Introduce the famfs superblock operations

Signed-off-by: John Groves <john@groves.net>
---
 fs/famfs/famfs_inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 fs/famfs/famfs_inode.c

diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c
new file mode 100644
index 000000000000..3329aff000d1
--- /dev/null
+++ b/fs/famfs/famfs_inode.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * famfs - dax file system for shared fabric-attached memory
+ *
+ * Copyright 2023-2024 Micron Technology, inc
+ *
+ * This file system, originally based on ramfs the dax support from xfs,
+ * is intended to allow multiple host systems to mount a common file system
+ * view of dax files that map to shared memory.
+ */
+
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/sched.h>
+#include <linux/parser.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
+#include <linux/seq_file.h>
+#include <linux/dax.h>
+#include <linux/hugetlb.h>
+#include <linux/uio.h>
+#include <linux/iomap.h>
+#include <linux/path.h>
+#include <linux/namei.h>
+#include <linux/pfn_t.h>
+#include <linux/blkdev.h>
+
+#include "famfs_internal.h"
+
+#define FAMFS_DEFAULT_MODE	0755
+
+static const struct super_operations famfs_ops;
+static const struct inode_operations famfs_file_inode_operations;
+static const struct inode_operations famfs_dir_inode_operations;
+
+/**********************************************************************************
+ * famfs super_operations
+ *
+ * TODO: implement a famfs_statfs() that shows size, free and available space, etc.
+ */
+
+/**
+ * famfs_show_options() - Display the mount options in /proc/mounts.
+ */
+static int famfs_show_options(
+	struct seq_file *m,
+	struct dentry   *root)
+{
+	struct famfs_fs_info *fsi = root->d_sb->s_fs_info;
+
+	if (fsi->mount_opts.mode != FAMFS_DEFAULT_MODE)
+		seq_printf(m, ",mode=%o", fsi->mount_opts.mode);
+
+	return 0;
+}
+
+static const struct super_operations famfs_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+	.show_options	= famfs_show_options,
+};
+
+
+MODULE_LICENSE("GPL");
-- 
2.43.0

On Fri, 23 Feb 2024 11:41:53 -0600
John Groves <John@Groves.net> wrote:

> Introduce the famfs superblock operations
> 
> Signed-off-by: John Groves <john@groves.net>
> ---
>  fs/famfs/famfs_inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 72 insertions(+)
>  create mode 100644 fs/famfs/famfs_inode.c
> 
> diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c
> new file mode 100644
> index 000000000000..3329aff000d1
> --- /dev/null
> +++ b/fs/famfs/famfs_inode.c
> @@ -0,0 +1,72 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * famfs - dax file system for shared fabric-attached memory
> + *
> + * Copyright 2023-2024 Micron Technology, inc
> + *
> + * This file system, originally based on ramfs the dax support from xfs,
> + * is intended to allow multiple host systems to mount a common file system
> + * view of dax files that map to shared memory.
> + */
> +
> +#include <linux/fs.h>
> +#include <linux/pagemap.h>
> +#include <linux/highmem.h>
> +#include <linux/time.h>
> +#include <linux/init.h>
> +#include <linux/string.h>
> +#include <linux/backing-dev.h>
> +#include <linux/sched.h>
> +#include <linux/parser.h>
> +#include <linux/magic.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <linux/fs_context.h>
> +#include <linux/fs_parser.h>
> +#include <linux/seq_file.h>
> +#include <linux/dax.h>
> +#include <linux/hugetlb.h>
> +#include <linux/uio.h>
> +#include <linux/iomap.h>
> +#include <linux/path.h>
> +#include <linux/namei.h>
> +#include <linux/pfn_t.h>
> +#include <linux/blkdev.h>

That's a lot of header for such a small patch.. I'm going to guess
they aren't all used - bring them in as you need them - I hope
you never need some of these!


> +
> +#include "famfs_internal.h"
> +
> +#define FAMFS_DEFAULT_MODE	0755
> +
> +static const struct super_operations famfs_ops;
> +static const struct inode_operations famfs_file_inode_operations;
> +static const struct inode_operations famfs_dir_inode_operations;

Why are these all up here?

> +
> +/**********************************************************************************
> + * famfs super_operations
> + *
> + * TODO: implement a famfs_statfs() that shows size, free and available space, etc.
> + */
> +
> +/**
> + * famfs_show_options() - Display the mount options in /proc/mounts.
Run kernel doc script + fix all warnings.

