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Date:   Sun, 22 Apr 2018 23:12:01 -0700
From:   "Darrick J. Wong" <darrick.wong@oracle.com>
To:     Andiry Xu <jix024@eng.ucsd.edu>
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvdimm@lists.01.org, dan.j.williams@intel.com,
        andy.rudoff@intel.com, coughlan@redhat.com, swanson@cs.ucsd.edu,
        david@fromorbit.com, jack@suse.com, swhiteho@redhat.com,
        miklos@szeredi.hu, andiry.xu@gmail.com,
        Andiry Xu <jix024@cs.ucsd.edu>
Subject: Re: [RFC v2 06/83] Add inode get/read methods.
Message-ID: <20180423061201.GC26268@magnolia>
References: <1520705944-6723-1-git-send-email-jix024@eng.ucsd.edu>
 <1520705944-6723-7-git-send-email-jix024@eng.ucsd.edu>
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[haaa, I finally found time to read more of these]

On Sat, Mar 10, 2018 at 10:17:47AM -0800, Andiry Xu wrote:
> From: Andiry Xu <jix024@cs.ucsd.edu>
> 
> These routines are incomplete and currently only support reserved inodes,
> whose addresses are fixed. This is necessary for fill_super to work.
> File/dir operations are left NULL.
> 
> Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
> ---
>  fs/nova/inode.c | 176 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/nova/inode.h |   3 +
>  2 files changed, 179 insertions(+)
>  create mode 100644 fs/nova/inode.c
> 
> diff --git a/fs/nova/inode.c b/fs/nova/inode.c
> new file mode 100644
> index 0000000..bfdc5dc
> --- /dev/null
> +++ b/fs/nova/inode.c
> @@ -0,0 +1,176 @@
> +/*
> + * BRIEF DESCRIPTION
> + *
> + * Inode methods (allocate/free/read/write).
> + *
> + * Copyright 2015-2016 Regents of the University of California,
> + * UCSD Non-Volatile Systems Lab, Andiry Xu <jix024@cs.ucsd.edu>
> + * Copyright 2012-2013 Intel Corporation
> + * Copyright 2009-2011 Marco Stornelli <marco.stornelli@gmail.com>
> + * Copyright 2003 Sony Corporation
> + * Copyright 2003 Matsushita Electric Industrial Co., Ltd.
> + * 2003-2004 (c) MontaVista Software, Inc. , Steve Longerbeam
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/fs.h>
> +#include <linux/aio.h>
> +#include <linux/highuid.h>
> +#include <linux/module.h>
> +#include <linux/mpage.h>
> +#include <linux/backing-dev.h>
> +#include <linux/types.h>
> +#include <linux/ratelimit.h>
> +#include "nova.h"
> +#include "inode.h"
> +
> +unsigned int blk_type_to_shift[NOVA_BLOCK_TYPE_MAX] = {12, 21, 30};
> +uint32_t blk_type_to_size[NOVA_BLOCK_TYPE_MAX] = {0x1000, 0x200000, 0x40000000};
> +
> +void nova_set_inode_flags(struct inode *inode, struct nova_inode *pi,
> +	unsigned int flags)
> +{
> +	inode->i_flags &=
> +		~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC);
> +	if (flags & FS_SYNC_FL)
> +		inode->i_flags |= S_SYNC;
> +	if (flags & FS_APPEND_FL)
> +		inode->i_flags |= S_APPEND;
> +	if (flags & FS_IMMUTABLE_FL)
> +		inode->i_flags |= S_IMMUTABLE;
> +	if (flags & FS_NOATIME_FL)
> +		inode->i_flags |= S_NOATIME;
> +	if (flags & FS_DIRSYNC_FL)
> +		inode->i_flags |= S_DIRSYNC;
> +	if (!pi->i_xattr)
> +		inode_has_no_xattr(inode);
> +	inode->i_flags |= S_DAX;
> +}
> +
> +/* copy persistent state to struct inode */
> +static int nova_read_inode(struct super_block *sb, struct inode *inode,
> +	u64 pi_addr)
> +{
> +	struct nova_inode_info *si = NOVA_I(inode);
> +	struct nova_inode *pi, fake_pi;
> +	struct nova_inode_info_header *sih = &si->header;
> +	int ret = -EIO;
> +	unsigned long ino;
> +
> +	ret = nova_get_reference(sb, pi_addr, &fake_pi,
> +			(void **)&pi, sizeof(struct nova_inode));
> +	if (ret) {
> +		nova_dbg("%s: read pi @ 0x%llx failed\n",
> +				__func__, pi_addr);
> +		goto bad_inode;
> +	}
> +
> +	inode->i_mode = sih->i_mode;

Hm, do you validate the on-pmem metadata as it's read in?  What if
i_mode is garbage?

> +	i_uid_write(inode, le32_to_cpu(pi->i_uid));
> +	i_gid_write(inode, le32_to_cpu(pi->i_gid));
> +//	set_nlink(inode, le16_to_cpu(pi->i_links_count));

C++ comment?

> +	inode->i_generation = le32_to_cpu(pi->i_generation);
> +	nova_set_inode_flags(inode, pi, le32_to_cpu(pi->i_flags));
> +	ino = inode->i_ino;
> +
> +	/* check if the inode is active. */
> +	if (inode->i_mode == 0 || pi->deleted == 1) {
> +		/* this inode is deleted */
> +		ret = -ESTALE;
> +		goto bad_inode;
> +	}
> +
> +	inode->i_blocks = sih->i_blocks;

Not le64_to_cpu(sih->i_blocks)?  Or is that somewhere else I'm
missing...

> +
> +	switch (inode->i_mode & S_IFMT) {
> +	case S_IFREG:
> +		break;
> +	case S_IFDIR:
> +		break;
> +	case S_IFLNK:
> +		break;
> +	default:
> +		init_special_inode(inode, inode->i_mode,
> +				   le32_to_cpu(pi->dev.rdev));
> +		break;
> +	}
> +
> +	/* Update size and time after rebuild the tree */
> +	inode->i_size = le64_to_cpu(sih->i_size);

FWIW the type of i_size is loff_t, which is an unsigned type.  Despite
this, the VFS does not support files with negative sizes... which means
that this probably ought to check for that.

--D

> +	inode->i_atime.tv_sec = (__s32)le32_to_cpu(pi->i_atime);
> +	inode->i_ctime.tv_sec = (__s32)le32_to_cpu(pi->i_ctime);
> +	inode->i_mtime.tv_sec = (__s32)le32_to_cpu(pi->i_mtime);
> +	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec =
> +					 inode->i_ctime.tv_nsec = 0;
> +	set_nlink(inode, le16_to_cpu(pi->i_links_count));
> +	return 0;
> +
> +bad_inode:
> +	make_bad_inode(inode);
> +	return ret;
> +}
> +
> +/* Get the address in PMEM of an inode by inode number.  Allocate additional
> + * block to store additional inodes if necessary.
> + */
> +int nova_get_inode_address(struct super_block *sb, u64 ino,
> +	u64 *pi_addr, int extendable)
> +{
> +	if (ino < NOVA_NORMAL_INODE_START) {
> +		*pi_addr = nova_get_reserved_inode_addr(sb, ino);
> +		return 0;
> +	}
> +
> +	*pi_addr = 0;
> +	return 0;
> +}
> +
> +struct inode *nova_iget(struct super_block *sb, unsigned long ino)
> +{
> +	struct nova_inode_info *si;
> +	struct inode *inode;
> +	u64 pi_addr;
> +	int err;
> +
> +	inode = iget_locked(sb, ino);
> +	if (unlikely(!inode))
> +		return ERR_PTR(-ENOMEM);
> +	if (!(inode->i_state & I_NEW))
> +		return inode;
> +
> +	si = NOVA_I(inode);
> +
> +	nova_dbgv("%s: inode %lu\n", __func__, ino);
> +
> +	err = nova_get_inode_address(sb, ino, &pi_addr, 0);
> +	if (err) {
> +		nova_dbg("%s: get inode %lu address failed %d\n",
> +			 __func__, ino, err);
> +		goto fail;
> +	}
> +
> +	if (pi_addr == 0) {
> +		nova_dbg("%s: failed to get pi_addr for inode %lu\n",
> +			 __func__, ino);
> +		err = -EACCES;
> +		goto fail;
> +	}
> +
> +	err = nova_read_inode(sb, inode, pi_addr);
> +	if (unlikely(err)) {
> +		nova_dbg("%s: failed to read inode %lu\n", __func__, ino);
> +		goto fail;
> +
> +	}
> +
> +	inode->i_ino = ino;
> +
> +	unlock_new_inode(inode);
> +	return inode;
> +fail:
> +	iget_failed(inode);
> +	return ERR_PTR(err);
> +}
> +
> diff --git a/fs/nova/inode.h b/fs/nova/inode.h
> index f9187e3..dbd5256 100644
> --- a/fs/nova/inode.h
> +++ b/fs/nova/inode.h
> @@ -184,4 +184,7 @@ static inline int nova_persist_inode(struct nova_inode *pi)
>  	return 0;
>  }
>  
> +int nova_get_inode_address(struct super_block *sb, u64 ino,
> +	u64 *pi_addr, int extendable);
> +struct inode *nova_iget(struct super_block *sb, unsigned long ino);
>  #endif
> -- 
> 2.7.4
>