[PATCH 4/5] xfs: simplify the fallocate path

[Mark Tinguely]

On 12/08/12 06:08, Christoph Hellwig wrote:
> Call xfs_alloc_file_space or xfs_free_file_space directly from
> xfs_file_fallocate instead of going through xfs_change_file_space.
>
> This simplified the code by removing the unessecary marshalling of the
> arguments into an xfs_flock64_t structure and allows removing checks that
> are already done in the VFS code.
>
> Signed-off-by: Christoph Hellwig<hch at lst.de>
>
> ---
>   fs/xfs/xfs_file.c     |   81 ++++++++++++++++++++++++++++++++------------------
>   fs/xfs/xfs_vnodeops.c |   39 ++----------------------
>   fs/xfs/xfs_vnodeops.h |    3 +
>   3 files changed, 60 insertions(+), 63 deletions(-)

patched code looks like:


STATIC long
xfs_file_fallocate(
	struct file		*file,
	int			mode,
	loff_t			offset,
	loff_t			len)
{
	struct inode		*inode = file->f_path.dentry->d_inode;
	struct xfs_inode	*ip = XFS_I(inode);
	struct xfs_trans	*tp;
	bool			setprealloc = false;
	long			error;
	loff_t			new_size = 0;

	if (!S_ISREG(inode->i_mode))
		return -EINVAL;

	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
		return -EOPNOTSUPP;

	xfs_ilock(ip, XFS_IOLOCK_EXCL);
	if (mode & FALLOC_FL_PUNCH_HOLE) {
		error = xfs_free_file_space(ip, offset, len);
		if (error)
			goto out_unlock;
	} else {
            ^^^^^^^^^   vvvvvvvvvvvvvvvv
		if (!(mode & FALLOC_FL_KEEP_SIZE) &&
		    offset + len > i_size_read(inode)) {
			new_size = offset + len;
			error = -inode_newsize_ok(inode, new_size);
			if (error)
				goto out_unlock;
		}

Since there is only the FALLOC_FL_KEEP_SIZE or FALLOC_FL_PUNCH_HOLE
bit set and the if statement makes them mutually exclusive, the block
highlighted should be for the FALLOC_FL_KEEP_SIZE and shouldn't the
comparison would never be true here? Shouldn't it be for the
FALLOC_FL_PUNCH_HOLE block?

--Mark.