lkml.org 
[lkml]   [2009]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[RFC][PATCH 09/11] check files for checkpointability
    From
    Date

    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@linux.vnet.ibm.com>
    ---

    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 | 13 +++++++++++++
    linux-2.6.git-dave/include/linux/fdtable.h | 3 +++
    4 files changed, 40 insertions(+)

    diff -puN fs/file.c~242c7afafb1a81c0d9a41085536f2197d81146e7 fs/file.c
    --- linux-2.6.git/fs/file.c~242c7afafb1a81c0d9a41085536f2197d81146e7 2009-03-05 08:37:04.000000000 -0800
    +++ linux-2.6.git-dave/fs/file.c 2009-03-05 08:37:04.000000000 -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~242c7afafb1a81c0d9a41085536f2197d81146e7 fs/open.c
    --- linux-2.6.git/fs/open.c~242c7afafb1a81c0d9a41085536f2197d81146e7 2009-03-05 08:37:04.000000000 -0800
    +++ linux-2.6.git-dave/fs/open.c 2009-03-05 08:37:04.000000000 -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~242c7afafb1a81c0d9a41085536f2197d81146e7 include/linux/checkpoint.h
    --- linux-2.6.git/include/linux/checkpoint.h~242c7afafb1a81c0d9a41085536f2197d81146e7 2009-03-05 08:37:04.000000000 -0800
    +++ linux-2.6.git-dave/include/linux/checkpoint.h 2009-03-05 08:37:04.000000000 -0800
    @@ -12,6 +12,7 @@

    #include <linux/path.h>
    #include <linux/fs.h>
    +#include <linux/fdtable.h>

    #ifdef CONFIG_CHECKPOINT_RESTART

    @@ -101,11 +102,23 @@ 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);
    +}
    +#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 /* !CONFIG_CHECKPOINT_RESTART */

    +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~242c7afafb1a81c0d9a41085536f2197d81146e7 include/linux/fdtable.h
    --- linux-2.6.git/include/linux/fdtable.h~242c7afafb1a81c0d9a41085536f2197d81146e7 2009-03-05 08:37:04.000000000 -0800
    +++ linux-2.6.git-dave/include/linux/fdtable.h 2009-03-05 08:37:04.000000000 -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
    */
    _

    \
     
     \ /
      Last update: 2009-03-05 17:45    [W:0.036 / U:13.716 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site