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authorLinus Torvalds <torvalds@linux-foundation.org>2018-04-12 22:28:32 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-12 22:28:32 +0300
commit7214dd4ea9048d2031e14fc552980cecd6573a9e (patch)
tree18c9ba52d252d29fcfe7d73d9c78205b285f91d0 /fs/super.c
parent19e8a2f875a56009c0ce30389964aca452a85510 (diff)
parent08fdc8a0138afaf324296a342f32ad26ec465e43 (diff)
downloadlinux-7214dd4ea9048d2031e14fc552980cecd6573a9e.tar.xz
Merge branch 'work.thaw' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs thaw updates from Al Viro: "An ancient series that has fallen through the cracks in the previous cycle" * 'work.thaw' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: buffer.c: call thaw_super during emergency thaw vfs: factor sb iteration out of do_emergency_remount
Diffstat (limited to 'fs/super.c')
-rw-r--r--fs/super.c105
1 files changed, 78 insertions, 27 deletions
diff --git a/fs/super.c b/fs/super.c
index 672538ca9831..5fa9a8d8d865 100644
--- 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);