From 6473ea760ca1707ade74de5b57e74189d14f8e10 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 19 Mar 2020 17:10:09 +0200
Subject: fsnotify: tidy up FS_ and FAN_ constants

Order by value, so the free value ranges are easier to find.

Link: https://lore.kernel.org/r/20200319151022.31456-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 include/linux/fsnotify_backend.h | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

(limited to 'include/linux/fsnotify_backend.h')

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 1915bdba2fad..db3cabb4600e 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -49,16 +49,15 @@
 #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 */
-#define FS_ISDIR		0x40000000	/* event occurred against dir */
-#define FS_IN_ONESHOT		0x80000000	/* only send event once */
-
-#define FS_DN_RENAME		0x10000000	/* file renamed */
-#define FS_DN_MULTISHOT		0x20000000	/* dnotify multishot */
-
 /* This inode cares about things that happen to its children.  Always set for
  * dnotify and inotify. */
 #define FS_EVENT_ON_CHILD	0x08000000
 
+#define FS_DN_RENAME		0x10000000	/* file 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 */
+
 #define FS_MOVE			(FS_MOVED_FROM | FS_MOVED_TO)
 
 /*
-- 
cgit v1.2.3


From aa93bdc5500cc93ba31afeda1a61610d117947ad Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 19 Mar 2020 17:10:12 +0200
Subject: fsnotify: use helpers to access data by data_type

Create helpers to access path and inode from different data types.

Link: https://lore.kernel.org/r/20200319151022.31456-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/notify/fanotify/fanotify.c        | 18 ++++++++----------
 fs/notify/fsnotify.c                 |  5 +++--
 fs/notify/inotify/inotify_fsnotify.c |  8 +++-----
 include/linux/fsnotify_backend.h     | 34 ++++++++++++++++++++++++++++++----
 kernel/audit_fsnotify.c              | 13 ++-----------
 kernel/audit_watch.c                 | 16 ++--------------
 6 files changed, 48 insertions(+), 46 deletions(-)

(limited to 'include/linux/fsnotify_backend.h')

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 5778d1347b35..19ec7a4f4d50 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -151,7 +151,7 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
 {
 	__u32 marks_mask = 0, marks_ignored_mask = 0;
 	__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS;
-	const struct path *path = data;
+	const struct path *path = fsnotify_data_path(data, data_type);
 	struct fsnotify_mark *mark;
 	int type;
 
@@ -160,7 +160,7 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
 
 	if (!FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
 		/* Do we have path to open a file descriptor? */
-		if (data_type != FSNOTIFY_EVENT_PATH)
+		if (!path)
 			return 0;
 		/* Path type events are only relevant for files and dirs */
 		if (!d_is_reg(path->dentry) && !d_can_lookup(path->dentry))
@@ -269,11 +269,8 @@ static struct inode *fanotify_fid_inode(struct inode *to_tell, u32 event_mask,
 {
 	if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)
 		return to_tell;
-	else if (data_type == FSNOTIFY_EVENT_INODE)
-		return (struct inode *)data;
-	else if (data_type == FSNOTIFY_EVENT_PATH)
-		return d_inode(((struct path *)data)->dentry);
-	return NULL;
+
+	return (struct inode *)fsnotify_data_inode(data, data_type);
 }
 
 struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
@@ -284,6 +281,7 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
 	struct fanotify_event *event = NULL;
 	gfp_t gfp = GFP_KERNEL_ACCOUNT;
 	struct inode *id = fanotify_fid_inode(inode, mask, data, data_type);
+	const struct path *path = fsnotify_data_path(data, data_type);
 
 	/*
 	 * For queues with unlimited length lost events are not expected and
@@ -324,10 +322,10 @@ init: __maybe_unused
 	if (id && FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
 		/* Report the event without a file identifier on encode error */
 		event->fh_type = fanotify_encode_fid(event, id, gfp, fsid);
-	} else if (data_type == FSNOTIFY_EVENT_PATH) {
+	} else if (path) {
 		event->fh_type = FILEID_ROOT;
-		event->path = *((struct path *)data);
-		path_get(&event->path);
+		event->path = *path;
+		path_get(path);
 	} else {
 		event->fh_type = FILEID_INVALID;
 		event->path.mnt = NULL;
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 46f225580009..a5d6467f89a0 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -318,6 +318,7 @@ static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
 int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	     const struct qstr *file_name, u32 cookie)
 {
+	const struct path *path = fsnotify_data_path(data, data_is);
 	struct fsnotify_iter_info iter_info = {};
 	struct super_block *sb = to_tell->i_sb;
 	struct mount *mnt = NULL;
@@ -325,8 +326,8 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	int ret = 0;
 	__u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS);
 
