This is a note to let you know that I've just added the patch titled
eventfs: Use simple_recursive_removal() to clean up dentries
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
eventfs-use-simple_recursive_removal-to-clean-up-dentries.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From SRS0=eEWY=JP=rostedt.homelinux.com=rostedt@xxxxxxxxxx Tue Feb 6 13:11:19 2024
From: Steven Rostedt <rostedt@xxxxxxxxxxx>
Date: Tue, 06 Feb 2024 07:09:28 -0500
Subject: eventfs: Use simple_recursive_removal() to clean up dentries
To: linux-kernel@xxxxxxxxxxxxxxx, stable@xxxxxxxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>, Sasha Levin <sashal@xxxxxxxxxx>, Masami Hiramatsu <mhiramat@xxxxxxxxxx>, Mark Rutland <mark.rutland@xxxxxxx>, Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Message-ID: <20240206120950.121281039@xxxxxxxxxxxxxxxxxxxxx>
From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
commit 407c6726ca71b33330d2d6345d9ea7ebc02575e9 upstream.
Looking at how dentry is removed via the tracefs system, I found that
eventfs does not do everything that it did under tracefs. The tracefs
removal of a dentry calls simple_recursive_removal() that does a lot more
than a simple d_invalidate().
As it should be a requirement that any eventfs_inode that has a dentry, so
does its parent. When removing a eventfs_inode, if it has a dentry, a call
to simple_recursive_removal() on that dentry should clean up all the
dentries underneath it.
Add WARN_ON_ONCE() to check for the parent having a dentry if any children
do.
Link: https://lore.kernel.org/all/20231101022553.GE1957730@ZenIV/
Link: https://lkml.kernel.org/r/20231101172650.552471568@xxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Fixes: 5bdcd5f5331a2 ("eventfs: Implement removal of meta data from eventfs")
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/tracefs/event_inode.c | 77 ++++++++++++++++++++++++++---------------------
fs/tracefs/internal.h | 2 -
2 files changed, 44 insertions(+), 35 deletions(-)
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -967,30 +967,29 @@ static void unhook_dentry(struct dentry
{
if (!dentry)
return;
-
- /* Keep the dentry from being freed yet (see eventfs_workfn()) */
+ /*
+ * Need to add a reference to the dentry that is expected by
+ * simple_recursive_removal(), which will include a dput().
+ */
dget(dentry);
- dentry->d_fsdata = NULL;
- d_invalidate(dentry);
- mutex_lock(&eventfs_mutex);
- /* dentry should now have at least a single reference */
- WARN_ONCE((int)d_count(dentry) < 1,
- "dentry %px (%s) less than one reference (%d) after invalidate\n",
- dentry, dentry->d_name.name, d_count(dentry));
- mutex_unlock(&eventfs_mutex);
+ /*
+ * Also add a reference for the dput() in eventfs_workfn().
+ * That is required as that dput() will free the ei after
+ * the SRCU grace period is over.
+ */
+ dget(dentry);
}
/**
* eventfs_remove_rec - remove eventfs dir or file from list
* @ei: eventfs_inode to be removed.
- * @head: the list head to place the deleted @ei and children
* @level: prevent recursion from going more than 3 levels deep.
*
* This function recursively removes eventfs_inodes which
* contains info of files and/or directories.
