diff options
Diffstat (limited to 'fs/efivarfs/super.c')
| -rw-r--r-- | fs/efivarfs/super.c | 52 |
1 files changed, 49 insertions, 3 deletions
diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c index 6eae8cf655c1..0486e9b68bc6 100644 --- a/fs/efivarfs/super.c +++ b/fs/efivarfs/super.c @@ -421,7 +421,7 @@ static bool efivarfs_actor(struct dir_context *ctx, const char *name, int len, if (err) size = 0; - inode_lock(inode); + inode_lock_nested(inode, I_MUTEX_CHILD); i_size_write(inode, size); inode_unlock(inode); @@ -474,12 +474,25 @@ static int efivarfs_check_missing(efi_char16_t *name16, efi_guid_t vendor, return err; } +static void efivarfs_deactivate_super_work(struct work_struct *work) +{ + struct super_block *s = container_of(work, struct super_block, + destroy_work); + /* + * note: here s->destroy_work is free for reuse (which + * will happen in deactivate_super) + */ + deactivate_super(s); +} + +static struct file_system_type efivarfs_type; + static int efivarfs_pm_notify(struct notifier_block *nb, unsigned long action, void *ptr) { struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info, pm_nb); - struct path path = { .mnt = NULL, .dentry = sfi->sb->s_root, }; + struct path path; struct efivarfs_ctx ectx = { .ctx = { .actor = efivarfs_actor, @@ -487,6 +500,7 @@ static int efivarfs_pm_notify(struct notifier_block *nb, unsigned long action, .sb = sfi->sb, }; struct file *file; + struct super_block *s = sfi->sb; static bool rescan_done = true; if (action == PM_HIBERNATION_PREPARE) { @@ -499,11 +513,43 @@ static int efivarfs_pm_notify(struct notifier_block *nb, unsigned long action, if (rescan_done) return NOTIFY_DONE; + /* ensure single superblock is alive and pin it */ + if (!atomic_inc_not_zero(&s->s_active)) + return NOTIFY_DONE; + pr_info("efivarfs: resyncing variable state\n"); - /* O_NOATIME is required to prevent oops on NULL mnt */ + path.dentry = sfi->sb->s_root; + + /* + * do not add SB_KERNMOUNT which a single superblock could + * expose to userspace and which also causes MNT_INTERNAL, see + * below + */ + path.mnt = vfs_kern_mount(&efivarfs_type, 0, + efivarfs_type.name, NULL); + if (IS_ERR(path.mnt)) { + pr_err("efivarfs: internal mount failed\n"); + /* + * We may be the last pinner of the superblock but + * calling efivarfs_kill_sb from within the notifier + * here would deadlock trying to unregister it + */ + INIT_WORK(&s->destroy_work, efivarfs_deactivate_super_work); + schedule_work(&s->destroy_work); + return PTR_ERR(path.mnt); + } + + /* path.mnt now has pin on superblock, so this must be above one */ + atomic_dec(&s->s_active); + file = kernel_file_open(&path, O_RDONLY | O_DIRECTORY | O_NOATIME, current_cred()); + /* + * safe even if last put because no MNT_INTERNAL means this + * will do delayed deactivate_super and not deadlock + */ + mntput(path.mnt); if (IS_ERR(file)) return NOTIFY_DONE; |