-	if (data_is == FSNOTIFY_EVENT_PATH) {
-		mnt = real_mount(((const struct path *)data)->mnt);
+	if (path) {
+		mnt = real_mount(path->mnt);
 		mnt_or_sb_mask |= mnt->mnt_fsnotify_mask;
 	}
 	/* An event "on child" is not intended for a mount/sb mark */
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index d510223d302c..6bb98522bbfd 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -61,6 +61,7 @@ int inotify_handle_event(struct fsnotify_group *group,
 			 const struct qstr *file_name, u32 cookie,
 			 struct fsnotify_iter_info *iter_info)
 {
+	const struct path *path = fsnotify_data_path(data, data_type);
 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
 	struct inotify_inode_mark *i_mark;
 	struct inotify_event_info *event;
@@ -73,12 +74,9 @@ int inotify_handle_event(struct fsnotify_group *group,
 		return 0;
 
 	if ((inode_mark->mask & FS_EXCL_UNLINK) &&
-	    (data_type == FSNOTIFY_EVENT_PATH)) {
-		const struct path *path = data;
+	    path && d_unlinked(path->dentry))
+		return 0;
 
-		if (d_unlinked(path->dentry))
-			return 0;
-	}
 	if (file_name) {
 		len = file_name->len;
 		alloc_len += len + 1;
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index db3cabb4600e..5cc838db422a 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -212,10 +212,36 @@ struct fsnotify_group {
 	};
 };
 
-/* when calling fsnotify tell it if the data is a path or inode */
-#define FSNOTIFY_EVENT_NONE	0
-#define FSNOTIFY_EVENT_PATH	1
-#define FSNOTIFY_EVENT_INODE	2
+/* When calling fsnotify tell it if the data is a path or inode */
+enum fsnotify_data_type {
+	FSNOTIFY_EVENT_NONE,
+	FSNOTIFY_EVENT_PATH,
+	FSNOTIFY_EVENT_INODE,
+};
+
+static inline const struct inode *fsnotify_data_inode(const void *data,
+						      int data_type)
+{
+	switch (data_type) {
+	case FSNOTIFY_EVENT_INODE:
+		return data;
+	case FSNOTIFY_EVENT_PATH:
+		return d_inode(((const struct path *)data)->dentry);
+	default:
+		return NULL;
+	}
+}
+
+static inline const struct path *fsnotify_data_path(const void *data,
+						    int data_type)
+{
+	switch (data_type) {
+	case FSNOTIFY_EVENT_PATH:
+		return data;
+	default:
+		return NULL;
+	}
+}
 
 enum fsnotify_obj_type {
 	FSNOTIFY_OBJ_TYPE_INODE,
diff --git a/kernel/audit_fsnotify.c b/kernel/audit_fsnotify.c
index f0d243318452..3596448bfdab 100644
--- a/kernel/audit_fsnotify.c
+++ b/kernel/audit_fsnotify.c
@@ -160,23 +160,14 @@ static int audit_mark_handle_event(struct fsnotify_group *group,
 {
 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
 	struct audit_fsnotify_mark *audit_mark;
-	const struct inode *inode = NULL;
+	const struct inode *inode = fsnotify_data_inode(data, data_type);
 
 	audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
 
 	BUG_ON(group != audit_fsnotify_group);
 
-	switch (data_type) {
-	case (FSNOTIFY_EVENT_PATH):
-		inode = ((const struct path *)data)->dentry->d_inode;
-		break;
-	case (FSNOTIFY_EVENT_INODE):
-		inode = (const struct inode *)data;
-		break;
-	default:
-		BUG();
+	if (WARN_ON(!inode))
 		return 0;
-	}
 
 	if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
 		if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index 4508d5e0cf69..dcfbb44c6720 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -473,25 +473,13 @@ static int audit_watch_handle_event(struct fsnotify_group *group,
 				    struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
-	const struct inode *inode;
+	const struct inode *inode = fsnotify_data_inode(data, data_type);
 	struct audit_parent *parent;
 
 	parent = container_of(inode_mark, struct audit_parent, mark);
 
 	BUG_ON(group != audit_watch_group);
-
-	switch (data_type) {
-	case (FSNOTIFY_EVENT_PATH):
-		inode = d_backing_inode(((const struct path *)data)->dentry);
-		break;
-	case (FSNOTIFY_EVENT_INODE):
-		inode = (const struct inode *)data;
-		break;
-	default:
-		BUG();
-		inode = NULL;
-		break;
-	}
+	WARN_ON(!inode);
 
 	if (mask & (FS_CREATE|FS_MOVED_TO) && inode)
 		audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0);
-- 
cgit v1.2.3


From 017de65fe58f2b0ca428b5830609520ded5898b9 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 19 Mar 2020 17:10:13 +0200
Subject: fsnotify: simplify arguments passing to fsnotify_parent()

Instead of passing both dentry and path and having to figure out which
one to use, pass data/data_type to simplify the code.

