[GitHub/LineageOS/android_kernel_samsung_universal7580.git] / fs / notify / inode_mark.c

/*
 *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>

#include <linux/atomic.h>

#include <linux/fsnotify_backend.h>
#include "fsnotify.h"

#include "../internal.h"

/*
 * Recalculate the mask of events relevant to a given inode locked.
 */
static void fsnotify_recalc_inode_mask_locked(struct inode *inode)
{
	struct fsnotify_mark *mark;
	__u32 new_mask = 0;

	assert_spin_locked(&inode->i_lock);

	hlist_for_each_entry(mark, &inode->i_fsnotify_marks, i.i_list)
		new_mask |= mark->mask;
	inode->i_fsnotify_mask = new_mask;
}

/*
 * Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types
 * any notifier is interested in hearing for this inode.
 */
void fsnotify_recalc_inode_mask(struct inode *inode)
{
	spin_lock(&inode->i_lock);
	fsnotify_recalc_inode_mask_locked(inode);
	spin_unlock(&inode->i_lock);

	__fsnotify_update_child_dentry_flags(inode);
}

void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
{
	struct inode *inode = mark->i.inode;

	BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
	assert_spin_locked(&mark->lock);

	spin_lock(&inode->i_lock);

	hlist_del_init_rcu(&mark->i.i_list);
	mark->i.inode = NULL;

	/*
	 * this mark is now off the inode->i_fsnotify_marks list and we
	 * hold the inode->i_lock, so this is the perfect time to update the
	 * inode->i_fsnotify_mask
	 */
	fsnotify_recalc_inode_mask_locked(inode);

	spin_unlock(&inode->i_lock);
}

/*
 * Given an inode, destroy all of the marks associated with that inode.
 */
void fsnotify_clear_marks_by_inode(struct inode *inode)
{
	struct fsnotify_mark *mark, *lmark;
	struct hlist_node *n;
	LIST_HEAD(free_list);

	spin_lock(&inode->i_lock);
	hlist_for_each_entry_safe(mark, n, &inode->i_fsnotify_marks, i.i_list) {
		list_add(&mark->i.free_i_list, &free_list);
		hlist_del_init_rcu(&mark->i.i_list);
		fsnotify_get_mark(mark);
	}
	spin_unlock(&inode->i_lock);

	list_for_each_entry_safe(mark, lmark, &free_list, i.free_i_list) {
		struct fsnotify_group *group;

		spin_lock(&mark->lock);
		fsnotify_get_group(mark->group);
		group = mark->group;
		spin_unlock(&mark->lock);

		fsnotify_destroy_mark(mark, group);
		fsnotify_put_mark(mark);
		fsnotify_put_group(group);
	}
}

/*
 * Given a group clear all of the inode marks associated with that group.
 */
void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
{
	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
}

/*
 * given a group and inode, find the mark associated with that combination.
 * if found take a reference to that mark and return it, else return NULL
 */
static struct fsnotify_mark *fsnotify_find_inode_mark_locked(
		struct fsnotify_group *group,
		struct inode *inode)
{
	struct fsnotify_mark *mark;

	assert_spin_locked(&inode->i_lock);

	hlist_for_each_entry(mark, &inode->i_fsnotify_marks, i.i_list) {
		if (mark->group == group) {
			fsnotify_get_mark(mark);
			return mark;
		}
	}
	return NULL;
}

/*
 * given a group and inode, find the mark associated with that combination.
 * if found take a reference to that mark and return it, else return NULL
 */
struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group,
					       struct inode *inode)
{
	struct fsnotify_mark *mark;

	spin_lock(&inode->i_lock);
	mark = fsnotify_find_inode_mark_locked(group, inode);
	spin_unlock(&inode->i_lock);

	return mark;
}

/*
 * If we are setting a mark mask on an inode mark we should pin the inode
 * in memory.
 */
void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark,
					 __u32 mask)
{
	struct inode *inode;

	assert_spin_locked(&mark->lock);

	if (mask &&
	    mark->i.inode &&
	    !(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) {
		mark->flags |= FSNOTIFY_MARK_FLAG_OBJECT_PINNED;
		inode = igrab(mark->i.inode);
		/*
		 * we shouldn't be able to get here if the inode wasn't
		 * already safely held in memory.  But bug in case it
		 * ever is wrong.
		 */
		BUG_ON(!inode);
	}
}

