[GitHub/mt8127/android_kernel_alcatel_ttab.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;
	struct hlist_node *pos;
	__u32 new_mask = 0;

	assert_spin_locked(&inode->i_lock);

	hlist_for_each_entry(mark, pos, &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;

	assert_spin_locked(&mark->lock);
	assert_spin_locked(&mark->group->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 *pos, *n;
	LIST_HEAD(free_list);

	spin_lock(&inode->i_lock);
	hlist_for_each_entry_safe(mark, pos, 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) {
		fsnotify_destroy_mark(mark);
		fsnotify_put_mark(mark);
	}
}

/*
 * 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
 */
struct fsnotify_mark *fsnotify_find_inode_mark_locked(struct fsnotify_group *group,
						      struct inode *inode)
{
	struct fsnotify_mark *mark;
	struct hlist_node *pos;

	assert_spin_locked(&inode->i_lock);

	hlist_for_each_entry(mark, pos, &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;
	struct hlist_node *node, *last = NULL;
	int ret = 0;

	mark->flags |= FSNOTIFY_MARK_FLAG_INODE;

	assert_spin_locked(&mark->lock);
	assert_spin_locked(&group->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, node, &inode->i_fsnotify_marks, i.i_list) {
		last = node;

		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, &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	struct hlist_node *pos;
	40	__u32 new_mask = 0;
	41
	42	assert_spin_locked(&inode->i_lock);
	43
841bdc10 EP	44	hlist_for_each_entry(mark, pos, &inode->i_fsnotify_marks, i.i_list)
841bdc10 EP	45	new_mask \|= mark->mask;
3be25f49 EP	46	inode->i_fsnotify_mask = new_mask;
	47	}
	48
	49	/*
	50	* Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types
	51	* any notifier is interested in hearing for this inode.
	52	*/
	53	void fsnotify_recalc_inode_mask(struct inode *inode)
	54	{
	55	spin_lock(&inode->i_lock);
	56	fsnotify_recalc_inode_mask_locked(inode);
	57	spin_unlock(&inode->i_lock);
c28f7e56 EP	58
c28f7e56 EP	59	__fsnotify_update_child_dentry_flags(inode);
3be25f49 EP	60	}
3be25f49 EP	61
5444e298	62	void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
3be25f49	63	{
5444e298	64	struct inode *inode = mark->i.inode;
3be25f49	65
5444e298 EP	66	assert_spin_locked(&mark->lock);
5444e298 EP	67	assert_spin_locked(&mark->group->mark_lock);
3be25f49	68
3be25f49 EP	69	spin_lock(&inode->i_lock);
3be25f49 EP	70
a4c6e996	71	hlist_del_init_rcu(&mark->i.i_list);
841bdc10	72	mark->i.inode = NULL;
3be25f49 EP	73
3be25f49 EP	74	/*
e61ce867	75	* this mark is now off the inode->i_fsnotify_marks list and we
3be25f49 EP	76	* hold the inode->i_lock, so this is the perfect time to update the
	77	* inode->i_fsnotify_mask
	78	*/
	79	fsnotify_recalc_inode_mask_locked(inode);
	80
	81	spin_unlock(&inode->i_lock);
3be25f49 EP	82	}
	83
	84	/*
	85	* Given an inode, destroy all of the marks associated with that inode.
	86	*/
	87	void fsnotify_clear_marks_by_inode(struct inode *inode)
	88	{
841bdc10	89	struct fsnotify_mark mark, lmark;
3be25f49 EP	90	struct hlist_node pos, n;
	91	LIST_HEAD(free_list);
	92
	93	spin_lock(&inode->i_lock);
841bdc10 EP	94	hlist_for_each_entry_safe(mark, pos, n, &inode->i_fsnotify_marks, i.i_list) {
841bdc10 EP	95	list_add(&mark->i.free_i_list, &free_list);
a4c6e996	96	hlist_del_init_rcu(&mark->i.i_list);
841bdc10	97	fsnotify_get_mark(mark);
3be25f49 EP	98	}
	99	spin_unlock(&inode->i_lock);
	100
841bdc10 EP	101	list_for_each_entry_safe(mark, lmark, &free_list, i.free_i_list) {
	102	fsnotify_destroy_mark(mark);
	103	fsnotify_put_mark(mark);
3be25f49 EP	104	}
	105	}
	106
4d92604c EP	107	/*