Link: https://lore.kernel.org/r/20200319151022.31456-6-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/notify/fsnotify.c             | 15 ++++-----------
 include/linux/fsnotify.h         | 14 ++------------
 include/linux/fsnotify_backend.h | 14 ++++++++------
 3 files changed, 14 insertions(+), 29 deletions(-)

(limited to 'include/linux/fsnotify_backend.h')

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index a5d6467f89a0..193530f57963 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -143,15 +143,13 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
 }
 
 /* Notify this dentry's parent about a child's events. */
-int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask)
+int fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
+		    int data_type)
 {
 	struct dentry *parent;
 	struct inode *p_inode;
 	int ret = 0;
 
-	if (!dentry)
-		dentry = path->dentry;
-
 	if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
 		return 0;
 
@@ -168,12 +166,7 @@ int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask
 		mask |= FS_EVENT_ON_CHILD;
 
 		take_dentry_name_snapshot(&name, dentry);
-		if (path)
-			ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
-				       &name.name, 0);
-		else
-			ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
-				       &name.name, 0);
+		ret = fsnotify(p_inode, mask, data, data_type, &name.name, 0);
 		release_dentry_name_snapshot(&name);
 	}
 
@@ -181,7 +174,7 @@ int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(__fsnotify_parent);
+EXPORT_SYMBOL_GPL(fsnotify_parent);
 
 static int send_to_group(struct inode *to_tell,
 			 __u32 mask, const void *data,
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 751da17e003d..860018f3e545 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -38,16 +38,6 @@ static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
 	fsnotify_name(dir, mask, d_inode(dentry), &dentry->d_name, 0);
 }
 
-/* Notify this dentry's parent about a child's events. */
-static inline int fsnotify_parent(const struct path *path,
-				  struct dentry *dentry, __u32 mask)
-{
-	if (!dentry)
-		dentry = path->dentry;
-
-	return __fsnotify_parent(path, dentry, mask);
-}
-
 /*
  * Simple wrappers to consolidate calls fsnotify_parent()/fsnotify() when
  * an event is on a file/dentry.
@@ -59,7 +49,7 @@ static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_ISDIR;
 
-	fsnotify_parent(NULL, dentry, mask);
+	fsnotify_parent(dentry, mask, inode, FSNOTIFY_EVENT_INODE);
 	fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
 }
 
@@ -75,7 +65,7 @@ static inline int fsnotify_file(struct file *file, __u32 mask)
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_ISDIR;
 
-	ret = fsnotify_parent(path, NULL, mask);
+	ret = fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH);
 	if (ret)
 		return ret;
 
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 5cc838db422a..337c87cf34d6 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -376,9 +376,10 @@ struct fsnotify_mark {
 /* called from the vfs helpers */
 
 /* main fsnotify call to send events */
-extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
-		    const struct qstr *name, u32 cookie);
-extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask);
+extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data,
+		    int data_type, const struct qstr *name, u32 cookie);
+extern int fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
+			   int data_type);
 extern void __fsnotify_inode_delete(struct inode *inode);
 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
 extern void fsnotify_sb_delete(struct super_block *sb);
@@ -533,13 +534,14 @@ static inline void fsnotify_init_event(struct fsnotify_event *event,
 
 #else
 
-static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
-			   const struct qstr *name, u32 cookie)
+static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data,
+			   int data_type, const struct qstr *name, u32 cookie)
 {
 	return 0;
 }
 
-static inline int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask)
+static inline int fsnotify_parent(struct dentry *dentry, __u32 mask,
+				  const void *data, int data_type)
 {
 	return 0;
 }
-- 
cgit v1.2.3


From dfc2d2594e4a79204a3967585245f00644b8f838 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 19 Mar 2020 17:10:15 +0200
Subject: fsnotify: replace inode pointer with an object id

The event inode field is used only for comparison in queue merges and
cannot be dereferenced after handle_event(), because it does not hold a
refcount on the inode.

Replace it with an abstract id to do the same thing.