/*
 * Attach an initialized mark to a given inode.
 * These marks may be used for the fsnotify backend to determine which
 * event types should be delivered to which group and for which inodes.  These
 * marks are ordered according to priority, highest number first, and then by
 * the group's location in memory.
 */
int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
			    struct fsnotify_group *group, struct inode *inode,
			    int allow_dups)
{
	struct fsnotify_mark *lmark, *last = NULL;
	int ret = 0;

	mark->flags |= FSNOTIFY_MARK_FLAG_INODE;

	BUG_ON(!mutex_is_locked(&group->mark_mutex));
	assert_spin_locked(&mark->lock);

	spin_lock(&inode->i_lock);

	mark->i.inode = inode;

	/* is mark the first mark? */
	if (hlist_empty(&inode->i_fsnotify_marks)) {
		hlist_add_head_rcu(&mark->i.i_list, &inode->i_fsnotify_marks);
		goto out;
	}

	/* should mark be in the middle of the current list? */
	hlist_for_each_entry(lmark, &inode->i_fsnotify_marks, i.i_list) {
		last = lmark;

		if ((lmark->group == group) && !allow_dups) {
			ret = -EEXIST;
			goto out;
		}

		if (mark->group->priority < lmark->group->priority)
			continue;

		if ((mark->group->priority == lmark->group->priority) &&
		    (mark->group < lmark->group))
			continue;

		hlist_add_before_rcu(&mark->i.i_list, &lmark->i.i_list);
		goto out;
	}

	BUG_ON(last == NULL);
	/* mark should be the last entry.  last is the current last entry */
	hlist_add_after_rcu(&last->i.i_list, &mark->i.i_list);
out:
	fsnotify_recalc_inode_mask_locked(inode);
	spin_unlock(&inode->i_lock);

	return ret;
}

/**
 * fsnotify_unmount_inodes - an sb is unmounting.  handle any watched inodes.
 * @list: list of inodes being unmounted (sb->s_inodes)
 *
 * Called during unmount with no locks held, so needs to be safe against
 * concurrent modifiers. We temporarily drop inode_sb_list_lock and CAN block.
 */
void fsnotify_unmount_inodes(struct list_head *list)
{
	struct inode *inode, *next_i, *need_iput = NULL;

	spin_lock(&inode_sb_list_lock);
	list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
		struct inode *need_iput_tmp;

		/*
		 * We cannot __iget() an inode in state I_FREEING,
		 * I_WILL_FREE, or I_NEW which is fine because by that point
		 * the inode cannot have any associated watches.
		 */
		spin_lock(&inode->i_lock);
		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
			spin_unlock(&inode->i_lock);
			continue;
		}

		/*
		 * If i_count is zero, the inode cannot have any watches and
		 * doing an __iget/iput with MS_ACTIVE clear would actually
		 * evict all inodes with zero i_count from icache which is
		 * unnecessarily violent and may in fact be illegal to do.
		 */
		if (!atomic_read(&inode->i_count)) {
			spin_unlock(&inode->i_lock);
			continue;
		}

		need_iput_tmp = need_iput;
		need_iput = NULL;

		/* In case fsnotify_inode_delete() drops a reference. */
		if (inode != need_iput_tmp)
			__iget(inode);
		else
			need_iput_tmp = NULL;
		spin_unlock(&inode->i_lock);

		/* In case the dropping of a reference would nuke next_i. */
		if ((&next_i->i_sb_list != list) &&
		    atomic_read(&next_i->i_count)) {
			spin_lock(&next_i->i_lock);
			if (!(next_i->i_state & (I_FREEING | I_WILL_FREE))) {
				__iget(next_i);
				need_iput = next_i;
			}
			spin_unlock(&next_i->i_lock);
		}

		/*
		 * We can safely drop inode_sb_list_lock here because we hold
		 * references on both inode and next_i.  Also no new inodes
		 * will be added since the umount has begun.
		 */
		spin_unlock(&inode_sb_list_lock);

		if (need_iput_tmp)
			iput(need_iput_tmp);

