the inode, so let the slab aware of that.
+ */
+void inode_init_once(struct inode *inode)
+{
+	memset(inode, 0, sizeof(*inode));
+	INIT_HLIST_NODE(&inode->i_hash);
+	INIT_LIST_HEAD(&inode->i_devices);
+	INIT_LIST_HEAD(&inode->i_io_list);
+	INIT_LIST_HEAD(&inode->i_wb_list);
+	INIT_LIST_HEAD(&inode->i_lru);
+	INIT_LIST_HEAD(&inode->i_sb_list);
+	__address_space_init_once(&inode->i_data);
+	i_size_ordered_init(inode);
+}
+EXPORT_SYMBOL(inode_init_once);
+
+static void init_once(void *foo)
+{
+	struct inode *inode = (struct inode *) foo;
+
+	inode_init_once(inode);
+}
+
+/*
+ * inode->i_lock must be held
+ */
+void __iget(struct inode *inode)
+{
+	atomic_inc(&inode->i_count);
+}
+
+/*
+ * get additional reference to inode; caller must already hold one.
+ */
+void ihold(struct inode *inode)
+{
+	WARN_ON(atomic_inc_return(&inode->i_count) < 2);
+}
+EXPORT_SYMBOL(ihold);
+
+static void __inode_add_lru(struct inode *inode, bool rotate)
+{
+	if (inode->i_state & (I_DIRTY_ALL | I_SYNC | I_FREEING | I_WILL_FREE))
+		return;
+	if (atomic_read(&inode->i_count))
+		return;
+	if (!(inode->i_sb->s_flags & SB_ACTIVE))
+		return;
+	if (!mapping_shrinkable(&inode->i_data))
+		return;
+
+	if (list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru))
+		this_cpu_inc(nr_unused);
+	else if (rotate)
+		inode->i_state |= I_REFERENCED;
+}
+
+/*
+ * Add inode to LRU if needed (inode is unused and clean).
+ *
+ * Needs inode->i_lock held.
+ */
+void inode_add_lru(struct inode *inode)
+{
+	__inode_add_lru(inode, false);
+}
+
+static void inode_lru_list_del(struct inode *inode)
+{
+	if (list_lru_del(&inode->i_sb->s_inode_lru, &inode->i_lru))
+		this_cpu_dec(nr_unused);
+}
+
+/**
+ * inode_sb_list_add - add inode to the superblock list of inodes
+ * @inode: inode to add
+ */
+void inode_sb_list_add(struct inode *inode)
+{
+	spin_lock(&inode->i_sb->s_inode_list_lock);
+	list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
+	spin_unlock(&inode->i_sb->s_inode_list_lock);
+}
+EXPORT_SYMBOL_GPL(inode_sb_list_add);
+
+static inline void inode_sb_list_del(struct inode *inode)
+{
+	if (!list_empty(&inode->i_sb_list)) {
+		spin_lock(&inode->i_sb->s_inode_list_lock);
+		list_del_init(&inode->i_sb_list);
+		spin_unlock(&inode->i_sb->s_inode_list_lock);
+	}
+}
+
+static unsigned long hash(struct super_block *sb, unsigned long hashval)
+{
+	unsigned long tmp;
+
+	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
+			L1_CACHE_BYTES;
+	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
+	return tmp & i_hash_mask;
+}
+
+/**
+ *	__insert_inode_hash - hash an inode
+ *	@inode: unhashed inode
+ *	@hashval: unsigned long value used to locate this object in the
+ *		inode_hashtable.
+ *
+ *	Add an inode to the inode hash for this superblock.
+ */
+void __insert_inode_hash(struct inode *inode, unsigned long hashval)
+{
+	struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
+
+	spin_lock(&inode_hash_lock);
+	spin_lock(&inode->i_lock);
+	hlist_add_head_rcu(&inode->i_hash, b);
+	spin_unlock(&inode->i_lock);
+	spin_unlock(&inode_hash_lock);
+}
+EXPORT_SYMBOL(__insert_inode_hash);
+
+/**
+ *	__remove_inode_hash - remove an inode from the hash
+ *	@inode: inode to unhash
+ *
+ *	Remove an inode from the superblock.
+ */
+void __remove_inode_hash(struct inode *inode)
+{
+	spin_lock(&inode_hash_lock);
+	spin_lock(&inode->i_lock);
+	hlist_del_init_rcu(&inode->i_hash);
+	spin_unlock(&inode->i_lock);
+	spin_unlock(&inode_hash_lock);
+}
+EXPORT_SYMBOL(__remove_inode_hash);
+
+void dump_mapping(const struct address_space *mapping)
+{
+	struct inode *host;
+	const struct address_space_operations *a_ops;
+	struct hlist_node *dentry_first;
+	struct dentry *dentry_ptr;
+	struct dentry dentry;
+	unsigned long ino;
+
+	/*
+	 * If mapping is an invalid pointer, we don't want to crash
+	 * accessing it, so probe everything depending on it carefully.
+	 */
+	if (get_kernel_nofault(host, &mapping->host) ||
+	    get_kernel_nofault(a_ops, &mapping->a_ops)) {
+		pr_warn("invalid mapping:%px\n", mapping);
+		return;
+	}
+
+	if (!host) {
+		pr_warn("aops:%ps\n", a_ops);
+		return;
+	}
+
+	if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
+	    get_kernel_nofault(ino, &host->i_ino)) {
+		pr_warn("aops:%ps invalid inode:%px\n", a_ops, host);
+		return;
+	}
+
+	if (!dentry_first) {
+		pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
+		return;
+	}
+
+	dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
+	if (get_kernel_nofault(dentry, dentry_ptr)) {
+		pr_warn("aops:%ps ino:%lx invalid dentry:%px\n",
+				a_ops, ino, dentry_ptr);
+		return;
+	}
+
+	/*
+	 * if dentry is corrupted, the %pd handler may still crash,
+	 * but it's unlikely that we reach here with a corrupt mapping
+	 */
+	pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n", a_ops, ino, &dentry);
+}
+
+void clear_inode(struct inode *inode)
+{
+	/*
+	 * We have to cycle the i_pages lock here because reclaim can be in the
+	 * process of removing the last page (in __filemap_remove_folio())
+	 * and we must not free the mapping under it.
+	 */
+	xa_lock_irq(&inode->i_data.i_pages);
+	BUG_ON(inode->i_data.nrpages);
+	/*
+	 * Almost always, mapping_empty(&inode->i_data) here; but there are
+	 * two known and long-standing ways in which nodes may get left behind
+	 * (when deep radix-tree node allocation failed partway; or when THP
+	 * collapse_file() failed). Until those two known cases are cleaned up,
+	 * or a cleanup function is called here, do not BUG_ON(!mapping_empty),
+	 * nor even WARN_ON(!mapping_empty).
+	 */
+	xa_unlock_irq(&inode->i_data.i_pages);
+	BUG_ON(!list_empty(&inode->i_data.private_list));
+	BUG_ON(!(inode->i_state & I_FREEING));
+	BUG_ON(inode->i_state & I_CLEAR);
+	BUG_ON(!list_empty(&inode->i_wb_list));
+	/* don't need i_lock here, no concurrent mods to i_state */
+	inode->i_state = I_FREEING | I_CLEAR;
+}
+EXPORT_SYMBOL(clear_inode);
+
+/*
+ * Free the inode passed in, removing it from the lists it is still connected
+ * to. We remove any pages still attached to the inode and wait for any IO that
+ * is still in progress before finally destroying the inode.
+ *
+ * An inode must already be marked I_FREEING so that we avoid the inode being
+ * moved back onto lists if we race with other code that manipulates the lists
+ * (e.g. writeback_single_inode). The caller is responsible for setting this.
+ *
+ * An inode must already be removed from the LRU list before being evicted from
+ * the cache. This should occur atomically with setting the I_FREEING state
+ * flag, so no inodes here should ever be on the LRU when being evicted.
+ */
+static void evict(struct inode *inode)
+{
+	const struct super_operations *op = inode->i_sb->s_op;
+
+	BUG_ON(!(inode->i_state & I_FREEING));
+	BUG_ON(!list_empty(&inode->i_lru));
+
+	if (!list_empty(&inode->i_io_list))
+		inode_io_list_del(inode);
+
+	inode_sb_list_del(inode);
+
+	/*
+	 * Wait for flusher thread to be done with the inode so that filesystem
+	 * does not start destroying it while writeback is still running. Since
+	 * the inode has I_FREEING set, flusher thread won't start new work on
+	 * the inode.  We just have to wait for running writeback to finish.