Link: https://lore.kernel.org/r/20200319151022.31456-8-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/notify/fanotify/fanotify.c        | 4 ++--
 fs/notify/inotify/inotify_fsnotify.c | 4 ++--
 fs/notify/inotify/inotify_user.c     | 2 +-
 include/linux/fsnotify_backend.h     | 7 +++----
 4 files changed, 8 insertions(+), 9 deletions(-)

(limited to 'include/linux/fsnotify_backend.h')

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 19ec7a4f4d50..6a202aaf941f 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -26,7 +26,7 @@ static bool should_merge(struct fsnotify_event *old_fsn,
 	old = FANOTIFY_E(old_fsn);
 	new = FANOTIFY_E(new_fsn);
 
-	if (old_fsn->inode != new_fsn->inode || old->pid != new->pid ||
+	if (old_fsn->objectid != new_fsn->objectid || old->pid != new->pid ||
 	    old->fh_type != new->fh_type || old->fh_len != new->fh_len)
 		return false;
 
@@ -312,7 +312,7 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
 	if (!event)
 		goto out;
 init: __maybe_unused
-	fsnotify_init_event(&event->fse, inode);
+	fsnotify_init_event(&event->fse, (unsigned long)inode);
 	event->mask = mask;
 	if (FAN_GROUP_FLAG(group, FAN_REPORT_TID))
 		event->pid = get_pid(task_pid(current));
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 6bb98522bbfd..2ebc89047153 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -39,7 +39,7 @@ static bool event_compare(struct fsnotify_event *old_fsn,
 	if (old->mask & FS_IN_IGNORED)
 		return false;
 	if ((old->mask == new->mask) &&
-	    (old_fsn->inode == new_fsn->inode) &&
+	    (old_fsn->objectid == new_fsn->objectid) &&
 	    (old->name_len == new->name_len) &&
 	    (!old->name_len || !strcmp(old->name, new->name)))
 		return true;
@@ -116,7 +116,7 @@ int inotify_handle_event(struct fsnotify_group *group,
 		mask &= ~IN_ISDIR;
 
 	fsn_event = &event->fse;
-	fsnotify_init_event(fsn_event, inode);
+	fsnotify_init_event(fsn_event, (unsigned long)inode);
 	event->mask = mask;
 	event->wd = i_mark->wd;
 	event->sync_cookie = cookie;
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 107537a543fd..81ffc8629fc4 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -635,7 +635,7 @@ static struct fsnotify_group *inotify_new_group(unsigned int max_events)
 		return ERR_PTR(-ENOMEM);
 	}
 	group->overflow_event = &oevent->fse;
-	fsnotify_init_event(group->overflow_event, NULL);
+	fsnotify_init_event(group->overflow_event, 0);
 	oevent->mask = FS_Q_OVERFLOW;
 	oevent->wd = -1;
 	oevent->sync_cookie = 0;
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 337c87cf34d6..c72cbea20ef7 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -132,8 +132,7 @@ struct fsnotify_ops {
  */
 struct fsnotify_event {
 	struct list_head list;
-	/* inode may ONLY be dereferenced during handle_event(). */
-	struct inode *inode;	/* either the inode the event happened to or its parent */
+	unsigned long objectid;	/* identifier for queue merges */
 };
 
 /*
@@ -526,10 +525,10 @@ extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
 
 static inline void fsnotify_init_event(struct fsnotify_event *event,
-				       struct inode *inode)
+				       unsigned long objectid)
 {
 	INIT_LIST_HEAD(&event->list);
-	event->inode = inode;
+	event->objectid = objectid;
 }
 
 #else
-- 
cgit v1.2.3


From 9e2ba2c34f1922ca1e0c7d31b30ace5842c2e7d1 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 19 Mar 2020 17:10:19 +0200
Subject: fanotify: send FAN_DIR_MODIFY event flavor with dir inode and name

Dirent events are going to be supported in two flavors:

1. Directory fid info + mask that includes the specific event types
   (e.g. FAN_CREATE) and an optional FAN_ONDIR flag.
2. Directory fid info + name + mask that includes only FAN_DIR_MODIFY.

To request the second event flavor, user needs to set the event type
FAN_DIR_MODIFY in the mark mask.

The first flavor is supported since kernel v5.1 for groups initialized
with flag FAN_REPORT_FID.  It is intended to be used for watching
directories in "batch mode" - the watcher is notified when directory is
changed and re-scans the directory content in response.  This event
flavor is stored more compactly in the event queue, so it is optimal
for workloads with frequent directory changes.

The second event flavor is intended to be used for watching large
directories, where the cost of re-scan of the directory on every change
is considered too high.  The watcher getting the event with the directory
fid and entry name is expected to call fstatat(2) to query the content of
the entry after the change.

