ext4: block direct I/O writes during ext4_truncate

Just as in ext4_punch_hole() it is important that we block DIO writes
while the truncate is proceeding, since during the overwriting DIO
write, we drop i_mutex, which means a truncate could start while the
Direct I/O operation is still in progress.

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

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 98b9bff92a8a2d0d42f290d21d5cd4000b6bdae8..3c5edf29e2ae8124dc0ccaf1319c116d025e7af2 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3659,12 +3659,16 @@ void ext4_truncate(struct inode *inode)
        if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
                ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
 
+       /* Wait all existing dio workers, newcomers will block on i_mutex */
+       ext4_inode_block_unlocked_dio(inode);
+       inode_dio_wait(inode);
+
        if (ext4_has_inline_data(inode)) {
                int has_inline = 1;
 
                ext4_inline_data_truncate(inode, &has_inline);
                if (has_inline)
-                       return;
+                       goto out_resume;
        }
 
        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
@@ -3675,7 +3679,7 @@ void ext4_truncate(struct inode *inode)
        handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
        if (IS_ERR(handle)) {
                ext4_std_error(inode->i_sb, PTR_ERR(handle));
-               return;
+               goto out_resume;
        }
 
        if (inode->i_size & (inode->i_sb->s_blocksize - 1))
@@ -3722,6 +3726,8 @@ out_stop:
        ext4_mark_inode_dirty(handle, inode);
        ext4_journal_stop(handle);
 
+out_resume:
+       ext4_inode_resume_unlocked_dio(inode);
        trace_ext4_truncate_exit(inode);
 }