fsnotify: split generic and inode specific mark code
currently all marking is done by functions in inode-mark.c. Some of this is pretty generic and should be instead done in a generic function and we should only put the inode specific code in inode-mark.c Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Eric Paris
parent
32c3263221
commit
5444e2981c
|
|
@ -1,4 +1,5 @@
|
|||
obj-$(CONFIG_FSNOTIFY) += fsnotify.o notification.o group.o inode_mark.o
|
||||
obj-$(CONFIG_FSNOTIFY) += fsnotify.o notification.o group.o inode_mark.o \
|
||||
mark.o
|
||||
|
||||
obj-y += dnotify/
|
||||
obj-y += inotify/
|
||||
|
|
|
|||
|
|
@ -95,7 +95,7 @@ static int dnotify_handle_event(struct fsnotify_group *group,
|
|||
|
||||
to_tell = event->to_tell;
|
||||
|
||||
fsn_mark = fsnotify_find_mark(group, to_tell);
|
||||
fsn_mark = fsnotify_find_inode_mark(group, to_tell);
|
||||
if (unlikely(!fsn_mark))
|
||||
return 0;
|
||||
dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
|
||||
|
|
@ -143,14 +143,14 @@ static bool dnotify_should_send_event(struct fsnotify_group *group,
|
|||
if (!S_ISDIR(inode->i_mode))
|
||||
return false;
|
||||
|
||||
fsn_mark = fsnotify_find_mark(group, inode);
|
||||
fsn_mark = fsnotify_find_inode_mark(group, inode);
|
||||
if (!fsn_mark)
|
||||
return false;
|
||||
|
||||
mask = (mask & ~FS_EVENT_ON_CHILD);
|
||||
send = (mask & fsn_mark->mask);
|
||||
|
||||
fsnotify_put_mark(fsn_mark); /* matches fsnotify_find_mark */
|
||||
fsnotify_put_mark(fsn_mark); /* matches fsnotify_find_inode_mark */
|
||||
|
||||
return send;
|
||||
}
|
||||
|
|
@ -193,7 +193,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
|
|||
if (!S_ISDIR(inode->i_mode))
|
||||
return;
|
||||
|
||||
fsn_mark = fsnotify_find_mark(dnotify_group, inode);
|
||||
fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode);
|
||||
if (!fsn_mark)
|
||||
return;
|
||||
dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
|
||||
|
|
@ -346,12 +346,12 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
|
|||
mutex_lock(&dnotify_mark_mutex);
|
||||
|
||||
/* add the new_fsn_mark or find an old one. */
|
||||
fsn_mark = fsnotify_find_mark(dnotify_group, inode);
|
||||
fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode);
|
||||
if (fsn_mark) {
|
||||
dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
|
||||
spin_lock(&fsn_mark->lock);
|
||||
} else {
|
||||
fsnotify_add_mark(new_fsn_mark, dnotify_group, inode, 0);
|
||||
fsnotify_add_mark(new_fsn_mark, dnotify_group, inode, NULL, 0);
|
||||
spin_lock(&new_fsn_mark->lock);
|
||||
fsn_mark = new_fsn_mark;
|
||||
dn_mark = new_dn_mark;
|
||||
|
|
|
|||
|
|
@ -118,7 +118,7 @@ static bool fanotify_should_send_event(struct fsnotify_group *group, struct inod
|
|||
if (data_type != FSNOTIFY_EVENT_PATH)
|
||||
return false;
|
||||
|
||||
fsn_mark = fsnotify_find_mark(group, inode);
|
||||
fsn_mark = fsnotify_find_inode_mark(group, inode);
|
||||
if (!fsn_mark)
|
||||
return false;
|
||||
|
||||
|
|
|
|||
|
|
@ -305,7 +305,7 @@ static int fanotify_remove_mark(struct fsnotify_group *group,
|
|||
pr_debug("%s: group=%p inode=%p mask=%x\n", __func__,
|
||||
group, inode, mask);
|
||||
|
||||
fsn_mark = fsnotify_find_mark(group, inode);
|
||||
fsn_mark = fsnotify_find_inode_mark(group, inode);
|
||||
if (!fsn_mark)
|
||||
return -ENOENT;
|
||||
|
||||
|
|
@ -321,7 +321,7 @@ static int fanotify_remove_mark(struct fsnotify_group *group,
|
|||
|
||||
fsnotify_recalc_group_mask(group);
|
||||
|
||||
/* matches the fsnotify_find_mark() */
|
||||
/* matches the fsnotify_find_inode_mark() */
|
||||
fsnotify_put_mark(fsn_mark);
|
||||
|
||||
return 0;
|
||||
|
|
@ -338,7 +338,7 @@ static int fanotify_add_mark(struct fsnotify_group *group,
|
|||
pr_debug("%s: group=%p inode=%p mask=%x\n", __func__,
|
||||
group, inode, mask);
|
||||
|
||||
fsn_mark = fsnotify_find_mark(group, inode);
|
||||
fsn_mark = fsnotify_find_inode_mark(group, inode);
|
||||
if (!fsn_mark) {
|
||||
struct fsnotify_mark *new_fsn_mark;