		/* for each watch, send FS_UNMOUNT and then remove it */
		fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);

		fsnotify_inode_delete(inode);

		iput(inode);

		spin_lock(&inode_sb_list_lock);
	}
	spin_unlock(&inode_sb_list_lock);
}
Commit	Line	Data
3be25f49 EP	1	/*
	2	* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2, or (at your option)
	7	* any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; see the file COPYING. If not, write to
	16	* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
	17	*/
	18
3be25f49 EP	19	#include <linux/fs.h>
	20	#include <linux/init.h>
	21	#include <linux/kernel.h>
	22	#include <linux/module.h>
	23	#include <linux/mutex.h>
3be25f49 EP	24	#include <linux/spinlock.h>
3be25f49 EP	25
60063497	26	#include <linux/atomic.h>
3be25f49 EP	27
	28	#include <linux/fsnotify_backend.h>
	29	#include "fsnotify.h"
	30
55fa6091 DC	31	#include "../internal.h"
55fa6091 DC	32
3be25f49 EP	33	/*
	34	* Recalculate the mask of events relevant to a given inode locked.
	35	*/
	36	static void fsnotify_recalc_inode_mask_locked(struct inode *inode)
	37	{
841bdc10	38	struct fsnotify_mark *mark;
3be25f49 EP	39	__u32 new_mask = 0;
	40
	41	assert_spin_locked(&inode->i_lock);
	42
b67bfe0d	43	hlist_for_each_entry(mark, &inode->i_fsnotify_marks, i.i_list)
841bdc10	44	new_mask \|= mark->mask;
3be25f49 EP	45	inode->i_fsnotify_mask = new_mask;
	46	}
	47
	48	/*
	49	* Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types
	50	* any notifier is interested in hearing for this inode.
	51	*/
	52	void fsnotify_recalc_inode_mask(struct inode *inode)
	53	{
	54	spin_lock(&inode->i_lock);
	55	fsnotify_recalc_inode_mask_locked(inode);
	56	spin_unlock(&inode->i_lock);
c28f7e56 EP	57
c28f7e56 EP	58	__fsnotify_update_child_dentry_flags(inode);
3be25f49 EP	59	}
3be25f49 EP	60
5444e298	61	void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
3be25f49	62	{
5444e298	63	struct inode *inode = mark->i.inode;
3be25f49	64
986ab098	65	BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
5444e298	66	assert_spin_locked(&mark->lock);
3be25f49	67
3be25f49 EP	68	spin_lock(&inode->i_lock);
3be25f49 EP	69
a4c6e996	70	hlist_del_init_rcu(&mark->i.i_list);
841bdc10	71	mark->i.inode = NULL;
3be25f49 EP	72
3be25f49 EP	73	/*
e61ce867	74	* this mark is now off the inode->i_fsnotify_marks list and we
3be25f49 EP	75	* hold the inode->i_lock, so this is the perfect time to update the
	76	* inode->i_fsnotify_mask
	77	*/
	78	fsnotify_recalc_inode_mask_locked(inode);
	79
	80	spin_unlock(&inode->i_lock);
3be25f49 EP	81	}
	82
	83	/*
	84	* Given an inode, destroy all of the marks associated with that inode.
	85	*/
	86	void fsnotify_clear_marks_by_inode(struct inode *inode)
	87	{
841bdc10	88	struct fsnotify_mark mark, lmark;
b67bfe0d	89	struct hlist_node *n;
3be25f49 EP	90	LIST_HEAD(free_list);
	91
	92	spin_lock(&inode->i_lock);
b67bfe0d	93	hlist_for_each_entry_safe(mark, n, &inode->i_fsnotify_marks, i.i_list) {
841bdc10	94	list_add(&mark->i.free_i_list, &free_list);
a4c6e996	95	hlist_del_init_rcu(&mark->i.i_list);
841bdc10	96	fsnotify_get_mark(mark);
3be25f49 EP	97	}
	98	spin_unlock(&inode->i_lock);
	99
841bdc10	100	list_for_each_entry_safe(mark, lmark, &free_list, i.free_i_list) {
e2a29943 LS	101	struct fsnotify_group *group;
	102
	103	spin_lock(&mark->lock);
	104	fsnotify_get_group(mark->group);
	105	group = mark->group;
	106	spin_unlock(&mark->lock);
	107
	108	fsnotify_destroy_mark(mark, group);
841bdc10	109	fsnotify_put_mark(mark);
e2a29943	110	fsnotify_put_group(group);
3be25f49 EP	111	}
	112	}
	113
4d92604c EP	114	/*
