drm/i915/gt: Drop i915_address_space::file (v2)

There's a big comment saying how useful it is but no one is using this
for anything anymore.

It was added in 2bfa996e ("drm/i915: Store owning file on the
i915_address_space") and used for debugfs at the time as well as telling
the difference between the global GTT and a PPGTT.  In f6e8aa38
("drm/i915: Report the number of closed vma held by each context in
debugfs") we removed one use of it by switching to a context walk and
comparing with the VM in the context.  Finally, VM stats for debugfs
were entirely nuked in db80a129 ("drm/i915/gem: Remove per-client
stats from debugfs/i915_gem_objects")

v2 (Daniel Vetter):
 - Delete a struct drm_i915_file_private pre-declaration
 - Add a comment to the commit message about history
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210708154835.528166-24-jason@jlekstrand.net

drivers/gpu/drm/i915/gem/i915_gem_context.c

@@ -1453,17 +1453,10 @@ static int gem_context_register(struct i915_gem_context *ctx,
 				u32 *id)
 {
 	struct drm_i915_private *i915 = ctx->i915;
-	struct i915_address_space *vm;
 	int ret;
 
 	ctx->file_priv = fpriv;
 
-	mutex_lock(&ctx->mutex);
-	vm = i915_gem_context_vm(ctx);
-	if (vm)
-		WRITE_ONCE(vm->file, fpriv); /* XXX */
-	mutex_unlock(&ctx->mutex);
-
 	ctx->pid = get_task_pid(current, PIDTYPE_PID);
 	snprintf(ctx->name, sizeof(ctx->name), "%s[%d]",
 		 current->comm, pid_nr(ctx->pid));
@@ -1562,8 +1555,6 @@ int i915_gem_vm_create_ioctl(struct drm_device *dev, void *data,
 	if (IS_ERR(ppgtt))
 		return PTR_ERR(ppgtt);
 
-	ppgtt->vm.file = file_priv;
-
 	if (args->extensions) {
 		err = i915_user_extensions(u64_to_user_ptr(args->extensions),
 					   NULL, 0,

drivers/gpu/drm/i915/gt/intel_gtt.h

@@ -140,7 +140,6 @@ typedef u64 gen8_pte_t;
 
 enum i915_cache_level;
 
-struct drm_i915_file_private;
 struct drm_i915_gem_object;
 struct i915_fence_reg;
 struct i915_vma;
@@ -220,16 +219,6 @@ struct i915_address_space {
 	struct intel_gt *gt;
 	struct drm_i915_private *i915;
 	struct device *dma;
-	/*
-	 * Every address space belongs to a struct file - except for the global
-	 * GTT that is owned by the driver (and so @file is set to NULL). In
-	 * principle, no information should leak from one context to another
-	 * (or between files/processes etc) unless explicitly shared by the
-	 * owner. Tracking the owner is important in order to free up per-file
-	 * objects along with the file, to aide resource tracking, and to
-	 * assign blame.
-	 */
-	struct drm_i915_file_private *file;
 	u64 total;		/* size addr space maps (ex. 2GB for ggtt) */
 	u64 reserved;		/* size addr space reserved */
 

drivers/gpu/drm/i915/selftests/mock_gtt.c

@@ -73,7 +73,6 @@ struct i915_ppgtt *mock_ppgtt(struct drm_i915_private *i915, const char *name)
 	ppgtt->vm.gt = &i915->gt;
 	ppgtt->vm.i915 = i915;
 	ppgtt->vm.total = round_down(U64_MAX, PAGE_SIZE);
-	ppgtt->vm.file = ERR_PTR(-ENODEV);
 	ppgtt->vm.dma = i915->drm.dev;
 
 	i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT);