Re: [PATCH v6 08/16] ntfs: update file operations

[Christoph Hellwig <hch@lst.de>]

Suggested commit message:

Rewrite the file operations to utilize the iomap infrastructure,
replacing the legacy buffer-head based implementation.

Implement ntfs_setattr() with size change handling, uid/gid/mode.

Add support for Direct I/O.

Add support for fallocate with the FALLOC_FL_KEEP_SIZE,
FALLOC_FL_PUNCH_HOLE, FALLOC_FL_COLLAPSE_RANGE, FALLOC_FL_INSERT_RANGE
and FALLOC_FL_ALLOCATE_RANGE modes.

Implement .llseek with SEEK_DATA / SEEK_HOLE support.

Implement ntfs_fiemap() using iomap_fiemap().

Add FS_IOC_SHUTDOWN, FS_IOC_[GS]ETFSLABEL, FITRIM ioctl support.

>  static int ntfs_file_open(struct inode *vi, struct file *filp)
>  {
> +	struct ntfs_inode *ni = NTFS_I(vi);
> +
> +	if (NVolShutdown(ni->vol))
> +		return -EIO;
> +
>  	if (sizeof(unsigned long) < 8) {
>  		if (i_size_read(vi) > MAX_LFS_FILESIZE)
>  			return -EOVERFLOW;
>  	}
> +	if (filp->f_flags & O_TRUNC && NInoNonResident(ni)) {
> +		int err;
>  
> +		mutex_lock(&ni->mrec_lock);
> +		down_read(&ni->runlist.lock);
> +		if (!ni->runlist.rl) {
> +			err = ntfs_attr_map_whole_runlist(ni);
> +			if (err) {
> +				up_read(&ni->runlist.lock);
> +				mutex_unlock(&ni->mrec_lock);
> +				return err;
> +			}
>  		}
> +		ni->lcn_seek_trunc = ni->runlist.rl->lcn;
> +		up_read(&ni->runlist.lock);
> +		mutex_unlock(&ni->mrec_lock);
>  	}

Do you ever hits this?  O_TRUNC should call into ->setattr to do
the truncation long before calling into ->open.

> +
> +	filp->f_mode |= FMODE_NOWAIT;

This should also set FMODE_CAN_ODIRECT instead of setting the noop
direct I/O method.

> +static int ntfs_file_release(struct inode *vi, struct file *filp)
>  {
> +	struct ntfs_inode *ni = NTFS_I(vi);
> +	struct ntfs_volume *vol = ni->vol;
> +	s64 aligned_data_size = round_up(ni->data_size, vol->cluster_size);
> +
> +	if (NInoCompressed(ni))
> +		return 0;
> +
> +	inode_lock(vi);
> +	mutex_lock(&ni->mrec_lock);
> +	down_write(&ni->runlist.lock);
> +	if (aligned_data_size < ni->allocated_size) {

Splitting the compresse handling into a helper would really help
the code maintainability here.  Also please add a comment why
this does work on final release, which is highly unusual.  And
even more unusual then doing it in ->flush which is called for
every close.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>