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eventfs: Use simple_recursive_removal() to clean up dentries
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@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 5bdcd5f533
("eventfs: Implement removal of meta data from eventfs")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
parent
62d65cac11
commit
407c6726ca
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@ -967,30 +967,29 @@ static void unhook_dentry(struct dentry *dentry)
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{
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if (!dentry)
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return;
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/* Keep the dentry from being freed yet (see eventfs_workfn()) */
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/*
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* Need to add a reference to the dentry that is expected by
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* simple_recursive_removal(), which will include a dput().
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*/
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dget(dentry);
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dentry->d_fsdata = NULL;
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d_invalidate(dentry);
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mutex_lock(&eventfs_mutex);
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/* dentry should now have at least a single reference */
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WARN_ONCE((int)d_count(dentry) < 1,
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"dentry %px (%s) less than one reference (%d) after invalidate\n",
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dentry, dentry->d_name.name, d_count(dentry));
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mutex_unlock(&eventfs_mutex);
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/*
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* Also add a reference for the dput() in eventfs_workfn().
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* That is required as that dput() will free the ei after
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* the SRCU grace period is over.
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*/
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dget(dentry);
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}
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/**
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* eventfs_remove_rec - remove eventfs dir or file from list
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* @ei: eventfs_inode to be removed.
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* @head: the list head to place the deleted @ei and children
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* @level: prevent recursion from going more than 3 levels deep.
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*
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* This function recursively removes eventfs_inodes which
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* contains info of files and/or directories.
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*/
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static void eventfs_remove_rec(struct eventfs_inode *ei, struct list_head *head, int level)
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static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
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{
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struct eventfs_inode *ei_child;
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@ -1009,13 +1008,26 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, struct list_head *head,
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/* search for nested folders or files */
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list_for_each_entry_srcu(ei_child, &ei->children, list,
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lockdep_is_held(&eventfs_mutex)) {
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eventfs_remove_rec(ei_child, head, level + 1);
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/* Children only have dentry if parent does */
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WARN_ON_ONCE(ei_child->dentry && !ei->dentry);
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eventfs_remove_rec(ei_child, level + 1);
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}
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ei->is_freed = 1;
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for (int i = 0; i < ei->nr_entries; i++) {
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if (ei->d_children[i]) {
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/* Children only have dentry if parent does */
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WARN_ON_ONCE(!ei->dentry);
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unhook_dentry(ei->d_children[i]);
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}
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}
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unhook_dentry(ei->dentry);
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list_del_rcu(&ei->list);
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list_add_tail(&ei->del_list, head);
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call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei);
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}
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/**
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@ -1026,30 +1038,22 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, struct list_head *head,
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*/
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void eventfs_remove_dir(struct eventfs_inode *ei)
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{
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struct eventfs_inode *tmp;
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LIST_HEAD(ei_del_list);
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struct dentry *dentry;
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if (!ei)
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return;
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/*
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* Move the deleted eventfs_inodes onto the ei_del_list
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* which will also set the is_freed value. Note, this has to be
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* done under the eventfs_mutex, but the deletions of
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* the dentries must be done outside the eventfs_mutex.
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* Hence moving them to this temporary list.
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*/
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mutex_lock(&eventfs_mutex);
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eventfs_remove_rec(ei, &ei_del_list, 0);
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dentry = ei->dentry;
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eventfs_remove_rec(ei, 0);
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mutex_unlock(&eventfs_mutex);
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list_for_each_entry_safe(ei, tmp, &ei_del_list, del_list) {
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for (int i = 0; i < ei->nr_entries; i++)
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unhook_dentry(ei->d_children[i]);
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unhook_dentry(ei->dentry);
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list_del(&ei->del_list);
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call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei);
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}
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/*
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* If any of the ei children has a dentry, then the ei itself
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* must have a dentry.
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*/
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if (dentry)
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simple_recursive_removal(dentry, NULL);
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}
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/**
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@ -1060,10 +1064,17 @@ void eventfs_remove_dir(struct eventfs_inode *ei)
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*/
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void eventfs_remove_events_dir(struct eventfs_inode *ei)
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{
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struct dentry *dentry = ei->dentry;
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struct dentry *dentry;
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dentry = ei->dentry;
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eventfs_remove_dir(ei);
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/* Matches the dget() from eventfs_create_events_dir() */
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/*
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* Matches the dget() done by tracefs_start_creating()
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* in eventfs_create_events_dir() when it the dentry was
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* created. In other words, it's a normal dentry that
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* sticks around while the other ei->dentry are created
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* and destroyed dynamically.
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*/
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dput(dentry);
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}
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@ -55,12 +55,10 @@ struct eventfs_inode {
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/*
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* Union - used for deletion
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* @llist: for calling dput() if needed after RCU
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* @del_list: list of eventfs_inode to delete
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* @rcu: eventfs_inode to delete in RCU
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*/
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union {
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struct llist_node llist;
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struct list_head del_list;
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struct rcu_head rcu;
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};
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unsigned int is_freed:1;
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