cleanup-pagecache-before-swap-i_data

   1 ext4: cleanup pagecache before swap i_data
   2
   3 From: yangerkun <yangerkun@huawei.com>
   4
   5 While do swap, we should make sure there has no new dirty page since we
   6 should swap i_data between two inode:
   7 1.We should lock i_mmap_sem with write to avoid new pagecache from mmap
   8 read/write;
   9 2.Change filemap_flush to filemap_write_and_wait and move them to the
  10 space protected by inode lock to avoid new pagecache from buffer read/write.
  11
  12 Signed-off-by: yangerkun <yangerkun@huawei.com>
  13 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  14 Cc: stable@kernel.org
  15 ---
  16  fs/ext4/ioctl.c | 16 ++++++++++++----
  17  1 file changed, 12 insertions(+), 4 deletions(-)
  18
  19 diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
  20 index 597e8b6..ea05e8d 100644
  21 --- a/fs/ext4/ioctl.c
  22 +++ b/fs/ext4/ioctl.c
  23 @@ -121,9 +121,6 @@ static long swap_inode_boot_loader(struct super_block *sb,
  24                 return PTR_ERR(inode_bl);
  25         ei_bl = EXT4_I(inode_bl);
  26
  27 -       filemap_flush(inode->i_mapping);
  28 -       filemap_flush(inode_bl->i_mapping);
  29 -
  30         /* Protect orig inodes against a truncate and make sure,
  31          * that only 1 swap_inode_boot_loader is running. */
  32         lock_two_nondirectories(inode, inode_bl);
  33 @@ -141,6 +138,15 @@ static long swap_inode_boot_loader(struct super_block *sb,
  34                 goto journal_err_out;
  35         }
  36
  37 +       down_write(&EXT4_I(inode)->i_mmap_sem);
  38 +       err = filemap_write_and_wait(inode->i_mapping);
  39 +       if (err)
  40 +               goto err_out;
  41 +
  42 +       err = filemap_write_and_wait(inode_bl->i_mapping);
  43 +       if (err)
  44 +               goto err_out;
  45 +
  46         /* Wait for all existing dio workers */
  47         inode_dio_wait(inode);
  48         inode_dio_wait(inode_bl);
  49 @@ -151,7 +157,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
  50         handle = ext4_journal_start(inode_bl, EXT4_HT_MOVE_EXTENTS, 2);
  51         if (IS_ERR(handle)) {
  52                 err = -EINVAL;
  53 -               goto journal_err_out;
  54 +               goto err_out;
  55         }
  56
  57         /* Protect extent tree against block allocations via delalloc */
  58 @@ -208,6 +214,8 @@ static long swap_inode_boot_loader(struct super_block *sb,
  59         ext4_journal_stop(handle);
  60         ext4_double_up_write_data_sem(inode, inode_bl);
  61
  62 +err_out:
  63 +       up_write(&EXT4_I(inode)->i_mmap_sem);
  64  journal_err_out:
  65         unlock_two_nondirectories(inode, inode_bl);
  66         iput(inode_bl);
  67 --
  68 2.9.5
  69
  70