• Tahsin Erdogan's avatar
    ext4: do not set posix acls on xattr inodes · 1b917ed8
    Tahsin Erdogan authored
    We don't need acls on xattr inodes because they are not directly
    accessible from user mode.
    
    Besides lockdep complains about recursive locking of xattr_sem as seen
    below.
    
      =============================================
      [ INFO: possible recursive locking detected ]
      4.11.0-rc8+ #402 Not tainted
      ---------------------------------------------
      python/1894 is trying to acquire lock:
       (&ei->xattr_sem){++++..}, at: [<ffffffff804878a6>] ext4_xattr_get+0x66/0x270
    
      but task is already holding lock:
       (&ei->xattr_sem){++++..}, at: [<ffffffff80489500>] ext4_xattr_set_handle+0xa0/0x5d0
    
      other info that might help us debug this:
       Possible unsafe locking scenario:
    
             CPU0
             ----
        lock(&ei->xattr_sem);
        lock(&ei->xattr_sem);
    
       *** DEADLOCK ***
    
       May be due to missing lock nesting notation
    
      3 locks held by python/1894:
       #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff803d829f>] mnt_want_write+0x1f/0x50
       #1:  (&sb->s_type->i_mutex_key#15){+.+...}, at: [<ffffffff803dda27>] vfs_setxattr+0x57/0xb0
       #2:  (&ei->xattr_sem){++++..}, at: [<ffffffff80489500>] ext4_xattr_set_handle+0xa0/0x5d0
    
      stack backtrace:
      CPU: 0 PID: 1894 Comm: python Not tainted 4.11.0-rc8+ #402
      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
      Call Trace:
       dump_stack+0x67/0x99
       __lock_acquire+0x5f3/0x1830
       lock_acquire+0xb5/0x1d0
       down_read+0x2f/0x60
       ext4_xattr_get+0x66/0x270
       ext4_get_acl+0x43/0x1e0
       get_acl+0x72/0xf0
       posix_acl_create+0x5e/0x170
       ext4_init_acl+0x21/0xc0
       __ext4_new_inode+0xffd/0x16b0
       ext4_xattr_set_entry+0x5ea/0xb70
       ext4_xattr_block_set+0x1b5/0x970
       ext4_xattr_set_handle+0x351/0x5d0
       ext4_xattr_set+0x124/0x180
       ext4_xattr_user_set+0x34/0x40
       __vfs_setxattr+0x66/0x80
       __vfs_setxattr_noperm+0x69/0x1c0
       vfs_setxattr+0xa2/0xb0
       setxattr+0x129/0x160
       path_setxattr+0x87/0xb0
       SyS_setxattr+0xf/0x20
       entry_SYSCALL_64_fastpath+0x18/0xad
    Signed-off-by: default avatarTahsin Erdogan <tahsin@google.com>
    Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
    1b917ed8
migrate.c 17.1 KB