|
||||
|
||||
|
|
@ -348,7 +348,7 @@ static int fanotify_add_mark(struct fsnotify_group *group,
|
|||
goto out;
|
||||
|
||||
fsnotify_init_mark(new_fsn_mark, fanotify_free_mark);
|
||||
ret = fsnotify_add_mark(new_fsn_mark, group, inode, 0);
|
||||
ret = fsnotify_add_mark(new_fsn_mark, group, inode, NULL, 0);
|
||||
if (ret) {
|
||||
fanotify_free_mark(new_fsn_mark);
|
||||
goto out;
|
||||
|
|
|
|||
|
|
@ -20,6 +20,11 @@ extern __u32 fsnotify_vfsmount_mask;
|
|||
/* destroy all events sitting in this groups notification queue */
|
||||
extern void fsnotify_flush_notify(struct fsnotify_group *group);
|
||||
|
||||
/* add a mark to an inode */
|
||||
extern int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
|
||||
struct fsnotify_group *group, struct inode *inode,
|
||||
int allow_dups);
|
||||
|
||||
/* add a group to the inode group list */
|
||||
extern void fsnotify_add_inode_group(struct fsnotify_group *group);
|
||||
/* add a group to the vfsmount group list */
|
||||
|
|
@ -27,6 +32,8 @@ extern void fsnotify_add_vfsmount_group(struct fsnotify_group *group);
|
|||
/* final kfree of a group */
|
||||
extern void fsnotify_final_destroy_group(struct fsnotify_group *group);
|
||||
|
||||
/* inode specific destruction of a mark */
|
||||
extern void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark);
|
||||
/* run the list of all marks associated with inode and flag them to be freed */
|
||||
extern void fsnotify_clear_marks_by_inode(struct inode *inode);
|
||||
/*
|
||||
|
|
|
|||
|
|
@ -16,72 +16,6 @@
|
|||
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
|
||||
*/
|
||||
|
||||
/*
|
||||
* fsnotify inode mark locking/lifetime/and refcnting
|
||||
*
|
||||
* REFCNT:
|
||||
* The mark->refcnt tells how many "things" in the kernel currently are
|
||||
* referencing this object. The object typically will live inside the kernel
|
||||
* with a refcnt of 2, one for each list it is on (i_list, g_list). Any task
|
||||
* which can find this object holding the appropriete locks, can take a reference
|
||||
* and the object itself is guarenteed to survive until the reference is dropped.
|
||||
*
|
||||
* LOCKING:
|
||||
* There are 3 spinlocks involved with fsnotify inode marks and they MUST
|
||||
* be taken in order as follows:
|
||||
*
|
||||
* mark->lock
|
||||
* group->mark_lock
|
||||
* inode->i_lock
|
||||
*
|
||||
* mark->lock protects 2 things, mark->group and mark->inode. You must hold
|
||||
* that lock to dereference either of these things (they could be NULL even with
|
||||
* the lock)
|
||||
*
|
||||
* group->mark_lock protects the marks_list anchored inside a given group
|
||||
* and each mark is hooked via the g_list. It also sorta protects the
|
||||
* free_g_list, which when used is anchored by a private list on the stack of the
|
||||
* task which held the group->mark_lock.
|
||||
*
|
||||
* inode->i_lock protects the i_fsnotify_marks list anchored inside a
|
||||
* given inode and each mark is hooked via the i_list. (and sorta the
|
||||
* free_i_list)
|
||||
*
|
||||
*
|
||||
* LIFETIME:
|
||||
* Inode marks survive between when they are added to an inode and when their
|
||||
* refcnt==0.
|
||||
*
|
||||
* The inode mark can be cleared for a number of different reasons including:
|
||||
* - The inode is unlinked for the last time. (fsnotify_inode_remove)
|
||||
* - The inode is being evicted from cache. (fsnotify_inode_delete)
|
||||
* - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes)
|
||||
* - Something explicitly requests that it be removed. (fsnotify_destroy_mark)
|
||||
* - The fsnotify_group associated with the mark is going away and all such marks
|
||||
* need to be cleaned up. (fsnotify_clear_marks_by_group)
|
||||
*
|
||||
* Worst case we are given an inode and need to clean up all the marks on that
|
||||
* inode. We take i_lock and walk the i_fsnotify_marks safely. For each
|
||||
* mark on the list we take a reference (so the mark can't disappear under us).
