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Date: Wed, 02 Dec 2009 09:15:05 -0500
From: Eric Paris <eparis@...hat.com>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc: viro@...iv.linux.org.uk, hch@...radead.org, agruen@...e.de,
eparis@...hat.com
Subject: [PATCH 3/4] 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@...hat.com>
---
fs/notify/Makefile | 3
fs/notify/dnotify/dnotify.c | 12 +
fs/notify/fanotify/fanotify.c | 2
fs/notify/fanotify/fanotify_user.c | 8 -
fs/notify/fsnotify.h | 7 +
fs/notify/inode_mark.c | 246 ++--------------------------
fs/notify/inotify/inotify_fsnotify.c | 4
fs/notify/inotify/inotify_user.c | 4
fs/notify/mark.c | 294 ++++++++++++++++++++++++++++++++++
include/linux/fsnotify_backend.h | 5 -
kernel/audit_tree.c | 8 -
kernel/audit_watch.c | 6 -
12 files changed, 347 insertions(+), 252 deletions(-)
create mode 100644 fs/notify/mark.c
diff --git a/fs/notify/Makefile b/fs/notify/Makefile
index 396a387..8f7f3b0 100644
--- a/fs/notify/Makefile
+++ b/fs/notify/Makefile
@@ -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/
diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index cac2eb8..69f42df 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -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;
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 881067d..aa5e926 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -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;
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 7cfb2f6..79376ec 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -310,7 +310,7 @@ 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;
@@ -326,7 +326,7 @@ 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;
@@ -343,7 +343,7 @@ 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;
@@ -353,7 +353,7 @@ 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;
diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h
index 2ba5915..7c7a904 100644
--- a/fs/notify/fsnotify.h
+++ b/fs/notify/fsnotify.h
@@ -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);
/*
diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 7468af1..b857ab2 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -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>
@@ -96,17 +30,6 @@
#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.
*/
@@ -136,44 +59,18 @@ 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;
-
- spin_lock(&mark->lock);
+ struct inode *inode = mark->i.inode;
- group = mark->group;
- inode = mark->i.inode;
+ assert_spin_locked(&mark->lock);
+ assert_spin_locked(&mark->group->mark_lock);
- 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
@@ -182,61 +79,6 @@ 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);
- }
}
/*
@@ -262,8 +104,12 @@ 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;
@@ -283,50 +129,26 @@ 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;
@@ -337,56 +159,26 @@ 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....
-
- if (unlikely(list_empty(&group->vfsmount_group_list)))
- fsnotify_add_vfsmount_group(group);
- */
+ assert_spin_locked(&mark->lock);
+ assert_spin_locked(&group->mark_lock);
- /*
- * 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;
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 3a20053..bd2468d 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -96,7 +96,7 @@ 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;
@@ -144,7 +144,7 @@ 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;
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 4d1c0f6..1ba7c86 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -571,7 +571,7 @@ 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;
@@ -649,7 +649,7 @@ 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);
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
new file mode 100644
index 0000000..e56e876
--- /dev/null
+++ b/fs/notify/mark.c
@@ -0,0 +1,294 @@
+/*
+ * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@...hat.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;
+}
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 7d93572..27cccbe 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -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 */
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index 001f4e7..1de235a 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -258,7 +258,7 @@ 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;
}
@@ -321,7 +321,7 @@ 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;
}
@@ -359,7 +359,7 @@ 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);
@@ -391,7 +391,7 @@ 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);
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index e8023ad..31f9be8 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -100,7 +100,7 @@ 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);
@@ -157,7 +157,7 @@ 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);
@@ -516,7 +516,7 @@ 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;
--
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