/*
 * Copyright (C) 2005-2016 Junjiro R. Okajima
 */

/*
 * module global variables and operations
 */

#include <linux/module.h>
#include <linux/seq_file.h>
#include "aufs.h"

/* shrinkable realloc */
void *au_krealloc(void *p, unsigned int new_sz, gfp_t gfp, int may_shrink)
{
	size_t sz;
	int diff;

	sz = 0;
	diff = -1;
	if (p) {
#if 0 /* unused */
		if (!new_sz) {
			au_delayed_kfree(p);
			p = NULL;
			goto out;
		}
#else
		AuDebugOn(!new_sz);
#endif
		sz = ksize(p);
		diff = au_kmidx_sub(sz, new_sz);
	}
	if (sz && !diff)
		goto out;

	if (sz < new_sz)
		/* expand or SLOB */
		p = krealloc(p, new_sz, gfp);
	else if (new_sz < sz && may_shrink) {
		/* shrink */
		void *q;

		q = kmalloc(new_sz, gfp);
		if (q) {
			if (p) {
				memcpy(q, p, new_sz);
				au_delayed_kfree(p);
			}
			p = q;
		} else
			p = NULL;
	}

out:
	return p;
}

void *au_kzrealloc(void *p, unsigned int nused, unsigned int new_sz, gfp_t gfp,
		   int may_shrink)
{
	p = au_krealloc(p, new_sz, gfp, may_shrink);
	if (p && new_sz > nused)
		memset(p + nused, 0, new_sz - nused);
	return p;
}

/* ---------------------------------------------------------------------- */
/*
 * aufs caches
 */

struct au_dfree au_dfree;

/* delayed free */
static void au_do_dfree(struct work_struct *work __maybe_unused)
{
	struct llist_head *head;
	struct llist_node *node, *next;

#define AU_CACHE_DFREE_DO_BODY(name, idx, lnode) do {			\
		head = &au_dfree.cache[AuCache_##idx].llist;		\
		node = llist_del_all(head);				\
		for (; node; node = next) {				\
			struct au_##name *p				\
				= llist_entry(node, struct au_##name,	\
					      lnode);			\
			next = llist_next(node);			\
			au_cache_free_##name(p);			\
		}							\
	} while (0)

	AU_CACHE_DFREE_DO_BODY(dinfo, DINFO, di_lnode);
	AU_CACHE_DFREE_DO_BODY(icntnr, ICNTNR, lnode);
	AU_CACHE_DFREE_DO_BODY(finfo, FINFO, fi_lnode);
	AU_CACHE_DFREE_DO_BODY(vdir, VDIR, vd_lnode);
	AU_CACHE_DFREE_DO_BODY(vdir_dehstr, DEHSTR, lnode);
#ifdef CONFIG_AUFS_HNOTIFY
	AU_CACHE_DFREE_DO_BODY(hnotify, HNOTIFY, hn_lnode);
#endif

#define AU_DFREE_DO_BODY(llist, func) do {		\
		node = llist_del_all(llist);		\
		for (; node; node = next) {		\
			next = llist_next(node);	\
			func(node);			\
		}					\
	} while (0)

	AU_DFREE_DO_BODY(au_dfree.llist + AU_DFREE_KFREE, kfree);
	AU_DFREE_DO_BODY(au_dfree.llist + AU_DFREE_FREE_PAGE, au_free_page);

#undef AU_CACHE_DFREE_DO_BODY
#undef AU_DFREE_DO_BODY
}

AU_CACHE_DFREE_FUNC(dinfo, DINFO, di_lnode);
AU_CACHE_DFREE_FUNC(icntnr, ICNTNR, lnode);
AU_CACHE_DFREE_FUNC(finfo, FINFO, fi_lnode);
AU_CACHE_DFREE_FUNC(vdir, VDIR, vd_lnode);
AU_CACHE_DFREE_FUNC(vdir_dehstr, DEHSTR, lnode);

static void au_cache_fin(void)
{
	int i;
	struct au_cache *cp;

	/*
	 * Make sure all delayed rcu free inodes are flushed before we
	 * destroy cache.
	 */
	rcu_barrier();

	/* excluding AuCache_HNOTIFY */
	BUILD_BUG_ON(AuCache_HNOTIFY + 1 != AuCache_Last);
	flush_delayed_work(&au_dfree.dwork);
	for (i = 0; i < AuCache_HNOTIFY; i++) {
		cp = au_dfree.cache + i;
		AuDebugOn(!llist_empty(&cp->llist));
		kmem_cache_destroy(cp->cache);
		cp->cache = NULL;
	}
}

static int __init au_cache_init(void)
{
	struct au_cache *cp;

	cp = au_dfree.cache;
	cp[AuCache_DINFO].cache = AuCacheCtor(au_dinfo, au_di_init_once);
	if (cp[AuCache_DINFO].cache)
		/* SLAB_DESTROY_BY_RCU */
		cp[AuCache_ICNTNR].cache = AuCacheCtor(au_icntnr,
						       au_icntnr_init_once);
	if (cp[AuCache_ICNTNR].cache)
		cp[AuCache_FINFO].cache = AuCacheCtor(au_finfo,
						      au_fi_init_once);
	if (cp[AuCache_FINFO].cache)
		cp[AuCache_VDIR].cache = AuCache(au_vdir);
	if (cp[AuCache_VDIR].cache)
		cp[AuCache_DEHSTR].cache = AuCache(au_vdir_dehstr);
	if (cp[AuCache_DEHSTR].cache)
		return 0;

	au_cache_fin();
	return -ENOMEM;
}

/* ---------------------------------------------------------------------- */

int au_dir_roflags;