|
||||
* We remove that mark form the inode's list of marks and we add this mark to a
|
||||
* private list anchored on the stack using i_free_list; At this point we no
|
||||
* longer fear anything finding the mark using the inode's list of marks.
|
||||
*
|
||||
* We can safely and locklessly run the private list on the stack of everything
|
||||
* we just unattached from the original inode. For each mark on the private list
|
||||
* we grab the mark-> and can thus dereference mark->group and mark->inode. If
|
||||
* we see the group and inode are not NULL we take those locks. Now holding all
|
||||
* 3 locks we can completely remove the mark from other tasks finding it in the
|
||||
* future. Remember, 10 things might already be referencing this mark, but they
|
||||
* better be holding a ref. We drop our reference we took before we unhooked it
|
||||
* from the inode. When the ref hits 0 we can free the mark.
|
||||
*
|
||||
* Very similarly for freeing by group, except we use free_g_list.
|
||||
*
|
||||
* This has the very interesting property of being able to run concurrently with
|
||||
* any (or all) other directions.
|
||||
*/
|
||||
|
||||
#include <linux/fs.h>
|
||||
#include <linux/init.h>
|
||||
#include <linux/kernel.h>
|
||||
|
|
@ -95,17 +29,6 @@
|
|||
#include <linux/fsnotify_backend.h>
|
||||
#include "fsnotify.h"
|
||||
|
||||
void fsnotify_get_mark(struct fsnotify_mark *mark)
|
||||
{
|
||||
atomic_inc(&mark->refcnt);
|
||||
}
|
||||
|
||||
void fsnotify_put_mark(struct fsnotify_mark *mark)
|
||||
{
|
||||
if (atomic_dec_and_test(&mark->refcnt))
|
||||
mark->free_mark(mark);
|
||||
}
|
||||
|
||||
/*
|
||||
* Recalculate the mask of events relevant to a given inode locked.
|
||||
*/
|
||||
|
|
@ -135,44 +58,18 @@ void fsnotify_recalc_inode_mask(struct inode *inode)
|
|||
__fsnotify_update_child_dentry_flags(inode);
|
||||
}
|
||||
|
||||
/*
|
||||
* Any time a mark is getting freed we end up here.
|
||||
* The caller had better be holding a reference to this mark so we don't actually
|
||||
* do the final put under the mark->lock
|
||||
*/
|
||||
void fsnotify_destroy_mark(struct fsnotify_mark *mark)
|
||||
void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
|
||||
{
|
||||
struct fsnotify_group *group;
|
||||
struct inode *inode;
|
||||
struct inode *inode = mark->i.inode;
|
||||
|
||||
spin_lock(&mark->lock);
|
||||
assert_spin_locked(&mark->lock);
|
||||
assert_spin_locked(&mark->group->mark_lock);
|
||||
|
||||
group = mark->group;
|
||||
inode = mark->i.inode;
|
||||
|
||||
BUG_ON(group && !inode);
|
||||
BUG_ON(!group && inode);
|
||||
|
||||
/* if !group something else already marked this to die */
|
||||
if (!group) {
|
||||
spin_unlock(&mark->lock);
|
||||
return;
|
||||
}
|
||||
|
||||
/* 1 from caller and 1 for being on i_list/g_list */
|
||||
BUG_ON(atomic_read(&mark->refcnt) < 2);
|
||||
|
||||
spin_lock(&group->mark_lock);
|
||||
spin_lock(&inode->i_lock);
|
||||
|
||||
hlist_del_init(&mark->i.i_list);
|
||||
mark->i.inode = NULL;
|
||||
|
||||
list_del_init(&mark->g_list);
|
||||
mark->group = NULL;
|
||||
|
||||
fsnotify_put_mark(mark); /* for i_list and g_list */
|
||||
|
||||
/*
|
||||
* 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
|
||||
|
|
@ -181,61 +78,6 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark)
|
|||
fsnotify_recalc_inode_mask_locked(inode);
|
||||
|
||||
spin_unlock(&inode->i_lock);
|
||||
spin_unlock(&group->mark_lock);
|
||||
spin_unlock(&mark->lock);
|
||||
|
||||
/*
|
||||
* Some groups like to know that marks are being freed. This is a
|
||||
* callback to the group function to let it know that this mark
|
||||
* is being freed.
|
||||
*/
|
||||
if (group->ops->freeing_mark)
|
||||
group->ops->freeing_mark(mark, group);
|
||||
|
||||
/*
|
||||
* __fsnotify_update_child_dentry_flags(inode);
|
||||
*
|
||||
* I really want to call that, but we can't, we have no idea if the inode
|
||||
* still exists the second we drop the mark->lock.
