Similar to events "on child" to watching directory, send event "on child"
with parent/name info if sb/mount/non-dir marks are interested in
parent/name info.
The FS_EVENT_ON_CHILD flag can be set on sb/mount/non-dir marks to specify
interest in parent/name info for events on non-directory inodes.
Events on "orphan" children (disconnected dentries) are sent without
parent/name info.
Events on direcories are send with parent/name info only if the parent
directory is watching.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fsnotify.c | 54 ++++++++++++++++++++++++++++----
include/linux/fsnotify.h | 10 ++++--
include/linux/fsnotify_backend.h | 32 ++++++++++++++++---
3 files changed, 84 insertions(+), 12 deletions(-)
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 7120c675e9a6..efa5c1c4908a 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -142,31 +142,73 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
spin_unlock(&inode->i_lock);
}
+/* Are inode/sb/mount interested in parent and name info with this event? */
+static bool fsnotify_event_needs_parent(struct inode *inode, struct mount *mnt,
+ __u32 mask)
+{
+ __u32 marks_mask = 0;
+
+ /* We only send parent/name to inode/sb/mount for events on non-dir */
+ if (mask & FS_ISDIR)
+ return false;
+
+ /* Did either inode/sb/mount subscribe for events with parent/name? */
+ marks_mask |= fsnotify_parent_needed_mask(inode->i_fsnotify_mask);
+ marks_mask |= fsnotify_parent_needed_mask(inode->i_sb->s_fsnotify_mask);
+ if (mnt)
+ marks_mask |= fsnotify_parent_needed_mask(mnt->mnt_fsnotify_mask);
+
+ /* Did they subscribe for this event with parent/name info? */
+ return mask & marks_mask;
+}
+
/*
* Notify this dentry's parent about a child's events with child name info
- * if parent is watching.
- * Notify only the child without name info if parent is not watching.
+ * if parent is watching or if inode/sb/mount are interested in events with
+ * parent and name info.
+ *
+ * Notify only the child without name info if parent is not watching and
+ * inode/sb/mount are not interested in events with parent and name info.
*/
int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
int data_type)
{
+ const struct path *path = fsnotify_data_path(data, data_type);
+ struct mount *mnt = path ? real_mount(path->mnt) : NULL;
struct inode *inode = d_inode(dentry);
struct dentry *parent;
+ bool parent_watched = dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED;
+ __u32 p_mask;
struct inode *p_inode;
struct name_snapshot name;
struct qstr *file_name = NULL;
int ret = 0;
+ /*
+ * Do inode/sb/mount care about parent and name info on non-dir?
+ * Do they care about any event at all?
+ */
+ if (!inode->i_fsnotify_marks && !inode->i_sb->s_fsnotify_marks &&
+ (!mnt || !mnt->mnt_fsnotify_marks) && !parent_watched)
+ return 0;
+
parent = NULL;
- if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
+ if (!parent_watched && !fsnotify_event_needs_parent(inode, mnt, mask))
goto notify;
+ /* Does parent inode care about events on children? */
parent = dget_parent(dentry);
p_inode = parent->d_inode;
-
- if (unlikely(!fsnotify_inode_watches_children(p_inode))) {
+ p_mask = fsnotify_inode_watches_children(p_inode);
+ if (unlikely(parent_watched && !p_mask))
__fsnotify_update_child_dentry_flags(p_inode);
- } else if (p_inode->i_fsnotify_mask & mask & ALL_FSNOTIFY_EVENTS) {
+
+ /*
+ * Include parent/name in notification either if some notification
+ * groups require parent info (!parent_watched case) or the parent is
+ * interested in this event.
+ */
+ if (!parent_watched || (mask & p_mask & ALL_FSNOTIFY_EVENTS)) {
/* When notifying parent, child should be passed as data */
WARN_ON_ONCE(inode != fsnotify_data_inode(data, data_type));
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 9b2566d273a9..044cae3a0628 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -44,10 +44,16 @@ static inline int fsnotify_parent(struct dentry *dentry, __u32 mask,
{
struct inode *inode = d_inode(dentry);
- if (S_ISDIR(inode->i_mode))
+ if (S_ISDIR(inode->i_mode)) {
mask |= FS_ISDIR;
- if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
+ /* sb/mount marks are not interested in name of directory */
+ if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
+ goto notify_child;
+ }
+
+ /* disconnected dentry cannot notify parent */
+ if (IS_ROOT(dentry))
goto notify_child;
return __fsnotify_parent(dentry, mask, data, data_type);
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 2c62628566c5..6f0df110e9f8 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -49,8 +49,11 @@
#define FS_OPEN_EXEC_PERM 0x00040000 /* open/exec event in a permission hook */
#define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
-/* This inode cares about things that happen to its children. Always set for
- * dnotify and inotify. */
+/*
+ * Set on inode mark that cares about things that happen to its children.
+ * Always set for dnotify and inotify.
+ * Set on inode/sb/mount marks that care about parenet/name info.
+ */
#define FS_EVENT_ON_CHILD 0x08000000
#define FS_DN_RENAME 0x10000000 /* file renamed */
@@ -72,14 +75,22 @@
FS_OPEN_EXEC_PERM)
/*
- * This is a list of all events that may get sent to a parent based on fs event
- * happening to inodes inside that directory.
+ * This is a list of all events that may get sent to a parent that is watching
+ * with flag FS_EVENT_ON_CHILD based on fs event on a child of that directory.
*/
#define FS_EVENTS_POSS_ON_CHILD (ALL_FSNOTIFY_PERM_EVENTS | \
FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \
FS_OPEN | FS_OPEN_EXEC)
+/*
+ * This is a list of all events that may get sent with the parent inode as the
+ * @to_tell argument of fsnotify().
+ * It may include events that can be sent to an inode/sb/mount mark, but cannot
+ * be sent to a parent watching children.
+ */
+#define FS_EVENTS_POSS_TO_PARENT (FS_EVENTS_POSS_ON_CHILD)
+
/* Events that can be reported to backends */
#define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
FS_EVENTS_POSS_ON_CHILD | \
@@ -398,6 +409,19 @@ extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
extern void fsnotify_sb_delete(struct super_block *sb);
extern u32 fsnotify_get_cookie(void);
+static inline __u32 fsnotify_parent_needed_mask(__u32 mask)
+{
+ /* FS_EVENT_ON_CHILD is set on marks that want parent/name info */
+ if (!(mask & FS_EVENT_ON_CHILD))
+ return 0;
+ /*
+ * This object might be watched by a mark that cares about parent/name
+ * info, does it care about the specific set of events that can be
+ * reported with parent/name info?
+ */
+ return mask & FS_EVENTS_POSS_TO_PARENT;
+}
+
static inline int fsnotify_inode_watches_children(struct inode *inode)
{
/* FS_EVENT_ON_CHILD is set if the inode may care */
--
2.17.1