+	 */
+	inode_wait_for_writeback(inode);
+
+	if (op->evict_inode) {
+		op->evict_inode(inode);
+	} else {
+		truncate_inode_pages_final(&inode->i_data);
+		clear_inode(inode);
+	}
+	if (S_ISCHR(inode->i_mode) && inode->i_cdev)
+		cd_forget(inode);
+
+	remove_inode_hash(inode);
+
+	spin_lock(&inode->i_lock);
+	wake_up_bit(&inode->i_state, __I_NEW);
+	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
+	spin_unlock(&inode->i_lock);
+
+	destroy_inode(inode);
+}
+
+/*
+ * dispose_list - dispose of the contents of a local list
+ * @head: the head of the list to free
+ *
+ * Dispose-list gets a local list with local inodes in it, so it doesn't
+ * need to worry about list corruption and SMP locks.
+ */
+static void dispose_list(struct list_head *head)
+{
+	while (!list_empty(head)) {
+		struct inode *inode;
+
+		inode = list_first_entry(head, struct inode, i_lru);
+		list_del_init(&inode->i_lru);
+
+		evict(inode);
+		cond_resched();
+	}
+}
+
+/**
+ * evict_inodes	- evict all evictable inodes for a superblock
+ * @sb:		superblock to operate on
+ *
+ * Make sure that no inodes with zero refcount are retained.  This is
+ * called by superblock shutdown after having SB_ACTIVE flag removed,
+ * so any inode reaching zero refcount during or after that call will
+ * be immediately evicted.
+ */
+void evict_inodes(struct super_block *sb)
+{
+	struct inode *inode, *next;
+	LIST_HEAD(dispose);
+
+again:
+	spin_lock(&sb->s_inode_list_lock);
+	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
+		if (atomic_read(&inode->i_count))
+			continue;
+
+		spin_lock(&inode->i_lock);
+		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+
+		inode->i_state |= I_FREEING;
+		inode_lru_list_del(inode);
+		spin_unlock(&inode->i_lock);
+		list_add(&inode->i_lru, &dispose);
+
+		/*
+		 * We can have a ton of inodes to evict at unmount time given
+		 * enough memory, check to see if we need to go to sleep for a
+		 * bit so we don't livelock.
+		 */
+		if (need_resched()) {
+			spin_unlock(&sb->s_inode_list_lock);
+			cond_resched();
+			dispose_list(&dispose);
+			goto again;
+		}
+	}
+	spin_unlock(&sb->s_inode_list_lock);
+
+	dispose_list(&dispose);
+}
+EXPORT_SYMBOL_GPL(evict_inodes);
+
+/**
+ * invalidate_inodes	- attempt to free all inodes on a superblock
+ * @sb:		superblock to operate on
+ *
+ * Attempts to free all inodes (including dirty inodes) for a given superblock.
+ */
+void invalidate_inodes(struct super_block *sb)
+{
+	struct inode *inode, *next;
+	LIST_HEAD(dispose);
+
+again:
+	spin_lock(&sb->s_inode_list_lock);
+	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
+		spin_lock(&inode->i_lock);
+		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+		if (atomic_read(&inode->i_count)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+
+		inode->i_state |= I_FREEING;
+		inode_lru_list_del(inode);
+		spin_unlock(&inode->i_lock);
+		list_add(&inode->i_lru, &dispose);
+		if (need_resched()) {
+			spin_unlock(&sb->s_inode_list_lock);
+			cond_resched();
+			dispose_list(&dispose);
+			goto again;
+		}
+	}
+	spin_unlock(&sb->s_inode_list_lock);
+
+	dispose_list(&dispose);
+}
+
+/*
+ * Isolate the inode from the LRU in preparation for freeing it.
+ *
+ * If the inode has the I_REFERENCED flag set, then it means that it has been
+ * used recently - the flag is set in iput_final(). When we encounter such an
+ * inode, clear the flag and move it to the back of the LRU so it gets another
+ * pass through the LRU before it gets reclaimed. This is necessary because of
+ * the fact we are doing lazy LRU updates to minimise lock contention so the
+ * LRU does not have strict ordering. Hence we don't want to reclaim inodes
+ * with this flag set because they are the inodes that are out of order.
+ */
+static enum lru_status inode_lru_isolate(struct list_head *item,
+		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+{
+	struct list_head *freeable = arg;
+	struct inode	*inode = container_of(item, struct inode, i_lru);
+
+	/*
+	 * We are inverting the lru lock/inode->i_lock here, so use a
+	 * trylock. If we fail to get the lock, just skip it.
+	 */
+	if (!spin_trylock(&inode->i_lock))
+		return LRU_SKIP;
+
+	/*
+	 * Inodes can get referenced, redirtied, or repopulated while
+	 * they're already on the LRU, and this can make them
+	 * unreclaimable for a while. Remove them lazily here; iput,
+	 * sync, or the last page cache deletion will requeue them.
+	 */
+	if (atomic_read(&inode->i_count) ||
+	    (inode->i_state & ~I_REFERENCED) ||
+	    !mapping_shrinkable(&inode->i_data)) {
+		list_lru_isolate(lru, &inode->i_lru);
+		spin_unlock(&inode->i_lock);
+		this_cpu_dec(nr_unused);
+		return LRU_REMOVED;
+	}
+
+	/* Recently referenced inodes get one more pass */
+	if (inode->i_state & I_REFERENCED) {
+		inode->i_state &= ~I_REFERENCED;
+		spin_unlock(&inode->i_lock);
+		return LRU_ROTATE;
+	}
+
+	/*
+	 * On highmem systems, mapping_shrinkable() permits dropping
+	 * page cache in order to free up struct inodes: lowmem might
+	 * be under pressure before the cache inside the highmem zone.
+	 */
+	if (inode_has_buffers(inode) || !mapping_empty(&inode->i_data)) {
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		spin_unlock(lru_lock);
+		if (remove_inode_buffers(inode)) {
+			unsigned long reap;
+			reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
+			if (current_is_kswapd())
+				__count_vm_events(KSWAPD_INODESTEAL, reap);
+			else
+				__count_vm_events(PGINODESTEAL, reap);
+			mm_account_reclaimed_pages(reap);
+		}
+		iput(inode);
+		spin_lock(lru_lock);
+		return LRU_RETRY;
+	}
+
+	WARN_ON(inode->i_state & I_NEW);
+	inode->i_state |= I_FREEING;
+	list_lru_isolate_move(lru, &inode->i_lru, freeable);
+	spin_unlock(&inode->i_lock);
+
+	this_cpu_dec(nr_unused);
+	return LRU_REMOVED;
+}
+
+/*
+ * Walk the superblock inode LRU for freeable inodes and attempt to free them.
+ * This is called from the superblock shrinker function with a number of inodes
+ * to trim from the LRU. Inodes to be freed are moved to a temporary list and
+ * then are freed outside inode_lock by dispose_list().
+ */
+long prune_icache_sb(struct super_block *sb, struct shrink_control *sc)
+{
+	LIST_HEAD(freeable);
+	long freed;
+
+	freed = list_lru_shrink_walk(&sb->s_inode_lru, sc,
+				     inode_lru_isolate, &freeable);
+	dispose_list(&freeable);
+	return freed;
+}
+
+static void __wait_on_freeing_inode(struct inode *inode);
+/*
+ * Called with the inode lock held.
+ */
+static struct inode *find_inode(struct super_block *sb,
+				struct hlist_head *head,
+				int (*test)(struct inode *, void *),
+				void *data)
+{
+	struct inode *inode = NULL;
+
+repeat:
+	hlist_for_each_entry(inode, head, i_hash) {
+		if (inode->i_sb != sb)
+			continue;
+		if (!test(inode, data))
+			continue;
+		spin_lock(&inode->i_lock);
+		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
+			__wait_on_freeing_inode(inode);
+			goto repeat;
+		}
+		if (unlikely(inode->i_state & I_CREATING)) {
+			spin_unlock(&inode->i_lock);
+			return ERR_PTR(-ESTALE);
+		}
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		return inode;
+	}
+	return NULL;
+}
+
+/*
+ * find_inode_fast is the fast path version of find_inode, see the comment at
+ * iget_locked for details.
+ */
+static struct inode *find_inode_fast(struct super_block *sb,
+				struct hlist_head *head, unsigned long ino)
+{
+	struct inode *inode = NULL;
+
+repeat:
+	hlist_for_each_entry(inode, head, i_hash) {
+		if (inode->i_ino != ino)
+			continue;
+		if (inode->i_sb != sb)
+			continue;
+		spin_lock(&inode->i_lock);
+		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
+			__wait_on_freeing_inode(inode);
+			goto repeat;
+		}
+		if (unlikely(inode->i_state & I_CREATING)) {
+			spin_unlock(&inode->i_lock);
+			return ERR_PTR(-ESTALE);
+		}
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		return inode;
+	}
+	return NULL;
+}
+
+/*
+ * Each cpu owns a range of LAST_INO_BATCH numbers.
+ * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
+ * to renew the exhausted range.
+ *
+ * This does not significantly increase overflow rate because every CPU can
+ * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
+ * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
+ * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
+ * overflow rate by 2x, which does not seem too significant.
+ *
+ * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
+ * error if st_ino won't fit in target struct field. Use 32bit counter
+ * here to attempt to avoid that.
+ */
+#define LAST_INO_BATCH 1024
+static DEFINE_PER_CPU(unsigned int, last_ino);
+
+unsigned int get_next_ino(void)
+{
+	unsigned int *p = &get_cpu_var(last_ino);
+	unsigned int res = *p;
+
+#ifdef CONFIG_SMP
+	if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
+		static atomic_t shared_last_ino;
+		int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
+
+		res = next - LAST_INO_BATCH;
+	}
+#endif
+
+	res++;
+	/* get_next_ino should not provide a 0 inode number */
+	if (unlikely(!res))
+		res++;
+	*p = res;
+	put_cpu_var(last_ino);
+	return res;
+}
+EXPORT_SYMBOL(get_next_ino);
+
+/**
+ *	new_inode_pseudo 	- obtain an inode
+ *	@sb: superblock
+ *
+ *	Allocates a new inode for given superblock.
+ *	Inode wont be chained in superblock s_inodes list
+ *	This means :
+ *	- fs can't be unmount
+ *	- quotas, fsnotify, writeback can't work
+ */
+struct inode *new_inode_pseudo(struct super_block *sb)
+{
+	struct inode *inode = alloc_inode(sb);
+
+	if (inode) {
+		spin_lock(&inode->i_lock);
+		inode->i_state = 0;
+		spin_unlock(&inode->i_lock);
+	}
+	return inode;
+}
+
+/**
+ *	new_inode 	- obtain an inode
+ *	@sb: superblock
+ *
+ *	Allocates a new inode for given superblock. The default gfp_mask
+ *	for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
+ *	If HIGHMEM pages are unsuitable or it is known that pages allocated
+ *	for the page cache are not reclaimable or migratable,
+ *	mapping_set_gfp_mask() must be called with suitable flags on the
+ *	newly created inode's mapping
+ *
+ */
+struct inode *new_inode(struct super_block *sb)
+{
+	struct inode *inode;
+
+	inode = new_inode_pseudo(sb);
+	if (inode)
+		inode_sb_list_add(inode);
+	return inode;
+}
+EXPORT_SYMBOL(new_inode);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void lockdep_annotate_inode_mutex_key(struct inode *inode)
+{
+	if (S_ISDIR(inode->i_mode)) {
+		struct file_system_type *type = inode->i_sb->s_type;
+
+		/* Set new key only if filesystem hasn't already changed it */
+		if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) {
+			/*
+			 * ensure nobody is actually holding i_mutex
+			 */
+			// mutex_destroy(&inode->i_mutex);
+			init_rwsem(&inode->i_rwsem);
+			lockdep_set_class(&inode->i_rwsem,
+					  &type->i_mutex_dir_key);
+		}
+	}
+}
+EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
+#endif
+
+/**
+ * unlock_new_inode - clear the I_NEW state and wake up any waiters
+ * @inode:	new inode to unlock
+ *
+ * Called when the inode is fully initialised to clear the new state of the
+ * inode and wake up anyone waiting for the inode to finish initialisation.
+ */
+void unlock_new_inode(struct inode *inode)
+{
+	lockdep_annotate_inode_mutex_key(inode);
+	spin_lock(&inode->i_lock);
+	WARN_ON(!(inode->i_state & I_NEW));
+	inode->i_state &= ~I_NEW & ~I_CREATING;
+	smp_mb();
+	wake_up_bit(&inode->i_state, __I_NEW);
+	spin_unlock(&inode->i_lock);
+}
+EXPORT_SYMBOL(unlock_new_inode);
+
+void discard_new_inode(struct inode *inode)
+{
+	lockdep_annotate_inode_mutex_key(inode);
+	spin_lock(&inode->i_lock);
+	WARN_ON(!(inode->i_state & I_NEW));
+	inode->i_state &= ~I_NEW;
+	smp_mb();
+	wake_up_bit(&inode->i_state, __I_NEW);
+	spin_unlock(&inode->i_lock);
+	iput(inode);
+}
+EXPORT_SYMBOL(discard_new_inode);
+
+/**
+ * lock_two_inodes - lock two inodes (may be regular files but also dirs)
+ *
+ * Lock any non-NULL argument. The caller must make sure that if he is passing
+ * in two directories, one is not ancestor of the other.  Zero, one or two
+ * objects may be locked by this function.
+ *
+ * @inode1: first inode to lock
+ * @inode2: second inode to lock
+ * @subclass1: inode lock subclass for the first lock obtained
+ * @subclass2: inode lock subclass for the second lock obtained
+ */
+void lock_two_inodes(struct inode *inode1, struct inode *inode2,
+		     unsigned subclass1, unsigned subclass2)
+{
+	if (!inode1 || !inode2) {
+		/*
+		 * Make sure @subclass1 will be used for the acquired lock.
+		 * This is not strictly necessary (no current caller cares) but
+		 * let's keep things consistent.
+		 */
+		if (!inode1)
+			swap(inode1, inode2);
+		goto lock;
+	}
+
+	/*
+	 * If one object is directory and the other is not, we must make sure
+	 * to lock directory first as the other object may be its child.
+	 */
+	if (S_ISDIR(inode2->i_mode) == S_ISDIR(inode1->i_mode)) {
+		if (inode1 > inode2)
+			swap(inode1, inode2);
+	} else if (!S_ISDIR(inode1->i_mode))
+		swap(inode1, inode2);
+lock:
+	if (inode1)
+		inode_lock_nested(inode1, subclass1);
+	if (inode2 && inode2 != inode1)
+		inode_lock_nested(inode2, subclass2);
+}
+
+/**
+ * lock_two_nondirectories - take two i_mutexes on non-directory objects
+ *
+ * Lock any non-NULL argument. Passed objects must not be directories.
+ * Zero, one or two objects may be locked by this function.
+ *
+ * @inode1: first inode to lock
+ * @inode2: second inode to lock
+ */
+void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
+{
+	if (inode1)
+		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
+	if (inode2)
+		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
+	lock_two_inodes(inode1, inode2, I_MUTEX_NORMAL, I_MUTEX_NONDIR2);
+}
+EXPORT_SYMBOL(lock_two_nondirectories);
+
+/**
+ * unlock_two_nondirectories - release locks from lock_two_nondirectories()
+ * @inode1: first inode to unlock
+ * @inode2: second inode to unlock
+ */
+void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
+{
+	if (inode1) {
+		WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
+		inode_unlock(inode1);
+	}
+	if (inode2 && inode2 != inode1) {
+		WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
+		inode_unlock(inode2);
+	}
+}
+EXPORT_SYMBOL(unlock_two_nondirectories);
+
+/**
+ * inode_insert5 - obtain an inode from a mounted file system
+ * @inode:	pre-allocated inode to use for insert to cache
+ * @hashval:	hash value (usually inode number) to get
+ * @test:	callback used for comparisons between inodes
+ * @set:	callback used to initialize a new struct inode
+ * @data:	opaque data pointer to pass to @test and @set
+ *
+ * Search for the inode specified by @hashval and @data in the inode cache,
+ * and if present it is return it with an increased reference count. This is
+ * a variant of iget5_locked() for callers that don't want to fail on memory
+ * allocation of inode.
+ *
+ * If the inode is not in cache, insert the pre-allocated inode to cache and
+ * return it locked, hashed, and with the I_NEW flag set. The file system gets
+ * to fill it in before unlocking it via unlock_new_inode().
+ *
+ * Note both @test and @set are called with the inode_hash_lock held, so can't
+ * sleep.
+ */
+struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
+			    int (*test)(struct inode *, void *),
+			    int (*set)(struct inode *, void *), void *data)
+{
+	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
+	struct inode *old;
+
+again:
+	spin_lock(&inode_hash_lock);
+	old = find_inode(inode->i_sb, head, test, data);
+	if (unlikely(old)) {
+		/*
+		 * Uhhuh, somebody else created the same inode under us.
+		 * Use the old inode instead of the preallocated one.