|
||||
*
|
||||
* The next time an event arrive to this inode from one of it's children
|
||||
* __fsnotify_parent will see that the inode doesn't care about it's
|
||||
* children and will update all of these flags then. So really this
|
||||
* is just a lazy update (and could be a perf win...)
|
||||
*/
|
||||
|
||||
|
||||
iput(inode);
|
||||
|
||||
/*
|
||||
* it's possible that this group tried to destroy itself, but this
|
||||
* this mark was simultaneously being freed by inode. If that's the
|
||||
* case, we finish freeing the group here.
|
||||
*/
|
||||
if (unlikely(atomic_dec_and_test(&group->num_marks)))
|
||||
fsnotify_final_destroy_group(group);
|
||||
}
|
||||
|
||||
/*
|
||||
* Given a group, destroy all of the marks associated with that group.
|
||||
*/
|
||||
void fsnotify_clear_marks_by_group(struct fsnotify_group *group)
|
||||
{
|
||||
struct fsnotify_mark *lmark, *mark;
|
||||
LIST_HEAD(free_list);
|
||||
|
||||
spin_lock(&group->mark_lock);
|
||||
list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
|
||||
list_add(&mark->free_g_list, &free_list);
|
||||
list_del_init(&mark->g_list);
|
||||
fsnotify_get_mark(mark);
|
||||
}
|
||||
spin_unlock(&group->mark_lock);
|
||||
|
||||
list_for_each_entry_safe(mark, lmark, &free_list, free_g_list) {
|
||||
fsnotify_destroy_mark(mark);
|
||||
fsnotify_put_mark(mark);
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
|
|
@ -261,8 +103,12 @@ void fsnotify_clear_marks_by_inode(struct inode *inode)
|
|||
}
|
||||
}
|
||||
|
||||
static struct fsnotify_mark *fsnotify_find_mark_locked(struct fsnotify_group *group,
|
||||
struct inode *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;
|
||||
|
|
@ -282,50 +128,26 @@ static struct fsnotify_mark *fsnotify_find_mark_locked(struct fsnotify_group *gr
|
|||
* 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_mark(struct fsnotify_group *group,
|
||||
struct inode *inode)
|
||||
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_mark_locked(group, inode);
|
||||
mark = fsnotify_find_inode_mark_locked(group, inode);
|
||||
spin_unlock(&inode->i_lock);
|
||||
|
||||
return mark;
|
||||
}
|
||||
|
||||
void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old)
|
||||
{
|
||||
assert_spin_locked(&old->lock);
|
||||
new->i.inode = old->i.inode;
|
||||
new->group = old->group;
|
||||
new->mask = old->mask;
|
||||
new->free_mark = old->free_mark;
|
||||
}
|
||||
|
||||
/*
|
||||
* Nothing fancy, just initialize lists and locks and counters.
|
||||
*/
|
||||
void fsnotify_init_mark(struct fsnotify_mark *mark,
|
||||
void (*free_mark)(struct fsnotify_mark *mark))
|
||||
{
|
||||
spin_lock_init(&mark->lock);
|
||||
atomic_set(&mark->refcnt, 1);
|
||||
INIT_HLIST_NODE(&mark->i.i_list);
|
||||
mark->group = NULL;
|
||||
mark->mask = 0;
|
||||
mark->i.inode = NULL;
|
||||
mark->free_mark = free_mark;
|
||||
}
|
||||
|
||||
/*
|
||||
* Attach an initialized mark mark to a given group and 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.
|
||||
*/
|
||||
int fsnotify_add_mark(struct fsnotify_mark *mark,
|
||||
struct fsnotify_group *group, struct inode *inode,
|
||||
int allow_dups)
|
||||
int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
|
||||
struct fsnotify_group *group, struct inode *inode,
|
||||
int allow_dups)
|
||||
{
|
||||
struct fsnotify_mark *lmark = NULL;
|
||||
int ret = 0;
|
||||
|
|
@ -336,56 +158,26 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
|
|||
|
||||
mark->flags = FSNOTIFY_MARK_FLAG_INODE;
|
||||
|
||||
/*
|
||||
* if this group isn't being testing for inode type events we need
|
||||
* to start testing
|
||||
*/
|
||||
if (unlikely(list_empty(&group->inode_group_list)))
|
||||
fsnotify_add_inode_group(group);
|
||||
/*
|
||||
* XXX This is where we could also do the fsnotify_add_vfsmount_group
|
||||
* if we are setting and vfsmount mark....
|
||||
assert_spin_locked(&mark->lock);
|
||||
assert_spin_locked(&group->mark_lock);
|
||||
|
||||
if (unlikely(list_empty(&group->vfsmount_group_list)))
|
||||
fsnotify_add_vfsmount_group(group);
|
||||
*/
|
||||
|
||||
/*
|
||||
* LOCKING ORDER!!!!
