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Pratyush Yadav (Google) 71e2b5eadb memfd: export alloc_file()
Patch series "mm: memfd_luo hotfixes".

This series contains a couple of fixes for memfd preservation using LUO.


This patch (of 3):

The Live Update Orchestrator's (LUO) memfd preservation works by
preserving all the folios of a memfd, re-creating an empty memfd on the
next boot, and then inserting back the preserved folios.

Currently it creates the file by directly calling shmem_file_setup(). 
This leaves out other work done by alloc_file() like setting up the file
mode, flags, or calling the security hooks.

Export alloc_file() to let memfd_luo use it.  Rename it to
memfd_alloc_file() since it is no longer private and thus needs a
subsystem prefix.

Link: https://lkml.kernel.org/r/20260122151842.4069702-1-pratyush@kernel.org
Link: https://lkml.kernel.org/r/20260122151842.4069702-2-pratyush@kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-01-26 19:03:47 -08:00

43 lines
1.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_MEMFD_H
#define __LINUX_MEMFD_H
#include <linux/file.h>
#define MEMFD_ANON_NAME "[memfd]"
#ifdef CONFIG_MEMFD_CREATE
extern long memfd_fcntl(struct file *file, unsigned int cmd, unsigned int arg);
struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx);
/*
* Check for any existing seals on mmap, return an error if access is denied due
* to sealing, or 0 otherwise.
*
* We also update VMA flags if appropriate by manipulating the VMA flags pointed
* to by vm_flags_ptr.
*/
int memfd_check_seals_mmap(struct file *file, vm_flags_t *vm_flags_ptr);
struct file *memfd_alloc_file(const char *name, unsigned int flags);
#else
static inline long memfd_fcntl(struct file *f, unsigned int c, unsigned int a)
{
return -EINVAL;
}
static inline struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx)
{
return ERR_PTR(-EINVAL);
}
static inline int memfd_check_seals_mmap(struct file *file,
vm_flags_t *vm_flags_ptr)
{
return 0;
}
static inline struct file *memfd_alloc_file(const char *name, unsigned int flags)
{
return ERR_PTR(-EINVAL);
}
#endif
#endif /* __LINUX_MEMFD_H */