diff options
Diffstat (limited to 'fs/super.c')
| -rw-r--r-- | fs/super.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/super.c b/fs/super.c index 61dce001dd5..6ce501447ad 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); @@ -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); } |