grab-missed-write_count-for-EXT4_IOC_SWAP_BOOT

   1 ext4: grab missed write_count for EXT4_IOC_SWAP_BOOT
   2
   3 From: Dmitry Monakhov <dmonakhov@openvz.org>
   4
   5 Otherwise this provokes complain like follows:
   6 WARNING: CPU: 12 PID: 5795 at fs/ext4/ext4_jbd2.c:48 ext4_journal_check_start+0x4e/0xa0()
   7 Modules linked in: brd iTCO_wdt lpc_ich mfd_core igb ptp dm_mirror dm_region_hash dm_log dm_mod
   8 CPU: 12 PID: 5795 Comm: python Not tainted 3.17.0-rc2-00175-gae5344f #158
   9 Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.99.99.x028.061320111235 06/13/2011
  10  0000000000000030 ffff8808116cfd28 ffffffff815c7dfc 0000000000000030
  11  0000000000000000 ffff8808116cfd68 ffffffff8106ce8c ffff8808116cfdc8
  12  ffff880813b16000 ffff880806ad6ae8 ffffffff81202008 0000000000000000
  13 Call Trace:
  14  [<ffffffff815c7dfc>] dump_stack+0x51/0x6d
  15  [<ffffffff8106ce8c>] warn_slowpath_common+0x8c/0xc0
  16  [<ffffffff81202008>] ? ext4_ioctl+0x9e8/0xeb0
  17  [<ffffffff8106ceda>] warn_slowpath_null+0x1a/0x20
  18  [<ffffffff8122867e>] ext4_journal_check_start+0x4e/0xa0
  19  [<ffffffff81228c10>] __ext4_journal_start_sb+0x90/0x110
  20  [<ffffffff81202008>] ext4_ioctl+0x9e8/0xeb0
  21  [<ffffffff8107b0bd>] ? ptrace_stop+0x24d/0x2f0
  22  [<ffffffff81088530>] ? alloc_pid+0x480/0x480
  23  [<ffffffff8107b1f2>] ? ptrace_do_notify+0x92/0xb0
  24  [<ffffffff81186545>] do_vfs_ioctl+0x4e5/0x550
  25  [<ffffffff815cdbcb>] ? _raw_spin_unlock_irq+0x2b/0x40
  26  [<ffffffff81186603>] SyS_ioctl+0x53/0x80
  27  [<ffffffff815ce2ce>] tracesys+0xd0/0xd5
  28
  29 Reviewed-by: Jan Kara <jack@suse.cz>
  30 Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
  31 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  32 ---
  33  fs/ext4/ioctl.c |   10 +++++++++-
  34  1 files changed, 9 insertions(+), 1 deletions(-)
  35
  36 diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
  37 index 0f2252e..3d5de16 100644
  38 --- a/fs/ext4/ioctl.c
  39 +++ b/fs/ext4/ioctl.c
  40 @@ -532,9 +532,17 @@ group_add_out:
  41         }
  42
  43         case EXT4_IOC_SWAP_BOOT:
  44 +       {
  45 +               int err;
  46                 if (!(filp->f_mode & FMODE_WRITE))
  47                         return -EBADF;
  48 -               return swap_inode_boot_loader(sb, inode);
  49 +               err = mnt_want_write_file(filp);
  50 +               if (err)
  51 +                       return err;
  52 +               err = swap_inode_boot_loader(sb, inode);
  53 +               mnt_drop_write_file(filp);
  54 +               return err;
  55 +       }
  56
  57         case EXT4_IOC_RESIZE_FS: {
  58                 ext4_fsblk_t n_blocks_count;
  59 --
  60 1.7.1
  61
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