From: Steven Rostedt <rostedt@goodmis.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] tracefs: dentry lookup crapectomy
Date: Tue, 30 Jan 2024 18:55:36 -0500 [thread overview]
Message-ID: <20240130185536.7ff14cb2@gandalf.local.home> (raw)
In-Reply-To: <20240130232621.GL2087318@ZenIV>
On Tue, 30 Jan 2024 23:26:21 +0000
Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Tue, Jan 30, 2024 at 11:03:52AM -0800, Linus Torvalds wrote:
> > The dentry lookup for eventfs files was very broken, and had lots of
> > signs of the old situation where the filesystem names were all created
> > statically in the dentry tree, rather than being looked up dynamically
> > based on the eventfs data structures.
> >
> > You could see it in the naming - how it claimed to "create" dentries
> > rather than just look up the dentries that were given it.
> >
> > You could see it in various nonsensical and very incorrect operations,
> > like using "simple_lookup()" on the dentries that were passed in, which
> > only results in those dentries becoming negative dentries. Which meant
> > that any other lookup would possibly return ENOENT if it saw that
> > negative dentry before the data rwas then later filled in.
> >
> > You could see it in the immesnse amount of nonsensical code that didn't
> > actually just do lookups.
>
> > -static struct dentry *create_file(const char *name, umode_t mode,
> > +static struct dentry *lookup_file(struct dentry *dentry,
> > + umode_t mode,
> > struct eventfs_attr *attr,
> > - struct dentry *parent, void *data,
> > + void *data,
> > const struct file_operations *fop)
> > {
> > struct tracefs_inode *ti;
> > - struct dentry *dentry;
> > struct inode *inode;
> >
> > if (!(mode & S_IFMT))
> > @@ -307,12 +304,6 @@ static struct dentry *create_file(const char *name, umode_t mode,
> > if (WARN_ON_ONCE(!S_ISREG(mode)))
> > return NULL;
> >
> > - WARN_ON_ONCE(!parent);
> > - dentry = eventfs_start_creating(name, parent);
>
> Used to lock the inode of parent.
Actually it's the tracefs_start_creating() locks the inode, the
eventfs_start_creating() doesn't.
-- Steve
>
> > if (unlikely(!inode))
> > return eventfs_failed_creating(dentry);
>
> ... and that still unlocks it.
>
> > @@ -331,29 +322,25 @@ static struct dentry *create_file(const char *name, umode_t mode,
> > ti->flags = TRACEFS_EVENT_INODE;
> > ti->private = NULL; // Directories have 'ei', files not
> >
> > - d_instantiate(dentry, inode);
> > + d_add(dentry, inode);
> > fsnotify_create(dentry->d_parent->d_inode, dentry);
> > return eventfs_end_creating(dentry);
>
> ... and so does this.
>
> > };
>
> Where has that inode_lock() gone and how could that possibly work?
next prev parent reply other threads:[~2024-01-30 23:55 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 19:03 [PATCH 1/6] tracefs: avoid using the ei->dentry pointer unnecessarily Linus Torvalds
2024-01-30 19:03 ` [PATCH 2/6] eventfsfs: initialize the tracefs inode properly Linus Torvalds
2024-01-30 19:48 ` Steven Rostedt
2024-01-30 19:56 ` Steven Rostedt
2024-01-30 19:49 ` Steven Rostedt
2024-01-30 19:03 ` [PATCH 3/6] tracefs: dentry lookup crapectomy Linus Torvalds
2024-01-30 23:26 ` Al Viro
2024-01-30 23:55 ` Steven Rostedt [this message]
2024-01-31 0:07 ` Al Viro
2024-01-31 0:23 ` Al Viro
2024-01-31 0:39 ` Linus Torvalds
2024-01-30 19:03 ` [PATCH 4/6] eventfs: remove unused 'd_parent' pointer field Linus Torvalds
2024-01-30 19:03 ` [PATCH 5/6] eventfs: get rid of dentry pointers without refcounts Linus Torvalds
2024-01-30 20:55 ` Steven Rostedt
2024-01-30 21:52 ` Linus Torvalds
2024-01-30 22:56 ` Steven Rostedt
2024-01-30 22:58 ` Linus Torvalds
2024-01-30 23:04 ` Steven Rostedt
2024-01-30 22:56 ` Linus Torvalds
2024-01-30 23:06 ` Linus Torvalds
2024-01-30 23:10 ` Steven Rostedt
2024-01-30 23:25 ` Linus Torvalds
2024-01-31 0:48 ` Al Viro
2024-01-31 5:09 ` Steven Rostedt
2024-01-31 5:25 ` Linus Torvalds
2024-01-31 5:33 ` Steven Rostedt
2024-01-31 5:57 ` Linus Torvalds
2024-01-31 6:20 ` Linus Torvalds
2024-01-31 12:57 ` Steven Rostedt
2024-01-31 13:14 ` Steven Rostedt
2024-01-31 18:08 ` Linus Torvalds
2024-01-31 18:39 ` Steven Rostedt
2024-01-30 19:03 ` [PATCH 6/6] eventfs: clean up dentry ops and add revalidate function Linus Torvalds
2024-01-30 21:25 ` Steven Rostedt
2024-01-30 21:36 ` Linus Torvalds
2024-01-31 1:12 ` Al Viro
2024-01-31 2:37 ` Linus Torvalds
2024-01-31 2:46 ` Al Viro
2024-01-31 3:39 ` Linus Torvalds
2024-01-31 4:28 ` Al Viro
2024-01-31 18:00 ` Steven Rostedt
2024-01-31 23:07 ` Masami Hiramatsu
2024-01-31 23:23 ` Steven Rostedt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240130185536.7ff14cb2@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=mhiramat@kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).