|
||||
* mark->lock
|
||||
* group->mark_lock
|
||||
* inode->i_lock
|
||||
*/
|
||||
spin_lock(&mark->lock);
|
||||
spin_lock(&group->mark_lock);
|
||||
spin_lock(&inode->i_lock);
|
||||
|
||||
if (!allow_dups)
|
||||
lmark = fsnotify_find_mark_locked(group, inode);
|
||||
lmark = fsnotify_find_inode_mark_locked(group, inode);
|
||||
if (!lmark) {
|
||||
mark->group = group;
|
||||
mark->i.inode = inode;
|
||||
|
||||
hlist_add_head(&mark->i.i_list, &inode->i_fsnotify_marks);
|
||||
list_add(&mark->g_list, &group->marks_list);
|
||||
|
||||
fsnotify_get_mark(mark); /* for i_list and g_list */
|
||||
|
||||
atomic_inc(&group->num_marks);
|
||||
|
||||
fsnotify_recalc_inode_mask_locked(inode);
|
||||
}
|
||||
|
||||
spin_unlock(&inode->i_lock);
|
||||
spin_unlock(&group->mark_lock);
|
||||
spin_unlock(&mark->lock);
|
||||
|
||||
if (lmark) {
|
||||
ret = -EEXIST;
|
||||
iput(inode);
|
||||
fsnotify_put_mark(lmark);
|
||||
} else {
|
||||
__fsnotify_update_child_dentry_flags(inode);
|
||||
}
|
||||
|
||||
return ret;
|
||||
|
|
|
|||
|
|
@ -97,7 +97,7 @@ static int inotify_handle_event(struct fsnotify_group *group, struct fsnotify_ev
|
|||
|
||||
to_tell = event->to_tell;
|
||||
|
||||
fsn_mark = fsnotify_find_mark(group, to_tell);
|
||||
fsn_mark = fsnotify_find_inode_mark(group, to_tell);
|
||||
/* race with watch removal? We already passes should_send */
|
||||
if (unlikely(!fsn_mark))
|
||||
return 0;
|
||||
|
|
@ -145,7 +145,7 @@ static bool inotify_should_send_event(struct fsnotify_group *group, struct inode
|
|||
struct fsnotify_mark *fsn_mark;
|
||||
bool send;
|
||||
|
||||
fsn_mark = fsnotify_find_mark(group, inode);
|
||||
fsn_mark = fsnotify_find_inode_mark(group, inode);
|
||||
if (!fsn_mark)
|
||||
return false;
|
||||
|
||||
|
|
|
|||
|
|
@ -566,7 +566,7 @@ static int inotify_update_existing_watch(struct fsnotify_group *group,
|
|||
if (unlikely(!mask))
|
||||
return -EINVAL;
|
||||
|
||||
fsn_mark = fsnotify_find_mark(group, inode);
|
||||
fsn_mark = fsnotify_find_inode_mark(group, inode);
|
||||
if (!fsn_mark)
|
||||
return -ENOENT;
|
||||
|
||||
|
|
@ -644,7 +644,7 @@ static int inotify_new_watch(struct fsnotify_group *group,
|
|||
goto out_err;
|
||||
|
||||
/* we are on the idr, now get on the inode */
|
||||
ret = fsnotify_add_mark(&tmp_i_mark->fsn_mark, group, inode, 0);
|
||||
ret = fsnotify_add_mark(&tmp_i_mark->fsn_mark, group, inode, NULL, 0);
|
||||
if (ret) {
|
||||
/* we failed to get on the inode, get off the idr */
|
||||
inotify_remove_from_idr(group, tmp_i_mark);
|
||||
|
|
|
|||
|
|
@ -0,0 +1,294 @@
|
|||
/*
|
||||
* 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.
|
||||
*/
|
||||
|
||||
/*
|
||||
* fsnotify inode mark locking/lifetime/and refcnting
|
||||
*
|
||||
* REFCNT:
|
||||
* The mark->refcnt tells how many "things" in the kernel currently are
|
||||
* referencing this object. The object typically will live inside the kernel
|
||||
* with a refcnt of 2, one for each list it is on (i_list, g_list). Any task
|
||||
* which can find this object holding the appropriete locks, can take a reference
|
||||
* and the object itself is guarenteed to survive until the reference is dropped.
|
||||
*
|
||||
* LOCKING:
|
||||
* There are 3 spinlocks involved with fsnotify inode marks and they MUST
|
||||
* be taken in order as follows:
|
||||
*
|
||||
* mark->lock
|
||||
* group->mark_lock
|
||||
* inode->i_lock
|
||||
*
|
||||
* mark->lock protects 2 things, mark->group and mark->inode. You must hold
|
||||
* that lock to dereference either of these things (they could be NULL even with
|
||||
* the lock)
|
||||
*
|
||||
* group->mark_lock protects the marks_list anchored inside a given group
|
||||
* and each mark is hooked via the g_list. It also sorta protects the
|
||||
* free_g_list, which when used is anchored by a private list on the stack of the
|
||||
* task which held the group->mark_lock.
