fs: move FMODE_UNSIGNED_OFFSET to fop_flags

This is another flag that is statically set and doesn't need to use up
an FMODE_* bit. Move it to ->fop_flags and free up another FMODE_* bit.

(1) mem_open() used from proc_mem_operations
(2) adi_open() used from adi_fops
(3) drm_open_helper():
    (3.1) accel_open() used from DRM_ACCEL_FOPS
    (3.2) drm_open() used from
    (3.2.1) amdgpu_driver_kms_fops
    (3.2.2) psb_gem_fops
    (3.2.3) i915_driver_fops
    (3.2.4) nouveau_driver_fops
    (3.2.5) panthor_drm_driver_fops
    (3.2.6) radeon_driver_kms_fops
    (3.2.7) tegra_drm_fops
    (3.2.8) vmwgfx_driver_fops
    (3.2.9) xe_driver_fops
    (3.2.10) DRM_GEM_FOPS
    (3.2.11) DEFINE_DRM_GEM_DMA_FOPS
(4) struct memdev sets fmode flags based on type of device opened. For
    devices using struct mem_fops unsigned offset is used.

Mark all these file operations as FOP_UNSIGNED_OFFSET and add asserts
into the open helper to ensure that the flag is always set.

Link: https://lore.kernel.org/r/20240809-work-fop_unsigned-v1-1-658e054d893e@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

drivers/char/adi.c

@@ -14,12 +14,6 @@
 
 #define MAX_BUF_SZ	PAGE_SIZE
 
-static int adi_open(struct inode *inode, struct file *file)
-{
-	file->f_mode |= FMODE_UNSIGNED_OFFSET;
-	return 0;
-}
-
 static int read_mcd_tag(unsigned long addr)
 {
 	long err;
@@ -206,9 +200,9 @@ static loff_t adi_llseek(struct file *file, loff_t offset, int whence)
 static const struct file_operations adi_fops = {
 	.owner		= THIS_MODULE,
 	.llseek		= adi_llseek,
-	.open		= adi_open,
 	.read		= adi_read,
 	.write		= adi_write,
+	.fop_flags	= FOP_UNSIGNED_OFFSET,
 };
 
 static struct miscdevice adi_miscdev = {

drivers/char/mem.c

@@ -643,6 +643,7 @@ static const struct file_operations __maybe_unused mem_fops = {
 	.get_unmapped_area = get_unmapped_area_mem,
 	.mmap_capabilities = memory_mmap_capabilities,
 #endif
+	.fop_flags	= FOP_UNSIGNED_OFFSET,
 };
 
 static const struct file_operations null_fops = {
@@ -693,7 +694,7 @@ static const struct memdev {
 	umode_t mode;
 } devlist[] = {
 #ifdef CONFIG_DEVMEM
-	[DEVMEM_MINOR] = { "mem", &mem_fops, FMODE_UNSIGNED_OFFSET, 0 },
+	[DEVMEM_MINOR] = { "mem", &mem_fops, 0, 0 },
 #endif
 	[3] = { "null", &null_fops, FMODE_NOWAIT, 0666 },
 #ifdef CONFIG_DEVPORT

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

@@ -2908,6 +2908,7 @@ static const struct file_operations amdgpu_driver_kms_fops = {
 #ifdef CONFIG_PROC_FS
 	.show_fdinfo = drm_show_fdinfo,
 #endif
+	.fop_flags = FOP_UNSIGNED_OFFSET,
 };
 
 int amdgpu_file_to_fpriv(struct file *filp, struct amdgpu_fpriv **fpriv)

drivers/gpu/drm/drm_file.c

@@ -318,6 +318,8 @@ int drm_open_helper(struct file *filp, struct drm_minor *minor)
 	if (dev->switch_power_state != DRM_SWITCH_POWER_ON &&
 	    dev->switch_power_state != DRM_SWITCH_POWER_DYNAMIC_OFF)
 		return -EINVAL;
+	if (WARN_ON_ONCE(!(filp->f_op->fop_flags & FOP_UNSIGNED_OFFSET)))
+		return -EINVAL;
 
 	drm_dbg_core(dev, "comm=\"%s\", pid=%d, minor=%d\n",
 		     current->comm, task_pid_nr(current), minor->index);
@@ -335,7 +337,6 @@ int drm_open_helper(struct file *filp, struct drm_minor *minor)
 	}
 
 	filp->private_data = priv;
-	filp->f_mode |= FMODE_UNSIGNED_OFFSET;
 	priv->filp = filp;
 
 	mutex_lock(&dev->filelist_mutex);

drivers/gpu/drm/gma500/psb_drv.c

@@ -498,6 +498,7 @@ static const struct file_operations psb_gem_fops = {
 	.mmap = drm_gem_mmap,
 	.poll = drm_poll,
 	.read = drm_read,
+	.fop_flags = FOP_UNSIGNED_OFFSET,
 };
 
 static const struct drm_driver driver = {

drivers/gpu/drm/i915/i915_driver.c

@@ -1671,6 +1671,7 @@ static const struct file_operations i915_driver_fops = {
 #ifdef CONFIG_PROC_FS
 	.show_fdinfo = drm_show_fdinfo,
 #endif
+	.fop_flags = FOP_UNSIGNED_OFFSET,
 };
 
 static int

drivers/gpu/drm/nouveau/nouveau_drm.c

@@ -1274,6 +1274,7 @@ nouveau_driver_fops = {
 	.compat_ioctl = nouveau_compat_ioctl,
 #endif
 	.llseek = noop_llseek,
+	.fop_flags = FOP_UNSIGNED_OFFSET,
 };
 
 static struct drm_driver

drivers/gpu/drm/radeon/radeon_drv.c

@@ -520,6 +520,7 @@ static const struct file_operations radeon_driver_kms_fops = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl = radeon_kms_compat_ioctl,
 #endif
+	.fop_flags = FOP_UNSIGNED_OFFSET,
 };
 
 static const struct drm_ioctl_desc radeon_ioctls_kms[] = {

drivers/gpu/drm/tegra/drm.c

@@ -801,6 +801,7 @@ static const struct file_operations tegra_drm_fops = {
 	.read = drm_read,
 	.compat_ioctl = drm_compat_ioctl,
 	.llseek = noop_llseek,
+	.fop_flags = FOP_UNSIGNED_OFFSET,
 };
 
 static int tegra_drm_context_cleanup(int id, void *p, void *data)

