diff options
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/fsnotify.c | 9 | ||||
| -rw-r--r-- | fs/notify/fsnotify.h | 10 | ||||
| -rw-r--r-- | fs/notify/inode_mark.c | 2 | ||||
| -rw-r--r-- | fs/notify/mark.c | 152 | ||||
| -rw-r--r-- | fs/notify/vfsmount_mark.c | 2 |
5 files changed, 125 insertions, 50 deletions
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index eae621a18ac9..d512ef9f75fc 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -228,7 +228,8 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, if ((mask & FS_MODIFY) || (test_mask & to_tell->i_fsnotify_mask)) { - inode_conn = lockless_dereference(to_tell->i_fsnotify_marks); + inode_conn = srcu_dereference(to_tell->i_fsnotify_marks, + &fsnotify_mark_srcu); if (inode_conn) inode_node = srcu_dereference(inode_conn->list.first, &fsnotify_mark_srcu); @@ -236,11 +237,13 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, if (mnt && ((mask & FS_MODIFY) || (test_mask & mnt->mnt_fsnotify_mask))) { - inode_conn = lockless_dereference(to_tell->i_fsnotify_marks); + inode_conn = srcu_dereference(to_tell->i_fsnotify_marks, + &fsnotify_mark_srcu); if (inode_conn) inode_node = srcu_dereference(inode_conn->list.first, &fsnotify_mark_srcu); - vfsmount_conn = lockless_dereference(mnt->mnt_fsnotify_marks); + vfsmount_conn = srcu_dereference(mnt->mnt_fsnotify_marks, + &fsnotify_mark_srcu); if (vfsmount_conn) vfsmount_node = srcu_dereference( vfsmount_conn->list.first, diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h index 510f027bdf0f..72050b75ca8c 100644 --- a/fs/notify/fsnotify.h +++ b/fs/notify/fsnotify.h @@ -20,19 +20,19 @@ extern int fsnotify_compare_groups(struct fsnotify_group *a, /* Find mark belonging to given group in the list of marks */ extern struct fsnotify_mark *fsnotify_find_mark( - struct fsnotify_mark_connector *conn, - struct fsnotify_group *group); + struct fsnotify_mark_connector __rcu **connp, + struct fsnotify_group *group); /* Destroy all marks connected via given connector */ -extern void fsnotify_destroy_marks(struct fsnotify_mark_connector *conn); +extern void fsnotify_destroy_marks(struct fsnotify_mark_connector __rcu **connp); /* run the list of all marks associated with inode and destroy them */ static inline void fsnotify_clear_marks_by_inode(struct inode *inode) { - fsnotify_destroy_marks(inode->i_fsnotify_marks); + fsnotify_destroy_marks(&inode->i_fsnotify_marks); } /* run the list of all marks associated with vfsmount and destroy them */ static inline void fsnotify_clear_marks_by_mount(struct vfsmount *mnt) { - fsnotify_destroy_marks(real_mount(mnt)->mnt_fsnotify_marks); + fsnotify_destroy_marks(&real_mount(mnt)->mnt_fsnotify_marks); } /* prepare for freeing all marks associated with given group */ extern void fsnotify_detach_group_marks(struct fsnotify_group *group); diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c index 080b6d8b9973..b9370316727e 100644 --- a/fs/notify/inode_mark.c +++ b/fs/notify/inode_mark.c @@ -50,7 +50,7 @@ void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group) struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode) { - return fsnotify_find_mark(inode->i_fsnotify_marks, group); + return fsnotify_find_mark(&inode->i_fsnotify_marks, group); } /** diff --git a/fs/notify/mark.c b/fs/notify/mark.c index bfb415d0d757..824095db5a3b 100644 --- a/fs/notify/mark.c +++ b/fs/notify/mark.c @@ -89,10 +89,14 @@ struct kmem_cache *fsnotify_mark_connector_cachep; static DEFINE_SPINLOCK(destroy_lock); static LIST_HEAD(destroy_list); +static struct fsnotify_mark_connector *connector_destroy_list; static void fsnotify_mark_destroy_workfn(struct work_struct *work); static DECLARE_DELAYED_WORK(reaper_work, fsnotify_mark_destroy_workfn); +static void fsnotify_connector_destroy_workfn(struct work_struct *work); +static DECLARE_WORK(connector_reaper_work, fsnotify_connector_destroy_workfn); + void fsnotify_get_mark(struct fsnotify_mark *mark) { atomic_inc(&mark->refcnt); @@ -139,22 +143,73 @@ void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn) __fsnotify_update_child_dentry_flags(conn->inode); } +/* Free all connectors queued for freeing once SRCU period ends */ +static void fsnotify_connector_destroy_workfn(struct work_struct *work) +{ + struct fsnotify_mark_connector *conn, *free; + + spin_lock(&destroy_lock); + conn = connector_destroy_list; + connector_destroy_list = NULL; + spin_unlock(&destroy_lock); + + synchronize_srcu(&fsnotify_mark_srcu); + while (conn) { + free = conn; + conn = conn->destroy_next; + kmem_cache_free(fsnotify_mark_connector_cachep, free); + } +} + + +static struct inode *fsnotify_detach_connector_from_object( + struct fsnotify_mark_connector *conn) +{ + struct inode *inode = NULL; + + if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE) { + inode = conn->inode; + rcu_assign_pointer(inode->i_fsnotify_marks, NULL); + inode->i_fsnotify_mask = 0; + conn->inode = NULL; + conn->flags &= ~FSNOTIFY_OBJ_TYPE_INODE; + } else if (conn->flags & FSNOTIFY_OBJ_TYPE_VFSMOUNT) { + rcu_assign_pointer(real_mount(conn->mnt)->mnt_fsnotify_marks, + NULL); + real_mount(conn->mnt)->mnt_fsnotify_mask = 0; + conn->mnt = NULL; + conn->flags &= ~FSNOTIFY_OBJ_TYPE_VFSMOUNT; + } + + return inode; +} + static struct inode *fsnotify_detach_from_object(struct fsnotify_mark *mark) { struct fsnotify_mark_connector *conn; struct inode *inode = NULL; + bool free_conn = false; conn = mark->connector; spin_lock(&conn->lock); hlist_del_init_rcu(&mark->obj_list); if (hlist_empty(&conn->list)) { - if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE) - inode = conn->inode; + inode = fsnotify_detach_connector_from_object(conn); + free_conn = true; + } else { + __fsnotify_recalc_mask(conn); } - __fsnotify_recalc_mask(conn); mark->connector = NULL; spin_unlock(&conn->lock); + if (free_conn) { + spin_lock(&destroy_lock); + conn->destroy_next = connector_destroy_list; + connector_destroy_list = conn; + spin_unlock(&destroy_lock); + queue_work(system_unbound_wq, &connector_reaper_work); + } + return inode; } @@ -259,14 +314,6 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark, fsnotify_free_mark(mark); } -void fsnotify_connector_free(struct fsnotify_mark_connector **connp) -{ - if (*connp) { - kmem_cache_free(fsnotify_mark_connector_cachep, *connp); - *connp = NULL; - } -} - void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask) { assert_spin_locked(&mark->lock); @@ -318,9 +365,9 @@ int fsnotify_compare_groups(struct fsnotify_group *a, struct fsnotify_group *b) } static int fsnotify_attach_connector_to_object( - struct fsnotify_mark_connector **connp, - struct inode *inode, - struct vfsmount *mnt) + struct fsnotify_mark_connector __rcu **connp, + struct inode *inode, + struct vfsmount *mnt) { struct fsnotify_mark_connector *conn; @@ -331,7 +378,7 @@ static int fsnotify_attach_connector_to_object( INIT_HLIST_HEAD(&conn->list); if (inode) { conn->flags = FSNOTIFY_OBJ_TYPE_INODE; - conn->inode = inode; + conn->inode = igrab(inode); } else { conn->flags = FSNOTIFY_OBJ_TYPE_VFSMOUNT; conn->mnt = mnt; @@ -342,6 +389,8 @@ static int fsnotify_attach_connector_to_object( */ if (cmpxchg(connp, NULL, conn)) { /* Someone else created list structure for us */ + if (inode) + iput(inode); kmem_cache_free(fsnotify_mark_connector_cachep, conn); } @@ -349,6 +398,34 @@ static int fsnotify_attach_connector_to_object( } /* + * Get mark connector, make sure it is alive and return with its lock held. + * This is for users that get connector pointer from inode or mount. Users that + * hold reference to a mark on the list may directly lock connector->lock as + * they are sure list cannot go away under them. + */ +static struct fsnotify_mark_connector *fsnotify_grab_connector( + struct fsnotify_mark_connector __rcu **connp) +{ + struct fsnotify_mark_connector *conn; + int idx; + + idx = srcu_read_lock(&fsnotify_mark_srcu); + conn = srcu_dereference(*connp, &fsnotify_mark_srcu); + if (!conn) + goto out; + spin_lock(&conn->lock); + if (!