Messages in this thread Patch in this message | | | Date | Sat, 13 Sep 2008 19:22:52 -0400 (EDT) | From | Oren Laadan <> | Subject | [RFC v5][PATCH 9/9] Restore open file descriprtors |
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Restore open file descriptors: for each FD read 'struct cr_hdr_fd_ent' and lookup objref in the hash table; if not found (first occurence), read in 'struct cr_hdr_fd_data', create a new FD and register in the hash. Otherwise attach the file pointer from the hash as an FD.
This patch only handles basic FDs - regular files, directories and also symbolic links.
Signed-off-by: Oren Laadan <orenl@cs.columbia.edu> --- checkpoint/Makefile | 2 +- checkpoint/restart.c | 4 + checkpoint/rstr_file.c | 202 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/checkpoint.h | 1 + 4 files changed, 208 insertions(+), 1 deletions(-) create mode 100644 checkpoint/rstr_file.c
diff --git a/checkpoint/Makefile b/checkpoint/Makefile index 7496695..88bbc10 100644 --- a/checkpoint/Makefile +++ b/checkpoint/Makefile @@ -3,4 +3,4 @@ # obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o objhash.o \ - ckpt_mem.o rstr_mem.o ckpt_file.o + ckpt_mem.o rstr_mem.o ckpt_file.o rstr_file.o diff --git a/checkpoint/restart.c b/checkpoint/restart.c index a0d5e60..956e274 100644 --- a/checkpoint/restart.c +++ b/checkpoint/restart.c @@ -212,6 +212,10 @@ static int cr_read_task(struct cr_ctx *ctx) cr_debug("memory: ret %d\n", ret); if (ret < 0) goto out; + ret = cr_read_files(ctx); + cr_debug("files: ret %d\n", ret); + if (ret < 0) + goto out; ret = cr_read_thread(ctx); cr_debug("thread: ret %d\n", ret); if (ret < 0) diff --git a/checkpoint/rstr_file.c b/checkpoint/rstr_file.c new file mode 100644 index 0000000..780c0fc --- /dev/null +++ b/checkpoint/rstr_file.c @@ -0,0 +1,202 @@ +/* + * Checkpoint file descriptors + * + * Copyright (C) 2008 Oren Laadan + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file COPYING in the main directory of the Linux + * distribution for more details. + */ + +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/fdtable.h> +#include <linux/fsnotify.h> +#include <linux/syscalls.h> +#include <linux/checkpoint.h> +#include <linux/checkpoint_hdr.h> + +#include "checkpoint_file.h" + +static int cr_close_all_fds(struct files_struct *files) +{ + int *fdtable; + int nfds; + + nfds = cr_scan_fds(files, &fdtable); + if (nfds < 0) + return nfds; + while (nfds--) + sys_close(fdtable[nfds]); + kfree(fdtable); + return 0; +} + +/** + * cr_attach_file - attach a lonely file ptr to a file descriptor + * @file: lonely file pointer + */ +static int cr_attach_file(struct file *file) +{ + int fd = get_unused_fd_flags(0); + + if (fd >= 0) { + fsnotify_open(file->f_path.dentry); + fd_install(fd, file); + } + return fd; +} + +#define CR_SETFL_MASK (O_APPEND|O_NONBLOCK|O_NDELAY|FASYNC|O_DIRECT|O_NOATIME) + +/* cr_read_fd_data - restore the state of a given file pointer */ +static int +cr_read_fd_data(struct cr_ctx *ctx, struct files_struct *files, int parent) +{ + struct cr_hdr_fd_data *hh = cr_hbuf_get(ctx, sizeof(*hh)); + struct file *file; + int fd, rparent, ret; + + rparent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_FD_DATA); + cr_debug("rparent %d parent %d flags %#x mode %#x how %d\n", + rparent, parent, hh->f_flags, hh->f_mode, hh->fd_type); + if (rparent < 0) + return rparent; + if (rparent != parent) + return -EINVAL; + /* FIX: more sanity checks on f_flags, f_mode etc */ + + switch (hh->fd_type) { + case CR_FD_FILE: + case CR_FD_DIR: + case CR_FD_LINK: + file = cr_read_open_fname(ctx, hh->f_flags, hh->f_mode); + break; + default: + file = ERR_PTR(-EINVAL); + break; + } + + if (IS_ERR(file)) + return PTR_ERR(file); + + /* FIX: need to restore uid, gid, owner etc */ + + fd = cr_attach_file(file); /* no need to cleanup 'file' below */ + if (fd < 0) { + filp_close(file, NULL); + return fd; + } + + /* register new <objref, file> tuple in hash table */ + ret = cr_obj_add_ref(ctx, (void *) file, parent, CR_OBJ_FILE, 0); + if (ret < 0) + goto out; + ret = sys_fcntl(fd, F_SETFL, hh->f_flags & CR_SETFL_MASK); + if (ret < 0) + goto out; + ret = vfs_llseek(file, hh->f_pos, SEEK_SET); + if (ret == -ESPIPE) /* ignore error on non-seekable files */ + ret = 0; + + out: + cr_hbuf_put(ctx, sizeof(*hh)); + return ret < 0 ? ret : fd; +} + +/** + * cr_read_fd_ent - restore the state of a given file descriptor + * @ctx: checkpoint context + * @files: files_struct pointer + * @parent: parent objref + * + * Restores the state of a file descriptor; looks up the objref (in the + * header) in the hash table, and if found picks the matching file and + * use it; otherwise calls cr_read_fd_data to restore the file too. + */ +static int +cr_read_fd_ent(struct cr_ctx *ctx, struct files_struct *files, int parent) +{ + struct cr_hdr_fd_ent *hh = cr_hbuf_get(ctx, sizeof(*hh)); + struct file *file; + int newfd, rparent; + + rparent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_FD_ENT); + cr_debug("rparent %d parent %d ref %d\n", rparent, parent, hh->objref); + if (rparent < 0) + return rparent; + if (rparent != parent) + return -EINVAL; + cr_debug("fd %d coe %d\n", hh->fd, hh->close_on_exec); + if (hh->objref <= 0) + return -EINVAL; + + file = cr_obj_get_by_ref(ctx, hh->objref, CR_OBJ_FILE); + if (IS_ERR(file)) + return PTR_ERR(file); + + if (file) { + newfd = cr_attach_file(file); + if (newfd < 0) + return newfd; + get_file(file); + } else { + /* create new file pointer (and register in hash table) */ + newfd = cr_read_fd_data(ctx, files, hh->objref); + if (newfd < 0) + return newfd; + } + + cr_debug("newfd got %d wanted %d\n", newfd, hh->fd); + + /* if newfd isn't desired fd then reposition it */ + if (newfd != hh->fd) { + int ret = sys_dup2(newfd, hh->fd); + if (ret < 0) + return ret; + sys_close(newfd); + } + + if (hh->close_on_exec) + set_close_on_exec(hh->fd, 1); + + cr_hbuf_put(ctx, sizeof(*hh)); + return 0; +} + +int cr_read_files(struct cr_ctx *ctx) +{ + struct cr_hdr_files *hh = cr_hbuf_get(ctx, sizeof(*hh)); + struct files_struct *files = current->files; + int i, parent, ret; + + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_FILES); + if (parent < 0) + return parent; +#if 0 /* activate when containers are used */ + if (parent != task_pid_vnr(current)) + return -EINVAL; +#endif + cr_debug("objref %d nfds %d\n", hh->objref, hh->nfds); + if (hh->objref < 0 || hh->nfds < 0) + return -EINVAL; + + if (hh->nfds > sysctl_nr_open) + return -EMFILE; + + /* point of no return -- close all file descriptors */ + ret = cr_close_all_fds(files); + if (ret < 0) + return ret; + + for (i = 0; i < hh->nfds; i++) { + ret = cr_read_fd_ent(ctx, files, hh->objref); + if (ret < 0) + break; + } + + cr_hbuf_put(ctx, sizeof(*hh)); + return ret; +} diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h index a202c54..fd3baac 100644 --- a/include/linux/checkpoint.h +++ b/include/linux/checkpoint.h @@ -89,6 +89,7 @@ extern int cr_write_files(struct cr_ctx *ctx, struct task_struct *t); extern int do_restart(struct cr_ctx *ctx); extern int cr_read_mm(struct cr_ctx *ctx); +extern int cr_read_files(struct cr_ctx *ctx); #define cr_debug(fmt, args...) \ pr_debug("[CR:%s] " fmt, __func__, ## args) -- 1.5.4.3
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