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-rw-r--r--fs/super.c26
1 files changed, 22 insertions, 4 deletions
diff --git a/fs/super.c b/fs/super.c
index 645e540..6ce5014 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -82,7 +82,22 @@ static struct super_block *alloc_super(struct file_system_type *type)
* lock ordering than usbfs:
*/
lockdep_set_class(&s->s_lock, &type->s_lock_key);
- down_write(&s->s_umount);
+ /*
+ * sget() can have s_umount recursion.
+ *
+ * When it cannot find a suitable sb, it allocates a new
+ * one (this one), and tries again to find a suitable old
+ * one.
+ *
+ * In case that succeeds, it will acquire the s_umount
+ * lock of the old one. Since these are clearly distrinct
+ * locks, and this object isn't exposed yet, there's no
+ * risk of deadlocks.
+ *
+ * Annotate this by putting this lock in a different
+ * subclass.
+ */
+ down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
s->s_count = S_BIAS;
atomic_set(&s->s_active, 1);
mutex_init(&s->s_vfs_rename_mutex);
@@ -301,7 +316,7 @@ void generic_shutdown_super(struct super_block *sb)
/*
* wait for asynchronous fs operations to finish before going further
*/
- async_synchronize_full_special(&sb->s_async_list);
+ async_synchronize_full_domain(&sb->s_async_list);
/* bad name - it should be evict_inodes() */
invalidate_inodes(sb);
@@ -356,8 +371,10 @@ retry:
continue;
if (!grab_super(old))
goto retry;
- if (s)
+ if (s) {
+ up_write(&s->s_umount);
destroy_super(s);
+ }
return old;
}
}
@@ -372,6 +389,7 @@ retry:
err = set(s, data);
if (err) {
spin_unlock(&sb_lock);
+ up_write(&s->s_umount);
destroy_super(s);
return ERR_PTR(err);
}
@@ -470,7 +488,7 @@ restart:
sb->s_count++;
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
- async_synchronize_full_special(&sb->s_async_list);
+ async_synchronize_full_domain(&sb->s_async_list);
if (sb->s_root && (wait || sb->s_dirt))
sb->s_op->sync_fs(sb, wait);
up_read(&sb->s_umount);
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