[PATCH 01/22] mm/shmem: introduce shmem_file_setup_with_mnt

Matthew Auld
2017-08-15T18:16:56Z

We are planning to use our own tmpfs mnt in i915 in place of the
shm_mnt, such that we can control the mount options, in particular
huge=, which we require to support huge-gtt-pages. So rather than roll
our own version of __shmem_file_setup, it would be preferred if we could
just give shmem our mnt, and let it do the rest.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
---
include/linux/shmem_fs.h | 2 ++
mm/shmem.c | 30 ++++++++++++++++++++++--------
2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index a7d6bd2a918f..27de676f0b63 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -53,6 +53,8 @@ extern struct file *shmem_file_setup(const char *name,
loff_t size, unsigned long flags);
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 *);
extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags);
diff --git a/mm/shmem.c b/mm/shmem.c
index 6540e5982444..0975e65ea61c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4141,7 +4141,7 @@ static const struct dentry_operations anon_ops = {
.d_dname = simple_dname
};

-static struct file *__shmem_file_setup(const char *name, loff_t size,
+static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
unsigned long flags, unsigned int i_flags)
{
struct file *res;
@@ -4150,8 +4150,8 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
struct super_block *sb;
struct qstr this;

- if (IS_ERR(shm_mnt))
- return ERR_CAST(shm_mnt);
+ if (IS_ERR(mnt))
+ return ERR_CAST(mnt);

if (size < 0 || size > MAX_LFS_FILESIZE)
return ERR_PTR(-EINVAL);
@@ -4163,8 +4163,8 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
this.name = name;
this.len = strlen(name);
this.hash = 0; /* will go */
- sb = shm_mnt->mnt_sb;
- path.mnt = mntget(shm_mnt);
+ sb = mnt->mnt_sb;
+ path.mnt = mntget(mnt);
path.dentry = d_alloc_pseudo(sb, &this);
if (!path.dentry)
goto put_memory;
@@ -4209,7 +4209,7 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
*/
struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
{
- return __shmem_file_setup(name, size, flags, S_PRIVATE);
+ return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
}

/**
@@ -4220,11 +4220,25 @@ struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned lon
*/
struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
{
- return __shmem_file_setup(name, size, flags, 0);
+ return __shmem_file_setup(shm_mnt, name, size, flags, 0);
}
EXPORT_SYMBOL_GPL(shmem_file_setup);

/**
+ * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
+ * @mnt: the tmpfs mount where the file will be created
+ * @name: name for dentry (to be seen in /proc/<pid>/maps
+ * @size: size to be set for the file
+ * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
+ */
+struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
+ loff_t size, unsigned long flags)
+{
+ return __shmem_file_setup(mnt, name, size, flags, 0);
+}
+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_pgoff
*/
@@ -4239,7 +4253,7 @@ 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_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE);
+ file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
if (IS_ERR(file))
return PTR_ERR(file);