Legacy inotify events are reported with name and event mask (e.g. "foo",
FAN_CREATE | FAN_ONDIR).  That can lead users to the conclusion that
there is *currently* an entry "foo" that is a sub-directory, when in fact
"foo" may be negative or non-dir by the time user gets the event.

To make it clear that the current state of the named entry is unknown,
when reporting an event with name info, fanotify obfuscates the specific
event types (e.g. create,delete,rename) and uses a common event type -
FAN_DIR_MODIFY to describe the change.  This should make it harder for
users to make wrong assumptions and write buggy filesystem monitors.

At this point, name info reporting is not yet implemented, so trying to
set FAN_DIR_MODIFY in mark mask will return -EINVAL.

Link: https://lore.kernel.org/r/20200319151022.31456-12-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/notify/fanotify/fanotify.c    | 7 ++++---
 fs/notify/fsnotify.c             | 2 +-
 include/linux/fsnotify.h         | 6 ++++++
 include/linux/fsnotify_backend.h | 4 +++-
 include/uapi/linux/fanotify.h    | 1 +
 5 files changed, 15 insertions(+), 5 deletions(-)

(limited to 'include/linux/fsnotify_backend.h')

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 39eb71f7c413..74676228f784 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -235,9 +235,9 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
 	test_mask = event_mask & marks_mask & ~marks_ignored_mask;
 
 	/*
-	 * dirent modification events (create/delete/move) do not carry the
-	 * child entry name/inode information. Instead, we report FAN_ONDIR
-	 * for mkdir/rmdir so user can differentiate them from creat/unlink.
+	 * For dirent modification events (create/delete/move) that do not carry
+	 * the child entry name information, we report FAN_ONDIR for mkdir/rmdir
+	 * so user can differentiate them from creat/unlink.
 	 *
 	 * For backward compatibility and consistency, do not report FAN_ONDIR
 	 * to user in legacy fanotify mode (reporting fd) and report FAN_ONDIR
@@ -463,6 +463,7 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 	BUILD_BUG_ON(FAN_MOVED_FROM != FS_MOVED_FROM);
 	BUILD_BUG_ON(FAN_CREATE != FS_CREATE);
 	BUILD_BUG_ON(FAN_DELETE != FS_DELETE);
+	BUILD_BUG_ON(FAN_DIR_MODIFY != FS_DIR_MODIFY);
 	BUILD_BUG_ON(FAN_DELETE_SELF != FS_DELETE_SELF);
 	BUILD_BUG_ON(FAN_MOVE_SELF != FS_MOVE_SELF);
 	BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 193530f57963..72d332ce8e12 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -383,7 +383,7 @@ static __init int fsnotify_init(void)
 {
 	int ret;
 
-	BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 25);
+	BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 26);
 
 	ret = init_srcu_struct(&fsnotify_mark_srcu);
 	if (ret)
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 860018f3e545..5ab28f6c7d26 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -30,6 +30,12 @@ static inline void fsnotify_name(struct inode *dir, __u32 mask,
 				 const struct qstr *name, u32 cookie)
 {
 	fsnotify(dir, mask, child, FSNOTIFY_EVENT_INODE, name, cookie);
+	/*
+	 * Send another flavor of the event without child inode data and
+	 * without the specific event type (e.g. FS_CREATE|FS_IS_DIR).
+	 * The name is relative to the dir inode the event is reported to.
+	 */
+	fsnotify(dir, FS_DIR_MODIFY, dir, FSNOTIFY_EVENT_INODE, name, 0);
 }
 
 static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index c72cbea20ef7..f0c506405b54 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -47,6 +47,7 @@
 #define FS_OPEN_PERM		0x00010000	/* open event in an permission hook */
 #define FS_ACCESS_PERM		0x00020000	/* access event in a permissions hook */
 #define FS_OPEN_EXEC_PERM	0x00040000	/* open/exec event in a permission hook */
+#define FS_DIR_MODIFY		0x00080000	/* Directory entry was modified */
 
 #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
@@ -66,7 +67,8 @@
  * 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_DIR_MODIFY)
 
 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \
 				  FS_OPEN_EXEC_PERM)
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index 2a1844edda47..615fa2c87179 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -24,6 +24,7 @@
 #define FAN_OPEN_PERM		0x00010000	/* File open in perm check */
 #define FAN_ACCESS_PERM		0x00020000	/* File accessed in perm check */
 #define FAN_OPEN_EXEC_PERM	0x00040000	/* File open/exec in perm check */
+#define FAN_DIR_MODIFY		0x00080000	/* Directory entry was modified */
 
 #define FAN_EVENT_ON_CHILD	0x08000000	/* Interested in child events */
 
-- 
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