ext4: add i_data_sem sanity check

Each caller of ext4_ext_dirty must hold i_data_sem,
The only exception is migration code, let's make it convenient.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

2 files changed, 9 insertions, 0 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index b30172dd55eb..ee93f82630c6 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -161,6 +161,8 @@ int __ext4_ext_dirty(const char *where, unsigned int line, handle_t *handle,
                      struct inode *inode, struct ext4_ext_path *path)
 {
         int err;
+
+        WARN_ON(!rwsem_is_locked(&EXT4_I(inode)->i_data_sem));
         if (path->p_bh) {
                 ext4_extent_block_csum_set(inode, ext_block_hdr(path->p_bh));
                 /* path points to block */
diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index ec092437d3e0..d3567f27bae7 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -39,6 +39,8 @@ static int finish_range(handle_t *handle, struct inode *inode,
         newext.ee_block = cpu_to_le32(lb->first_block);
         newext.ee_len   = cpu_to_le16(lb->last_block - lb->first_block + 1);
         ext4_ext_store_pblock(&newext, lb->first_pblock);
+        /* Locking only for convinience since we are operating on temp inode */
+        down_write(&EXT4_I(inode)->i_data_sem);
         path = ext4_ext_find_extent(inode, lb->first_block, NULL, 0);
 
         if (IS_ERR(path)) {
@@ -61,7 +63,9 @@ static int finish_range(handle_t *handle, struct inode *inode,
          */
         if (needed && ext4_handle_has_enough_credits(handle,
                                                 EXT4_RESERVE_TRANS_BLOCKS)) {
+                up_write((&EXT4_I(inode)->i_data_sem));
                 retval = ext4_journal_restart(handle, needed);
+                down_write((&EXT4_I(inode)->i_data_sem));
                 if (retval)
                         goto err_out;
         } else if (needed) {
@@ -70,13 +74,16 @@ static int finish_range(handle_t *handle, struct inode *inode,
                         /*
                          * IF not able to extend the journal restart the journal
                          */
+                        up_write((&EXT4_I(inode)->i_data_sem));
                         retval = ext4_journal_restart(handle, needed);
+                        down_write((&EXT4_I(inode)->i_data_sem));
                         if (retval)
                                 goto err_out;
                 }
         }
         retval = ext4_ext_insert_extent(handle, inode, path, &newext, 0);
 err_out:
+        up_write((&EXT4_I(inode)->i_data_sem));
         if (path) {
                 ext4_ext_drop_refs(path);
                 kfree(path);