Serge E. Hallyn wrote:
> Checkpoint and restore task->fs. Tasks sharing task->fs will
> share them again after restart.
>
> The fs/fs_struct.c part should of course be broken out, but
> this does the right thing for me.
>
> Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
Looks good. See a few comments below.
> ---
> checkpoint/files.c | 211 ++++++++++++++++++++++++++++++++++++++++
> checkpoint/objhash.c | 9 ++
> checkpoint/process.c | 13 +++
> fs/open.c | 53 ++++++----
> include/linux/checkpoint.h | 10 ++-
> include/linux/checkpoint_hdr.h | 10 ++
> include/linux/fs.h | 4 +
> 7 files changed, 287 insertions(+), 23 deletions(-)
>
> diff --git a/checkpoint/files.c b/checkpoint/files.c
> index b622588..c8e8d7f 100644
> --- a/checkpoint/files.c
> +++ b/checkpoint/files.c
> @@ -24,6 +24,9 @@
> #include <linux/checkpoint_hdr.h>
> #include <linux/eventpoll.h>
> #include <linux/eventfd.h>
> +#include <linux/fs.h>
> +#include <linux/fs_struct.h>
> +#include <linux/namei.h>
> #include <net/sock.h>
>
>
> @@ -449,6 +452,71 @@ int ckpt_collect_file_table(struct ckpt_ctx *ctx, struct task_struct *t)
> return ret;
> }
>
> +int checkpoint_get_task_fs(struct ckpt_ctx *ctx, struct task_struct *t)
> +{
> + struct fs_struct *fs;
> + int fs_objref;
> + int kill;
> +
> + task_lock(current);
> + fs = t->fs;
> + write_lock(&fs->lock);
> + fs->users++;
> + write_unlock(&fs->lock);
3 lines above are the same in obj_task_fs_grab()...
> + task_unlock(current);
> +
> + fs_objref = checkpoint_obj(ctx, fs, CKPT_OBJ_TASK_FS);
> + write_lock(&fs->lock);
> + kill = !--fs->users;
> + write_unlock(&fs->lock);
> + if (kill)
> + free_fs_struct(fs);
And last 5 lines are the same in obj_task_fs_drop().
Perhaps put as helpers in fs_struct.h ?
> +
> + return fs_objref;
> +}
> +
> +/*
> + * called with fs read_lock()d
> + */
Am I right to guess that this comment is stale ?
> +int checkpoint_obj_task_fs(struct ckpt_ctx *ctx, struct fs_struct *fs)
> +{
> + struct ckpt_hdr_task_fs *h;
> + int ret;
> + struct fs_struct *fscopy;
> +
...
> +/* this is the fn called by objhash when it runs into a
> + * CKPT_OBJ_TASK_FS entry. Creates an fs_struct and
> + * places it in the hash. */
> +static struct fs_struct *restore_obj_task_fs(struct ckpt_ctx *ctx)
> +{
> + struct ckpt_hdr_task_fs *h;
> + struct fs_struct *fs;
> + int ret = 0;
> + char *root, *cwd;
> + int len;
> +
> + h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_TASK_FS);
> + if (IS_ERR(h))
> + return ERR_PTR(PTR_ERR(h));
> + ckpt_hdr_put(ctx, h);
> +
> + fs = copy_fs_struct(current->fs);
> + if (!fs)
> + return ERR_PTR(-ENOMEM);
> +
> + len = ckpt_read_payload(ctx, (void **) &root,
> + PATH_MAX, CKPT_HDR_FILE_NAME);
Test for len < 0 ... ?
Since this is another place where we read file-name (also in
checkpoint/files.c), perhaps introduce a ckpt_read_fname() ?
> + ret = restore_chroot(ctx, fs, root);
> + kfree(root);
> + if (ret) {
> + free_fs_struct(fs);
> + return ERR_PTR(ret);
> + }
> +
> + len = ckpt_read_payload(ctx, (void **) &cwd,
> + PATH_MAX, CKPT_HDR_FILE_NAME);
> + ret = restore_cwd(ctx, fs, cwd);
> + kfree(cwd);
> +
> + if (ret) {
> + free_fs_struct(fs);
> + return ERR_PTR(ret);
> + }
> + return fs;
> +}
...
Oren.
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