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SubjectRe: [PATCH] knfsd: add nfs-export support to ramfs
the subject is unsuitable? i mean the prefix should be fs/ramfs rather
than knfsd?

2019-05-22 3:25 GMT+12:00, Haodong Wong <haydenw.kernel@gmail.com>:
> Refer to tmpfs, use inode number and generation number
> to construct the filehandle for nfs-export

would you like to describe what is happening without this patch?

BTW, i guess you can keep Andrew Morton in the loop to review the
patch when you resend it.

>
> Signed-off-by: Haodong Wong <haydenw.kernel@gmail.com>
> ---
> fs/ramfs/inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 72 insertions(+)
>
> diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
> index 11201b2d06b9..418b2551f6fd 100644
> --- a/fs/ramfs/inode.c
> +++ b/fs/ramfs/inode.c
> @@ -36,6 +36,7 @@
> #include <linux/magic.h>
> #include <linux/slab.h>
> #include <linux/uaccess.h>
> +#include <linux/exportfs.h>
> #include "internal.h"
>
> struct ramfs_mount_opts {
> @@ -66,6 +67,7 @@ struct inode *ramfs_get_inode(struct super_block *sb,
> if (inode) {
> inode->i_ino = get_next_ino();
> inode_init_owner(inode, dir, mode);
> + inode->i_generation = get_seconds();
> inode->i_mapping->a_ops = &ramfs_aops;
> mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
> mapping_set_unevictable(inode->i_mapping);
> @@ -217,6 +219,75 @@ static int ramfs_parse_options(char *data, struct
> ramfs_mount_opts *opts)
> return 0;
> }
>
> +static struct dentry *ramfs_get_parent(struct dentry *child)
> +{
> + return ERR_PTR(-ESTALE);
> +}
> +
> +static int ramfs_match(struct inode *ino, void *vfh)
> +{
> + __u32 *fh = vfh;
> + __u64 inum = fh[2];
> +
> + inum = (inum << 32) | fh[1];
> + return ino->i_ino == inum && fh[0] == ino->i_generation;
> +}
> +
> +static struct dentry *ramfs_fh_to_dentry(struct super_block *sb,
> + struct fid *fid, int fh_len, int fh_type)
> +
> +{
> + struct inode *inode;
> + struct dentry *dentry = NULL;
> + u64 inum;
> +
> + if (fh_len < 3)
> + return NULL;
> +
> + inum = fid->raw[2];
> + inum = (inum << 32) | fid->raw[1];
> + inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
> + ramfs_match, fid->raw);
> +
> + if (inode) {
> + dentry = d_find_alias(inode);
> + iput(inode);
> + }
> +
> + return dentry;
> +}
> +
> +static int ramfs_encode_fh(struct inode *inode, __u32 *fh, int *len,
> + struct inode *parent)
> +{
> + if (*len < 3) {
> + *len = 3;
> + return FILEID_INVALID;
> + }
> +
> + if (inode_unhashed(inode)) {
> + static DEFINE_SPINLOCK(lock);
> +
> + spin_lock(&lock);
> + if (inode_unhashed(inode))
> + __insert_inode_hash(inode,
> + inode->i_ino + inode->i_generation);
> + spin_unlock(&lock);
> + }
> + fh[0] = inode->i_generation;
> + fh[1] = inode->i_ino;
> + fh[2] = ((__u64)inode->i_ino) >> 32;
> +
> + *len = 3;
> + return 1;
> +}
> +
> +static const struct export_operations ramfs_export_ops = {
> + .get_parent = ramfs_get_parent,
> + .encode_fh = ramfs_encode_fh,
> + .fh_to_dentry = ramfs_fh_to_dentry,
> +};
> +
> int ramfs_fill_super(struct super_block *sb, void *data, int silent)
> {
> struct ramfs_fs_info *fsi;
> @@ -238,6 +309,7 @@ int ramfs_fill_super(struct super_block *sb, void *data,
> int silent)
> sb->s_magic = RAMFS_MAGIC;
> sb->s_op = &ramfs_ops;
> sb->s_time_gran = 1;
> + sb->s_export_op = &ramfs_export_ops;
>
> inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
> sb->s_root = d_make_root(inode);
> --
> 2.17.1
>
>

-barry

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