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Message-Id: <1200410094.26045.29.camel@twins>
Date: Tue, 15 Jan 2008 16:14:54 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Pekka J Enberg <penberg@...helsinki.fi>
Cc: alan@...hat.com, viro@...iv.linux.org.uk, hch@...radead.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [RFC/PATCH 4/8] revoke: core code V7
On Fri, 2007-12-14 at 17:16 +0200, Pekka J Enberg wrote:
> +static int revoke_files(struct inode *inode)
> +{
> + struct super_block *sb;
> + struct file *file;
> + int err = 0;
> +
> + sb = inode->i_sb;
> + if (!sb)
> + return -EINVAL;
> +
> +restart:
> + file_list_lock();
> + list_for_each_entry(file, &sb->s_files, f_u.fu_list) {
> + struct dentry *dentry = file->f_path.dentry;
> +
> + if (dentry->d_inode != inode)
> + continue;
> +
> + if (file->f_op != inode->i_fop)
> + continue;
> +
> + get_file(file);
> +
> + /*
> + * inode->i_mutex cannot be acquired under files_lock
> + */
> + file_list_unlock();
> +
> + err = file->f_op->revoke(file);
> + make_revoked_file(inode, file);
> + fput(file);
> +
> + if (err)
> + goto out;
> +
> + if (signal_pending(current)) {
> + err = -EINTR;
> + goto out;
> + }
> + cond_resched();
> + goto restart;
> + }
> + file_list_unlock();
> +out:
> + return err;
> +}
Humm, we were trying to get rid of file_list_lock(), this puts up
another user of the sb file list.
Also, that loop looks horribly expensive: n*(1+m); where n is the list
size, and m the number of matching fds.
Granted, I see no other options either.
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