> + */
> +static int famfs_show_options(
> +	struct seq_file *m,
> +	struct dentry   *root)
Not that familiar with fs code, but this unusual kernel style. I'd go with 
something more common

static int famfs_show_options(struct seq_file *m, struct dentry *root)

> +{
> +	struct famfs_fs_info *fsi = root->d_sb->s_fs_info;
> +
> +	if (fsi->mount_opts.mode != FAMFS_DEFAULT_MODE)
> +		seq_printf(m, ",mode=%o", fsi->mount_opts.mode);
> +
> +	return 0;
> +}
> +
> +static const struct super_operations famfs_ops = {
> +	.statfs		= simple_statfs,
> +	.drop_inode	= generic_delete_inode,
> +	.show_options	= famfs_show_options,
> +};
> +
> +
One blank line probably fine.


Add the rest of the stuff a module normally has, author etc in this
patch.

> +MODULE_LICENSE("GPL");

On 24/02/26 12:51PM, Jonathan Cameron wrote:
> On Fri, 23 Feb 2024 11:41:53 -0600
> John Groves <John@Groves.net> wrote:
> > + */
> > +static int famfs_show_options(
> > +	struct seq_file *m,
> > +	struct dentry   *root)
> Not that familiar with fs code, but this unusual kernel style. I'd go with 
> something more common
> 
> static int famfs_show_options(struct seq_file *m, struct dentry *root)

Actually, xfs does function declarations and prototypes this way, not sure if
it's everywhere. But I like this format because changing one argument usually
doesn't put un-changed args into the diff.

So I may keep this style after all.

John

On 24/02/26 12:51PM, Jonathan Cameron wrote:
> On Fri, 23 Feb 2024 11:41:53 -0600
> John Groves <John@Groves.net> wrote:
> 
> > Introduce the famfs superblock operations
> > 
> > Signed-off-by: John Groves <john@groves.net>
> > ---
> >  fs/famfs/famfs_inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 72 insertions(+)
> >  create mode 100644 fs/famfs/famfs_inode.c
> > 
> > diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c
> > new file mode 100644
> > index 000000000000..3329aff000d1
> > --- /dev/null
> > +++ b/fs/famfs/famfs_inode.c
> > @@ -0,0 +1,72 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * famfs - dax file system for shared fabric-attached memory
> > + *
> > + * Copyright 2023-2024 Micron Technology, inc
> > + *
> > + * This file system, originally based on ramfs the dax support from xfs,
> > + * is intended to allow multiple host systems to mount a common file system
> > + * view of dax files that map to shared memory.
> > + */
> > +
> > +#include <linux/fs.h>
> > +#include <linux/pagemap.h>
> > +#include <linux/highmem.h>
> > +#include <linux/time.h>
> > +#include <linux/init.h>
> > +#include <linux/string.h>
> > +#include <linux/backing-dev.h>
> > +#include <linux/sched.h>
> > +#include <linux/parser.h>
> > +#include <linux/magic.h>
> > +#include <linux/slab.h>
> > +#include <linux/uaccess.h>
> > +#include <linux/fs_context.h>
> > +#include <linux/fs_parser.h>
> > +#include <linux/seq_file.h>
> > +#include <linux/dax.h>
> > +#include <linux/hugetlb.h>
> > +#include <linux/uio.h>
> > +#include <linux/iomap.h>
> > +#include <linux/path.h>
> > +#include <linux/namei.h>
> > +#include <linux/pfn_t.h>
> > +#include <linux/blkdev.h>
> 
> That's a lot of header for such a small patch.. I'm going to guess
> they aren't all used - bring them in as you need them - I hope
> you never need some of these!

I didn't phase in headers in this series. Based on these recommendations,
the next version of this series is gonna have to be 100% constructed from
scratch, but okay. My head hurts just thinking about it. I need a nap...

I've been rebasing for 3 weeks to get this series out, and it occurs to
me that maybe there are tools I'm not aware of that make it eaiser? I'm
just typing "rebase -i..." 200 times a day. Is there a less soul-crushing way?

> 
> 
> > +
> > +#include "famfs_internal.h"
> > +
> > +#define FAMFS_DEFAULT_MODE	0755
> > +
> > +static const struct super_operations famfs_ops;
> > +static const struct inode_operations famfs_file_inode_operations;
> > +static const struct inode_operations famfs_dir_inode_operations;
> 
> Why are these all up here?

These forward declarations are needed by a later patch in the series.
They were in famfs_internal.h, but they are only used in this file, so
I moved them here.

For all answers such as this, I will hereafter reply "rebase fu", with
further clarification only if necessary.

> 
> > +
> > +/**********************************************************************************
> > + * famfs super_operations
> > + *
> > + * TODO: implement a famfs_statfs() that shows size, free and available space, etc.
> > + */
> > +
> > +/**
> > + * famfs_show_options() - Display the mount options in /proc/mounts.
> Run kernel doc script + fix all warnings.