*/
-static void eventfs_remove_rec(struct eventfs_inode *ei, struct list_head *head, int level)
+static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
{
struct eventfs_inode *ei_child;
@@ -1009,13 +1008,26 @@ static void eventfs_remove_rec(struct ev
/* search for nested folders or files */
list_for_each_entry_srcu(ei_child, &ei->children, list,
lockdep_is_held(&eventfs_mutex)) {
- eventfs_remove_rec(ei_child, head, level + 1);
+ /* Children only have dentry if parent does */
+ WARN_ON_ONCE(ei_child->dentry && !ei->dentry);
+ eventfs_remove_rec(ei_child, level + 1);
}
+
ei->is_freed = 1;
+ for (int i = 0; i < ei->nr_entries; i++) {
+ if (ei->d_children[i]) {
+ /* Children only have dentry if parent does */
+ WARN_ON_ONCE(!ei->dentry);
+ unhook_dentry(ei->d_children[i]);
+ }
+ }
+
+ unhook_dentry(ei->dentry);
+
list_del_rcu(&ei->list);
- list_add_tail(&ei->del_list, head);
+ call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei);
}
/**
@@ -1026,30 +1038,22 @@ static void eventfs_remove_rec(struct ev
*/
void eventfs_remove_dir(struct eventfs_inode *ei)
{
- struct eventfs_inode *tmp;
- LIST_HEAD(ei_del_list);
+ struct dentry *dentry;
if (!ei)
return;
- /*
- * Move the deleted eventfs_inodes onto the ei_del_list
- * which will also set the is_freed value. Note, this has to be
- * done under the eventfs_mutex, but the deletions of
- * the dentries must be done outside the eventfs_mutex.
- * Hence moving them to this temporary list.
- */
mutex_lock(&eventfs_mutex);
- eventfs_remove_rec(ei, &ei_del_list, 0);
+ dentry = ei->dentry;
+ eventfs_remove_rec(ei, 0);
mutex_unlock(&eventfs_mutex);
- list_for_each_entry_safe(ei, tmp, &ei_del_list, del_list) {
- for (int i = 0; i < ei->nr_entries; i++)
- unhook_dentry(ei->d_children[i]);
- unhook_dentry(ei->dentry);
- list_del(&ei->del_list);
- call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei);
- }
+ /*
+ * If any of the ei children has a dentry, then the ei itself
+ * must have a dentry.
+ */
+ if (dentry)
+ simple_recursive_removal(dentry, NULL);
}
/**
@@ -1060,10 +1064,17 @@ void eventfs_remove_dir(struct eventfs_i
*/
void eventfs_remove_events_dir(struct eventfs_inode *ei)
{
- struct dentry *dentry = ei->dentry;
+ struct dentry *dentry;
+ dentry = ei->dentry;
eventfs_remove_dir(ei);
- /* Matches the dget() from eventfs_create_events_dir() */
+ /*
+ * Matches the dget() done by tracefs_start_creating()
+ * in eventfs_create_events_dir() when it the dentry was
+ * created. In other words, it's a normal dentry that
+ * sticks around while the other ei->dentry are created
+ * and destroyed dynamically.
+ */
dput(dentry);
}
--- a/fs/tracefs/internal.h
+++ b/fs/tracefs/internal.h
@@ -55,12 +55,10 @@ struct eventfs_inode {
/*
* Union - used for deletion
* @llist: for calling dput() if needed after RCU
- * @del_list: list of eventfs_inode to delete
* @rcu: eventfs_inode to delete in RCU
*/
union {
struct llist_node llist;
- struct list_head del_list;
struct rcu_head rcu;
};
unsigned int is_freed:1;
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxx are
queue-6.6/eventfs-keep-all-directory-links-at-1.patch
queue-6.6/eventfs-make-sure-that-parent-d_inode-is-locked-in-creating-files-dirs.patch
queue-6.6/eventfs-save-directory-inodes-in-the-eventfs_inode-structure.patch
queue-6.6/revert-eventfs-save-ownership-and-mode.patch
queue-6.6/tracefs-zero-out-the-tracefs_inode-when-allocating-it.patch
