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Subject[PATCH 7/7] fsnotify: replace the groups mutex with the groups mark list mutex
Date
This patch replaces the group mutex with the group mark_mutex to ensure
race-free addition and removal of marks to/from groups.
It also replaces calls to fsnotify_[add|remove]_mark() with calls to
fsnotify_[add|remove]_mark_locked() whenever the group mark_mutex is already
held.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
---
fs/notify/dnotify/dnotify.c | 13 +++++++------
fs/notify/fanotify/fanotify_user.c | 24 ++++++++++++------------
fs/notify/group.c | 1 -
include/linux/fsnotify_backend.h | 1 -
4 files changed, 19 insertions(+), 20 deletions(-)
diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 5dfd35a..9aa4ccd 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -182,7 +182,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
return;
dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);

- mutex_lock(&dnotify_group->mutex);
+ mutex_lock(&dnotify_group->mark_mutex);

spin_lock(&fsn_mark->lock);
prev = &dn_mark->dn;
@@ -200,9 +200,9 @@ void dnotify_flush(struct file *filp, fl_owner_t id)

/* nothing else could have found us thanks to the dnotify_group mutex */
if (dn_mark->dn == NULL)
- fsnotify_remove_mark(fsn_mark, dnotify_group);
+ fsnotify_remove_mark_locked(fsn_mark, dnotify_group);

- mutex_unlock(&dnotify_group->mutex);
+ mutex_unlock(&dnotify_group->mark_mutex);

fsnotify_put_mark(fsn_mark);
}
@@ -325,7 +325,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
new_dn_mark->dn = NULL;

/* this is needed to prevent the fcntl/close race described below */
- mutex_lock(&dnotify_group->mutex);
+ mutex_lock(&dnotify_group->mark_mutex);

/* add the new_fsn_mark or find an old one. */
fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode);
@@ -333,7 +333,8 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
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, NULL, 0);
+ fsnotify_add_mark_locked(new_fsn_mark, dnotify_group, inode,
+ NULL, 0);
spin_lock(&new_fsn_mark->lock);
fsn_mark = new_fsn_mark;
dn_mark = new_dn_mark;
@@ -386,7 +387,7 @@ out:
if (destroy)
fsnotify_remove_mark(fsn_mark, dnotify_group);

- mutex_unlock(&dnotify_group->mutex);
+ mutex_unlock(&dnotify_group->mark_mutex);
fsnotify_put_mark(fsn_mark);
out_err:
if (new_fsn_mark)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index c441b91..f52b47b 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -547,7 +547,7 @@ static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
int destroy_mark;
int ret;

- mutex_lock(&group->mutex);
+ mutex_lock(&group->mark_mutex);
ret = -ENOENT;
fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
if (!fsn_mark)
@@ -556,14 +556,14 @@ static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
&destroy_mark);
if (destroy_mark)
- fsnotify_remove_mark(fsn_mark, group);
+ fsnotify_remove_mark_locked(fsn_mark, group);

fsnotify_put_mark(fsn_mark);
if (removed & mnt->mnt_fsnotify_mask)
fsnotify_recalc_vfsmount_mask(mnt);
ret = 0;
err:
- mutex_unlock(&group->mutex);
+ mutex_unlock(&group->mark_mutex);

return ret;
}
@@ -577,7 +577,7 @@ static int fanotify_remove_inode_mark(struct fsnotify_group *group,
int destroy_mark;
int ret;

- mutex_lock(&group->mutex);
+ mutex_lock(&group->mark_mutex);
ret = -ENOENT;
fsn_mark = fsnotify_find_inode_mark(group, inode);
if (!fsn_mark)
@@ -586,7 +586,7 @@ static int fanotify_remove_inode_mark(struct fsnotify_group *group,
removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
&destroy_mark);
if (destroy_mark)
- fsnotify_remove_mark(fsn_mark, group);
+ fsnotify_remove_mark_locked(fsn_mark, group);

/* matches the fsnotify_find_inode_mark() */
fsnotify_put_mark(fsn_mark);
@@ -594,7 +594,7 @@ static int fanotify_remove_inode_mark(struct fsnotify_group *group,
fsnotify_recalc_inode_mask(inode);
ret = 0;
err:
- mutex_unlock(&group->mutex);
+ mutex_unlock(&group->mark_mutex);

return ret;
}
@@ -634,7 +634,7 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
__u32 added;
int ret;

- mutex_lock(&group->mutex);
+ mutex_lock(&group->mark_mutex);
fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
if (!fsn_mark) {
ret = -ENOSPC;
@@ -648,7 +648,7 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
goto err;

fsnotify_init_mark(fsn_mark, fanotify_free_mark);
- ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0);
+ ret = fsnotify_add_mark_locked(fsn_mark, group, NULL, mnt, 0);
if (ret)
goto err2;
}
@@ -660,7 +660,7 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
err2:
fsnotify_put_mark(fsn_mark);
err:
- mutex_unlock(&group->mutex);
+ mutex_unlock(&group->mark_mutex);
return ret;
}

@@ -684,7 +684,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
(atomic_read(&inode->i_writecount) > 0))
return 0;

- mutex_lock(&group->mutex);
+ mutex_lock(&group->mark_mutex);
fsn_mark = fsnotify_find_inode_mark(group, inode);
if (!fsn_mark) {
ret = -ENOSPC;
@@ -698,7 +698,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
goto err;

fsnotify_init_mark(fsn_mark, fanotify_free_mark);
- ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0);
+ ret = fsnotify_add_mark_locked(fsn_mark, group, inode, NULL, 0);
if (ret)
goto err2;
}
@@ -710,7 +710,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
err2:
fsnotify_put_mark(fsn_mark);
err:
- mutex_unlock(&group->mutex);
+ mutex_unlock(&group->mark_mutex);
return ret;
}

diff --git a/fs/notify/group.c b/fs/notify/group.c
index a45bbfb..c86e3fb 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -90,7 +90,6 @@ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
*/
atomic_set(&group->num_marks, 1);

- mutex_init(&group->mutex);
mutex_init(&group->notification_mutex);
INIT_LIST_HEAD(&group->notification_list);
init_waitqueue_head(&group->notification_waitq);
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 073f6a9..e4100db 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -125,7 +125,6 @@ struct fsnotify_group {

const struct fsnotify_ops *ops; /* how this group handles things */

- struct mutex mutex;
/* needed to send notification to userspace */
struct mutex notification_mutex; /* protect the notification_list */
struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
--
1.5.6.5


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