From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758922AbZBSSWZ (ORCPT ); Thu, 19 Feb 2009 13:22:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755603AbZBSSU0 (ORCPT ); Thu, 19 Feb 2009 13:20:26 -0500 Received: from e32.co.us.ibm.com ([32.97.110.150]:36413 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753701AbZBSSUO (ORCPT ); Thu, 19 Feb 2009 13:20:14 -0500 Subject: [RFC][PATCH 3/5] check files for checkpointability To: Ingo Molnar Cc: containers , "linux-kernel@vger.kernel.org" , "Serge E. Hallyn" , Oren Laadan , Alexey Dobriyan , Dave Hansen From: Dave Hansen Date: Thu, 19 Feb 2009 10:20:10 -0800 References: <20090219182007.B4B47C1F@kernel> In-Reply-To: <20090219182007.B4B47C1F@kernel> Message-Id: <20090219182009.1A3E8860@kernel> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Introduce a files_struct counter to indicate whether a particular file_struct has ever contained a file which can not be checkpointed. This flag is a one-way trip; once it is set, it may not be unset. We assume at allocation that a new files_struct is clean and may be checkpointed. However, as soon as it has had its files filled from its parent's, we check it for real in __scan_files_for_cr(). At that point, we mark it if it contained any uncheckpointable files. We also check each 'struct file' when it is installed in a fd slot. This way, if anyone open()s or managed to dup() an unsuppored file, we can catch it. Signed-off-by: Dave Hansen --- linux-2.6.git-dave/fs/file.c | 19 +++++++++++++++++++ linux-2.6.git-dave/fs/open.c | 5 +++++ linux-2.6.git-dave/include/linux/checkpoint.h | 17 ++++++++++++++++- linux-2.6.git-dave/include/linux/fdtable.h | 3 +++ 4 files changed, 43 insertions(+), 1 deletion(-) diff -puN fs/file.c~deny-ckpt fs/file.c --- linux-2.6.git/fs/file.c~deny-ckpt 2009-02-19 10:17:25.000000000 -0800 +++ linux-2.6.git-dave/fs/file.c 2009-02-19 10:17:25.000000000 -0800 @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -285,6 +286,20 @@ static int count_open_files(struct fdtab return i; } +static void __scan_files_for_cr(struct files_struct *files) +{ + int i; + + for (i = 0; i < files->fdtab.max_fds; i++) { + struct file *f = fcheck_files(files, i); + if (!f) + continue; + if (cr_file_supported(f)) + continue; + files_deny_checkpointing(files); + } +} + /* * Allocate a new files structure and copy contents from the * passed in files structure. @@ -303,6 +318,9 @@ struct files_struct *dup_fd(struct files goto out; atomic_set(&newf->count, 1); +#ifdef CONFIG_CHECKPOINT_RESTART + atomic_set(&newf->may_checkpoint, 1); +#endif spin_lock_init(&newf->file_lock); newf->next_fd = 0; @@ -396,6 +414,7 @@ struct files_struct *dup_fd(struct files rcu_assign_pointer(newf->fdt, new_fdt); + __scan_files_for_cr(newf); return newf; out_release: diff -puN fs/open.c~deny-ckpt fs/open.c --- linux-2.6.git/fs/open.c~deny-ckpt 2009-02-19 10:17:25.000000000 -0800 +++ linux-2.6.git-dave/fs/open.c 2009-02-19 10:17:25.000000000 -0800 @@ -29,6 +29,7 @@ #include #include #include +#include int vfs_statfs(struct dentry *dentry, struct kstatfs *buf) { @@ -998,6 +999,10 @@ void fd_install(unsigned int fd, struct { struct files_struct *files = current->files; struct fdtable *fdt; + + if (!cr_file_supported(file)) + files_deny_checkpointing(files); + spin_lock(&files->file_lock); fdt = files_fdtable(files); BUG_ON(fdt->fd[fd] != NULL); diff -puN include/linux/checkpoint.h~deny-ckpt include/linux/checkpoint.h --- linux-2.6.git/include/linux/checkpoint.h~deny-ckpt 2009-02-19 10:17:25.000000000 -0800 +++ linux-2.6.git-dave/include/linux/checkpoint.h 2009-02-19 10:17:25.000000000 -0800 @@ -12,6 +12,7 @@ #include #include +#include #ifdef CONFIG_CHECKPOINT_RESTART @@ -101,17 +102,31 @@ extern int cr_read_files(struct cr_ctx * #define pr_fmt(fmt) "[%d:c/r:%s] " fmt, task_pid_vnr(current), __func__ +static inline void __files_deny_checkpointing(struct files_struct *files, + char *file, int line) +{ + if (!atomic_dec_and_test(&files->may_checkpoint)) + return; + printk(KERN_INFO "process performed an action that can not be " + "checkpointed at: %s:%d\n", file, line); + WARN_ON(1); +} +#define files_deny_checkpointing(f) \ + __files_deny_checkpointing(f, __FILE__, __LINE__) + int cr_explain_file(struct file *file, char *explain, int left); int cr_file_supported(struct file *file); #else +static inline void files_deny_checkpointing(struct files_struct *files) {} + static inline int cr_explain_file(struct file *file, char *explain, int left) { return 0; } -int cr_file_supported(struct file *file) +static int cr_file_supported(struct file *file) { return 0; } diff -puN include/linux/fdtable.h~deny-ckpt include/linux/fdtable.h --- linux-2.6.git/include/linux/fdtable.h~deny-ckpt 2009-02-19 10:17:25.000000000 -0800 +++ linux-2.6.git-dave/include/linux/fdtable.h 2009-02-19 10:17:25.000000000 -0800 @@ -45,6 +45,9 @@ struct files_struct { atomic_t count; struct fdtable *fdt; struct fdtable fdtab; +#ifdef CONFIG_CHECKPOINT_RESTART + atomic_t may_checkpoint; +#endif /* * written part on a separate cache line in SMP */ _