Merge branch 'work.thaw' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

[linux-block.git] / fs / super.c

diff --git a/fs/super.c b/fs/super.c
index 672538ca983183e0e4a6dff83db28ff5c9341054..5fa9a8d8d865c46a77d4a0e8fb7b05499809840f 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -37,6 +37,7 @@
 #include <linux/user_namespace.h>
 #include "internal.h"
 
+static int thaw_super_locked(struct super_block *sb);
 
 static LIST_HEAD(super_blocks);
 static DEFINE_SPINLOCK(sb_lock);
@@ -574,6 +575,28 @@ void drop_super_exclusive(struct super_block *sb)
 }
 EXPORT_SYMBOL(drop_super_exclusive);
 
+static void __iterate_supers(void (*f)(struct super_block *))
+{
+       struct super_block *sb, *p = NULL;
+
+       spin_lock(&sb_lock);
+       list_for_each_entry(sb, &super_blocks, s_list) {
+               if (hlist_unhashed(&sb->s_instances))
+                       continue;
+               sb->s_count++;
+               spin_unlock(&sb_lock);
+
+               f(sb);
+
+               spin_lock(&sb_lock);
+               if (p)
+                       __put_super(p);
+               p = sb;
+       }
+       if (p)
+               __put_super(p);
+       spin_unlock(&sb_lock);
+}
 /**
  *     iterate_supers - call function for all active superblocks
  *     @f: function to call
@@ -881,33 +904,22 @@ cancel_readonly:
        return retval;
 }
 
-static void do_emergency_remount(struct work_struct *work)
+static void do_emergency_remount_callback(struct super_block *sb)
 {
-       struct super_block *sb, *p = NULL;
-
-       spin_lock(&sb_lock);
-       list_for_each_entry(sb, &super_blocks, s_list) {
-               if (hlist_unhashed(&sb->s_instances))
-                       continue;
-               sb->s_count++;
-               spin_unlock(&sb_lock);
-               down_write(&sb->s_umount);
-               if (sb->s_root && sb->s_bdev && (sb->s_flags & SB_BORN) &&
-                   !sb_rdonly(sb)) {
-                       /*
-                        * What lock protects sb->s_flags??
-                        */
-                       do_remount_sb(sb, SB_RDONLY, NULL, 1);
-               }
-               up_write(&sb->s_umount);
-               spin_lock(&sb_lock);
-               if (p)
-                       __put_super(p);
-               p = sb;
+       down_write(&sb->s_umount);
+       if (sb->s_root && sb->s_bdev && (sb->s_flags & SB_BORN) &&
+           !sb_rdonly(sb)) {
+               /*
+                * What lock protects sb->s_flags??
+                */
+               do_remount_sb(sb, SB_RDONLY, NULL, 1);
        }
-       if (p)
-               __put_super(p);
-       spin_unlock(&sb_lock);
+       up_write(&sb->s_umount);
+}
+
+static void do_emergency_remount(struct work_struct *work)
+{
+       __iterate_supers(do_emergency_remount_callback);
        kfree(work);
        printk("Emergency Remount complete\n");
 }
@@ -923,6 +935,40 @@ void emergency_remount(void)
        }
 }
 
+static void do_thaw_all_callback(struct super_block *sb)
+{
+       down_write(&sb->s_umount);
+       if (sb->s_root && sb->s_flags & MS_BORN) {
+               emergency_thaw_bdev(sb);
+               thaw_super_locked(sb);
+       } else {
+               up_write(&sb->s_umount);
+       }
+}
+
+static void do_thaw_all(struct work_struct *work)
+{
+       __iterate_supers(do_thaw_all_callback);
+       kfree(work);
+       printk(KERN_WARNING "Emergency Thaw complete\n");
+}
+
+/**
+ * emergency_thaw_all -- forcibly thaw every frozen filesystem
+ *
+ * Used for emergency unfreeze of all filesystems via SysRq
+ */
+void emergency_thaw_all(void)
+{
+       struct work_struct *work;
+
+       work = kmalloc(sizeof(*work), GFP_ATOMIC);
+       if (work) {
+               INIT_WORK(work, do_thaw_all);
+               schedule_work(work);
+       }
+}
+
 /*
  * Unnamed block devices are dummy devices used by virtual
  * filesystems which don't use real block-devices.  -- jrs
@@ -1492,11 +1538,10 @@ EXPORT_SYMBOL(freeze_super);
  *
  * Unlocks the filesystem and marks it writeable again after freeze_super().
  */
-int thaw_super(struct super_block *sb)
+static int thaw_super_locked(struct super_block *sb)
 {
        int error;
 
-       down_write(&sb->s_umount);
        if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) {
                up_write(&sb->s_umount);
                return -EINVAL;
@@ -1527,4 +1572,10 @@ out:
        deactivate_locked_super(sb);
        return 0;
 }
+
+int thaw_super(struct super_block *sb)
+{
+       down_write(&sb->s_umount);
+       return thaw_super_locked(sb);
+}
 EXPORT_SYMBOL(thaw_super);