From: Taotao Chen <chentaotao@didiglobal.com>

Replace the write_begin/write_end loop in
i915_gem_object_create_shmem_from_data() with call to kernel_write().

This function initializes shmem-backed GEM objects. kernel_write()
simplifies the code by removing manual folio handling.

Part of a series refactoring address_space_operations write_begin and
write_end callbacks to use struct kiocb for passing write context and
flags.

Signed-off-by: Taotao Chen <chentaotao@didiglobal.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 31 ++++++-----------------
 1 file changed, 8 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 19a3eb82dc6a..d08ade934d15 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -637,8 +637,7 @@ i915_gem_object_create_shmem_from_data(struct drm_i915_private *i915,
 {
 	struct drm_i915_gem_object *obj;
 	struct file *file;
-	const struct address_space_operations *aops;
-	loff_t pos;
+	loff_t pos = 0;
 	int err;
 
 	GEM_WARN_ON(IS_DGFX(i915));
@@ -649,29 +648,15 @@ i915_gem_object_create_shmem_from_data(struct drm_i915_private *i915,
 	GEM_BUG_ON(obj->write_domain != I915_GEM_DOMAIN_CPU);
 
 	file = obj->base.filp;
-	aops = file->f_mapping->a_ops;
-	pos = 0;
-	do {
-		unsigned int len = min_t(typeof(size), size, PAGE_SIZE);
-		struct folio *folio;
-		void *fsdata;
-
-		err = aops->write_begin(file, file->f_mapping, pos, len,
-					&folio, &fsdata);
-		if (err < 0)
-			goto fail;
+	err = kernel_write(file, data, size, &pos);
 
-		memcpy_to_folio(folio, offset_in_folio(folio, pos), data, len);
+	if (err < 0)
+		goto fail;
 
-		err = aops->write_end(file, file->f_mapping, pos, len, len,
-				      folio, fsdata);
-		if (err < 0)
-			goto fail;
-
-		size -= len;
-		data += len;
-		pos += len;
-	} while (size);
+	if (err != size) {
+		err = -EIO;
+		goto fail;
+	}
 
 	return obj;
 
-- 
2.34.1

On Tue, Jun 24, 2025 at 12:12:04PM +0000, 陈涛涛 Taotao Chen wrote:
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> @@ -637,8 +637,7 @@ i915_gem_object_create_shmem_from_data(struct drm_i915_private *i915,
>  {
>  	struct drm_i915_gem_object *obj;
>  	struct file *file;
> -	const struct address_space_operations *aops;
> -	loff_t pos;
> +	loff_t pos = 0;
>  	int err;

I think 'err' needs to become ssize_t to avoid writes larger than 2GB
from being misinterpreted as errors.

在 2025/6/24 20:23, Matthew Wilcox 写道:
> On Tue, Jun 24, 2025 at 12:12:04PM +0000, 陈涛涛 Taotao Chen wrote:
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
>> @@ -637,8 +637,7 @@ i915_gem_object_create_shmem_from_data(struct drm_i915_private *i915,
>>   {
>>   	struct drm_i915_gem_object *obj;
>>   	struct file *file;
>> -	const struct address_space_operations *aops;
>> -	loff_t pos;
>> +	loff_t pos = 0;
>>   	int err;
> I think 'err' needs to become ssize_t to avoid writes larger than 2GB
> from being misinterpreted as errors.

Thanks for the great catch! I’ve changed int err; to ssize_t err; as you 
suggested.