[PATCH 03/10] fs: consistently use file_has_valid_mmap_hooks() helper

Lorenzo Stoakes
2025-06-16T19:35:09Z

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().

Additionally, commit bb666b7c2707 ("mm: add mmap_prepare() compatibility
layer for nested file systems") permits the use of the .mmap_prepare() hook
even in nested filesystems like overlayfs.

There are a number of places where we check only for f_op->mmap - this is
incorrect now mmap_prepare exists, so update all of these to use the
general helper file_has_valid_mmap_hooks().

Most notably, this updates the elf logic to allow for the ability to
execute binaries on filesystems which have the .mmap_prepare hook, but
additionally we update nested filesystems.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
fs/backing-file.c | 2 +-
fs/binfmt_elf.c | 4 ++--
fs/binfmt_elf_fdpic.c | 2 +-
fs/coda/file.c | 2 +-
fs/ecryptfs/file.c | 2 +-
5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/backing-file.c b/fs/backing-file.c
index 04018679bf69..5761db9a52a9 100644
--- a/fs/backing-file.c
+++ b/fs/backing-file.c
@@ -333,7 +333,7 @@ int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)))
return -EIO;

- if (!file->f_op->mmap)
+ if (!file_has_valid_mmap_hooks(file))
return -ENODEV;

vma_set_file(vma, file);
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a43363d593e5..a6750bd9392a 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -646,7 +646,7 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
if (!elf_check_arch(interp_elf_ex) ||
elf_check_fdpic(interp_elf_ex))
goto out;
- if (!interpreter->f_op->mmap)
+ if (!file_has_valid_mmap_hooks(interpreter))
goto out;

total_size = total_mapping_size(interp_elf_phdata,
@@ -848,7 +848,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
goto out;
if (elf_check_fdpic(elf_ex))
goto out;
- if (!bprm->file->f_op->mmap)
+ if (!file_has_valid_mmap_hooks(bprm->file))
goto out;

elf_phdata = load_elf_phdrs(elf_ex, bprm->file);
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 9133f3827f90..699bb9a65c27 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -109,7 +109,7 @@ static int is_elf(struct elfhdr *hdr, struct file *file)
return 0;
if (!elf_check_arch(hdr))
return 0;
- if (!file->f_op->mmap)
+ if (!file_has_valid_mmap_hooks(file))
return 0;
return 1;
}
diff --git a/fs/coda/file.c b/fs/coda/file.c
index 2e6ea9319b35..eed45a80e9bc 100644
--- a/fs/coda/file.c
+++ b/fs/coda/file.c
@@ -160,7 +160,7 @@ coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
size_t count;
int ret;

- if (!host_file->f_op->mmap)
+ if (!file_has_valid_mmap_hooks(host_file))
return -ENODEV;

if (WARN_ON(coda_file != vma->vm_file))
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index ce0a3c5ed0ca..2bd50d1de5ef 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -193,7 +193,7 @@ static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
* natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
* allows recursive mounting, this will need to be extended.
*/
- if (!lower_file->f_op->mmap)
+ if (!file_has_valid_mmap_hooks(lower_file))
return -ENODEV;
return generic_file_mmap(file, vma);
}
--
2.49.0