	108	* Given a group clear all of the inode marks associated with that group.
	109	*/
	110	void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
	111	{
	112	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
	113	}
	114
3be25f49 EP	115	/*
	116	* given a group and inode, find the mark associated with that combination.
	117	* if found take a reference to that mark and return it, else return NULL
	118	*/
5444e298 EP	119	struct fsnotify_mark fsnotify_find_inode_mark_locked(struct fsnotify_group group,
5444e298 EP	120	struct inode *inode)
3be25f49	121	{
841bdc10	122	struct fsnotify_mark *mark;
3be25f49 EP	123	struct hlist_node *pos;
	124
	125	assert_spin_locked(&inode->i_lock);
	126
841bdc10 EP	127	hlist_for_each_entry(mark, pos, &inode->i_fsnotify_marks, i.i_list) {
	128	if (mark->group == group) {
	129	fsnotify_get_mark(mark);
	130	return mark;
3be25f49 EP	131	}
	132	}
	133	return NULL;
	134	}
	135
	136	/*
35566087 AG	137	* given a group and inode, find the mark associated with that combination.
35566087 AG	138	* if found take a reference to that mark and return it, else return NULL
3be25f49	139	*/
5444e298 EP	140	struct fsnotify_mark fsnotify_find_inode_mark(struct fsnotify_group group,
5444e298 EP	141	struct inode *inode)
35566087 AG	142	{
	143	struct fsnotify_mark *mark;
	144
	145	spin_lock(&inode->i_lock);
5444e298	146	mark = fsnotify_find_inode_mark_locked(group, inode);
35566087 AG	147	spin_unlock(&inode->i_lock);
	148
	149	return mark;
	150	}
3be25f49	151
3be25f49	152	/*
90b1e7a5 EP	153	* If we are setting a mark mask on an inode mark we should pin the inode
	154	* in memory.
	155	*/
	156	void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark,
	157	__u32 mask)
3be25f49	158	{
90b1e7a5 EP	159	struct inode *inode;
	160
	161	assert_spin_locked(&mark->lock);
	162
	163	if (mask &&
	164	mark->i.inode &&
	165	!(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) {
	166	mark->flags \|= FSNOTIFY_MARK_FLAG_OBJECT_PINNED;
	167	inode = igrab(mark->i.inode);
	168	/*
	169	* we shouldn't be able to get here if the inode wasn't
	170	* already safely held in memory. But bug in case it
	171	* ever is wrong.
	172	*/
	173	BUG_ON(!inode);
	174	}
3be25f49 EP	175	}
	176
	177	/*
0c6532e4	178	* Attach an initialized mark to a given inode.
3be25f49	179	* These marks may be used for the fsnotify backend to determine which
0c6532e4	180	* event types should be delivered to which group and for which inodes. These
6ad2d4e3 EP	181	* marks are ordered according to priority, highest number first, and then by
6ad2d4e3 EP	182	* the group's location in memory.
3be25f49	183	*/
5444e298 EP	184	int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
	185	struct fsnotify_group group, struct inode inode,
	186	int allow_dups)
3be25f49	187	{
0c6532e4 EP	188	struct fsnotify_mark *lmark;
0c6532e4 EP	189	struct hlist_node node, last = NULL;
3be25f49 EP	190	int ret = 0;
3be25f49 EP	191
700307a2	192	mark->flags \|= FSNOTIFY_MARK_FLAG_INODE;
098cf2fc	193
5444e298 EP	194	assert_spin_locked(&mark->lock);
5444e298 EP	195	assert_spin_locked(&group->mark_lock);
1ef5f13c	196
3be25f49 EP	197	spin_lock(&inode->i_lock);
3be25f49 EP	198
0c6532e4	199	mark->i.inode = inode;
9f0d793b	200
0c6532e4 EP	201	/* is mark the first mark? */
0c6532e4 EP	202	if (hlist_empty(&inode->i_fsnotify_marks)) {
a4c6e996	203	hlist_add_head_rcu(&mark->i.i_list, &inode->i_fsnotify_marks);
0c6532e4 EP	204	goto out;
0c6532e4 EP	205	}
3be25f49	206
0c6532e4 EP	207	/* should mark be in the middle of the current list? */
	208	hlist_for_each_entry(lmark, node, &inode->i_fsnotify_marks, i.i_list) {