+		 */
+		spin_unlock(&inode_hash_lock);
+		if (IS_ERR(old))
+			return NULL;
+		wait_on_inode(old);
+		if (unlikely(inode_unhashed(old))) {
+			iput(old);
+			goto again;
+		}
+		return old;
+	}
+
+	if (set && unlikely(set(inode, data))) {
+		inode = NULL;
+		goto unlock;
+	}
+
+	/*
+	 * Return the locked inode with I_NEW set, the
+	 * caller is responsible for filling in the contents
+	 */
+	spin_lock(&inode->i_lock);
+	inode->i_state |= I_NEW;
+	hlist_add_head_rcu(&inode->i_hash, head);
+	spin_unlock(&inode->i_lock);
+
+	/*
+	 * Add inode to the sb list if it's not already. It has I_NEW at this
+	 * point, so it should be safe to test i_sb_list locklessly.
+	 */
+	if (list_empty(&inode->i_sb_list))
+		inode_sb_list_add(inode);
+unlock:
+	spin_unlock(&inode_hash_lock);
+
+	return inode;
+}
+EXPORT_SYMBOL(inode_insert5);
+
+/**
+ * iget5_locked - obtain an inode from a mounted file system
+ * @sb:		super block of file system
+ * @hashval:	hash value (usually inode number) to get
+ * @test:	callback used for comparisons between inodes
+ * @set:	callback used to initialize a new struct inode
+ * @data:	opaque data pointer to pass to @test and @set
+ *
+ * Search for the inode specified by @hashval and @data in the inode cache,
+ * and if present it is return it with an increased reference count. This is
+ * a generalized version of iget_locked() for file systems where the inode
+ * number is not sufficient for unique identification of an inode.
+ *
+ * If the inode is not in cache, allocate a new inode and return it locked,
+ * hashed, and with the I_NEW flag set. The file system gets to fill it in
+ * before unlocking it via unlock_new_inode().
+ *
+ * Note both @test and @set are called with the inode_hash_lock held, so can't
+ * sleep.
+ */
+struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
+		int (*test)(struct inode *, void *),
+		int (*set)(struct inode *, void *), void *data)
+{
+	struct inode *inode = ilookup5(sb, hashval, test, data);
+
+	if (!inode) {
+		struct inode *new = alloc_inode(sb);
+
+		if (new) {
+			new->i_state = 0;
+			inode = inode_insert5(new, hashval, test, set, data);
+			if (unlikely(inode != new))
+				destroy_inode(new);
+		}
+	}
+	return inode;
+}
+EXPORT_SYMBOL(iget5_locked);
+
+/**
+ * iget_locked - obtain an inode from a mounted file system
+ * @sb:		super block of file system
+ * @ino:	inode number to get
+ *
+ * Search for the inode specified by @ino in the inode cache and if present
+ * return it with an increased reference count. This is for file systems
+ * where the inode number is sufficient for unique identification of an inode.
+ *
+ * If the inode is not in cache, allocate a new inode and return it locked,
+ * hashed, and with the I_NEW flag set.  The file system gets to fill it in
+ * before unlocking it via unlock_new_inode().
+ */
+struct inode *iget_locked(struct super_block *sb, unsigned long ino)
+{
+	struct hlist_head *head = inode_hashtable + hash(sb, ino);
+	struct inode *inode;
+again:
+	spin_lock(&inode_hash_lock);
+	inode = find_inode_fast(sb, head, ino);
+	spin_unlock(&inode_hash_lock);
+	if (inode) {
+		if (IS_ERR(inode))
+			return NULL;
+		wait_on_inode(inode);
+		if (unlikely(inode_unhashed(inode))) {
+			iput(inode);
+			goto again;
+		}
+		return inode;
+	}
+
+	inode = alloc_inode(sb);
+	if (inode) {
+		struct inode *old;
+
+		spin_lock(&inode_hash_lock);
+		/* We released the lock, so.. */
+		old = find_inode_fast(sb, head, ino);
+		if (!old) {
+			inode->i_ino = ino;
+			spin_lock(&inode->i_lock);
+			inode->i_state = I_NEW;
+			hlist_add_head_rcu(&inode->i_hash, head);
+			spin_unlock(&inode->i_lock);
+			inode_sb_list_add(inode);
+			spin_unlock(&inode_hash_lock);
+
+			/* Return the locked inode with I_NEW set, the
+			 * caller is responsible for filling in the contents
+			 */
+			return inode;
+		}
+
+		/*
+		 * Uhhuh, somebody else created the same inode under
+		 * us. Use the old inode instead of the one we just
+		 * allocated.
+		 */
+		spin_unlock(&inode_hash_lock);
+		destroy_inode(inode);
+		if (IS_ERR(old))
+			return NULL;
+		inode = old;
+		wait_on_inode(inode);
+		if (unlikely(inode_unhashed(inode))) {
+			iput(inode);
+			goto again;
+		}
+	}
+	return inode;
+}
+EXPORT_SYMBOL(iget_locked);
+
+/*
+ * search the inode cache for a matching inode number.
+ * If we find one, then the inode number we are trying to
+ * allocate is not unique and so we should not use it.
+ *
+ * Returns 1 if the inode number is unique, 0 if it is not.
+ */
+static int test_inode_iunique(struct super_block *sb, unsigned long ino)
+{
+	struct hlist_head *b = inode_hashtable + hash(sb, ino);
+	struct inode *inode;
+
+	hlist_for_each_entry_rcu(inode, b, i_hash) {
+		if (inode->i_ino == ino && inode->i_sb == sb)
+			return 0;
+	}
+	return 1;
+}
+
+/**
+ *	iunique - get a unique inode number
+ *	@sb: superblock
+ *	@max_reserved: highest reserved inode number
+ *
+ *	Obtain an inode number that is unique on the system for a given
+ *	superblock. This is used by file systems that have no natural
+ *	permanent inode numbering system. An inode number is returned that
+ *	is higher than the reserved limit but unique.
+ *
+ *	BUGS:
+ *	With a large number of inodes live on the file system this function
+ *	currently becomes quite slow.
+ */
+ino_t iunique(struct super_block *sb, ino_t max_reserved)
+{
+	/*
+	 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
+	 * error if st_ino won't fit in target struct field. Use 32bit counter
+	 * here to attempt to avoid that.
+	 */
+	static DEFINE_SPINLOCK(iunique_lock);
+	static unsigned int counter;
+	ino_t res;
+
+	rcu_read_lock();
+	spin_lock(&iunique_lock);
+	do {
+		if (counter <= max_reserved)
+			counter = max_reserved + 1;
+		res = counter++;
+	} while (!test_inode_iunique(sb, res));
+	spin_unlock(&iunique_lock);
+	rcu_read_unlock();
+
+	return res;
+}
+EXPORT_SYMBOL(iunique);
+
+struct inode *igrab(struct inode *inode)
+{
+	spin_lock(&inode->i_lock);
+	if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+	} else {
+		spin_unlock(&inode->i_lock);
+		/*
+		 * Handle the case where s_op->clear_inode is not been
+		 * called yet, and somebody is calling igrab
+		 * while the inode is getting freed.
+		 */
+		inode = NULL;
+	}
+	return inode;
+}
+EXPORT_SYMBOL(igrab);
+
+/**
+ * ilookup5_nowait - search for an inode in the inode cache
+ * @sb:		super block of file system to search
+ * @hashval:	hash value (usually inode number) to search for
+ * @test:	callback used for comparisons between inodes
+ * @data:	opaque data pointer to pass to @test
+ *
+ * Search for the inode specified by @hashval and @data in the inode cache.
+ * If the inode is in the cache, the inode is returned with an incremented
+ * reference count.
+ *
+ * Note: I_NEW is not waited upon so you have to be very careful what you do
+ * with the returned inode.  You probably should be using ilookup5() instead.
+ *
+ * Note2: @test is called with the inode_hash_lock held, so can't sleep.
+ */
+struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
+		int (*test)(struct inode *, void *), void *data)
+{
+	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+	struct inode *inode;
+
+	spin_lock(&inode_hash_lock);
+	inode = find_inode(sb, head, test, data);
+	spin_unlock(&inode_hash_lock);
+
+	return IS_ERR(inode) ? NULL : inode;
+}
+EXPORT_SYMBOL(ilookup5_nowait);
+
+/**
+ * ilookup5 - search for an inode in the inode cache
+ * @sb:		super block of file system to search
+ * @hashval:	hash value (usually inode number) to search for
+ * @test:	callback used for comparisons between inodes
+ * @data:	opaque data pointer to pass to @test
+ *
+ * Search for the inode specified by @hashval and @data in the inode cache,
+ * and if the inode is in the cache, return the inode with an incremented
+ * reference count.  Waits on I_NEW before returning the inode.
+ * returned with an incremented reference count.
+ *
+ * This is a generalized version of ilookup() for file systems where the
+ * inode number is not sufficient for unique identification of an inode.
+ *
+ * Note: @test is called with the inode_hash_lock held, so can't sleep.
