FIFOs are almost like pipes. Checkpoints adds the FIFO pathname. The first time the FIFO is found it also assigns an @objref and dumps the contents in the buffers.
To restore, use the @objref only to determine whether a particular FIFO has already been restored earlier. Note that it ignores the file pointer that matches that @objref (unlike with pipes, where that file corresponds to the other end of the pipe). Instead, it creates a new FIFO using the saved pathname. Signed-off-by: Oren Laadan <[email protected]> --- checkpoint/files.c | 6 +++ fs/pipe.c | 82 +++++++++++++++++++++++++++++++++++++++- include/linux/checkpoint_hdr.h | 1 + include/linux/pipe_fs_i.h | 2 + 4 files changed, 89 insertions(+), 2 deletions(-) diff --git a/checkpoint/files.c b/checkpoint/files.c index bcdc774..0642649 100644 --- a/checkpoint/files.c +++ b/checkpoint/files.c @@ -548,6 +548,12 @@ static struct restore_file_ops restore_file_ops[] = { .file_type = CKPT_FILE_PIPE, .restore = pipe_file_restore, }, + /* fifo */ + { + .file_name = "FIFO", + .file_type = CKPT_FILE_FIFO, + .restore = fifo_file_restore, + }, }; static struct file *do_restore_file(struct ckpt_ctx *ctx) diff --git a/fs/pipe.c b/fs/pipe.c index 550de0b..00ef5a2 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -811,6 +811,8 @@ pipe_rdwr_open(struct inode *inode, struct file *filp) return 0; } +static struct vfsmount *pipe_mnt __read_mostly; + #ifdef CONFIG_CHECKPOINT static int checkpoint_pipe(struct ckpt_ctx *ctx, struct inode *inode) { @@ -858,7 +860,11 @@ static int pipe_file_checkpoint(struct ckpt_ctx *ctx, struct file *file) if (!h) return -ENOMEM; - h->common.f_type = CKPT_FILE_PIPE; + /* fifo and pipe are similar at checkpoint, differ on restore */ + if (inode->i_sb == pipe_mnt->mnt_sb) + h->common.f_type = CKPT_FILE_PIPE; + else + h->common.f_type = CKPT_FILE_FIFO; h->pipe_objref = objref; ret = checkpoint_file_common(ctx, file, &h->common); @@ -868,6 +874,13 @@ static int pipe_file_checkpoint(struct ckpt_ctx *ctx, struct file *file) if (ret < 0) goto out; + /* FIFO also needs a file name */ + if (h->common.f_type == CKPT_FILE_FIFO) { + ret = checkpoint_fname(ctx, &file->f_path, &ctx->fs_mnt); + if (ret < 0) + goto out; + } + if (first) ret = checkpoint_pipe(ctx, inode); out: @@ -959,8 +972,74 @@ struct file *pipe_file_restore(struct ckpt_ctx *ctx, struct ckpt_hdr_file *ptr) return file; } + +struct file *fifo_file_restore(struct ckpt_ctx *ctx, struct ckpt_hdr_file *ptr) +{ + struct ckpt_hdr_file_pipe *h = (struct ckpt_hdr_file_pipe *) ptr; + struct file *file; + int first, ret; + + if (ptr->h.type != CKPT_HDR_FILE || + ptr->h.len != sizeof(*h) || ptr->f_type != CKPT_FILE_FIFO) + return ERR_PTR(-EINVAL); + + if (h->pipe_objref <= 0) + return ERR_PTR(-EINVAL); + + /* + * If ckpt_obj_fetch() returned ERR_PTR(-EINVAL), this is the + * first time for this fifo. + */ + file = ckpt_obj_fetch(ctx, h->pipe_objref, CKPT_OBJ_FILE); + if (!IS_ERR(file)) + first = 0; + else if (PTR_ERR(file) == -EINVAL) + first = 1; + else + return file; + + /* + * To avoid blocking, always open the fifo with O_RDWR; + * then fix flags below. + */ + file = restore_open_fname(ctx, (ptr->f_flags & ~O_ACCMODE) | O_RDWR); + if (IS_ERR(file)) + return file; + + if ((ptr->f_flags & O_ACCMODE) == O_RDONLY) { + file->f_flags = (file->f_flags & ~O_ACCMODE) | O_RDONLY; + file->f_mode &= ~FMODE_WRITE; + } else if ((ptr->f_flags & O_ACCMODE) == O_WRONLY) { + file->f_flags = (file->f_flags & ~O_ACCMODE) | O_WRONLY; + file->f_mode &= ~FMODE_READ; + } else if ((ptr->f_flags & O_ACCMODE) != O_RDWR) { + ret = -EINVAL; + goto out; + } + + /* first time: add to objhash and restore fifo's contents */ + if (first) { + ret = ckpt_obj_insert(ctx, file, h->pipe_objref, CKPT_OBJ_FILE); + if (ret < 0) + goto out; + + ret = restore_pipe(ctx, file); + if (ret < 0) + goto out; + } + + ret = restore_file_common(ctx, file, ptr); + out: + if (ret < 0) { + fput(file); + file = ERR_PTR(ret); + } + + return file; +} #else #define pipe_file_checkpoint NULL +#define fifo_file_checkpoint NULL #endif /* CONFIG_CHECKPOINT */ /* @@ -1043,7 +1122,6 @@ void free_pipe_info(struct inode *inode) inode->i_pipe = NULL; } -static struct vfsmount *pipe_mnt __read_mostly; static int pipefs_delete_dentry(struct dentry *dentry) { /* diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h index e37fa72..4b85956 100644 --- a/include/linux/checkpoint_hdr.h +++ b/include/linux/checkpoint_hdr.h @@ -326,6 +326,7 @@ enum file_type { CKPT_FILE_IGNORE = 0, CKPT_FILE_GENERIC, CKPT_FILE_PIPE, + CKPT_FILE_FIFO, CKPT_FILE_MAX }; diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index e526a12..596403e 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -160,6 +160,8 @@ struct ckpt_ctx; struct ckpt_hdr_file; extern struct file *pipe_file_restore(struct ckpt_ctx *ctx, struct ckpt_hdr_file *ptr); +extern struct file *fifo_file_restore(struct ckpt_ctx *ctx, + struct ckpt_hdr_file *ptr); #endif #endif -- 1.6.0.4 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
