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 <[email protected]>
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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