	209	last = node;
3be25f49	210
0c6532e4 EP	211	if ((lmark->group == group) && !allow_dups) {
	212	ret = -EEXIST;
	213	goto out;
	214	}
3be25f49	215
6ad2d4e3 EP	216	if (mark->group->priority < lmark->group->priority)
	217	continue;
	218
	219	if ((mark->group->priority == lmark->group->priority) &&
	220	(mark->group < lmark->group))
0c6532e4	221	continue;
3be25f49	222
a4c6e996	223	hlist_add_before_rcu(&mark->i.i_list, &lmark->i.i_list);
0c6532e4	224	goto out;
3be25f49 EP	225	}
3be25f49 EP	226
0c6532e4 EP	227	BUG_ON(last == NULL);
0c6532e4 EP	228	/* mark should be the last entry. last is the current last entry */
a4c6e996	229	hlist_add_after_rcu(last, &mark->i.i_list);
0c6532e4 EP	230	out:
0c6532e4 EP	231	fsnotify_recalc_inode_mask_locked(inode);
3be25f49	232	spin_unlock(&inode->i_lock);
3be25f49 EP	233
	234	return ret;
	235	}
164bc619 EP	236
	237	/**
	238	* fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
	239	* @list: list of inodes being unmounted (sb->s_inodes)
	240	*
55fa6091 DC	241	* Called during unmount with no locks held, so needs to be safe against
55fa6091 DC	242	* concurrent modifiers. We temporarily drop inode_sb_list_lock and CAN block.
164bc619 EP	243	*/
	244	void fsnotify_unmount_inodes(struct list_head *list)
	245	{
	246	struct inode inode, next_i, *need_iput = NULL;
	247
55fa6091	248	spin_lock(&inode_sb_list_lock);
164bc619 EP	249	list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
	250	struct inode *need_iput_tmp;
	251
	252	/*
a4ffdde6	253	* We cannot __iget() an inode in state I_FREEING,
164bc619 EP	254	* I_WILL_FREE, or I_NEW which is fine because by that point
	255	* the inode cannot have any associated watches.
	256	*/
250df6ed DC	257	spin_lock(&inode->i_lock);
	258	if (inode->i_state & (I_FREEING\|I_WILL_FREE\|I_NEW)) {
	259	spin_unlock(&inode->i_lock);
164bc619	260	continue;
250df6ed	261	}
164bc619 EP	262
	263	/*
	264	* If i_count is zero, the inode cannot have any watches and
	265	* doing an __iget/iput with MS_ACTIVE clear would actually
	266	* evict all inodes with zero i_count from icache which is
	267	* unnecessarily violent and may in fact be illegal to do.
	268	*/
250df6ed DC	269	if (!atomic_read(&inode->i_count)) {
250df6ed DC	270	spin_unlock(&inode->i_lock);
164bc619	271	continue;
250df6ed	272	}
164bc619 EP	273
	274	need_iput_tmp = need_iput;
	275	need_iput = NULL;
	276
	277	/* In case fsnotify_inode_delete() drops a reference. */
	278	if (inode != need_iput_tmp)
	279	__iget(inode);
	280	else
	281	need_iput_tmp = NULL;
250df6ed	282	spin_unlock(&inode->i_lock);
164bc619 EP	283
	284	/* In case the dropping of a reference would nuke next_i. */
	285	if ((&next_i->i_sb_list != list) &&
250df6ed DC	286	atomic_read(&next_i->i_count)) {
	287	spin_lock(&next_i->i_lock);
	288	if (!(next_i->i_state & (I_FREEING \| I_WILL_FREE))) {
	289	__iget(next_i);
	290	need_iput = next_i;
	291	}
	292	spin_unlock(&next_i->i_lock);
164bc619 EP	293	}
	294
	295	/*
55fa6091	296	* We can safely drop inode_sb_list_lock here because we hold
164bc619	297	* references on both inode and next_i. Also no new inodes
55fa6091	298	* will be added since the umount has begun.
164bc619	299	*/
55fa6091	300	spin_unlock(&inode_sb_list_lock);
164bc619 EP	301
	302	if (need_iput_tmp)
	303	iput(need_iput_tmp);
	304
	305	/* for each watch, send FS_UNMOUNT and then remove it */
	306	fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
	307
	308	fsnotify_inode_delete(inode);
	309
	310	iput(inode);
	311
55fa6091	312	spin_lock(&inode_sb_list_lock);
164bc619	313	}
55fa6091	314	spin_unlock(&inode_sb_list_lock);
164bc619	315	}