|
||||
*
|
||||
* inode->i_lock protects the i_fsnotify_marks list anchored inside a
|
||||
* given inode and each mark is hooked via the i_list. (and sorta the
|
||||
* free_i_list)
|
||||
*
|
||||
*
|
||||
* LIFETIME:
|
||||
* Inode marks survive between when they are added to an inode and when their
|
||||
* refcnt==0.
|
||||
*
|
||||
* The inode mark can be cleared for a number of different reasons including:
|
||||
* - The inode is unlinked for the last time. (fsnotify_inode_remove)
|
||||
* - The inode is being evicted from cache. (fsnotify_inode_delete)
|
||||
* - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes)
|
||||
* - Something explicitly requests that it be removed. (fsnotify_destroy_mark)
|
||||
* - The fsnotify_group associated with the mark is going away and all such marks
|
||||
* need to be cleaned up. (fsnotify_clear_marks_by_group)
|
||||
*
|
||||
* Worst case we are given an inode and need to clean up all the marks on that
|
||||
* inode. We take i_lock and walk the i_fsnotify_marks safely. For each
|
||||
* mark on the list we take a reference (so the mark can't disappear under us).
|
||||
* We remove that mark form the inode's list of marks and we add this mark to a
|
||||
* private list anchored on the stack using i_free_list; At this point we no
|
||||
* longer fear anything finding the mark using the inode's list of marks.
|
||||
*
|
||||
* We can safely and locklessly run the private list on the stack of everything
|
||||
* we just unattached from the original inode. For each mark on the private list
|
||||
* we grab the mark-> and can thus dereference mark->group and mark->inode. If
|
||||
* we see the group and inode are not NULL we take those locks. Now holding all
|
||||
* 3 locks we can completely remove the mark from other tasks finding it in the
|
||||
* future. Remember, 10 things might already be referencing this mark, but they
|
||||
* better be holding a ref. We drop our reference we took before we unhooked it
|
||||
* from the inode. When the ref hits 0 we can free the mark.
|
||||
*
|
||||
* Very similarly for freeing by group, except we use free_g_list.
|
||||
*
|
||||
* This has the very interesting property of being able to run concurrently with
|
||||
* any (or all) other directions.
|
||||
*/
|
||||
|
||||
#include <linux/fs.h>
|
||||
#include <linux/init.h>
|
||||
#include <linux/kernel.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/mutex.h>
|
||||
#include <linux/slab.h>
|
||||
#include <linux/spinlock.h>
|
||||
#include <linux/writeback.h> /* for inode_lock */
|
||||
|
||||
#include <asm/atomic.h>
|
||||
|
||||
#include <linux/fsnotify_backend.h>
|
||||
#include "fsnotify.h"
|
||||
|
||||
void fsnotify_get_mark(struct fsnotify_mark *mark)
|
||||
{
|
||||
atomic_inc(&mark->refcnt);
|
||||
}
|
||||
|
||||
void fsnotify_put_mark(struct fsnotify_mark *mark)
|
||||
{
|
||||
if (atomic_dec_and_test(&mark->refcnt))
|
||||
mark->free_mark(mark);
|
||||
}
|
||||
|
||||
/*
|
||||
* Any time a mark is getting freed we end up here.
|
||||
* The caller had better be holding a reference to this mark so we don't actually
|
||||
* do the final put under the mark->lock
|
||||
*/
|
||||
void fsnotify_destroy_mark(struct fsnotify_mark *mark)
|
||||
{
|
||||
struct fsnotify_group *group;
|
||||
struct inode *inode;
|
||||
|
||||
spin_lock(&mark->lock);
|
||||
|
||||
group = mark->group;
|
||||
inode = mark->i.inode;
|
||||
|
||||
BUG_ON(group && !inode);
|
||||
BUG_ON(!group && inode);
|
||||
|
||||
/* if !group something else already marked this to die */
|
||||
if (!group) {
|
||||
spin_unlock(&mark->lock);
|
||||
return;
|
||||
}
|
||||
|
||||
/* 1 from caller and 1 for being on i_list/g_list */
|
||||
BUG_ON(atomic_read(&mark->refcnt) < 2);
|
||||
|
||||
spin_lock(&group->mark_lock);
|
||||
|
||||
if (mark->flags & FSNOTIFY_MARK_FLAG_INODE)
|
||||
fsnotify_destroy_inode_mark(mark);
|
||||
else
|
||||
BUG();
|
||||
|
||||
list_del_init(&mark->g_list);
|
||||
mark->group = NULL;
|
||||
|
||||
fsnotify_put_mark(mark); /* for i_list and g_list */
|
||||
|
||||
spin_unlock(&group->mark_lock);
|
||||
spin_unlock(&mark->lock);
|
||||
|
||||
/*
|
||||
* Some groups like to know that marks are being freed. This is a
|
||||
* callback to the group function to let it know that this mark
|
||||
* is being freed.
