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mm: add shmem_zero_setup_desc()

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Add the ability to set up a shared anonymous mapping based on a VMA
descriptor rather than a VMA.

This is a prerequisite for converting to the char mm driver to use the
mmap_prepare hook.

Link: https://lkml.kernel.org/r/d9181517a7e3d6b014a5697c6990d3722c2c9fcd.1760959442.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chatre, Reinette <reinette.chatre@intel.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Dave Martin <dave.martin@arm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Morse <james.morse@arm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Robin Murohy <robin.murphy@arm.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes
2025-10-20 13:11:30 +01:00
committed by Andrew Morton
parent ea52cb24cd
commit 89646d9c74
2 changed files with 35 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/shmem_fs.h
View File

@@ -94,7 +94,8 @@ extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
unsigned long flags);
extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
const char *name, loff_t size, unsigned long flags);
extern int shmem_zero_setup(struct vm_area_struct *);
int shmem_zero_setup(struct vm_area_struct *vma);
int shmem_zero_setup_desc(struct vm_area_desc *desc);
extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags);
extern int shmem_lock(struct file *file, int lock, struct ucounts *ucounts);

41
mm/shmem.c
View File

@@ -5880,14 +5880,9 @@ struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
}
EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
/**
* shmem_zero_setup - setup a shared anonymous mapping
* @vma: the vma to be mmapped is prepared by do_mmap
*/
int shmem_zero_setup(struct vm_area_struct *vma)
static struct file *__shmem_zero_setup(unsigned long start, unsigned long end, vm_flags_t vm_flags)
{
struct file *file;
loff_t size = vma->vm_end - vma->vm_start;
loff_t size = end - start;
/*
* Cloning a new file under mmap_lock leads to a lock ordering conflict
@@ -5895,7 +5890,18 @@ int shmem_zero_setup(struct vm_area_struct *vma)
* accessible to the user through its mapping, use S_PRIVATE flag to
* bypass file security, in the same way as shmem_kernel_file_setup().
*/
file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
return shmem_kernel_file_setup("dev/zero", size, vm_flags);
}
/**
* shmem_zero_setup - setup a shared anonymous mapping
* @vma: the vma to be mmapped is prepared by do_mmap
* Returns: 0 on success, or error
*/
int shmem_zero_setup(struct vm_area_struct *vma)
{
struct file *file = __shmem_zero_setup(vma->vm_start, vma->vm_end, vma->vm_flags);
if (IS_ERR(file))
return PTR_ERR(file);
@@ -5907,6 +5913,25 @@ int shmem_zero_setup(struct vm_area_struct *vma)
return 0;
}
/**
* shmem_zero_setup_desc - same as shmem_zero_setup, but determined by VMA
* descriptor for convenience.
* @desc: Describes VMA
* Returns: 0 on success, or error
*/
int shmem_zero_setup_desc(struct vm_area_desc *desc)
{
struct file *file = __shmem_zero_setup(desc->start, desc->end, desc->vm_flags);
if (IS_ERR(file))
return PTR_ERR(file);
desc->vm_file = file;
desc->vm_ops = &shmem_anon_vm_ops;
return 0;
}
/**
* shmem_read_folio_gfp - read into page cache, using specified page allocation flags.
* @mapping: the folio's address_space