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Diffstat (limited to 'fs/super.c')
-rw-r--r--fs/super.c81
1 files changed, 60 insertions, 21 deletions
diff --git a/fs/super.c b/fs/super.c
index c183835566c1..1709ed029a2c 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -244,7 +244,6 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
mutex_init(&s->s_vfs_rename_mutex);
lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
mutex_init(&s->s_dquot.dqio_mutex);
- mutex_init(&s->s_dquot.dqonoff_mutex);
s->s_maxbytes = MAX_NON_LFS;
s->s_op = &default_op;
s->s_time_gran = 1000000000;
@@ -558,6 +557,13 @@ void drop_super(struct super_block *sb)
EXPORT_SYMBOL(drop_super);
+void drop_super_exclusive(struct super_block *sb)
+{
+ up_write(&sb->s_umount);
+ put_super(sb);
+}
+EXPORT_SYMBOL(drop_super_exclusive);
+
/**
* iterate_supers - call function for all active superblocks
* @f: function to call
@@ -628,15 +634,7 @@ void iterate_supers_type(struct file_system_type *type,
EXPORT_SYMBOL(iterate_supers_type);
-/**
- * get_super - get the superblock of a device
- * @bdev: device to get the superblock for
- *
- * Scans the superblock list and finds the superblock of the file system
- * mounted on the device given. %NULL is returned if no match is found.
- */
-
-struct super_block *get_super(struct block_device *bdev)
+static struct super_block *__get_super(struct block_device *bdev, bool excl)
{
struct super_block *sb;
@@ -651,11 +649,17 @@ rescan:
if (sb->s_bdev == bdev) {
sb->s_count++;
spin_unlock(&sb_lock);
- down_read(&sb->s_umount);
+ if (!excl)
+ down_read(&sb->s_umount);
+ else
+ down_write(&sb->s_umount);
/* still alive? */
if (sb->s_root && (sb->s_flags & MS_BORN))
return sb;
- up_read(&sb->s_umount);
+ if (!excl)
+ up_read(&sb->s_umount);
+ else
+ up_write(&sb->s_umount);
/* nope, got unmounted */
spin_lock(&sb_lock);
__put_super(sb);
@@ -666,32 +670,67 @@ rescan:
return NULL;
}
-EXPORT_SYMBOL(get_super);
-
/**
- * get_super_thawed - get thawed superblock of a device
+ * get_super - get the superblock of a device
* @bdev: device to get the superblock for
*
* Scans the superblock list and finds the superblock of the file system
- * mounted on the device. The superblock is returned once it is thawed
- * (or immediately if it was not frozen). %NULL is returned if no match
- * is found.
+ * mounted on the device given. %NULL is returned if no match is found.
*/
-struct super_block *get_super_thawed(struct block_device *bdev)
+struct super_block *get_super(struct block_device *bdev)
+{
+ return __get_super(bdev, false);
+}
+EXPORT_SYMBOL(get_super);
+
+static struct super_block *__get_super_thawed(struct block_device *bdev,
+ bool excl)
{
while (1) {
- struct super_block *s = get_super(bdev);
+ struct super_block *s = __get_super(bdev, excl);
if (!s || s->s_writers.frozen == SB_UNFROZEN)
return s;
- up_read(&s->s_umount);
+ if (!excl)
+ up_read(&s->s_umount);
+ else
+ up_write(&s->s_umount);
wait_event(s->s_writers.wait_unfrozen,
s->s_writers.frozen == SB_UNFROZEN);
put_super(s);
}
}
+
+/**
+ * get_super_thawed - get thawed superblock of a device
+ * @bdev: device to get the superblock for
+ *
+ * Scans the superblock list and finds the superblock of the file system
+ * mounted on the device. The superblock is returned once it is thawed
+ * (or immediately if it was not frozen). %NULL is returned if no match
+ * is found.
+ */
+struct super_block *get_super_thawed(struct block_device *bdev)
+{
+ return __get_super_thawed(bdev, false);
+}
EXPORT_SYMBOL(get_super_thawed);
/**
+ * get_super_exclusive_thawed - get thawed superblock of a device
+ * @bdev: device to get the superblock for
+ *
+ * Scans the superblock list and finds the superblock of the file system
+ * mounted on the device. The superblock is returned once it is thawed
+ * (or immediately if it was not frozen) and s_umount semaphore is held
+ * in exclusive mode. %NULL is returned if no match is found.
+ */
+struct super_block *get_super_exclusive_thawed(struct block_device *bdev)
+{
+ return __get_super_thawed(bdev, true);
+}
+EXPORT_SYMBOL(get_super_exclusive_thawed);
+
+/**
* get_active_super - get an active reference to the superblock of a device
* @bdev: device to get the superblock for
*