fsnotify: generate FS_RENAME event with rich information

The dnotify FS_DN_RENAME event is used to request notification about
a move within the same parent directory and was always coupled with
the FS_MOVED_FROM event.

Rename the FS_DN_RENAME event flag to FS_RENAME, decouple it from
FS_MOVED_FROM and report it with the moved dentry instead of the moved
inode, so it has the information about both old and new parent and name.

Generate the FS_RENAME event regardless of same parent dir and apply
the "same parent" rule in the generic fsnotify_handle_event() helper
that is used to call backends with ->handle_inode_event() method
(i.e. dnotify).  The ->handle_inode_event() method is not rich enough to
report both old and new parent and name anyway.

The enriched event is reported to fanotify over the ->handle_event()
method with the old and new dir inode marks in marks array slots for
ITER_TYPE_INODE and a new iter type slot ITER_TYPE_INODE2.

The enriched event will be used for reporting old and new parent+name to
fanotify groups with FAN_RENAME events.

Link: https://lore.kernel.org/r/20211129201537.1932819-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index e85e13c..d5ebebb 100644 (file)
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -196,7 +196,7 @@ static __u32 convert_arg(unsigned long arg)
        if (arg & DN_ATTRIB)
                new_mask |= FS_ATTRIB;
        if (arg & DN_RENAME)
-               new_mask |= FS_DN_RENAME;
+               new_mask |= FS_RENAME;
        if (arg & DN_CREATE)
                new_mask |= (FS_CREATE | FS_MOVED_TO);
 

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 0c94457..ab81a07 100644 (file)
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -279,6 +279,18 @@ static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask,
            WARN_ON_ONCE(fsnotify_iter_vfsmount_mark(iter_info)))
                return 0;
 
+       /*
+        * For FS_RENAME, 'dir' is old dir and 'data' is new dentry.
+        * The only ->handle_inode_event() backend that supports FS_RENAME is
+        * dnotify, where it means file was renamed within same parent.
+        */
+       if (mask & FS_RENAME) {
+               struct dentry *moved = fsnotify_data_dentry(data, data_type);
+
+               if (dir != moved->d_parent->d_inode)
+                       return 0;
+       }
+
        if (parent_mark) {
                /*
                 * parent_mark indicates that the parent inode is watching
@@ -469,7 +481,9 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
        struct super_block *sb = fsnotify_data_sb(data, data_type);
        struct fsnotify_iter_info iter_info = {};
        struct mount *mnt = NULL;
-       struct inode *parent = NULL;
+       struct inode *inode2 = NULL;
+       struct dentry *moved;
+       int inode2_type;
        int ret = 0;
        __u32 test_mask, marks_mask;
 
@@ -479,12 +493,19 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
        if (!inode) {
                /* Dirent event - report on TYPE_INODE to dir */
                inode = dir;
+               /* For FS_RENAME, inode is old_dir and inode2 is new_dir */
+               if (mask & FS_RENAME) {
+                       moved = fsnotify_data_dentry(data, data_type);
+                       inode2 = moved->d_parent->d_inode;
+                       inode2_type = FSNOTIFY_ITER_TYPE_INODE2;
+               }
        } else if (mask & FS_EVENT_ON_CHILD) {
                /*
                 * Event on child - report on TYPE_PARENT to dir if it is
                 * watching children and on TYPE_INODE to child.
                 */
-               parent = dir;
+               inode2 = dir;
+               inode2_type = FSNOTIFY_ITER_TYPE_PARENT;
        }
 
        /*
@@ -497,7 +518,7 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
        if (!sb->s_fsnotify_marks &&
            (!mnt || !mnt->mnt_fsnotify_marks) &&
            (!inode || !inode->i_fsnotify_marks) &&
-           (!parent || !parent->i_fsnotify_marks))
+           (!inode2 || !inode2->i_fsnotify_marks))
                return 0;
 
        marks_mask = sb->s_fsnotify_mask;
@@ -505,8 +526,8 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
                marks_mask |= mnt->mnt_fsnotify_mask;
        if (inode)
                marks_mask |= inode->i_fsnotify_mask;
-       if (parent)
-               marks_mask |= parent->i_fsnotify_mask;
+       if (inode2)
+               marks_mask |= inode2->i_fsnotify_mask;
 
