[XFS] remove permission check from xfs_change_file_space

Both callers of xfs_change_file_space alreaedy do the file->f_mode &
FMODE_WRITE check to ensure we have a file descriptor that has been opened
for write mode, so there is no need to re-check that with xfs_iaccess.
Especially as the later might wrongly deny it for corner cases like file
descriptor passing through unix domain sockets.

SGI-PV: 971186
SGI-Modid: xfs-linux-melb:xfs-kern:30365a
Signed-off-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

fs/xfs/xfs_vnodeops.c

@@ -4317,21 +4317,9 @@ xfs_change_file_space(
 
 	xfs_itrace_entry(ip);
 
-	/*
-	 * must be a regular file and have write permission
-	 */
 	if (!S_ISREG(ip->i_d.di_mode))
 		return XFS_ERROR(EINVAL);
 
-	xfs_ilock(ip, XFS_ILOCK_SHARED);
-
-	if ((error = xfs_iaccess(ip, S_IWUSR, credp))) {
-		xfs_iunlock(ip, XFS_ILOCK_SHARED);
-		return error;
-	}
-
-	xfs_iunlock(ip, XFS_ILOCK_SHARED);
-
 	switch (bf->l_whence) {
 	case 0: /*SEEK_SET*/
 		break;