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Sender: John Groves <grovesaustin@gmail.com>
Date: Mon, 26 Feb 2024 17:09:36 -0600
From: John Groves <John@groves.net>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: John Groves <jgroves@micron.com>, Jonathan Corbet <corbet@lwn.net>, 
	Dan Williams <dan.j.williams@intel.com>, Vishal Verma <vishal.l.verma@intel.com>, 
	Dave Jiang <dave.jiang@intel.com>, Alexander Viro <viro@zeniv.linux.org.uk>, 
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>, Matthew Wilcox <willy@infradead.org>, 
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	Dave Chinner <david@fromorbit.com>, Christoph Hellwig <hch@infradead.org>, 
	dave.hansen@linux.intel.com, gregory.price@memverge.com
Subject: Re: [RFC PATCH 14/20] famfs: Add struct file_operations
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References: <cover.1708709155.git.john@groves.net>
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 <20240226133237.0000593c@Huawei.com>
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In-Reply-To: <20240226133237.0000593c@Huawei.com>

On 24/02/26 01:32PM, Jonathan Cameron wrote:
> On Fri, 23 Feb 2024 11:41:58 -0600
> John Groves <John@Groves.net> wrote:
> 
> > This commit introduces the famfs file_operations. We call
> > thp_get_unmapped_area() to force PMD page alignment. Our read and
> > write handlers (famfs_dax_read_iter() and famfs_dax_write_iter())
> > call dax_iomap_rw() to do the work.
> > 
> > famfs_file_invalid() checks for various ways a famfs file can be
> > in an invalid state so we can fail I/O or fault resolution in those
> > cases. Those cases include the following:
> > 
> > * No famfs metadata
> > * file i_size does not match the originally allocated size
> > * file is not flagged as DAX
> > * errors were detected previously on the file
> > 
> > An invalid file can often be fixed by replaying the log, or by
> > umount/mount/log replay - all of which are user space operations.
> > 
> > Signed-off-by: John Groves <john@groves.net>
> > ---
> >  fs/famfs/famfs_file.c | 136 ++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 136 insertions(+)
> > 
> > diff --git a/fs/famfs/famfs_file.c b/fs/famfs/famfs_file.c
> > index fc667d5f7be8..5228e9de1e3b 100644
> > --- a/fs/famfs/famfs_file.c
> > +++ b/fs/famfs/famfs_file.c
> > @@ -19,6 +19,142 @@
> >  #include <uapi/linux/famfs_ioctl.h>
> >  #include "famfs_internal.h"
> >  
> > +/*********************************************************************
> > + * file_operations
> > + */
> > +
> > +/* Reject I/O to files that aren't in a valid state */
> > +static ssize_t
> > +famfs_file_invalid(struct inode *inode)
> > +{
> > +	size_t i_size       = i_size_read(inode);
> > +	struct famfs_file_meta *meta = inode->i_private;
> > +
> > +	if (!meta) {
> > +		pr_err("%s: un-initialized famfs file\n", __func__);
> > +		return -EIO;
> > +	}
> > +	if (i_size != meta->file_size) {
> > +		pr_err("%s: something changed the size from  %ld to %ld\n",
> > +		       __func__, meta->file_size, i_size);
> > +		meta->error = 1;
> > +		return -ENXIO;
> > +	}
> > +	if (!IS_DAX(inode)) {
> > +		pr_err("%s: inode %llx IS_DAX is false\n", __func__, (u64)inode);
> > +		meta->error = 1;
> > +		return -ENXIO;
> > +	}
> > +	if (meta->error) {
> > +		pr_err("%s: previously detected metadata errors\n", __func__);
> > +		meta->error = 1;
> 
> Already set?  If treating it as only a boolean, maybe make it one?

Done, thanks

John