+ */
+struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
+		int (*test)(struct inode *, void *), void *data)
+{
+	struct inode *inode;
+again:
+	inode = ilookup5_nowait(sb, hashval, test, data);
+	if (inode) {
+		wait_on_inode(inode);
+		if (unlikely(inode_unhashed(inode))) {
+			iput(inode);
+			goto again;
+		}
+	}
+	return inode;
+}
+EXPORT_SYMBOL(ilookup5);
+
+/**
+ * ilookup - search for an inode in the inode cache
+ * @sb:		super block of file system to search
+ * @ino:	inode number to search for
+ *
+ * Search for the inode @ino in the inode cache, and if the inode is in the
+ * cache, the inode is returned with an incremented reference count.
+ */
+struct inode *ilookup(struct super_block *sb, unsigned long ino)
+{
+	struct hlist_head *head = inode_hashtable + hash(sb, ino);
+	struct inode *inode;
+again:
+	spin_lock(&inode_hash_lock);
+	inode = find_inode_fast(sb, head, ino);
+	spin_unlock(&inode_hash_lock);
+
+	if (inode) {
+		if (IS_ERR(inode))
+			return NULL;
+		wait_on_inode(inode);
+		if (unlikely(inode_unhashed(inode))) {
+			iput(inode);
+			goto again;
+		}
+	}
+	return inode;
+}
+EXPORT_SYMBOL(ilookup);
+
+/**
+ * find_inode_nowait - find an inode in the inode cache
+ * @sb:		super block of file system to search
+ * @hashval:	hash value (usually inode number) to search for
+ * @match:	callback used for comparisons between inodes
+ * @data:	opaque data pointer to pass to @match
+ *
+ * Search for the inode specified by @hashval and @data in the inode
+ * cache, where the helper function @match will return 0 if the inode
+ * does not match, 1 if the inode does match, and -1 if the search
+ * should be stopped.  The @match function must be responsible for
+ * taking the i_lock spin_lock and checking i_state for an inode being
+ * freed or being initialized, and incrementing the reference count
+ * before returning 1.  It also must not sleep, since it is called with
+ * the inode_hash_lock spinlock held.
+ *
+ * This is a even more generalized version of ilookup5() when the
+ * function must never block --- find_inode() can block in
+ * __wait_on_freeing_inode() --- or when the caller can not increment
+ * the reference count because the resulting iput() might cause an
+ * inode eviction.  The tradeoff is that the @match funtion must be
+ * very carefully implemented.
+ */
+struct inode *find_inode_nowait(struct super_block *sb,
+				unsigned long hashval,
+				int (*match)(struct inode *, unsigned long,
+					     void *),
+				void *data)
+{
+	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+	struct inode *inode, *ret_inode = NULL;
+	int mval;
+
+	spin_lock(&inode_hash_lock);
+	hlist_for_each_entry(inode, head, i_hash) {
+		if (inode->i_sb != sb)
+			continue;
+		mval = match(inode, hashval, data);
+		if (mval == 0)
+			continue;
+		if (mval == 1)
+			ret_inode = inode;
+		goto out;
+	}
+out:
+	spin_unlock(&inode_hash_lock);
+	return ret_inode;
+}
+EXPORT_SYMBOL(find_inode_nowait);
+
+/**
+ * find_inode_rcu - find an inode in the inode cache
+ * @sb:		Super block of file system to search
+ * @hashval:	Key to hash
+ * @test:	Function to test match on an inode
+ * @data:	Data for test function
+ *
+ * Search for the inode specified by @hashval and @data in the inode cache,
+ * where the helper function @test will return 0 if the inode does not match
+ * and 1 if it does.  The @test function must be responsible for taking the
+ * i_lock spin_lock and checking i_state for an inode being freed or being
+ * initialized.
+ *
+ * If successful, this will return the inode for which the @test function
+ * returned 1 and NULL otherwise.
+ *
+ * The @test function is not permitted to take a ref on any inode presented.
+ * It is also not permitted to sleep.
+ *
+ * The caller must hold the RCU read lock.
+ */
+struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval,
+			     int (*test)(struct inode *, void *), void *data)
+{
+	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+	struct inode *inode;
+
+	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
+			 "suspicious find_inode_rcu() usage");
+
+	hlist_for_each_entry_rcu(inode, head, i_hash) {
+		if (inode->i_sb == sb &&
+		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)) &&
+		    test(inode, data))
+			return inode;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(find_inode_rcu);
+
+/**
+ * find_inode_by_ino_rcu - Find an inode in the inode cache
+ * @sb:		Super block of file system to search
+ * @ino:	The inode number to match
+ *
+ * Search for the inode specified by @hashval and @data in the inode cache,
+ * where the helper function @test will return 0 if the inode does not match
+ * and 1 if it does.  The @test function must be responsible for taking the
+ * i_lock spin_lock and checking i_state for an inode being freed or being
+ * initialized.
+ *
+ * If successful, this will return the inode for which the @test function
+ * returned 1 and NULL otherwise.
+ *
+ * The @test function is not permitted to take a ref on any inode presented.
+ * It is also not permitted to sleep.
+ *
+ * The caller must hold the RCU read lock.
+ */
+struct inode *find_inode_by_ino_rcu(struct super_block *sb,
+				    unsigned long ino)
+{
+	struct hlist_head *head = inode_hashtable + hash(sb, ino);
+	struct inode *inode;
+
+	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
+			 "suspicious find_inode_by_ino_rcu() usage");
+
+	hlist_for_each_entry_rcu(inode, head, i_hash) {
+		if (inode->i_ino == ino &&
+		    inode->i_sb == sb &&
+		    !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)))
+		    return inode;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(find_inode_by_ino_rcu);
+
+int insert_inode_locked(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	ino_t ino = inode->i_ino;
+	struct hlist_head *head = inode_hashtable + hash(sb, ino);
+
+	while (1) {
+		struct inode *old = NULL;
+		spin_lock(&inode_hash_lock);
+		hlist_for_each_entry(old, head, i_hash) {
+			if (old->i_ino != ino)
+				continue;
+			if (old->i_sb != sb)
+				continue;
+			spin_lock(&old->i_lock);
+			if (old->i_state & (I_FREEING|I_WILL_FREE)) {
+				spin_unlock(&old->i_lock);
+				continue;
+			}
+			break;
+		}
+		if (likely(!old)) {
+			spin_lock(&inode->i_lock);
+			inode->i_state |= I_NEW | I_CREATING;
+			hlist_add_head_rcu(&inode->i_hash, head);
+			spin_unlock(&inode->i_lock);
+			spin_unlock(&inode_hash_lock);
+			return 0;
+		}
+		if (unlikely(old->i_state & I_CREATING)) {
+			spin_unlock(&old->i_lock);
+			spin_unlock(&inode_hash_lock);
+			return -EBUSY;
+		}
+		__iget(old);
+		spin_unlock(&old->i_lock);
+		spin_unlock(&inode_hash_lock);
+		wait_on_inode(old);
+		if (unlikely(!inode_unhashed(old))) {
+			iput(old);
+			return -EBUSY;
+		}
+		iput(old);
+	}
+}
+EXPORT_SYMBOL(insert_inode_locked);
+
+int insert_inode_locked4(struct inode *inode, unsigned long hashval,
+		int (*test)(struct inode *, void *), void *data)
+{
+	struct inode *old;
+
+	inode->i_state |= I_CREATING;
+	old = inode_insert5(inode, hashval, test, NULL, data);
+
+	if (old != inode) {
+		iput(old);
+		return -EBUSY;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(insert_inode_locked4);
+
+
+int generic_delete_inode(struct inode *inode)
+{
+	return 1;
+}
+EXPORT_SYMBOL(generic_delete_inode);
+
+/*
+ * Called when we're dropping the last reference
+ * to an inode.
+ *
+ * Call the FS "drop_inode()" function, defaulting to
+ * the legacy UNIX filesystem behaviour.  If it tells
+ * us to evict inode, do so.  Otherwise, retain inode
+ * in cache if fs is alive, sync and evict if fs is
+ * shutting down.
+ */
+static void iput_final(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	const struct super_operations *op = inode->i_sb->s_op;
+	unsigned long state;
+	int drop;
+
+	WARN_ON(inode->i_state & I_NEW);
+
+	if (op->drop_inode)
+		drop = op->drop_inode(inode);
+	else
+		drop = generic_drop_inode(inode);
+
+	if (!drop &&
+	    !(inode->i_state & I_DONTCACHE) &&
+	    (sb->s_flags & SB_ACTIVE)) {
+		__inode_add_lru(inode, true);
+		spin_unlock(&inode->i_lock);
+		return;
+	}
+
+	state = inode->i_state;
+	if (!drop) {
+		WRITE_ONCE(inode->i_state, state | I_WILL_FREE);
+		spin_unlock(&inode->i_lock);
+
+		write_inode_now(inode, 1);
+
+		spin_lock(&inode->i_lock);
+		state = inode->i_state;
+		WARN_ON(state & I_NEW);
+		state &= ~I_WILL_FREE;
+	}
+
+	WRITE_ONCE(inode->i_state, state | I_FREEING);
+	if (!list_empty(&inode->i_lru))
+		inode_lru_list_del(inode);
+	spin_unlock(&inode->i_lock);
+
+	evict(inode);
+}
+
+/**
+ *	iput	- put an inode
+ *	@inode: inode to put
+ *
+ *	Puts an inode, dropping its usage count. If the inode use count hits
+ *	zero, the inode is then freed and may also be destroyed.