 
        /*
@@ -529,9 +550,9 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
                iter_info.marks[FSNOTIFY_ITER_TYPE_INODE] =
                        fsnotify_first_mark(&inode->i_fsnotify_marks);
        }
-       if (parent) {
-               iter_info.marks[FSNOTIFY_ITER_TYPE_PARENT] =
-                       fsnotify_first_mark(&parent->i_fsnotify_marks);
+       if (inode2) {
+               iter_info.marks[inode2_type] =
+                       fsnotify_first_mark(&inode2->i_fsnotify_marks);
        }
 
        /*

diff --git a/include/linux/dnotify.h b/include/linux/dnotify.h
index 0aad774..b87c3b8 100644 (file)
--- a/include/linux/dnotify.h
+++ b/include/linux/dnotify.h
@@ -26,7 +26,7 @@ struct dnotify_struct {
                            FS_MODIFY | FS_MODIFY_CHILD |\
                            FS_ACCESS | FS_ACCESS_CHILD |\
                            FS_ATTRIB | FS_ATTRIB_CHILD |\
-                           FS_CREATE | FS_DN_RENAME |\
+                           FS_CREATE | FS_RENAME |\
                            FS_MOVED_FROM | FS_MOVED_TO)
 
 extern int dir_notify_enable;

diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 787545e..3a2d7dc 100644 (file)
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -144,16 +144,19 @@ static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
        u32 fs_cookie = fsnotify_get_cookie();
        __u32 old_dir_mask = FS_MOVED_FROM;
        __u32 new_dir_mask = FS_MOVED_TO;
+       __u32 rename_mask = FS_RENAME;
        const struct qstr *new_name = &moved->d_name;
 
-       if (old_dir == new_dir)
-               old_dir_mask |= FS_DN_RENAME;
-
        if (isdir) {
                old_dir_mask |= FS_ISDIR;
                new_dir_mask |= FS_ISDIR;
+               rename_mask |= FS_ISDIR;
        }
 
+       /* Event with information about both old and new parent+name */
+       fsnotify_name(rename_mask, moved, FSNOTIFY_EVENT_DENTRY,
+                     old_dir, old_name, 0);
+
        fsnotify_name(old_dir_mask, source, FSNOTIFY_EVENT_INODE,
                      old_dir, old_name, fs_cookie);
        fsnotify_name(new_dir_mask, source, FSNOTIFY_EVENT_INODE,

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 73739fe..790c318 100644 (file)
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -63,7 +63,7 @@
  */
 #define FS_EVENT_ON_CHILD      0x08000000
 
-#define FS_DN_RENAME           0x10000000      /* file renamed */
+#define FS_RENAME              0x10000000      /* File was renamed */
 #define FS_DN_MULTISHOT                0x20000000      /* dnotify multishot */
 #define FS_ISDIR               0x40000000      /* event occurred against dir */
 #define FS_IN_ONESHOT          0x80000000      /* only send event once */
@@ -76,7 +76,7 @@
  * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event
  * when a directory entry inside a child subdir changes.
  */
-#define ALL_FSNOTIFY_DIRENT_EVENTS     (FS_CREATE | FS_DELETE | FS_MOVE)
+#define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE | FS_RENAME)
 
 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \
                                  FS_OPEN_EXEC_PERM)
@@ -101,7 +101,7 @@
 /* Events that can be reported to backends */
 #define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
                             FS_EVENTS_POSS_ON_CHILD | \
-                            FS_DELETE_SELF | FS_MOVE_SELF | FS_DN_RENAME | \
+                            FS_DELETE_SELF | FS_MOVE_SELF | \
                             FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
                             FS_ERROR)
 
@@ -349,6 +349,7 @@ enum fsnotify_iter_type {
        FSNOTIFY_ITER_TYPE_VFSMOUNT,
        FSNOTIFY_ITER_TYPE_SB,
        FSNOTIFY_ITER_TYPE_PARENT,
+       FSNOTIFY_ITER_TYPE_INODE2,
        FSNOTIFY_ITER_TYPE_COUNT
 };