[PATCH v3 09/16] mtdchar: replace deprecated mmap hook with mmap_prepare, clean up

Lorenzo Stoakes (Oracle)
2026-03-19T18:24:14Z

Replace the deprecated mmap callback with mmap_prepare.

Commit f5cf8f07423b ("mtd: Disable mtdchar mmap on MMU systems") commented
out the CONFIG_MMU part of this function back in 2012, so after ~14 years
it's probably reasonable to remove this altogether rather than updating
dead code.

Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
---
drivers/mtd/mtdchar.c | 21 +++------------------
1 file changed, 3 insertions(+), 18 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 55a43682c567..bf01e6ac7293 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -1376,27 +1376,12 @@ static unsigned mtdchar_mmap_capabilities(struct file *file)
/*
* set up a mapping for shared memory segments
*/
-static int mtdchar_mmap(struct file *file, struct vm_area_struct *vma)
+static int mtdchar_mmap_prepare(struct vm_area_desc *desc)
{
#ifdef CONFIG_MMU
- struct mtd_file_info *mfi = file->private_data;
- struct mtd_info *mtd = mfi->mtd;
- struct map_info *map = mtd->priv;
-
- /* This is broken because it assumes the MTD device is map-based
- and that mtd->priv is a valid struct map_info. It should be
- replaced with something that uses the mtd_get_unmapped_area()
- operation properly. */
- if (0 /*mtd->type == MTD_RAM || mtd->type == MTD_ROM*/) {
-#ifdef pgprot_noncached
- if (file->f_flags & O_DSYNC || map->phys >= __pa(high_memory))
- vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-#endif
- return vm_iomap_memory(vma, map->phys, map->size);
- }
return -ENODEV;
#else
- return vma->vm_flags & VM_SHARED ? 0 : -EACCES;
+ return vma_desc_test(desc, VMA_SHARED_BIT) ? 0 : -EACCES;
#endif
}

@@ -1411,7 +1396,7 @@ static const struct file_operations mtd_fops = {
#endif
.open = mtdchar_open,
.release = mtdchar_close,
- .mmap = mtdchar_mmap,
+ .mmap_prepare = mtdchar_mmap_prepare,
#ifndef CONFIG_MMU
.get_unmapped_area = mtdchar_get_unmapped_area,
.mmap_capabilities = mtdchar_mmap_capabilities,
--
2.53.0