|
||||
*/
|
||||
if (group->ops->freeing_mark)
|
||||
group->ops->freeing_mark(mark, group);
|
||||
|
||||
/*
|
||||
* __fsnotify_update_child_dentry_flags(inode);
|
||||
*
|
||||
* I really want to call that, but we can't, we have no idea if the inode
|
||||
* still exists the second we drop the mark->lock.
|
||||
*
|
||||
* The next time an event arrive to this inode from one of it's children
|
||||
* __fsnotify_parent will see that the inode doesn't care about it's
|
||||
* children and will update all of these flags then. So really this
|
||||
* is just a lazy update (and could be a perf win...)
|
||||
*/
|
||||
|
||||
|
||||
iput(inode);
|
||||
|
||||
/*
|
||||
* it's possible that this group tried to destroy itself, but this
|
||||
* this mark was simultaneously being freed by inode. If that's the
|
||||
* case, we finish freeing the group here.
|
||||
*/
|
||||
if (unlikely(atomic_dec_and_test(&group->num_marks)))
|
||||
fsnotify_final_destroy_group(group);
|
||||
}
|
||||
|
||||
/*
|
||||
* Attach an initialized mark to a given group and fs object.
|
||||
* These marks may be used for the fsnotify backend to determine which
|
||||
* event types should be delivered to which group.
|
||||
*/
|
||||
int fsnotify_add_mark(struct fsnotify_mark *mark,
|
||||
struct fsnotify_group *group, struct inode *inode,
|
||||
struct vfsmount *mnt, int allow_dups)
|
||||
{
|
||||
int ret = 0;
|
||||
|
||||
BUG_ON(mnt);
|
||||
BUG_ON(inode && mnt);
|
||||
BUG_ON(!inode && !mnt);
|
||||
|
||||
/*
|
||||
* if this group isn't being testing for inode type events we need
|
||||
* to start testing
|
||||
*/
|
||||
if (inode && unlikely(list_empty(&group->inode_group_list)))
|
||||
fsnotify_add_inode_group(group);
|
||||
else if (mnt && unlikely(list_empty(&group->vfsmount_group_list)))
|
||||
fsnotify_add_vfsmount_group(group);
|
||||
|
||||
/*
|
||||
* LOCKING ORDER!!!!
|
||||
* mark->lock
|
||||
* group->mark_lock
|
||||
* inode->i_lock
|
||||
*/
|
||||
spin_lock(&mark->lock);
|
||||
spin_lock(&group->mark_lock);
|
||||
|
||||
mark->group = group;
|
||||
list_add(&mark->g_list, &group->marks_list);
|
||||
atomic_inc(&group->num_marks);
|
||||
fsnotify_get_mark(mark); /* for i_list and g_list */
|
||||
|
||||
if (inode) {
|
||||
ret = fsnotify_add_inode_mark(mark, group, inode, allow_dups);
|
||||
if (ret)
|
||||
goto err;
|
||||
} else {
|
||||
BUG();
|
||||
}
|
||||
|
||||
spin_unlock(&group->mark_lock);
|
||||
spin_unlock(&mark->lock);
|
||||
|
||||
if (inode)
|
||||
__fsnotify_update_child_dentry_flags(inode);
|
||||
|
||||
return ret;
|
||||
err:
|
||||
mark->group = NULL;
|
||||
list_del_init(&mark->g_list);
|
||||
atomic_dec(&group->num_marks);
|
||||
fsnotify_put_mark(mark);
|
||||
|
||||
spin_unlock(&group->mark_lock);
|
||||
spin_unlock(&mark->lock);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* Given a group, destroy all of the marks associated with that group.
|
||||
*/
|
||||
void fsnotify_clear_marks_by_group(struct fsnotify_group *group)
|
||||
{
|
||||
struct fsnotify_mark *lmark, *mark;
|
||||
LIST_HEAD(free_list);
|
||||
|
||||
spin_lock(&group->mark_lock);
|
||||
list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
|
||||
list_add(&mark->free_g_list, &free_list);
|
||||
list_del_init(&mark->g_list);
|
||||
fsnotify_get_mark(mark);
|
||||
}
|
||||
spin_unlock(&group->mark_lock);
|
||||
|
||||
list_for_each_entry_safe(mark, lmark, &free_list, free_g_list) {
|
||||
fsnotify_destroy_mark(mark);
|
||||
fsnotify_put_mark(mark);
|
||||
}
|
||||
}
|
||||
|
||||
void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old)
|
||||
{
|
||||
assert_spin_locked(&old->lock);
|
||||
new->i.inode = old->i.inode;
|
||||
new->m.mnt = old->m.mnt;
|
||||
new->group = old->group;
|
||||
new->mask = old->mask;
|
||||
new->free_mark = old->free_mark;
|
||||
}
|
||||
|
||||
/*
|
||||
* Nothing fancy, just initialize lists and locks and counters.