#ifdef CONFIG_AUFS_SBILIST
/*
 * iterate_supers_type() doesn't protect us from
 * remounting (branch management)
 */
struct au_sphlhead au_sbilist;
#endif

/*
 * functions for module interface.
 */
MODULE_LICENSE("GPL");
/* MODULE_LICENSE("GPL v2"); */
MODULE_AUTHOR("Junjiro R. Okajima <aufs-users@lists.sourceforge.net>");
MODULE_DESCRIPTION(AUFS_NAME
	" -- Advanced multi layered unification filesystem");
MODULE_VERSION(AUFS_VERSION);

/* this module parameter has no meaning when SYSFS is disabled */
int sysaufs_brs = 1;
MODULE_PARM_DESC(brs, "use <sysfs>/fs/aufs/si_*/brN");
module_param_named(brs, sysaufs_brs, int, S_IRUGO);

/* this module parameter has no meaning when USER_NS is disabled */
bool au_userns;
MODULE_PARM_DESC(allow_userns, "allow unprivileged to mount under userns");
module_param_named(allow_userns, au_userns, bool, S_IRUGO);

/* ---------------------------------------------------------------------- */

static char au_esc_chars[0x20 + 3]; /* 0x01-0x20, backslash, del, and NULL */

int au_seq_path(struct seq_file *seq, struct path *path)
{
	int err;

	err = seq_path(seq, path, au_esc_chars);
	if (err > 0)
		err = 0;
	else if (err < 0)
		err = -ENOMEM;

	return err;
}

/* ---------------------------------------------------------------------- */

static int __init aufs_init(void)
{
	int err, i;
	char *p;
	struct au_cache *cp;

	p = au_esc_chars;
	for (i = 1; i <= ' '; i++)
		*p++ = i;
	*p++ = '\\';
	*p++ = '\x7f';
	*p = 0;

	au_dir_roflags = au_file_roflags(O_DIRECTORY | O_LARGEFILE);

	memcpy(aufs_iop_nogetattr, aufs_iop, sizeof(aufs_iop));
	for (i = 0; i < AuIop_Last; i++)
		aufs_iop_nogetattr[i].getattr = NULL;

	/* First, initialize au_dfree */
	for (i = 0; i < AuCache_Last; i++) {	/* including hnotify */
		cp = au_dfree.cache + i;
		cp->cache = NULL;
		init_llist_head(&cp->llist);
	}
	for (i = 0; i < AU_DFREE_Last; i++)
		init_llist_head(au_dfree.llist + i);
	INIT_DELAYED_WORK(&au_dfree.dwork, au_do_dfree);

	au_sbilist_init();
	sysaufs_brs_init();
	au_debug_init();
	au_dy_init();
	err = sysaufs_init();
	if (unlikely(err))
		goto out;
	err = au_procfs_init();
	if (unlikely(err))
		goto out_sysaufs;
	err = au_wkq_init();
	if (unlikely(err))
		goto out_procfs;
	err = au_loopback_init();
	if (unlikely(err))
		goto out_wkq;
	err = au_hnotify_init();
	if (unlikely(err))
		goto out_loopback;
	err = au_sysrq_init();
	if (unlikely(err))
		goto out_hin;
	err = au_cache_init();
	if (unlikely(err))
		goto out_sysrq;

	aufs_fs_type.fs_flags |= au_userns ? FS_USERNS_MOUNT : 0;
	err = register_filesystem(&aufs_fs_type);
	if (unlikely(err))
		goto out_cache;

	/* since we define pr_fmt, call printk directly */
	printk(KERN_INFO AUFS_NAME " " AUFS_VERSION "\n");
	goto out; /* success */

out_cache:
	au_cache_fin();
out_sysrq:
	au_sysrq_fin();
out_hin:
	au_hnotify_fin();
out_loopback:
	au_loopback_fin();
out_wkq:
	au_wkq_fin();
out_procfs:
	au_procfs_fin();
out_sysaufs:
	sysaufs_fin();
	au_dy_fin();
	flush_delayed_work(&au_dfree.dwork);
out:
	return err;
}

static void __exit aufs_exit(void)
{
	unregister_filesystem(&aufs_fs_type);
	au_cache_fin();
	au_sysrq_fin();
	au_hnotify_fin();
	au_loopback_fin();
	au_wkq_fin();
	au_procfs_fin();
	sysaufs_fin();
	au_dy_fin();
	flush_delayed_work(&au_dfree.dwork);
}

module_init(aufs_init);
module_exit(aufs_exit);