[PATCH 07/10] mm/filemap: introduce generic_file_*_mmap_prepare() helpers
From: Lorenzo Stoakes <hidden>
Date: 2025-06-16 19:35:19
Also in:
ceph-devel, intel-gfx, linux-bcachefs, linux-btrfs, linux-cifs, linux-ext4, linux-f2fs-devel, linux-fsdevel, linux-mm, linux-nfs, linux-um, linux-unionfs, linux-xfs, lkml, ntfs3, nvdimm, ocfs2-devel, v9fs
Subsystem:
filesystems (vfs and infrastructure), memory management, page cache, the rest · Maintainers:
Alexander Viro, Christian Brauner, Andrew Morton, Matthew Wilcox, Linus Torvalds
Since commit c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file
callback"), the f_op->mmap() hook has been deprecated in favour of
f_op->mmap_prepare().
The generic mmap handlers are very simple, so we can very easily convert
these in advance of converting file systems which use them.
This patch does so.
Signed-off-by: Lorenzo Stoakes <redacted>
---
include/linux/fs.h | 6 ++++--
mm/filemap.c | 29 +++++++++++++++++++++++++++++
2 files changed, 33 insertions(+), 2 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7120f80255b3..65cffc445fcc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -3395,8 +3395,10 @@ extern void inode_add_lru(struct inode *inode); extern int sb_set_blocksize(struct super_block *, int); extern int sb_min_blocksize(struct super_block *, int); -extern int generic_file_mmap(struct file *, struct vm_area_struct *); -extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *); +int generic_file_mmap(struct file *, struct vm_area_struct *); +int generic_file_mmap_prepare(struct vm_area_desc *desc); +int generic_file_readonly_mmap(struct file *, struct vm_area_struct *); +int generic_file_readonly_mmap_prepare(struct vm_area_desc *desc); extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *); int generic_write_checks_count(struct kiocb *iocb, loff_t *count); extern int generic_write_check_limits(struct file *file, loff_t pos,
diff --git a/mm/filemap.c b/mm/filemap.c
index 93fbc2ef232a..e75608cbf420 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -3847,6 +3847,18 @@ int generic_file_mmap(struct file *file, struct vm_area_struct *vma) return 0; } +int generic_file_mmap_prepare(struct vm_area_desc *desc) +{ + struct file *file = desc->file; + struct address_space *mapping = file->f_mapping; + + if (!mapping->a_ops->read_folio) + return -ENOEXEC; + file_accessed(file); + desc->vm_ops = &generic_file_vm_ops; + return 0; +} + /* * This is for filesystems which do not implement ->writepage. */
@@ -3856,6 +3868,13 @@ int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) return -EINVAL; return generic_file_mmap(file, vma); } + +int generic_file_readonly_mmap_prepare(struct vm_area_desc *desc) +{ + if (is_shared_maywrite(desc->vm_flags)) + return -EINVAL; + return generic_file_mmap_prepare(desc); +} #else vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf) {
@@ -3865,15 +3884,25 @@ int generic_file_mmap(struct file *file, struct vm_area_struct *vma) { return -ENOSYS; } +int generic_file_mmap_prepare(struct vm_area_desc *desc) +{ + return -ENOSYS; +} int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) { return -ENOSYS; } +int generic_file_readonly_mmap_prepare(struct vm_area_desc *desc) +{ + return -ENOSYS; +} #endif /* CONFIG_MMU */ EXPORT_SYMBOL(filemap_page_mkwrite); EXPORT_SYMBOL(generic_file_mmap); +EXPORT_SYMBOL(generic_file_mmap_prepare); EXPORT_SYMBOL(generic_file_readonly_mmap); +EXPORT_SYMBOL(generic_file_readonly_mmap_prepare); static struct folio *do_read_cache_folio(struct address_space *mapping, pgoff_t index, filler_t filler, struct file *file, gfp_t gfp)
--
2.49.0