(conn->flags & (FSNOTIFY_OBJ_TYPE_INODE | + FSNOTIFY_OBJ_TYPE_VFSMOUNT))) { + spin_unlock(&conn->lock); + srcu_read_unlock(&fsnotify_mark_srcu, idx); + return NULL; + } +out: + srcu_read_unlock(&fsnotify_mark_srcu, idx); + return conn; +} + +/* * Add mark into proper place in given list of marks. 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 @@ -360,7 +437,7 @@ static int fsnotify_add_mark_list(struct fsnotify_mark *mark, { struct fsnotify_mark *lmark, *last = NULL; struct fsnotify_mark_connector *conn; - struct fsnotify_mark_connector **connp; + struct fsnotify_mark_connector __rcu **connp; int cmp; int err = 0; @@ -370,21 +447,20 @@ static int fsnotify_add_mark_list(struct fsnotify_mark *mark, connp = &inode->i_fsnotify_marks; else connp = &real_mount(mnt)->mnt_fsnotify_marks; - - if (!*connp) { +restart: + spin_lock(&mark->lock); + conn = fsnotify_grab_connector(connp); + if (!conn) { + spin_unlock(&mark->lock); err = fsnotify_attach_connector_to_object(connp, inode, mnt); if (err) return err; + goto restart; } - spin_lock(&mark->lock); - conn = *connp; - spin_lock(&conn->lock); /* is mark the first mark? */ if (hlist_empty(&conn->list)) { hlist_add_head_rcu(&mark->obj_list, &conn->list); - if (inode) - igrab(inode); goto added; } @@ -486,15 +562,17 @@ int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, * Given a list of marks, find the mark associated with given group. If found * take a reference to that mark and return it, else return NULL. */ -struct fsnotify_mark *fsnotify_find_mark(struct fsnotify_mark_connector *conn, - struct fsnotify_group *group) +struct fsnotify_mark *fsnotify_find_mark( + struct fsnotify_mark_connector __rcu **connp, + struct fsnotify_group *group) { + struct fsnotify_mark_connector *conn; struct fsnotify_mark *mark; + conn = fsnotify_grab_connector(connp); if (!conn) return NULL; - spin_lock(&conn->lock); hlist_for_each_entry(mark, &conn->list, obj_list) { if (mark->group == group) { fsnotify_get_mark(mark); @@ -572,26 +650,20 @@ void fsnotify_detach_group_marks(struct fsnotify_group *group) } } -void fsnotify_destroy_marks(struct fsnotify_mark_connector *conn) +/* Destroy all marks attached to inode / vfsmount */ +void fsnotify_destroy_marks(struct fsnotify_mark_connector __rcu **connp) { + struct fsnotify_mark_connector *conn; struct fsnotify_mark *mark; - if (!conn) - return; - - while (1) { + while ((conn = fsnotify_grab_connector(connp))) { /* * We have to be careful since we can race with e.g. - * fsnotify_clear_marks_by_group() and once we drop 'lock', - * mark can get removed from the obj_list and destroyed. But - * we are holding mark reference so mark cannot be freed and - * calling fsnotify_destroy_mark() more than once is fine. + * fsnotify_clear_marks_by_group() and once we drop the list + * lock, mark can get removed from the obj_list and destroyed. + * But we are holding mark reference so mark cannot be freed + * and calling fsnotify_destroy_mark() more than once is fine. */ - spin_lock(&conn->lock); - if (hlist_empty(&conn->list)) { - spin_unlock(&conn->lock); - break; - } mark = hlist_entry(conn->list.first, struct fsnotify_mark, obj_list); fsnotify_get_mark(mark); diff --git a/fs/notify/vfsmount_mark.c b/fs/notify/vfsmount_mark.c index 26da5c209944..dd5f3fcbccfb 100644 --- a/fs/notify/vfsmount_mark.c +++ b/fs/notify/vfsmount_mark.c @@ -48,5 +48,5 @@ struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, { struct mount *m = real_mount(mnt); - return fsnotify_find_mark(m->mnt_fsnotify_marks, group); + return fsnotify_find_mark(&m->mnt_fsnotify_marks, group); } |