	115	* Given a group clear all of the inode marks associated with that group.
	116	*/
	117	void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
	118	{
	119	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
	120	}
	121
3be25f49 EP	122	/*
	123	* given a group and inode, find the mark associated with that combination.
	124	* if found take a reference to that mark and return it, else return NULL
	125	*/
ac5f121b TB	126	static struct fsnotify_mark *fsnotify_find_inode_mark_locked(
	127	struct fsnotify_group *group,
	128	struct inode *inode)
3be25f49	129	{
841bdc10	130	struct fsnotify_mark *mark;
3be25f49 EP	131
	132	assert_spin_locked(&inode->i_lock);
	133
b67bfe0d	134	hlist_for_each_entry(mark, &inode->i_fsnotify_marks, i.i_list) {
841bdc10 EP	135	if (mark->group == group) {
	136	fsnotify_get_mark(mark);
	137	return mark;
3be25f49 EP	138	}
	139	}
	140	return NULL;
	141	}
	142
	143	/*
35566087 AG	144	* given a group and inode, find the mark associated with that combination.
35566087 AG	145	* if found take a reference to that mark and return it, else return NULL
3be25f49	146	*/
5444e298 EP	147	struct fsnotify_mark fsnotify_find_inode_mark(struct fsnotify_group group,
5444e298 EP	148	struct inode *inode)
35566087 AG	149	{
	150	struct fsnotify_mark *mark;
	151
	152	spin_lock(&inode->i_lock);
5444e298	153	mark = fsnotify_find_inode_mark_locked(group, inode);
35566087 AG	154	spin_unlock(&inode->i_lock);
	155
	156	return mark;
	157	}
3be25f49	158
3be25f49	159	/*
90b1e7a5 EP	160	* If we are setting a mark mask on an inode mark we should pin the inode
	161	* in memory.
	162	*/
	163	void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark,
	164	__u32 mask)
3be25f49	165	{
90b1e7a5 EP	166	struct inode *inode;
	167
	168	assert_spin_locked(&mark->lock);
	169
	170	if (mask &&
	171	mark->i.inode &&
	172	!(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) {
	173	mark->flags \|= FSNOTIFY_MARK_FLAG_OBJECT_PINNED;
	174	inode = igrab(mark->i.inode);
	175	/*
	176	* we shouldn't be able to get here if the inode wasn't
	177	* already safely held in memory. But bug in case it
	178	* ever is wrong.
	179	*/
	180	BUG_ON(!inode);
	181	}
3be25f49 EP	182	}
	183
	184	/*
0c6532e4	185	* Attach an initialized mark to a given inode.
3be25f49	186	* These marks may be used for the fsnotify backend to determine which
0c6532e4	187	* event types should be delivered to which group and for which inodes. These
6ad2d4e3 EP	188	* marks are ordered according to priority, highest number first, and then by
6ad2d4e3 EP	189	* the group's location in memory.
3be25f49	190	*/
5444e298 EP	191	int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
	192	struct fsnotify_group group, struct inode inode,
	193	int allow_dups)
3be25f49	194	{
b67bfe0d	195	struct fsnotify_mark lmark, last = NULL;
3be25f49 EP	196	int ret = 0;
3be25f49 EP	197
700307a2	198	mark->flags \|= FSNOTIFY_MARK_FLAG_INODE;
098cf2fc	199
986ab098	200	BUG_ON(!mutex_is_locked(&group->mark_mutex));
5444e298	201	assert_spin_locked(&mark->lock);
1ef5f13c	202
3be25f49 EP	203	spin_lock(&inode->i_lock);
3be25f49 EP	204
0c6532e4	205	mark->i.inode = inode;
9f0d793b	206
0c6532e4 EP	207	/* is mark the first mark? */
0c6532e4 EP	208	if (hlist_empty(&inode->i_fsnotify_marks)) {
a4c6e996	209	hlist_add_head_rcu(&mark->i.i_list, &inode->i_fsnotify_marks);
0c6532e4 EP	210	goto out;
0c6532e4 EP	211	}
3be25f49	212
0c6532e4	213	/* should mark be in the middle of the current list? */
b67bfe0d SL	214	hlist_for_each_entry(lmark, &inode->i_fsnotify_marks, i.i_list) {
b67bfe0d SL	215	last = lmark;
3be25f49	216