Will do; I actually think I have already fixed those...

> 
> > + */
> > +static int famfs_show_options(
> > +	struct seq_file *m,
> > +	struct dentry   *root)
> Not that familiar with fs code, but this unusual kernel style. I'd go with 
> something more common
> 
> static int famfs_show_options(struct seq_file *m, struct dentry *root)

Done. To all functions...

> 
> > +{
> > +	struct famfs_fs_info *fsi = root->d_sb->s_fs_info;
> > +
> > +	if (fsi->mount_opts.mode != FAMFS_DEFAULT_MODE)
> > +		seq_printf(m, ",mode=%o", fsi->mount_opts.mode);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct super_operations famfs_ops = {
> > +	.statfs		= simple_statfs,
> > +	.drop_inode	= generic_delete_inode,
> > +	.show_options	= famfs_show_options,
> > +};
> > +
> > +
> One blank line probably fine.

Done

> 
> 
> Add the rest of the stuff a module normally has, author etc in this
> patch.

Because "rebase fu" I'm not sure the order will remain the same. Will
try not to make anybody tell me this again though...

John

On Mon, 26 Feb 2024 15:47:53 -0600
John Groves <John@groves.net> wrote:

> On 24/02/26 12:51PM, Jonathan Cameron wrote:
> > On Fri, 23 Feb 2024 11:41:53 -0600
> > John Groves <John@Groves.net> wrote:
> >   
> > > Introduce the famfs superblock operations
> > > 
> > > Signed-off-by: John Groves <john@groves.net>
> > > ---
> > >  fs/famfs/famfs_inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 72 insertions(+)
> > >  create mode 100644 fs/famfs/famfs_inode.c
> > > 
> > > diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c
> > > new file mode 100644
> > > index 000000000000..3329aff000d1
> > > --- /dev/null
> > > +++ b/fs/famfs/famfs_inode.c
> > > @@ -0,0 +1,72 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * famfs - dax file system for shared fabric-attached memory
> > > + *
> > > + * Copyright 2023-2024 Micron Technology, inc
> > > + *
> > > + * This file system, originally based on ramfs the dax support from xfs,
> > > + * is intended to allow multiple host systems to mount a common file system
> > > + * view of dax files that map to shared memory.
> > > + */
> > > +
> > > +#include <linux/fs.h>
> > > +#include <linux/pagemap.h>
> > > +#include <linux/highmem.h>
> > > +#include <linux/time.h>
> > > +#include <linux/init.h>
> > > +#include <linux/string.h>
> > > +#include <linux/backing-dev.h>
> > > +#include <linux/sched.h>
> > > +#include <linux/parser.h>
> > > +#include <linux/magic.h>
> > > +#include <linux/slab.h>
> > > +#include <linux/uaccess.h>
> > > +#include <linux/fs_context.h>
> > > +#include <linux/fs_parser.h>
> > > +#include <linux/seq_file.h>
> > > +#include <linux/dax.h>
> > > +#include <linux/hugetlb.h>
> > > +#include <linux/uio.h>
> > > +#include <linux/iomap.h>
> > > +#include <linux/path.h>
> > > +#include <linux/namei.h>
> > > +#include <linux/pfn_t.h>
> > > +#include <linux/blkdev.h>  
> > 
> > That's a lot of header for such a small patch.. I'm going to guess
> > they aren't all used - bring them in as you need them - I hope
> > you never need some of these!  
> 
> I didn't phase in headers in this series. Based on these recommendations,
> the next version of this series is gonna have to be 100% constructed from
> scratch, but okay. My head hurts just thinking about it. I need a nap...
> 
> I've been rebasing for 3 weeks to get this series out, and it occurs to
> me that maybe there are tools I'm not aware of that make it eaiser? I'm
> just typing "rebase -i..." 200 times a day. Is there a less soul-crushing way?

Hmm. There are things that make it easier to pick and chose parts of a
big diff for different patches.  Some combination of 
git reset HEAD~1
and one of the 'graphical' tools like tig that let you pick lines.

That lets you quickly break up a patch where you want to move things, then
you can reorder the patches to put them next to where you want to move
changes to and rely on git rebase -i with f or s to squash them.

Figuring out optimum path to the eventual break up you want is
a skill though.  When doing this sort of mangling I tend to get it wrong
and shout at my computer a few times a day ;)
Then git rebase --abort and try again.

End result is that you end up with coherent series and it looks like
you wrote perfect code in nice steps from the start!

Jonathan