+ *
+ *	Consequently, iput() can sleep.
+ */
+void iput(struct inode *inode)
+{
+	if (!inode)
+		return;
+	BUG_ON(inode->i_state & I_CLEAR);
+retry:
+	if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
+		if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
+			atomic_inc(&inode->i_count);
+			spin_unlock(&inode->i_lock);
+			trace_writeback_lazytime_iput(inode);
+			mark_inode_dirty_sync(inode);
+			goto retry;
+		}
+		iput_final(inode);
+	}
+}
+EXPORT_SYMBOL(iput);
+
+#ifdef CONFIG_BLOCK
+/**
+ *	bmap	- find a block number in a file
+ *	@inode:  inode owning the block number being requested
+ *	@block: pointer containing the block to find
+ *
+ *	Replaces the value in ``*block`` with the block number on the device holding
+ *	corresponding to the requested block number in the file.
+ *	That is, asked for block 4 of inode 1 the function will replace the
+ *	4 in ``*block``, with disk block relative to the disk start that holds that
+ *	block of the file.
+ *
+ *	Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
+ *	hole, returns 0 and ``*block`` is also set to 0.
+ */
+int bmap(struct inode *inode, sector_t *block)
+{
+	if (!inode->i_mapping->a_ops->bmap)
+		return -EINVAL;
+
+	*block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
+	return 0;
+}
+EXPORT_SYMBOL(bmap);
+#endif
+
+/*
+ * With relative atime, only update atime if the previous atime is
+ * earlier than or equal to either the ctime or mtime,
+ * or if at least a day has passed since the last atime update.
+ */
+static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
+			     struct timespec64 now)
+{
+	struct timespec64 ctime;
+
+	if (!(mnt->mnt_flags & MNT_RELATIME))
+		return 1;
+	/*
+	 * Is mtime younger than or equal to atime? If yes, update atime:
+	 */
+	if (timespec64_compare(&inode->i_mtime, &inode->i_atime) >= 0)
+		return 1;
+	/*
+	 * Is ctime younger than or equal to atime? If yes, update atime:
+	 */
+	ctime = inode_get_ctime(inode);
+	if (timespec64_compare(&ctime, &inode->i_atime) >= 0)
+		return 1;
+
+	/*
+	 * Is the previous atime value older than a day? If yes,
+	 * update atime:
+	 */
+	if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
+		return 1;
+	/*
+	 * Good, we can skip the atime update:
+	 */
+	return 0;
+}
+
+/**
+ * inode_update_timestamps - update the timestamps on the inode
+ * @inode: inode to be updated
+ * @flags: S_* flags that needed to be updated
+ *
+ * The update_time function is called when an inode's timestamps need to be
+ * updated for a read or write operation. This function handles updating the
+ * actual timestamps. It's up to the caller to ensure that the inode is marked
+ * dirty appropriately.
+ *
+ * In the case where any of S_MTIME, S_CTIME, or S_VERSION need to be updated,
+ * attempt to update all three of them. S_ATIME updates can be handled
+ * independently of the rest.
+ *
+ * Returns a set of S_* flags indicating which values changed.
+ */
+int inode_update_timestamps(struct inode *inode, int flags)
+{
+	int updated = 0;
+	struct timespec64 now;
+
+	if (flags & (S_MTIME|S_CTIME|S_VERSION)) {
+		struct timespec64 ctime = inode_get_ctime(inode);
+
+		now = inode_set_ctime_current(inode);
+		if (!timespec64_equal(&now, &ctime))
+			updated |= S_CTIME;
+		if (!timespec64_equal(&now, &inode->i_mtime)) {
+			inode->i_mtime = now;
+			updated |= S_MTIME;
+		}
+		if (IS_I_VERSION(inode) && inode_maybe_inc_iversion(inode, updated))
+			updated |= S_VERSION;
+	} else {
+		now = current_time(inode);
+	}
+
+	if (flags & S_ATIME) {
+		if (!timespec64_equal(&now, &inode->i_atime)) {
+			inode->i_atime = now;
+			updated |= S_ATIME;
+		}
+	}
+	return updated;
+}
+EXPORT_SYMBOL(inode_update_timestamps);
+
+/**
+ * generic_update_time - update the timestamps on the inode
+ * @inode: inode to be updated
+ * @flags: S_* flags that needed to be updated
+ *
+ * The update_time function is called when an inode's timestamps need to be
+ * updated for a read or write operation. In the case where any of S_MTIME, S_CTIME,
+ * or S_VERSION need to be updated we attempt to update all three of them. S_ATIME
+ * updates can be handled done independently of the rest.
+ *
+ * Returns a S_* mask indicating which fields were updated.
+ */
+int generic_update_time(struct inode *inode, int flags)
+{
+	int updated = inode_update_timestamps(inode, flags);
+	int dirty_flags = 0;
+
+	if (updated & (S_ATIME|S_MTIME|S_CTIME))
+		dirty_flags = inode->i_sb->s_flags & SB_LAZYTIME ? I_DIRTY_TIME : I_DIRTY_SYNC;
+	if (updated & S_VERSION)
+		dirty_flags |= I_DIRTY_SYNC;
+	__mark_inode_dirty(inode, dirty_flags);
+	return updated;
+}
+EXPORT_SYMBOL(generic_update_time);
+
+/*
+ * This does the actual work of updating an inodes time or version.  Must have
+ * had called mnt_want_write() before calling this.
+ */
+int inode_update_time(struct inode *inode, int flags)
+{
+	if (inode->i_op->update_time)
+		return inode->i_op->update_time(inode, flags);
+	generic_update_time(inode, flags);
+	return 0;
+}
+EXPORT_SYMBOL(inode_update_time);
+
+/**
+ *	atime_needs_update	-	update the access time
+ *	@path: the &struct path to update
+ *	@inode: inode to update
+ *
+ *	Update the accessed time on an inode and mark it for writeback.
+ *	This function automatically handles read only file systems and media,
+ *	as well as the "noatime" flag and inode specific "noatime" markers.
+ */
+bool atime_needs_update(const struct path *path, struct inode *inode)
+{
+	struct vfsmount *mnt = path->mnt;
+	struct timespec64 now;
+
+	if (inode->i_flags & S_NOATIME)
+		return false;
+
+	/* Atime updates will likely cause i_uid and i_gid to be written
+	 * back improprely if their true value is unknown to the vfs.
+	 */
+	if (HAS_UNMAPPED_ID(mnt_idmap(mnt), inode))
+		return false;
+
+	if (IS_NOATIME(inode))
+		return false;
+	if ((inode->i_sb->s_flags & SB_NODIRATIME) && S_ISDIR(inode->i_mode))
+		return false;
+
+	if (mnt->mnt_flags & MNT_NOATIME)
+		return false;
+	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
+		return false;
+
+	now = current_time(inode);
+
+	if (!relatime_need_update(mnt, inode, now))
+		return false;
+
+	if (timespec64_equal(&inode->i_atime, &now))
+		return false;
+
+	return true;
+}
+
+void touch_atime(const struct path *path)
+{
+	struct vfsmount *mnt = path->mnt;
+	struct inode *inode = d_inode(path->dentry);
+
+	if (!atime_needs_update(path, inode))
+		return;
+
+	if (!sb_start_write_trylock(inode->i_sb))
+		return;
+
+	if (__mnt_want_write(mnt) != 0)
+		goto skip_update;
+	/*
+	 * File systems can error out when updating inodes if they need to
+	 * allocate new space to modify an inode (such is the case for
+	 * Btrfs), but since we touch atime while walking down the path we
+	 * really don't care if we failed to update the atime of the file,
+	 * so just ignore the return value.
+	 * We may also fail on filesystems that have the ability to make parts
+	 * of the fs read only, e.g. subvolumes in Btrfs.
+	 */
+	inode_update_time(inode, S_ATIME);
+	__mnt_drop_write(mnt);
+skip_update:
+	sb_end_write(inode->i_sb);
+}
+EXPORT_SYMBOL(touch_atime);
+
+/*
+ * Return mask of changes for notify_change() that need to be done as a
+ * response to write or truncate. Return 0 if nothing has to be changed.