|
||||
*/
|
||||
void fsnotify_init_mark(struct fsnotify_mark *mark,
|
||||
void (*free_mark)(struct fsnotify_mark *mark))
|
||||
{
|
||||
spin_lock_init(&mark->lock);
|
||||
atomic_set(&mark->refcnt, 1);
|
||||
INIT_HLIST_NODE(&mark->i.i_list);
|
||||
mark->group = NULL;
|
||||
mark->mask = 0;
|
||||
mark->i.inode = NULL;
|
||||
mark->free_mark = free_mark;
|
||||
}
|
||||
|
|
@ -364,11 +364,12 @@ extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group
|
|||
extern void fsnotify_recalc_inode_mask(struct inode *inode);
|
||||
extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
|
||||
/* find (and take a reference) to a mark associated with group and inode */
|
||||
extern struct fsnotify_mark *fsnotify_find_mark(struct fsnotify_group *group, struct inode *inode);
|
||||
extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
|
||||
/* copy the values from old into new */
|
||||
extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
|
||||
/* attach the mark to both the group and the inode */
|
||||
extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, struct inode *inode, int allow_dups);
|
||||
extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
|
||||
struct inode *inode, struct vfsmount *mnt, int allow_dups);
|
||||
/* given a mark, flag it to be freed when all references are dropped */
|
||||
extern void fsnotify_destroy_mark(struct fsnotify_mark *mark);
|
||||
/* run all the marks in a group, and flag them to be freed */
|
||||
|
|
|
|||
|
|
@ -259,7 +259,7 @@ static void untag_chunk(struct node *p)
|
|||
if (!new)
|
||||
goto Fallback;
|
||||
fsnotify_duplicate_mark(&new->mark, entry);
|
||||
if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, 1)) {
|
||||
if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
|
||||
free_chunk(new);
|
||||
goto Fallback;
|
||||
}
|
||||
|
|
@ -322,7 +322,7 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
|
|||
return -ENOMEM;
|
||||
|
||||
entry = &chunk->mark;
|
||||
if (fsnotify_add_mark(entry, audit_tree_group, inode, 0)) {
|
||||
if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
|
||||
free_chunk(chunk);
|
||||
return -ENOSPC;
|
||||
}
|
||||
|
|
@ -360,7 +360,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
|
|||
struct node *p;
|
||||
int n;
|
||||
|
||||
old_entry = fsnotify_find_mark(audit_tree_group, inode);
|
||||
old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
|
||||
if (!old_entry)
|
||||
return create_chunk(inode, tree);
|
||||
|
||||
|
|
@ -395,7 +395,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
|
|||
}
|
||||
|
||||
fsnotify_duplicate_mark(chunk_entry, old_entry);
|
||||
if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, 1)) {
|
||||
if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
|
||||
spin_unlock(&old_entry->lock);
|
||||
free_chunk(chunk);
|
||||
fsnotify_put_mark(old_entry);
|
||||
|
|
|
|||
|
|
@ -101,7 +101,7 @@ static inline struct audit_parent *audit_find_parent(struct inode *inode)
|
|||
struct audit_parent *parent = NULL;
|
||||
struct fsnotify_mark *entry;
|
||||
|
||||
entry = fsnotify_find_mark(audit_watch_group, inode);
|
||||
entry = fsnotify_find_inode_mark(audit_watch_group, inode);
|
||||
if (entry)
|
||||
parent = container_of(entry, struct audit_parent, mark);
|
||||
|
||||
|
|
@ -158,7 +158,7 @@ static struct audit_parent *audit_init_parent(struct nameidata *ndp)
|
|||
|
||||
fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
|
||||
parent->mark.mask = AUDIT_FS_WATCH;
|
||||
ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, 0);
|
||||
ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, NULL, 0);
|
||||
if (ret < 0) {
|
||||
audit_free_parent(parent);
|
||||
return ERR_PTR(ret);
|
||||
|
|
@ -517,7 +517,7 @@ static bool audit_watch_should_send_event(struct fsnotify_group *group, struct i
|
|||
struct fsnotify_mark *entry;
|
||||
bool send;
|
||||
|
||||
entry = fsnotify_find_mark(group, inode);
|
||||
entry = fsnotify_find_inode_mark(group, inode);
|
||||
if (!entry)
|
||||
return false;
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue