[1/3] 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>
---
 fs/ext4/extents.c |    2 ++
 fs/ext4/migrate.c |    7 +++++++
 2 files changed, 9 insertions(+), 0 deletions(-)

On Mon 21-07-14 19:04:47, Dmitry Monakhov wrote:
> 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>
  Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/ext4/extents.c |    2 ++
>  fs/ext4/migrate.c |    7 +++++++
>  2 files changed, 9 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index b30172d..ee93f82 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 ec09243..d3567f2 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);
> -- 
> 1.7.1
> 
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On Mon, Jul 21, 2014 at 09:35:10PM +0200, Jan Kara wrote:
> On Mon 21-07-14 19:04:47, Dmitry Monakhov wrote:
> > 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>
>   Looks good. You can add:
> Reviewed-by: Jan Kara <jack@suse.cz>

Thanks, applied.

						- Ted
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