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c

@@ -1609,6 +1609,7 @@ static const struct file_operations vmwgfx_driver_fops = {
 	.compat_ioctl = vmw_compat_ioctl,
 #endif
 	.llseek = noop_llseek,
+	.fop_flags = FOP_UNSIGNED_OFFSET,
 };
 
 static const struct drm_driver driver = {

drivers/gpu/drm/xe/xe_device.c

@@ -238,6 +238,7 @@ static const struct file_operations xe_driver_fops = {
 #ifdef CONFIG_PROC_FS
 	.show_fdinfo = drm_show_fdinfo,
 #endif
+	.fop_flags = FOP_UNSIGNED_OFFSET,
 };
 
 static struct drm_driver driver = {

fs/proc/base.c

@@ -827,12 +827,9 @@ static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)
 
 static int mem_open(struct inode *inode, struct file *file)
 {
-	int ret = __mem_open(inode, file, PTRACE_MODE_ATTACH);
-
-	/* OK to pass negative loff_t, we can catch out-of-range */
-	file->f_mode |= FMODE_UNSIGNED_OFFSET;
-
-	return ret;
+	if (WARN_ON_ONCE(!(file->f_op->fop_flags & FOP_UNSIGNED_OFFSET)))
+		return -EINVAL;
+	return __mem_open(inode, file, PTRACE_MODE_ATTACH);
 }
 
 static ssize_t mem_rw(struct file *file, char __user *buf,
@@ -932,6 +929,7 @@ static const struct file_operations proc_mem_operations = {
 	.write		= mem_write,
 	.open		= mem_open,
 	.release	= mem_release,
+	.fop_flags	= FOP_UNSIGNED_OFFSET,
 };
 
 static int environ_open(struct inode *inode, struct file *file)

fs/read_write.c

@@ -36,7 +36,7 @@ EXPORT_SYMBOL(generic_ro_fops);
 
 static inline bool unsigned_offsets(struct file *file)
 {
-	return file->f_mode & FMODE_UNSIGNED_OFFSET;
+	return file->f_op->fop_flags & FOP_UNSIGNED_OFFSET;
 }
 
 /**

include/drm/drm_accel.h

@@ -28,7 +28,8 @@
 	.poll		= drm_poll,\
 	.read		= drm_read,\
 	.llseek		= noop_llseek, \
-	.mmap		= drm_gem_mmap
+	.mmap		= drm_gem_mmap, \
+	.fop_flags	= FOP_UNSIGNED_OFFSET
 
 /**
  * DEFINE_DRM_ACCEL_FOPS() - macro to generate file operations for accelerators drivers

include/drm/drm_gem.h

@@ -447,7 +447,8 @@ struct drm_gem_object {
 	.poll		= drm_poll,\
 	.read		= drm_read,\
 	.llseek		= noop_llseek,\
-	.mmap		= drm_gem_mmap
+	.mmap		= drm_gem_mmap, \
+	.fop_flags	= FOP_UNSIGNED_OFFSET
 
 /**
  * DEFINE_DRM_GEM_FOPS() - macro to generate file operations for GEM drivers

include/drm/drm_gem_dma_helper.h

@@ -267,6 +267,7 @@ unsigned long drm_gem_dma_get_unmapped_area(struct file *filp,
 		.read		= drm_read,\
 		.llseek		= noop_llseek,\
 		.mmap		= drm_gem_mmap,\
+		.fop_flags = FOP_UNSIGNED_OFFSET, \
 		DRM_GEM_DMA_UNMAPPED_AREA_FOPS \
 	}
 

include/linux/fs.h

@@ -146,8 +146,7 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 /* Expect random access pattern */
 #define FMODE_RANDOM		((__force fmode_t)(1 << 12))
 
-/* File is huge (eg. /dev/mem): treat loff_t as unsigned */
-#define FMODE_UNSIGNED_OFFSET	((__force fmode_t)(1 << 13))
+/* FMODE_* bit 13 */
 
 /* File is opened with O_PATH; almost nothing can be done with it */
 #define FMODE_PATH		((__force fmode_t)(1 << 14))
@@ -2073,6 +2072,8 @@ struct file_operations {
 #define FOP_DIO_PARALLEL_WRITE	((__force fop_flags_t)(1 << 3))
 /* Contains huge pages */
 #define FOP_HUGE_PAGES		((__force fop_flags_t)(1 << 4))
+/* Treat loff_t as unsigned (e.g., /dev/mem) */
+#define FOP_UNSIGNED_OFFSET	((__force fop_flags_t)(1 << 5))
 
 /* Wrap a directory iterator that needs exclusive inode access */
 int wrap_directory_iterator(struct file *, struct dir_context *,

mm/mmap.c

@@ -1229,7 +1229,7 @@ static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
 		return MAX_LFS_FILESIZE;
 
 	/* Special "we do even unsigned file positions" case */
-	if (file->f_mode & FMODE_UNSIGNED_OFFSET)
+	if (file->f_op->fop_flags & FOP_UNSIGNED_OFFSET)
 		return 0;
 
 	/* Yes, random drivers might want more. But I'm tired of buggy drivers */