Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754907AbZGVKOc (ORCPT ); Wed, 22 Jul 2009 06:14:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754564AbZGVKOa (ORCPT ); Wed, 22 Jul 2009 06:14:30 -0400 Received: from smtp161.dfw.emailsrvr.com ([67.192.241.161]:40236 "EHLO smtp161.dfw.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754525AbZGVKKu (ORCPT ); Wed, 22 Jul 2009 06:10:50 -0400 From: Oren Laadan To: Andrew Morton Cc: Linus Torvalds , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, Serge Hallyn , Dave Hansen , Ingo Molnar , "H. Peter Anvin" , Alexander Viro , Pavel Emelyanov , Alexey Dobriyan , Oren Laadan , Oren Laadan Subject: [RFC v17][PATCH 34/60] c/r: restore open file descriptors Date: Wed, 22 Jul 2009 05:59:56 -0400 Message-Id: <1248256822-23416-35-git-send-email-orenl@librato.com> X-Mailer: git-send-email 1.6.0.4 In-Reply-To: <1248256822-23416-1-git-send-email-orenl@librato.com> References: <1248256822-23416-1-git-send-email-orenl@librato.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 12163 Lines: 449 For each fd read 'struct ckpt_hdr_file_desc' and lookup objref in the hash table; If not found in the hash table, (first occurence), read in 'struct ckpt_hdr_file', create a new file and register in the hash. Otherwise attach the file pointer from the hash as an FD. Changelog[v17]: - Validate f_mode after restore against saved f_mode - Fail if f_flags have O_CREAT|O_EXCL|O_NOCTTY|O_TRUN - Reorder patch (move earlier in series) - Handle shared files_struct objects Changelog[v14]: - Introduce a per file-type restore() callback - Revert change to pr_debug(), back to ckpt_debug() - Rename: restore_files() => restore_fd_table() - Rename: ckpt_read_fd_data() => restore_file() - Check whether calls to ckpt_hbuf_get() fail - Discard field 'hh->parent' Changelog[v12]: - Replace obsolete ckpt_debug() with pr_debug() Changelog[v6]: - Balance all calls to ckpt_hbuf_get() with matching ckpt_hbuf_put() (even though it's not really needed) Signed-off-by: Oren Laadan --- checkpoint/files.c | 310 ++++++++++++++++++++++++++++++++++++++++++++ checkpoint/objhash.c | 2 + checkpoint/process.c | 20 +++ include/linux/checkpoint.h | 7 + 4 files changed, 339 insertions(+), 0 deletions(-) diff --git a/checkpoint/files.c b/checkpoint/files.c index 5ff9925..88d7adf 100644 --- a/checkpoint/files.c +++ b/checkpoint/files.c @@ -16,6 +16,8 @@ #include #include #include +#include +#include #include #include @@ -380,3 +382,311 @@ int ckpt_collect_file_table(struct ckpt_ctx *ctx, struct task_struct *t) return ret; } + +/************************************************************************** + * Restart + */ + +/** + * restore_open_fname - read a file name and open a file + * @ctx: checkpoint context + * @flags: file flags + */ +struct file *restore_open_fname(struct ckpt_ctx *ctx, int flags) +{ + struct ckpt_hdr *h; + struct file *file; + char *fname; + + /* prevent bad input from doing bad things */ + if (flags & (O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC)) + return ERR_PTR(-EINVAL); + + h = ckpt_read_buf_type(ctx, PATH_MAX, CKPT_HDR_FILE_NAME); + if (IS_ERR(h)) + return (struct file *) h; + fname = (char *) (h + 1); + ckpt_debug("fname '%s' flags %#x\n", fname, flags); + + file = filp_open(fname, flags, 0); + ckpt_hdr_put(ctx, h); + + return file; +} + +static int close_all_fds(struct files_struct *files) +{ + int *fdtable; + int nfds; + + nfds = scan_fds(files, &fdtable); + if (nfds < 0) + return nfds; + while (nfds--) + sys_close(fdtable[nfds]); + kfree(fdtable); + return 0; +} + +/** + * attach_file - attach a lonely file ptr to a file descriptor + * @file: lonely file pointer + */ +static int attach_file(struct file *file) +{ + int fd = get_unused_fd_flags(0); + + if (fd >= 0) { + get_file(file); + fsnotify_open(file->f_path.dentry); + fd_install(fd, file); + } + return fd; +} + +#define CKPT_SETFL_MASK \ + (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME) + +int restore_file_common(struct ckpt_ctx *ctx, struct file *file, + struct ckpt_hdr_file *h) +{ + fmode_t new_mode = (__force fmode_t) file->f_mode; + fmode_t saved_mode = (__force