• Ye Bin's avatar
    xfs: fix BUG_ON in xfs_getbmap() · 8ee81ed5
    Ye Bin authored
    There's issue as follows:
    XFS: Assertion failed: (bmv->bmv_iflags & BMV_IF_DELALLOC) != 0, file: fs/xfs/xfs_bmap_util.c, line: 329
    ------------[ cut here ]------------
    kernel BUG at fs/xfs/xfs_message.c:102!
    invalid opcode: 0000 [#1] PREEMPT SMP KASAN
    CPU: 1 PID: 14612 Comm: xfs_io Not tainted 6.3.0-rc2-next-20230315-00006-g2729d23ddb3b-dirty #422
    RIP: 0010:assfail+0x96/0xa0
    RSP: 0018:ffffc9000fa178c0 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff888179a18000
    RDX: 0000000000000000 RSI: ffff888179a18000 RDI: 0000000000000002
    RBP: 0000000000000000 R08: ffffffff8321aab6 R09: 0000000000000000
    R10: 0000000000000001 R11: ffffed1105f85139 R12: ffffffff8aacc4c0
    R13: 0000000000000149 R14: ffff888269f58000 R15: 000000000000000c
    FS:  00007f42f27a4740(0000) GS:ffff88882fc00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000000b92388 CR3: 000000024f006000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     <TASK>
     xfs_getbmap+0x1a5b/0x1e40
     xfs_ioc_getbmap+0x1fd/0x5b0
     xfs_file_ioctl+0x2cb/0x1d50
     __x64_sys_ioctl+0x197/0x210
     do_syscall_64+0x39/0xb0
     entry_SYSCALL_64_after_hwframe+0x63/0xcd
    
    Above issue may happen as follows:
             ThreadA                       ThreadB
    do_shared_fault
     __do_fault
      xfs_filemap_fault
       __xfs_filemap_fault
        filemap_fault
                                 xfs_ioc_getbmap -> Without BMV_IF_DELALLOC flag
    			      xfs_getbmap
    			       xfs_ilock(ip, XFS_IOLOCK_SHARED);
    			       filemap_write_and_wait
     do_page_mkwrite
      xfs_filemap_page_mkwrite
       __xfs_filemap_fault
        xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
        iomap_page_mkwrite
         ...
         xfs_buffered_write_iomap_begin
          xfs_bmapi_reserve_delalloc -> Allocate delay extent
                                  xfs_ilock_data_map_shared(ip)
    	                      xfs_getbmap_report_one
    			       ASSERT((bmv->bmv_iflags & BMV_IF_DELALLOC) != 0)
    	                        -> trigger BUG_ON
    
    As xfs_filemap_page_mkwrite() only hold XFS_MMAPLOCK_SHARED lock, there's
    small window mkwrite can produce delay extent after file write in xfs_getbmap().
    To solve above issue, just skip delalloc extents.
    Signed-off-by: default avatarYe Bin <yebin10@huawei.com>
    Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
    Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
    Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
    8ee81ed5
xfs_bmap_util.c 48.3 KB