0c6532e4 EP	217	if ((lmark->group == group) && !allow_dups) {
	218	ret = -EEXIST;
	219	goto out;
	220	}
3be25f49	221
6ad2d4e3 EP	222	if (mark->group->priority < lmark->group->priority)
	223	continue;
	224
	225	if ((mark->group->priority == lmark->group->priority) &&
	226	(mark->group < lmark->group))
0c6532e4	227	continue;
3be25f49	228
a4c6e996	229	hlist_add_before_rcu(&mark->i.i_list, &lmark->i.i_list);
0c6532e4	230	goto out;
3be25f49 EP	231	}
3be25f49 EP	232
0c6532e4 EP	233	BUG_ON(last == NULL);
0c6532e4 EP	234	/* mark should be the last entry. last is the current last entry */
b67bfe0d	235	hlist_add_after_rcu(&last->i.i_list, &mark->i.i_list);
0c6532e4 EP	236	out:
0c6532e4 EP	237	fsnotify_recalc_inode_mask_locked(inode);
3be25f49	238	spin_unlock(&inode->i_lock);
3be25f49 EP	239
	240	return ret;
	241	}
164bc619 EP	242
	243	/**
	244	* fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
	245	* @list: list of inodes being unmounted (sb->s_inodes)
	246	*
55fa6091 DC	247	* Called during unmount with no locks held, so needs to be safe against
55fa6091 DC	248	* concurrent modifiers. We temporarily drop inode_sb_list_lock and CAN block.
164bc619 EP	249	*/
	250	void fsnotify_unmount_inodes(struct list_head *list)
	251	{
	252	struct inode inode, next_i, *need_iput = NULL;
	253
55fa6091	254	spin_lock(&inode_sb_list_lock);
164bc619 EP	255	list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
	256	struct inode *need_iput_tmp;
	257
	258	/*
a4ffdde6	259	* We cannot __iget() an inode in state I_FREEING,
164bc619 EP	260	* I_WILL_FREE, or I_NEW which is fine because by that point
	261	* the inode cannot have any associated watches.
	262	*/
250df6ed DC	263	spin_lock(&inode->i_lock);
	264	if (inode->i_state & (I_FREEING\|I_WILL_FREE\|I_NEW)) {
	265	spin_unlock(&inode->i_lock);
164bc619	266	continue;
250df6ed	267	}
164bc619 EP	268
	269	/*
	270	* If i_count is zero, the inode cannot have any watches and
	271	* doing an __iget/iput with MS_ACTIVE clear would actually
	272	* evict all inodes with zero i_count from icache which is
	273	* unnecessarily violent and may in fact be illegal to do.
	274	*/
250df6ed DC	275	if (!atomic_read(&inode->i_count)) {
250df6ed DC	276	spin_unlock(&inode->i_lock);
164bc619	277	continue;
250df6ed	278	}
164bc619 EP	279
	280	need_iput_tmp = need_iput;
	281	need_iput = NULL;
	282
	283	/* In case fsnotify_inode_delete() drops a reference. */
	284	if (inode != need_iput_tmp)
	285	__iget(inode);
	286	else
	287	need_iput_tmp = NULL;
250df6ed	288	spin_unlock(&inode->i_lock);
164bc619 EP	289
	290	/* In case the dropping of a reference would nuke next_i. */
	291	if ((&next_i->i_sb_list != list) &&
250df6ed DC	292	atomic_read(&next_i->i_count)) {
	293	spin_lock(&next_i->i_lock);
	294	if (!(next_i->i_state & (I_FREEING \| I_WILL_FREE))) {
	295	__iget(next_i);
	296	need_iput = next_i;
	297	}
	298	spin_unlock(&next_i->i_lock);
164bc619 EP	299	}
	300
	301	/*
55fa6091	302	* We can safely drop inode_sb_list_lock here because we hold
164bc619	303	* references on both inode and next_i. Also no new inodes
55fa6091	304	* will be added since the umount has begun.
164bc619	305	*/
55fa6091	306	spin_unlock(&inode_sb_list_lock);
164bc619 EP	307
	308	if (need_iput_tmp)
	309	iput(need_iput_tmp);
	310
	311	/* for each watch, send FS_UNMOUNT and then remove it */
	312	fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
	313
	314	fsnotify_inode_delete(inode);
	315
	316	iput(inode);
	317
55fa6091	318	spin_lock(&inode_sb_list_lock);
164bc619	319	}
55fa6091	320	spin_unlock(&inode_sb_list_lock);
164bc619	321	}