memfd: export memfd_{add,get}_seals()

Patch series "mm: memfd_luo: preserve file seals", v2.

This series adds support for preserving file seals when preserving a memfd
using LUO.  Patch 1 exports some memfd seal manipulation functions and
patch 2 adds support for preserving them.  Since it makes changes to the
serialized data structure for memfd, it also bumps the version number.

This patch (of 2):

Support for preserving file seals will be added to memfd preservation
using the Live Update Orchestrator (LUO).  Export memfd_{add,get}_seals)()
so memfd_luo can use them to manipulate the seals.

Link: https://lkml.kernel.org/r/20260216185946.1215770-1-pratyush@kernel.org
Link: https://lkml.kernel.org/r/20260216185946.1215770-2-pratyush@kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: Samiullah Khawaja <skhawaja@google.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/memfd.h b/include/linux/memfd.h
index c328a7b356d0e558842b8fbc718205f1ed80f922..b4fda09dab9f618d8f976516194e515f39ab2da2 100644 (file)
--- a/include/linux/memfd.h
+++ b/include/linux/memfd.h
@@ -18,6 +18,8 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx);
  */
 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);
+int memfd_get_seals(struct file *file);
+int memfd_add_seals(struct file *file, unsigned int seals);
 #else
 static inline long memfd_fcntl(struct file *f, unsigned int c, unsigned int a)
 {
@@ -37,6 +39,16 @@ static inline struct file *memfd_alloc_file(const char *name, unsigned int flags
 {
        return ERR_PTR(-EINVAL);
 }
+
+static inline int memfd_get_seals(struct file *file)
+{
+       return -EINVAL;
+}
+
+static inline int memfd_add_seals(struct file *file, unsigned int seals)
+{
+       return -EINVAL;
+}
 #endif
 
 #endif /* __LINUX_MEMFD_H */

diff --git a/mm/memfd.c b/mm/memfd.c
index 919c2a53eb96963eaa7417654bcd61184d74f253..fb425f4e315f457575d609eb70bceb0e7ecaadfa 100644 (file)
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -227,7 +227,7 @@ static unsigned int *memfd_file_seals_ptr(struct file *file)
                     F_SEAL_WRITE | \
                     F_SEAL_FUTURE_WRITE)
 
-static int memfd_add_seals(struct file *file, unsigned int seals)
+int memfd_add_seals(struct file *file, unsigned int seals)
 {
        struct inode *inode = file_inode(file);
        unsigned int *file_seals;
@@ -309,7 +309,7 @@ unlock:
        return error;
 }
 
-static int memfd_get_seals(struct file *file)
+int memfd_get_seals(struct file *file)
 {
        unsigned int *seals = memfd_file_seals_ptr(file);