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    Subject[ 10/23] [Suspend2] Add support for freezing filesystem bdevs.
    Date

    Add support for freezing and thawing bdevs of filesystems. Filesystems
    are frozen in reverse order so that nested filesystems don't cause
    deadlocks.

    Signed-off-by: Nigel Cunningham <nigel@suspend2.net>

    kernel/power/process.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 50 insertions(+), 0 deletions(-)

    diff --git a/kernel/power/process.c b/kernel/power/process.c
    index 09fc9ca..0e377ed 100644
    --- a/kernel/power/process.c
    +++ b/kernel/power/process.c
    @@ -48,6 +48,56 @@
    DECLARE_COMPLETION(thaw);
    static atomic_t nr_frozen;

    +struct frozen_fs
    +{
    + struct list_head fsb_list;
    + struct super_block *sb;
    +};
    +
    +LIST_HEAD(frozen_fs_list);
    +
    +void freezer_make_fses_rw(void)
    +{
    + struct frozen_fs *fs, *next_fs;
    +
    + list_for_each_entry_safe(fs, next_fs, &frozen_fs_list, fsb_list) {
    + thaw_bdev(fs->sb->s_bdev, fs->sb);
    +
    + list_del(&fs->fsb_list);
    + kfree(fs);
    + }
    +}
    +
    +/*
    + * Done after userspace is frozen, so there should be no danger of
    + * fses being unmounted while we're in here.
    + */
    +int freezer_make_fses_ro(void)
    +{
    + struct frozen_fs *fs;
    + struct super_block *sb;
    +
    + /* Generate the list */
    + list_for_each_entry(sb, &super_blocks, s_list) {
    + if (!sb->s_root || !sb->s_bdev ||
    + (sb->s_frozen == SB_FREEZE_TRANS) ||
    + (sb->s_flags & MS_RDONLY))
    + continue;
    +
    + fs = kmalloc(sizeof(struct frozen_fs), GFP_ATOMIC);
    + fs->sb = sb;
    + list_add_tail(&fs->fsb_list, &frozen_fs_list);
    + };
    +
    + /* Do the freezing in reverse order so filesystems dependant
    + * upon others are frozen in the right order. (Eg loopback
    + * on ext3). */
    + list_for_each_entry_reverse(fs, &frozen_fs_list, fsb_list)
    + freeze_bdev(fs->sb->s_bdev);
    +
    + return 0;
    +}
    +
    static inline int freezeable(struct task_struct * p)
    {
    if ((p == current) ||
    --
    Nigel Cunningham nigel at suspend2 dot net
    -
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