Quoting Oren Laadan (orenl@xxxxxxxxxxxxxxx):
> From: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
>
> Right now, we assume all normal files and directories
> can be checkpointed. However, as usual in the VFS, there
> are specialized places that will always need an ability
> to override these defaults. We could do this completely
> in the checkpoint code, but that would bitrot quickly.
>
> This adds a new 'file_operations' function for
> checkpointing a file. I did this under the assumption
> that we should have a dirt-simple way to make something
> (un)checkpointable that fits in with current code.
>
> As you can see in the ext[234] and /proc patches, all
> that we have to do to make something simple be
> supported is add a single "generic" f_op entry.
>
> Signed-off-by: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Oooh, I see - for some reason I was convinced you'd put this patch
further back in the stack.
Acked-by: Serge Hallyn <serue@xxxxxxxxxx>
(of course that is assymetric with restart)
> ---
> checkpoint/ckpt_file.c | 31 +++++++++++++++----------------
> include/linux/fs.h | 11 +++++++++++
> 2 files changed, 26 insertions(+), 16 deletions(-)
>
> diff --git a/checkpoint/ckpt_file.c b/checkpoint/ckpt_file.c
> index 9c344c7..0fe68bf 100644
> --- a/checkpoint/ckpt_file.c
> +++ b/checkpoint/ckpt_file.c
> @@ -91,6 +91,11 @@ static int cr_write_file_generic(struct cr_ctx *ctx, struct file *file,
>
> hh->fd_type = CR_FD_GENERIC;
>
> + /*
> + * FIXME: when we'll add support for unlinked files/dirs, we'll
> + * need to distinguish between unlinked filed and unlinked dirs.
> + */
> +
> ret = cr_write_obj(ctx, &h, hh);
> if (ret < 0)
> return ret;
> @@ -98,12 +103,16 @@ static int cr_write_file_generic(struct cr_ctx *ctx, struct file *file,
> return cr_write_fname(ctx, &file->f_path, &ctx->fs_mnt);
> }
>
> +int generic_file_checkpoint(struct cr_ctx *ctx, struct file *file,
> + struct cr_hdr_file *hh)
> +{
> + return cr_write_file_generic(ctx, file, hh);
> +}
> +
> /* cr_write_file - dump the state of a given file pointer */
> static int cr_write_file(struct cr_ctx *ctx, struct file *file)
> {
> struct cr_hdr_file *hh;
> - struct dentry *dent = file->f_dentry;
> - struct inode *inode = dent->d_inode;
> int ret;
>
> hh = cr_hbuf_get(ctx, sizeof(*hh));
> @@ -116,21 +125,11 @@ static int cr_write_file(struct cr_ctx *ctx, struct file *file)
> hh->f_version = file->f_version;
> /* FIX: need also file->uid, file->gid, file->f_owner, etc */
>
> - /*
> - * FIXME: when we'll add support for unlinked files/dirs, we'll
> - * need to distinguish between unlinked filed and unlinked dirs.
> - */
> - switch (inode->i_mode & S_IFMT) {
> - case S_IFREG:
> - case S_IFDIR:
> - ret = cr_write_file_generic(ctx, file, hh);
> - break;
> - default:
> - ret = -EBADF;
> - break;
> - }
> - cr_hbuf_put(ctx, sizeof(*hh));
> + ret = -EBADF;
> + if (file->f_op->checkpoint)
> + ret = file->f_op->checkpoint(ctx, file, hh);
>
> + cr_hbuf_put(ctx, sizeof(*hh));
> return ret;
> }
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 3bf5057..835ee9e 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1296,6 +1296,14 @@ int generic_osync_inode(struct inode *, struct address_space *, int);
> typedef int (*filldir_t)(void *, const char *, int, loff_t, u64, unsigned);
> struct block_device_operations;
>
> +#ifdef CONFIG_CHECKPOINT
> +struct cr_ctx;
> +struct cr_hdr_file;
> +int generic_file_checkpoint(struct cr_ctx *, struct file *, struct cr_hdr_file *);
> +#else
> +#define generic_file_checkpoint NULL
> +#endif
> +
> /* These macros are for out of kernel modules to test that
> * the kernel supports the unlocked_ioctl and compat_ioctl
> * fields in struct file_operations. */
> @@ -1334,6 +1342,9 @@ struct file_operations {
> ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
> ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
> int (*setlease)(struct file *, long, struct file_lock **);
> +#ifdef CONFIG_CHECKPOINT
> + int (*checkpoint)(struct cr_ctx *, struct file *file, struct cr_hdr_file *);
> +#endif
> };
>
> struct inode_operations {
> --
> 1.5.4.3
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