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 <dave@xxxxxxxxxxxxxxxxxx> --- 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 | 14 ++++++++++++++ linux-2.6.git-dave/include/linux/fdtable.h | 3 +++ 4 files changed, 41 insertions(+) diff -puN fs/file.c~track-files_struct-checkpointability fs/file.c --- linux-2.6.git/fs/file.c~track-files_struct-checkpointability 2009-02-27 12:07:41.000000000 -0800 +++ linux-2.6.git-dave/fs/file.c 2009-02-27 12:07:41.000000000 -0800 @@ -15,6 +15,7 @@ #include <linux/file.h> #include <linux/fdtable.h> #include <linux/bitops.h> +#include <linux/checkpoint.h> #include <linux/interrupt.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> @@ -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 + 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~track-files_struct-checkpointability fs/open.c --- linux-2.6.git/fs/open.c~track-files_struct-checkpointability 2009-02-27 12:07:41.000000000 -0800 +++ linux-2.6.git-dave/fs/open.c 2009-02-27 12:07:41.000000000 -0800 @@ -29,6 +29,7 @@ #include <linux/rcupdate.h> #include <linux/audit.h> #include <linux/falloc.h> +#include <linux/checkpoint.h> int vfs_statfs(struct dentry *dentry, struct kstatfs *buf) { @@ -1015,6 +1016,10 @@ 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~track-files_struct-checkpointability include/linux/checkpoint.h --- linux-2.6.git/include/linux/checkpoint.h~track-files_struct-checkpointability 2009-02-27 12:07:41.000000000 -0800 +++ linux-2.6.git-dave/include/linux/checkpoint.h 2009-02-27 12:07:41.000000000 -0800 @@ -12,6 +12,7 @@ #include <linux/path.h> #include <linux/fs.h> +#include <linux/fdtable.h> #ifdef CONFIG_CHECKPOINT_RESTART @@ -102,6 +103,18 @@ 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 (!test_and_clear_bit(0, &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); int generic_file_checkpoint(struct file *, struct cr_ctx *, struct cr_hdr_fd *); @@ -112,6 +125,7 @@ struct cr_hdr_fd; #define generic_file_checkpoint NULL +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; diff -puN include/linux/fdtable.h~track-files_struct-checkpointability include/linux/fdtable.h --- linux-2.6.git/include/linux/fdtable.h~track-files_struct-checkpointability 2009-02-27 12:07:41.000000000 -0800 +++ linux-2.6.git-dave/include/linux/fdtable.h 2009-02-27 12:07:41.000000000 -0800 @@ -45,6 +45,9 @@ struct files_struct { atomic_t count; struct fdtable *fdt; struct fdtable fdtab; +#ifdef CONFIG_CHECKPOINT_RESTART + unsigned long may_checkpoint; +#endif /* * written part on a separate cache line in SMP */ _ _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers