eventfs: Do not invalidate dentry in create_file/dir_dentry()

With the call to simple_recursive_removal() on the entire eventfs sub
system when the directory is removed, it performs the d_invalidate on all
the dentries when it is removed. There's no need to do clean ups when a
dentry is being created while the directory is being deleted.

As dentries are cleaned up by the simpler_recursive_removal(), trying to
do d_invalidate() in these functions will cause the dentry to be
invalidated twice, and crash the kernel.

Link: https://lore.kernel.org/all/20231116123016.140576-1-naresh.kamboju@linaro.org/
Link: https://lkml.kernel.org/r/20231120235154.422970988@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 407c6726ca71 ("eventfs: Use simple_recursive_removal() to clean up dentries")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index f239b2b..3eb6c62 100644 (file)
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -326,7 +326,6 @@ create_file_dentry(struct eventfs_inode *ei, int idx,
        struct eventfs_attr *attr = NULL;
        struct dentry **e_dentry = &ei->d_children[idx];
        struct dentry *dentry;
-       bool invalidate = false;
 
        mutex_lock(&eventfs_mutex);
        if (ei->is_freed) {
@@ -389,17 +388,14 @@ create_file_dentry(struct eventfs_inode *ei, int idx,
                 * Otherwise it means two dentries exist with the same name.
                 */
                WARN_ON_ONCE(!ei->is_freed);
-               invalidate = true;
+               dentry = NULL;
        }
        mutex_unlock(&eventfs_mutex);
 
-       if (invalidate)
-               d_invalidate(dentry);
-
-       if (lookup || invalidate)
+       if (lookup)
                dput(dentry);
 
-       return invalidate ? NULL : dentry;
+       return dentry;
 }
 
 /**
@@ -439,7 +435,6 @@ static struct dentry *
 create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei,
                  struct dentry *parent, bool lookup)
 {
-       bool invalidate = false;
        struct dentry *dentry = NULL;
 
        mutex_lock(&eventfs_mutex);
@@ -495,16 +490,14 @@ create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei,
                 * Otherwise it means two dentries exist with the same name.
                 */
                WARN_ON_ONCE(!ei->is_freed);
-               invalidate = true;
+               dentry = NULL;
        }
        mutex_unlock(&eventfs_mutex);
-       if (invalidate)
-               d_invalidate(dentry);
 
-       if (lookup || invalidate)
+       if (lookup)
                dput(dentry);
 
-       return invalidate ? NULL : dentry;
+       return dentry;
 }
 
 /**