fmode_t) h->f_mode; + int ret; + + /* FIX: need to restore uid, gid, owner etc */ + + /* safe to set 1st arg (fd) to 0, as command is F_SETFL */ + ret = vfs_fcntl(0, F_SETFL, h->f_flags & CKPT_SETFL_MASK, file); + if (ret < 0) + return ret; + + /* + * Normally f_mode is set by open, and modified only via + * fcntl(), so its value now should match that at checkpoint. + * However, a file may be downgraded from (read-)write to + * read-only, e.g: + * - mark_files_ro() unsets FMODE_WRITE + * - nfs4_file_downgrade() too, and also sert FMODE_READ + * Validate the new f_mode against saved f_mode, allowing: + * - new with FMODE_WRITE, saved without FMODE_WRITE + * - new without FMODE_READ, saved with FMODE_READ + */ + if ((new_mode & FMODE_WRITE) && !(saved_mode & FMODE_WRITE)) { + new_mode &= ~FMODE_WRITE; + if (!(new_mode & FMODE_READ) && (saved_mode & FMODE_READ)) + new_mode |= FMODE_READ; + } + /* finally, at this point new mode should match saved mode */ + if (new_mode ^ saved_mode) + return -EINVAL; + + if (file->f_mode & FMODE_LSEEK) + ret = vfs_llseek(file, h->f_pos, SEEK_SET); + + return ret; +} + +static struct file *generic_file_restore(struct ckpt_ctx *ctx, + struct ckpt_hdr_file *ptr) +{ + struct file *file; + int ret; + + if (ptr->h.type != CKPT_HDR_FILE || + ptr->h.len != sizeof(*ptr) || ptr->f_type != CKPT_FILE_GENERIC) + return ERR_PTR(-EINVAL); + + file = restore_open_fname(ctx, ptr->f_flags); + if (IS_ERR(file)) + return file; + + ret = restore_file_common(ctx, file, ptr); + if (ret < 0) { + fput(file); + file = ERR_PTR(ret); + } + return file; +} + +struct restore_file_ops { + char *file_name; + enum file_type file_type; + struct file * (*restore) (struct ckpt_ctx *ctx, + struct ckpt_hdr_file *ptr); +}; + +static struct restore_file_ops restore_file_ops[] = { + /* ignored file */ + { + .file_name = "IGNORE", + .file_type = CKPT_FILE_IGNORE, + .restore = NULL, + }, + /* regular file/directory */ + { + .file_name = "GENERIC", + .file_type = CKPT_FILE_GENERIC, + .restore = generic_file_restore, + }, +}; + +static struct file *do_restore_file(struct ckpt_ctx *ctx) +{ + struct restore_file_ops *ops; + struct ckpt_hdr_file *h; + struct file *file = ERR_PTR(-EINVAL); + + /* + * All 'struct ckpt_hdr_file_...' begin with ckpt_hdr_file, + * but the actual object depends on the file type. The length + * should never be more than page. + */ + h = ckpt_read_buf_type(ctx, PAGE_SIZE, CKPT_HDR_FILE); + if (IS_ERR(h)) + return (struct file *) h; + ckpt_debug("flags %#x mode %#x type %d\n", + h->f_flags, h->f_mode, h->f_type); + + if (h->f_type >= CKPT_FILE_MAX) + goto out; + + ops = &restore_file_ops[h->f_type]; + BUG_ON(ops->file_type != h->f_type); + + if (ops->restore) + file = ops->restore(ctx, h); + out: + ckpt_hdr_put(ctx, h); + return file; +} + +/* restore callback for file pointer */ +void *restore_file(struct ckpt_ctx *ctx) +{ + return (void *) do_restore_file(ctx); +} + +/** + * ckpt_read_file_desc - restore the state of a given file descriptor + * @ctx: checkpoint context + * + * 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 restore_file to restore the file too. + */ +static int restore_file_desc(struct ckpt_ctx *ctx) +{ + struct ckpt_hdr_file_desc *h; + struct file *file; + int newfd, ret; + + h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_FILE_DESC); + if (IS_ERR(h)) + return PTR_ERR(h); + ckpt_debug("ref %d fd %d c.o.e %d\n", + h->fd_objref, h->fd_descriptor, h->fd_close_on_exec); + + ret = -EINVAL; + if (h->fd_objref <= 0 || h->fd_descriptor < 0) + goto out; + + file = ckpt_obj_fetch(ctx, h->fd_objref, CKPT_OBJ_FILE); + if (IS_ERR(file)) { + ret = PTR_ERR(file); + goto out; + } + + newfd = attach_file(file); + if (newfd < 0) { + ret = newfd; + goto out; + } + + ckpt_debug("newfd got %d wanted %d\n", newfd, h->fd_descriptor); + + /* reposition if newfd isn't desired fd */ + if (newfd != h->fd_descriptor) { + ret = sys_dup2(newfd, h->fd_descriptor); + if (ret < 0) + goto out; + sys_close(newfd); + } + + if (h->fd_close_on_exec) + set_close_on_exec(h->fd_descriptor, 1); + + ret = 0; + out: + ckpt_hdr_put(ctx, h); + return ret; +} + +/* restore callback for file table */ +static struct files_struct *do_restore_file_table(struct ckpt_ctx *ctx) +{ + struct ckpt_hdr_file_table *h; + struct files_struct *files; + int i, ret; + + h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_FILE_TABLE); + if (IS_ERR(h)) + return (struct files_struct *) h; + + ckpt_debug("nfds %d\n", h->fdt_nfds); + + ret = -EMFILE; + if (h->fdt_nfds < 0 || h->fdt_nfds > sysctl_nr_open) + goto out; + + /* + * We assume that restarting tasks, as created in user-space, + * have distinct files_struct objects each. If not, we need to + * call dup_fd() to make sure we don't overwrite an already + * restored one. + */ + + /* point of no return -- close all file descriptors */ + ret = close_all_fds(current->files); + if (ret < 0) + goto out; + + for (i = 0; i < h->fdt_nfds; i++) { + ret = restore_file_desc(ctx); + if (ret < 0) + break; + } + out: + ckpt_hdr_put(ctx, h); + if (!ret) { + files = current->files; + atomic_inc(&files->count); + } else { + files = ERR_PTR(ret); + } + return files; +} + +void *restore_file_table(struct ckpt_ctx *ctx) +{ + return (void *) do_restore_file_table(ctx); +} + +int restore_obj_file_table(struct ckpt_ctx *ctx, int files_objref) +{ + struct files_struct *files; + + files = ckpt_obj_fetch(ctx, files_objref, CKPT_OBJ_FILE_TABLE); + if (IS_ERR(files)) + return PTR_ERR(files); + + if (files != current->files) { + task_lock(current); + put_files_struct(current->files); + current->files = files; + task_unlock(current); + atomic_inc(&files->count); + } + + return 0; +} diff --git a/checkpoint/objhash.c b/checkpoint/objhash.c index d77e8c4..fae6bfc 100644 --- a/checkpoint/objhash.c +++ b/checkpoint/objhash.c @@ -122,6 +122,7 @@ static struct ckpt_obj_ops ckpt_obj_ops[] = { .ref_grab = obj_file_table_grab, .ref_users = obj_file_table_users, .checkpoint = checkpoint_file_table, + .restore = restore_file_table, }, /* file object */ { @@ -131,6 +132,7 @@ static struct ckpt_obj_ops ckpt_obj_ops[] = { .ref_grab = obj_file_grab, .ref_users = obj_file_users, .checkpoint = checkpoint_file, + .restore = restore_file, }, }; diff --git a/checkpoint/process.c b/checkpoint/process.c index 61caa01..8cbbace 100644 --- a/checkpoint/process.c +++ b/checkpoint/process.c @@ -343,6 +343,22 @@ static int restore_task_struct(struct ckpt_ctx *ctx) return ret; } +static int restore_task_objs(struct ckpt_ctx *ctx) +{ + struct ckpt_hdr_task_objs *h; + int ret; + + h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_TASK_OBJS); + if (IS_ERR(h)) + return PTR_ERR(h); + + ret = restore_obj_file_table(ctx, h->files_objref); + ckpt_debug("file_table: ret %d (%p)\n", ret, current->files); + + ckpt_hdr_put(ctx, h); + return ret; +} + int restore_restart_block(struct ckpt_ctx *ctx) { struct ckpt_hdr_restart_block *h; @@ -462,6 +478,10 @@ int restore_task(struct ckpt_ctx *ctx) if (ret) goto out; + ret = restore_task_objs(ctx); + ckpt_debug("objs %d\n", ret); + if (ret < 0) + goto out; ret = restore_thread(ctx); ckpt_debug("thread %d\n", ret); if (ret < 0) diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h index 67845dc..3f28a06 100644 --- a/include/linux/checkpoint.h +++ b/include/linux/checkpoint.h @@ -128,15 +128,22 @@ extern int restore_restart_block(struct ckpt_ctx *ctx); extern int ckpt_collect_file_table(struct ckpt_ctx *ctx, struct task_struct *t); extern int checkpoint_obj_file_table(struct ckpt_ctx *ctx, struct task_struct *t); +extern int restore_obj_file_table(struct ckpt_ctx *ctx, int files_objref); extern int checkpoint_file_table(struct ckpt_ctx *ctx, void *ptr); +extern void *restore_file_table(struct ckpt_ctx *ctx); /* files */ extern int checkpoint_fname(struct ckpt_ctx *ctx, struct path *path, struct path *root); +extern struct file *restore_open_fname(struct ckpt_ctx *ctx, int flags); + extern int checkpoint_file(struct ckpt_ctx *ctx, void *ptr); +extern void *restore_file(struct ckpt_ctx *ctx); extern int checkpoint_file_common(struct ckpt_ctx *ctx, struct file *file, struct ckpt_hdr_file *h); +extern int restore_file_common(struct ckpt_ctx *ctx, struct file *file, + struct ckpt_hdr_file *h); /* debugging flags */ -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/