queue-6.6/eventfs-read-ei-entries-before-ei-children-in-eventfs_iterate.patch
queue-6.6/eventfs-do-not-invalidate-dentry-in-create_file-dir_dentry.patch
queue-6.6/eventfs-fix-file-and-directory-uid-and-gid-ownership.patch
queue-6.6/eventfs-remove-lookup-parameter-from-create_dir-file_dentry.patch
queue-6.6/eventfs-use-gfp_nofs-for-allocation-when-eventfs_mutex-is-held.patch
queue-6.6/eventfs-remove-fsnotify-functions-from-lookup.patch
queue-6.6/eventfs-use-err_cast-in-eventfs_create_events_dir.patch
queue-6.6/revert-eventfs-use-simple_recursive_removal-to-clean-up-dentries.patch
queue-6.6/eventfs-use-simple_recursive_removal-to-clean-up-dentries.patch
queue-6.6/eventfs-stop-using-dcache_readdir-for-getdents.patch
queue-6.6/eventfs-have-event-files-and-directories-default-to-parent-uid-and-gid.patch
queue-6.6/eventfs-use-eventfs_remove_events_dir.patch
queue-6.6/eventfs-delete-eventfs_inode-when-the-last-dentry-is-freed.patch
queue-6.6/tracefs-avoid-using-the-ei-dentry-pointer-unnecessarily.patch
queue-6.6/tracefs-remove-stale-update_gid-code.patch
queue-6.6/eventfs-initialize-the-tracefs-inode-properly.patch
queue-6.6/eventfs-remove-special-processing-of-dput-of-events-directory.patch
queue-6.6/eventfs-save-ownership-and-mode.patch
queue-6.6/tracefs-check-for-dentry-d_inode-exists-in-set_gid.patch
queue-6.6/eventfs-do-ctx-pos-update-for-all-iterations-in-eventfs_iterate.patch
queue-6.6/tracefs-dentry-lookup-crapectomy.patch
queue-6.6/eventfs-move-taking-of-inode_lock-into-dcache_dir_open_wrapper.patch
queue-6.6/eventfs-have-a-free_ei-that-just-frees-the-eventfs_inode.patch
queue-6.6/revert-eventfs-remove-is_freed-union-with-rcu-head.patch
queue-6.6/eventfs-have-the-inodes-all-for-files-and-directories-all-be-the-same.patch
queue-6.6/eventfs-use-kcalloc-instead-of-kzalloc.patch
queue-6.6/eventfs-test-for-ei-is_freed-when-accessing-ei-dentry.patch
queue-6.6/eventfs-fix-bitwise-fields-for-is_events.patch
queue-6.6/eventfs-fix-warn_on-in-create_file_dentry.patch
queue-6.6/eventfs-fix-events-beyond-name_max-blocking-tasks.patch
queue-6.6/eventfs-shortcut-eventfs_iterate-by-skipping-entries-already-read.patch
queue-6.6/revert-eventfs-do-not-allow-null-parent-to-eventfs_start_creating.patch
queue-6.6/eventfs-do-not-allow-null-parent-to-eventfs_start_creating.patch
queue-6.6/eventfs-do-not-create-dentries-nor-inodes-in-iterate_shared.patch
queue-6.6/eventfs-have-eventfs_iterate-stop-immediately-if-ei-is_freed-is-set.patch
queue-6.6/eventfs-fix-typo-in-eventfs_inode-union-comment.patch
queue-6.6/eventfs-remove-expectation-that-ei-is_freed-means-ei-dentry-null.patch
queue-6.6/eventfs-restructure-eventfs_inode-structure-to-be-more-condensed.patch
queue-6.6/eventfs-warn-if-an-eventfs_inode-is-freed-without-is_freed-being-set.patch
queue-6.6/eventfs-get-rid-of-dentry-pointers-without-refcounts.patch
queue-6.6/eventfs-remove-unused-d_parent-pointer-field.patch
queue-6.6/eventfs-hold-eventfs_mutex-when-calling-callback-functions.patch
queue-6.6/eventfs-remove-is_freed-union-with-rcu-head.patch
queue-6.6/tracefs-eventfs-modify-mismatched-function-name.patch
queue-6.6/eventfs-fix-kerneldoc-of-eventfs_remove_rec.patch
queue-6.6/tracefs-eventfs-use-root-and-instance-inodes-as-default-ownership.patch
queue-6.6/revert-eventfs-check-for-null-ef-in-eventfs_set_attr.patch
queue-6.6/eventfs-fix-failure-path-in-eventfs_create_events_dir.patch
queue-6.6/eventfs-clean-up-dentry-ops-and-add-revalidate-function.patch