+ * Negative value on error (change should be denied).
+ */
+int dentry_needs_remove_privs(struct mnt_idmap *idmap,
+			      struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+	int mask = 0;
+	int ret;
+
+	if (IS_NOSEC(inode))
+		return 0;
+
+	mask = setattr_should_drop_suidgid(idmap, inode);
+	ret = security_inode_need_killpriv(dentry);
+	if (ret < 0)
+		return ret;
+	if (ret)
+		mask |= ATTR_KILL_PRIV;
+	return mask;
+}
+
+static int __remove_privs(struct mnt_idmap *idmap,
+			  struct dentry *dentry, int kill)
+{
+	struct iattr newattrs;
+
+	newattrs.ia_valid = ATTR_FORCE | kill;
+	/*
+	 * Note we call this on write, so notify_change will not
+	 * encounter any conflicting delegations:
+	 */
+	return notify_change(idmap, dentry, &newattrs, NULL);
+}
+
+static int __file_remove_privs(struct file *file, unsigned int flags)
+{
+	struct dentry *dentry = file_dentry(file);
+	struct inode *inode = file_inode(file);
+	int error = 0;
+	int kill;
+
+	if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
+		return 0;
+
+	kill = dentry_needs_remove_privs(file_mnt_idmap(file), dentry);
+	if (kill < 0)
+		return kill;
+
+	if (kill) {
+		if (flags & IOCB_NOWAIT)
+			return -EAGAIN;
+
+		error = __remove_privs(file_mnt_idmap(file), dentry, kill);
+	}
+
+	if (!error)
+		inode_has_no_xattr(inode);
+	return error;
+}
+
+/**
+ * file_remove_privs - remove special file privileges (suid, capabilities)
+ * @file: file to remove privileges from
+ *
+ * When file is modified by a write or truncation ensure that special
+ * file privileges are removed.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int file_remove_privs(struct file *file)
+{
+	return __file_remove_privs(file, 0);
+}
+EXPORT_SYMBOL(file_remove_privs);
+
+static int inode_needs_update_time(struct inode *inode)
+{
+	int sync_it = 0;
+	struct timespec64 now = current_time(inode);
+	struct timespec64 ctime;
+
+	/* First try to exhaust all avenues to not sync */
+	if (IS_NOCMTIME(inode))
+		return 0;
+
+	if (!timespec64_equal(&inode->i_mtime, &now))
+		sync_it = S_MTIME;
+
+	ctime = inode_get_ctime(inode);
+	if (!timespec64_equal(&ctime, &now))
+		sync_it |= S_CTIME;
+
+	if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
+		sync_it |= S_VERSION;
+
+	return sync_it;
+}
+
+static int __file_update_time(struct file *file, int sync_mode)
+{
+	int ret = 0;
+	struct inode *inode = file_inode(file);
+
+	/* try to update time settings */
+	if (!__mnt_want_write_file(file)) {
+		ret = inode_update_time(inode, sync_mode);
+		__mnt_drop_write_file(file);
+	}
+
+	return ret;
+}
+
+/**
+ * file_update_time - update mtime and ctime time
+ * @file: file accessed
+ *
+ * Update the mtime and ctime members of an inode and mark the inode for
+ * writeback. Note that this function is meant exclusively for usage in
+ * the file write path of filesystems, and filesystems may choose to
+ * explicitly ignore updates via this function with the _NOCMTIME inode
+ * flag, e.g. for network filesystem where these imestamps are handled
+ * by the server. This can return an error for file systems who need to
+ * allocate space in order to update an inode.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int file_update_time(struct file *file)
+{
+	int ret;
+	struct inode *inode = file_inode(file);
+
+	ret = inode_needs_update_time(inode);
+	if (ret <= 0)
+		return ret;
+
+	return __file_update_time(file, ret);
+}
+EXPORT_SYMBOL(file_update_time);
+
+/**
+ * file_modified_flags - handle mandated vfs changes when modifying a file
+ * @file: file that was modified
+ * @flags: kiocb flags
+ *
+ * When file has been modified ensure that special
+ * file privileges are removed and time settings are updated.
+ *
+ * If IOCB_NOWAIT is set, special file privileges will not be removed and
+ * time settings will not be updated. It will return -EAGAIN.
+ *
+ * Context: Caller must hold the file's inode lock.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static int file_modified_flags(struct file *file, int flags)
+{
+	int ret;
+	struct inode *inode = file_inode(file);
+
+	/*
+	 * Clear the security bits if the process is not being run by root.
+	 * This keeps people from modifying setuid and setgid binaries.
+	 */
+	ret = __file_remove_privs(file, flags);
+	if (ret)
+		return ret;
+
+	if (unlikely(file->f_mode & FMODE_NOCMTIME))
+		return 0;
+
+	ret = inode_needs_update_time(inode);
+	if (ret <= 0)
+		return ret;
+	if (flags & IOCB_NOWAIT)
+		return -EAGAIN;
+
+	return __file_update_time(file, ret);
+}
+
+/**
+ * file_modified - handle mandated vfs changes when modifying a file
+ * @file: file that was modified
+ *
+ * When file has been modified ensure that special
+ * file privileges are removed and time settings are updated.
+ *
+ * Context: Caller must hold the file's inode lock.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int file_modified(struct file *file)
+{
+	return file_modified_flags(file, 0);
+}
+EXPORT_SYMBOL(file_modified);
+
+/**
+ * kiocb_modified - handle mandated vfs changes when modifying a file
+ * @iocb: iocb that was modified
+ *
+ * When file has been modified ensure that special
+ * file privileges are removed and time settings are updated.
+ *
+ * Context: Caller must hold the file's inode lock.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int kiocb_modified(struct kiocb *iocb)
+{
+	return file_modified_flags(iocb->ki_filp, iocb->ki_flags);
+}
+EXPORT_SYMBOL_GPL(kiocb_modified);
+
+int inode_needs_sync(struct inode *inode)
+{
+	if (IS_SYNC(inode))
+		return 1;
+	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
+		return 1;
+	return 0;
+}
+EXPORT_SYMBOL(inode_needs_sync);
+
+/*
+ * If we try to find an inode in the inode hash while it is being
+ * deleted, we have to wait until the filesystem completes its
+ * deletion before reporting that it isn't found.  This function waits
+ * until the deletion _might_ have completed.  Callers are responsible
+ * to recheck inode state.
+ *
+ * It doesn't matter if I_NEW is not set initially, a call to
+ * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
+ * will DTRT.
+ */
+static void __wait_on_freeing_inode(struct inode *inode)
+{
+	wait_queue_head_t *wq;
+	DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
+	wq = bit_waitqueue(&inode->i_state, __I_NEW);
+	prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
+	spin_unlock(&inode->i_lock);
+	spin_unlock(&inode_hash_lock);
+	schedule();
+	finish_wait(wq, &wait.wq_entry);
+	spin_lock(&inode_hash_lock);
+}
+
+static __initdata unsigned long ihash_entries;
+static int __init set_ihash_entries(char *str)
+{
+	if (!str)
+		return 0;
+	ihash_entries = simple_strtoul(str, &str, 0);
+	return 1;
+}
+__setup("ihash_entries=", set_ihash_entries);
+
+/*
+ * Initialize the waitqueues and inode hash table.
+ */
+void __init inode_init_early(void)
+{
+	/* If hashes are distributed across NUMA nodes, defer
+	 * hash allocation until vmalloc space is available.
+	 */
+	if (hashdist)
+		return;
+
+	inode_hashtable =
+		alloc_large_system_hash("Inode-cache",
+					sizeof(struct hlist_head),
+					ihash_entries,
+					14,
+					HASH_EARLY | HASH_ZERO,
+					&i_hash_shift,
+					&i_hash_mask,
+					0,
+					0);
+}
+
+void __init inode_init(void)
+{
+	/* inode slab cache */
+	inode_cachep = kmem_cache_create("inode_cache",
+					 sizeof(struct inode),
+					 0,
+					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
+					 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
+					 init_once);
+
+	/* Hash may have been set up in inode_init_early */
+	if (!hashdist)
+		return;
+
+	inode_hashtable =
+		alloc_large_system_hash("Inode-cache",
+					sizeof(struct hlist_head),
+					ihash_entries,
+					14,
+					HASH_ZERO,
+					&i_hash_shift,
+					&i_hash_mask,
+					0,
+					0);
+}
+
+void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
+{
+	inode->i_mode = mode;
+	if (S_ISCHR(mode)) {
+		inode->i_fop = &def_chr_fops;
+		inode->i_rdev = rdev;
+	} else if (S_ISBLK(mode)) {
+		if (IS_ENABLED(CONFIG_BLOCK))
+			inode->i_fop = &def_blk_fops;
+		inode->i_rdev = rdev;
+	} else if (S_ISFIFO(mode))
+		inode->i_fop = &pipefifo_fops;
+	else if (S_ISSOCK(mode))
+		;	/* leave it no_open_fops */
+	else
+		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
+				  " inode %s:%lu\n", mode, inode->i_sb->s_id,
+				  inode->i_ino);
+}
+EXPORT_SYMBOL(init_special_inode);
+
+/**
+ * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
+ * @idmap: idmap of the mount the inode was created from
+ * @inode: New inode
+ * @dir: Directory inode
+ * @mode: mode of the new inode
+ *
+ * If the inode has been created through an idmapped mount the idmap of
+ * the vfsmount must be passed through @idmap. This function will then take
+ * care to map the inode according to @idmap before checking permissions
+ * and initializing i_uid and i_gid. On non-idmapped mounts or if permission
+ * checking is to be performed on the raw inode simply pass @nop_mnt_idmap.
