ext4: cleanup pagecache before swap i_data

While do swap, we should make sure there has no new dirty page since we
should swap i_data between two inode:
1.We should lock i_mmap_sem with write to avoid new pagecache from mmap
read/write;
2.Change filemap_flush to filemap_write_and_wait and move them to the
space protected by inode lock to avoid new pagecache from buffer read/write.

Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 597e8b617f92f32e40331c12e0ad19adbb81e0ef..ea05e8d641e90c41958d44e38a5b32d2c92bfbb9 100644 (file)
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -121,9 +121,6 @@ static long swap_inode_boot_loader(struct super_block *sb,
                return PTR_ERR(inode_bl);
        ei_bl = EXT4_I(inode_bl);
 
-       filemap_flush(inode->i_mapping);
-       filemap_flush(inode_bl->i_mapping);
-
        /* Protect orig inodes against a truncate and make sure,
         * that only 1 swap_inode_boot_loader is running. */
        lock_two_nondirectories(inode, inode_bl);
@@ -141,6 +138,15 @@ static long swap_inode_boot_loader(struct super_block *sb,
                goto journal_err_out;
        }
 
+       down_write(&EXT4_I(inode)->i_mmap_sem);
+       err = filemap_write_and_wait(inode->i_mapping);
+       if (err)
+               goto err_out;
+
+       err = filemap_write_and_wait(inode_bl->i_mapping);
+       if (err)
+               goto err_out;
+
        /* Wait for all existing dio workers */
        inode_dio_wait(inode);
        inode_dio_wait(inode_bl);
@@ -151,7 +157,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
        handle = ext4_journal_start(inode_bl, EXT4_HT_MOVE_EXTENTS, 2);
        if (IS_ERR(handle)) {
                err = -EINVAL;
-               goto journal_err_out;
+               goto err_out;
        }
 
        /* Protect extent tree against block allocations via delalloc */
@@ -208,6 +214,8 @@ static long swap_inode_boot_loader(struct super_block *sb,
        ext4_journal_stop(handle);
        ext4_double_up_write_data_sem(inode, inode_bl);
 
+err_out:
+       up_write(&EXT4_I(inode)->i_mmap_sem);
 journal_err_out:
        unlock_two_nondirectories(inode, inode_bl);
        iput(inode_bl);