Merge tag 'vfs-6.14-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - Fix fsnotify FMODE_NONOTIFY* handling.

   This also disables fsnotify on all pseudo files by default apart from
   very select exceptions. This carries a regression risk so we need to
   watch out and adapt accordingly. However, it is overall a significant
   improvement over the current status quo where every rando file can
   get fsnotify enabled.

 - Cleanup and simplify lockref_init() after recent lockref changes.

 - Fix vboxfs build with gcc-15.

 - Add an assert into inode_set_cached_link() to catch corrupt links.

 - Allow users to also use an empty string check to detect whether a
   given mount option string was empty or not.

 - Fix how security options were appended to statmount()'s ->mnt_opt
   field.

 - Fix statmount() selftests to always check the returned mask.

 - Fix uninitialized value in vfs_statx_path().

 - Fix pidfs_ioctl() sanity checks to guard against ioctl() overloading
   and preserve extensibility.

* tag 'vfs-6.14-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  vfs: sanity check the length passed to inode_set_cached_link()
  pidfs: improve ioctl handling
  fsnotify: disable pre-content and permission events by default
  selftests: always check mask returned by statmount(2)
  fsnotify: disable notification by default for all pseudo files
  fs: fix adding security options to statmount.mnt_opt
  fsnotify: use accessor to set FMODE_NONOTIFY_*
  lockref: remove count argument of lockref_init
  gfs2: switch to lockref_init(..., 1)
  gfs2: use lockref_init for gl_lockref
  statmount: let unset strings be empty
  vboxsf: fix building with GCC 15
  fs/stat.c: avoid harmless garbage value problem in vfs_statx_path()

3 files changed, 25 insertions, 6 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index be3ad155ec9f..2c3b2f8a621f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -222,7 +222,6 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 #define FMODE_FSNOTIFY_HSM(mode)	0
 #endif
 
-
 /*
  * Attribute flags.  These should be or-ed together to figure out what
  * has been changed!
@@ -791,6 +790,19 @@ struct inode {
 
 static inline void inode_set_cached_link(struct inode *inode, char *link, int linklen)
 {
+	int testlen;
+
+	/*
+	 * TODO: patch it into a debug-only check if relevant macros show up.
+	 * In the meantime, since we are suffering strlen even on production kernels
+	 * to find the right length, do a fixup if the wrong value got passed.
+	 */
+	testlen = strlen(link);
+	if (testlen != linklen) {
+		WARN_ONCE(1, "bad length passed for symlink [%s] (got %d, expected %d)",
+			  link, linklen, testlen);
+		linklen = testlen;
+	}
 	inode->i_link = link;
 	inode->i_linklen = linklen;
 	inode->i_opflags |= IOP_CACHED_LINK;
@@ -3140,6 +3152,12 @@ static inline void exe_file_allow_write_access(struct file *exe_file)
 	allow_write_access(exe_file);
 }
 
+static inline void file_set_fsnotify_mode(struct file *file, fmode_t mode)
+{
+	file->f_mode &= ~FMODE_FSNOTIFY_MASK;
+	file->f_mode |= mode;
+}
+
 static inline bool inode_is_open_for_write(const struct inode *inode)
 {
 	return atomic_read(&inode->i_writecount) > 0;
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 1a9ef8f6784d..6a33288bd6a1 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(struct file *file);
+void file_set_fsnotify_mode_from_watchers(struct file *file);
 
 /*
  * fsnotify_file_area_perm - permission hook before access to file range
@@ -213,7 +213,7 @@ static inline int fsnotify_open_perm(struct file *file)
 }
 
 #else
-static inline void file_set_fsnotify_mode(struct file *file)
+static inline void file_set_fsnotify_mode_from_watchers(struct file *file)
 {
 }
 
diff --git a/include/linux/lockref.h b/include/linux/lockref.h
index c39f119659ba..676721ee878d 100644
--- a/include/linux/lockref.h
+++ b/include/linux/lockref.h
@@ -37,12 +37,13 @@ struct lockref {
 /**
  * lockref_init - Initialize a lockref
  * @lockref: pointer to lockref structure
- * @count: initial count
+ *
+ * Initializes @lockref->count to 1.
  */
-static inline void lockref_init(struct lockref *lockref, unsigned int count)
+static inline void lockref_init(struct lockref *lockref)
 {
 	spin_lock_init(&lockref->lock);
-	lockref->count = count;
+	lockref->count = 1;
 }
 
 void lockref_get(struct lockref *lockref);