Merge tag 'fsnotify_for_v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull fsnotify updates from Jan Kara:
 "A couple of small improvements for fsnotify subsystem.

  The most interesting is probably Amir's change modifying the meaning
  of fsnotify fmode bits (and I spell it out specifically because I know
  you care about those). There's no change for the common cases of no
  fsnotify watches or no permission event watches. But when there are
  permission watches (either for open or for pre-content events) but no
  FAN_ACCESS_PERM watch (which nobody uses in practice) we are now able
  optimize away unnecessary cache loads from the read path"

* tag 'fsnotify_for_v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: optimize FMODE_NONOTIFY_PERM for the common cases
  fsnotify: merge file_set_fsnotify_mode_from_watchers() with open perm hook
  samples: fix building fs-monitor on musl systems
  fanotify: sanitize handle_type values when reporting fid

2 files changed, 11 insertions, 36 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2ec4807d4ea8..8b16f90f81bc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -200,12 +200,12 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 
 /*
  * The two FMODE_NONOTIFY* define which fsnotify events should not be generated
- * for a file. These are the possible values of (f->f_mode &
- * FMODE_FSNOTIFY_MASK) and their meaning:
+ * for an open file. These are the possible values of
+ * (f->f_mode & FMODE_FSNOTIFY_MASK) and their meaning:
  *
  * FMODE_NONOTIFY - suppress all (incl. non-permission) events.
  * FMODE_NONOTIFY_PERM - suppress permission (incl. pre-content) events.
- * FMODE_NONOTIFY | FMODE_NONOTIFY_PERM - suppress only pre-content events.
+ * FMODE_NONOTIFY | FMODE_NONOTIFY_PERM - suppress only FAN_ACCESS_PERM.
  */
 #define FMODE_FSNOTIFY_MASK \
 	(FMODE_NONOTIFY | FMODE_NONOTIFY_PERM)
@@ -213,13 +213,13 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 #define FMODE_FSNOTIFY_NONE(mode) \
 	((mode & FMODE_FSNOTIFY_MASK) == FMODE_NONOTIFY)
 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
-#define FMODE_FSNOTIFY_PERM(mode) \
+#define FMODE_FSNOTIFY_HSM(mode) \
 	((mode & FMODE_FSNOTIFY_MASK) == 0 || \
 	 (mode & FMODE_FSNOTIFY_MASK) == (FMODE_NONOTIFY | FMODE_NONOTIFY_PERM))
-#define FMODE_FSNOTIFY_HSM(mode) \
+#define FMODE_FSNOTIFY_ACCESS_PERM(mode) \
 	((mode & FMODE_FSNOTIFY_MASK) == 0)
 #else
-#define FMODE_FSNOTIFY_PERM(mode)	0
+#define FMODE_FSNOTIFY_ACCESS_PERM(mode) 0
 #define FMODE_FSNOTIFY_HSM(mode)	0
 #endif
 
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 454d8e466958..28a9cb13fbfa 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -129,7 +129,7 @@ static inline int fsnotify_file(struct file *file, __u32 mask)
 
 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
 
-void file_set_fsnotify_mode_from_watchers(struct file *file);
+int fsnotify_open_perm_and_set_mode(struct file *file);
 
 /*
  * fsnotify_file_area_perm - permission hook before access to file range
@@ -147,9 +147,6 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
 	if (!(perm_mask & (MAY_READ | MAY_WRITE | MAY_ACCESS)))
 		return 0;
 
-	if (likely(!FMODE_FSNOTIFY_PERM(file->f_mode)))
-		return 0;
-
 	/*
 	 * read()/write() and other types of access generate pre-content events.
 	 */
@@ -160,7 +157,8 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
 			return ret;
 	}
 
-	if (!(perm_mask & MAY_READ))
+	if (!(perm_mask & MAY_READ) ||
+	    likely(!FMODE_FSNOTIFY_ACCESS_PERM(file->f_mode)))
 		return 0;
 
 	/*
@@ -208,28 +206,10 @@ static inline int fsnotify_file_perm(struct file *file, int perm_mask)
 	return fsnotify_file_area_perm(file, perm_mask, NULL, 0);
 }
 
-/*
- * fsnotify_open_perm - permission hook before file open
- */
-static inline int fsnotify_open_perm(struct file *file)
-{
-	int ret;
-
-	if (likely(!FMODE_FSNOTIFY_PERM(file->f_mode)))
-		return 0;
-
-	if (file->f_flags & __FMODE_EXEC) {
-		ret = fsnotify_path(&file->f_path, FS_OPEN_EXEC_PERM);
-		if (ret)
-			return ret;
-	}
-
-	return fsnotify_path(&file->f_path, FS_OPEN_PERM);
-}
-
 #else
-static inline void file_set_fsnotify_mode_from_watchers(struct file *file)
+static inline int fsnotify_open_perm_and_set_mode(struct file *file)
 {
+	return 0;
 }
 
 static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
@@ -253,11 +233,6 @@ static inline int fsnotify_file_perm(struct file *file, int perm_mask)
 {
 	return 0;
 }
-
-static inline int fsnotify_open_perm(struct file *file)
-{
-	return 0;
-}
 #endif
 
 /*