From: Al Viro <viro@zeniv.linux.org.uk>
To: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: Linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"regressions@lists.linux.dev" <regressions@lists.linux.dev>,
LKML <linux-kernel@vger.kernel.org>,
"Christian Brauner (Microsoft)" <brauner@kernel.org>,
Pierre Labastie <pierre.labastie@neuf.fr>,
Miklos Szeredi <miklos@szeredi.hu>,
linux-unionfs@vger.kernel.org
Subject: Re: [regression, bisected] Bug 216738 - Adding O_APPEND to O_RDWR with fcntl(fd, F_SETFL) does not work on overlayfs
Date: Thu, 24 Nov 2022 17:03:11 +0000 [thread overview]
Message-ID: <Y3+jz5CVA9S+h2+b@ZenIV> (raw)
In-Reply-To: <2505800d-8625-dab0-576a-3a0221954ba3@leemhuis.info>
On Thu, Nov 24, 2022 at 04:47:56PM +0100, Thorsten Leemhuis wrote:
> Hi, this is your Linux kernel regression tracker speaking.
>
> I noticed a regression report in bugzilla.kernel.org. As many (most?)
> kernel developer don't keep an eye on it, I decided to forward it by
> mail. Quoting from https://bugzilla.kernel.org/show_bug.cgi?id=216738 :
>
> > Pierre Labastie 2022-11-24 14:53:33 UTC
> >
> > Created attachment 303287 [details]
> > C program for reproducing the bug
> >
> > Not sure this is the right place to report this, but at least the offending commit
>
> [offending commit is 164f4064ca8 ("keep iocb_flags() result cached in
> struct file"), as specified in the "Kernel Version:" field in bugzilla]
So basically we have this
static int ovl_change_flags(struct file *file, unsigned int flags)
{
struct inode *inode = file_inode(file);
int err;
flags &= OVL_SETFL_MASK;
if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
return -EPERM;
if ((flags & O_DIRECT) && !(file->f_mode & FMODE_CAN_ODIRECT))
return -EINVAL;
if (file->f_op->check_flags) {
err = file->f_op->check_flags(flags);
if (err)
return err;
}
spin_lock(&file->f_lock);
file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
spin_unlock(&file->f_lock);
return 0;
}
open-coding what setfl() would've done, without updating ->f_iocb_flags...
Not hard to deal with...
I could pick it in vfs.git #fixes, or Miklos could put it through his tree.
Miklos, which way would you prefer that to go?
[PATCH] update ->f_iocb_flags when ovl_change_flags() modifies ->f_flags
ovl_change_flags() is an open-coded variant of fs/fcntl.c:setfl() and it got
missed by 164f4064ca81e "keep iocb_flags() result cached in struct file";
the same change applies there.
Reported-by: Pierre Labastie <pierre.labastie@neuf.fr>
Fixes: 164f4064ca81e "keep iocb_flags() result cached in struct file"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index a1a22f58ba18..dd688a842b0b 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -96,6 +96,7 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
spin_lock(&file->f_lock);
file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
+ file->f_iocb_flags = iocb_flags(file);
spin_unlock(&file->f_lock);
return 0;
next prev parent reply other threads:[~2022-11-24 17:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-24 15:47 [regression, bisected] Bug 216738 - Adding O_APPEND to O_RDWR with fcntl(fd, F_SETFL) does not work on overlayfs Thorsten Leemhuis
2022-11-24 17:03 ` Al Viro [this message]
2022-11-24 20:33 ` Miklos Szeredi
2022-11-25 4:09 ` Al Viro
2022-11-25 7:38 ` Thorsten Leemhuis
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