+ */
+void inode_init_owner(struct mnt_idmap *idmap, struct inode *inode,
+		      const struct inode *dir, umode_t mode)
+{
+	inode_fsuid_set(inode, idmap);
+	if (dir && dir->i_mode & S_ISGID) {
+		inode->i_gid = dir->i_gid;
+
+		/* Directories are special, and always inherit S_ISGID */
+		if (S_ISDIR(mode))
+			mode |= S_ISGID;
+	} else
+		inode_fsgid_set(inode, idmap);
+	inode->i_mode = mode;
+}
+EXPORT_SYMBOL(inode_init_owner);
+
+/**
+ * inode_owner_or_capable - check current task permissions to inode
+ * @idmap: idmap of the mount the inode was found from
+ * @inode: inode being checked
+ *
+ * Return true if current either has CAP_FOWNER in a namespace with the
+ * inode owner uid mapped, or owns the file.
+ *
+ * If the inode has been found through an idmapped mount the idmap of
+ * the vfsmount must be passed through @idmap. This function will then take
+ * care to map the inode according to @idmap before checking permissions.
+ * On non-idmapped mounts or if permission checking is to be performed on the
+ * raw inode simply passs @nop_mnt_idmap.
+ */
+bool inode_owner_or_capable(struct mnt_idmap *idmap,
+			    const struct inode *inode)
+{
+	vfsuid_t vfsuid;
+	struct user_namespace *ns;
+
+	vfsuid = i_uid_into_vfsuid(idmap, inode);
+	if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
+		return true;
+
+	ns = current_user_ns();
+	if (vfsuid_has_mapping(ns, vfsuid) && ns_capable(ns, CAP_FOWNER))
+		return true;
+	return false;
+}
+EXPORT_SYMBOL(inode_owner_or_capable);
+
+/*
+ * Direct i/o helper functions
+ */
+static void __inode_dio_wait(struct inode *inode)
+{
+	wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP);
+	DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP);
+
+	do {
+		prepare_to_wait(wq, &q.wq_entry, TASK_UNINTERRUPTIBLE);
+		if (atomic_read(&inode->i_dio_count))
+			schedule();
+	} while (atomic_read(&inode->i_dio_count));
+	finish_wait(wq, &q.wq_entry);
+}
+
+/**
+ * inode_dio_wait - wait for outstanding DIO requests to finish
+ * @inode: inode to wait for
+ *
+ * Waits for all pending direct I/O requests to finish so that we can
+ * proceed with a truncate or equivalent operation.
+ *
+ * Must be called under a lock that serializes taking new references
+ * to i_dio_count, usually by inode->i_mutex.
+ */
+void inode_dio_wait(struct inode *inode)
+{
+	if (atomic_read(&inode->i_dio_count))
+		__inode_dio_wait(inode);
+}
+EXPORT_SYMBOL(inode_dio_wait);
+
+/*
+ * inode_set_flags - atomically set some inode flags
+ *
+ * Note: the caller should be holding i_mutex, or else be sure that
+ * they have exclusive access to the inode structure (i.e., while the
+ * inode is being instantiated).  The reason for the cmpxchg() loop
+ * --- which wouldn't be necessary if all code paths which modify
+ * i_flags actually followed this rule, is that there is at least one
+ * code path which doesn't today so we use cmpxchg() out of an abundance
+ * of caution.
+ *
+ * In the long run, i_mutex is overkill, and we should probably look
+ * at using the i_lock spinlock to protect i_flags, and then make sure
+ * it is so documented in include/linux/fs.h and that all code follows
+ * the locking convention!!
+ */
+void inode_set_flags(struct inode *inode, unsigned int flags,
+		     unsigned int mask)
+{
+	WARN_ON_ONCE(flags & ~mask);
+	set_mask_bits(&inode->i_flags, mask, flags);
+}
+EXPORT_SYMBOL(inode_set_flags);
+
+void inode_nohighmem(struct inode *inode)
+{
+	mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
+}
+EXPORT_SYMBOL(inode_nohighmem);
+
+/**
+ * timestamp_truncate - Truncate timespec to a granularity
+ * @t: Timespec
+ * @inode: inode being updated
+ *
+ * Truncate a timespec to the granularity supported by the fs
+ * containing the inode. Always rounds down. gran must
+ * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
+ */
+struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	unsigned int gran = sb->s_time_gran;
+
+	t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);
+	if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))
+		t.tv_nsec = 0;
+
+	/* Avoid division in the common cases 1 ns and 1 s. */
+	if (gran == 1)
+		; /* nothing */
+	else if (gran == NSEC_PER_SEC)
+		t.tv_nsec = 0;
+	else if (gran > 1 && gran < NSEC_PER_SEC)
+		t.tv_nsec -= t.tv_nsec % gran;
+	else
+		WARN(1, "invalid file time granularity: %u", gran);
+	return t;
+}
+EXPORT_SYMBOL(timestamp_truncate);
+
+/**
+ * current_time - Return FS time
+ * @inode: inode.
+ *
+ * Return the current time truncated to the time granularity supported by
+ * the fs.
+ *
+ * Note that inode and inode->sb cannot be NULL.
+ * Otherwise, the function warns and returns time without truncation.
+ */
+struct timespec64 current_time(struct inode *inode)
+{
+	struct timespec64 now;
+
+	ktime_get_coarse_real_ts64(&now);
+	return timestamp_truncate(now, inode);
+}
+EXPORT_SYMBOL(current_time);
+
+/**
+ * inode_set_ctime_current - set the ctime to current_time
+ * @inode: inode
+ *
+ * Set the inode->i_ctime to the current value for the inode. Returns
+ * the current value that was assigned to i_ctime.
+ */
+struct timespec64 inode_set_ctime_current(struct inode *inode)
+{
+	struct timespec64 now = current_time(inode);
+
+	inode_set_ctime(inode, now.tv_sec, now.tv_nsec);
+	return now;
+}
+EXPORT_SYMBOL(inode_set_ctime_current);
+
+/**
+ * in_group_or_capable - check whether caller is CAP_FSETID privileged
+ * @idmap:	idmap of the mount @inode was found from
+ * @inode:	inode to check
+ * @vfsgid:	the new/current vfsgid of @inode
+ *
+ * Check wether @vfsgid is in the caller's group list or if the caller is
+ * privileged with CAP_FSETID over @inode. This can be used to determine
+ * whether the setgid bit can be kept or must be dropped.
+ *
+ * Return: true if the caller is sufficiently privileged, false if not.
+ */
+bool in_group_or_capable(struct mnt_idmap *idmap,
+			 const struct inode *inode, vfsgid_t vfsgid)
+{
+	if (vfsgid_in_group_p(vfsgid))
+		return true;
+	if (capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
+		return true;
+	return false;
+}
+
+/**
+ * mode_strip_sgid - handle the sgid bit for non-directories
+ * @idmap: idmap of the mount the inode was created from
+ * @dir: parent directory inode
+ * @mode: mode of the file to be created in @dir
+ *
+ * If the @mode of the new file has both the S_ISGID and S_IXGRP bit
+ * raised and @dir has the S_ISGID bit raised ensure that the caller is
+ * either in the group of the parent directory or they have CAP_FSETID
+ * in their user namespace and are privileged over the parent directory.
+ * In all other cases, strip the S_ISGID bit from @mode.
+ *
+ * Return: the new mode to use for the file
+ */
+umode_t mode_strip_sgid(struct mnt_idmap *idmap,
+			const struct inode *dir, umode_t mode)
+{
+	if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP))
+		return mode;
+	if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID))
+		return mode;
+	if (in_group_or_capable(idmap, dir, i_gid_into_vfsgid(idmap, dir)))
+		return mode;
+	return mode & ~S_ISGID;
+}
+EXPORT_SYMBOL(mode_strip_sgid);