1 files changed, 138 insertions, 0 deletions
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
new file mode 100644
index 000000000..a5a5d1d4d
--- /dev/null
+++ b/include/linux/shmem_fs.h
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __SHMEM_FS_H
+#define __SHMEM_FS_H
+
+#include <linux/file.h>
+#include <linux/swap.h>
+#include <linux/mempolicy.h>
+#include <linux/pagemap.h>
+#include <linux/percpu_counter.h>
+#include <linux/xattr.h>
+#include <linux/fs_parser.h>
+
+/* inode in-kernel data */
+
+struct shmem_inode_info {
+	spinlock_t		lock;
+	unsigned int		seals;		/* shmem seals */
+	unsigned long		flags;
+	unsigned long		alloced;	/* data pages alloced to file */
+	unsigned long		swapped;	/* subtotal assigned to swap */
+	struct list_head        shrinklist;     /* shrinkable hpage inodes */
+	struct list_head	swaplist;	/* chain of maybes on swap */
+	struct shared_policy	policy;		/* NUMA memory alloc policy */
+	struct simple_xattrs	xattrs;		/* list of xattrs */
+	atomic_t		stop_eviction;	/* hold when working on inode */
+	struct inode		vfs_inode;
+};
+
+struct shmem_sb_info {
+	unsigned long max_blocks;   /* How many blocks are allowed */
+	struct percpu_counter used_blocks;  /* How many are allocated */
+	unsigned long max_inodes;   /* How many inodes are allowed */
+	unsigned long free_inodes;  /* How many are left for allocation */
+	spinlock_t stat_lock;	    /* Serialize shmem_sb_info changes */
+	umode_t mode;		    /* Mount mode for root directory */
+	unsigned char huge;	    /* Whether to try for hugepages */
+	kuid_t uid;		    /* Mount uid for root directory */
+	kgid_t gid;		    /* Mount gid for root directory */
+	bool full_inums;	    /* If i_ino should be uint or ino_t */
+	ino_t next_ino;		    /* The next per-sb inode number to use */
+	ino_t __percpu *ino_batch;  /* The next per-cpu inode number to use */
+	struct mempolicy *mpol;     /* default memory policy for mappings */
+	spinlock_t shrinklist_lock;   /* Protects shrinklist */
+	struct list_head shrinklist;  /* List of shinkable inodes */
+	unsigned long shrinklist_len; /* Length of shrinklist */
+};
+
+static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
+{
+	return container_of(inode, struct shmem_inode_info, vfs_inode);
+}
+
+/*
+ * Functions in mm/shmem.c called directly from elsewhere:
+ */
+extern const struct fs_parameter_spec shmem_fs_parameters[];
+extern int shmem_init(void);
+extern int shmem_init_fs_context(struct fs_context *fc);
+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);
+extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
+#ifdef CONFIG_SHMEM
+extern bool shmem_mapping(struct address_space *mapping);
+#else
+static inline bool shmem_mapping(struct address_space *mapping)
+{
+	return false;
+}
+#endif /* CONFIG_SHMEM */
+extern void shmem_unlock_mapping(struct address_space *mapping);
+extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
+					pgoff_t index, gfp_t gfp_mask);
+extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
+extern int shmem_unuse(unsigned int type, bool frontswap,
+		       unsigned long *fs_pages_to_unuse);
+
+extern bool shmem_huge_enabled(struct vm_area_struct *vma);
+extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
+extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
+						pgoff_t start, pgoff_t end);
+
+/* Flag allocation requirements to shmem_getpage */
+enum sgp_type {
+	SGP_READ,	/* don't exceed i_size, don't allocate page */
+	SGP_CACHE,	/* don't exceed i_size, may allocate page */
+	SGP_NOHUGE,	/* like SGP_CACHE, but no huge pages */
+	SGP_HUGE,	/* like SGP_CACHE, huge pages preferred */
+	SGP_WRITE,	/* may exceed i_size, may allocate !Uptodate page */
+	SGP_FALLOC,	/* like SGP_WRITE, but make existing page Uptodate */
+};
+
+extern int shmem_getpage(struct inode *inode, pgoff_t index,
+		struct page **pagep, enum sgp_type sgp);
+
+static inline struct page *shmem_read_mapping_page(
+				struct address_space *mapping, pgoff_t index)
+{
+	return shmem_read_mapping_page_gfp(mapping, index,
+					mapping_gfp_mask(mapping));
+}
+
+static inline bool shmem_file(struct file *file)
+{
+	if (!IS_ENABLED(CONFIG_SHMEM))
+		return false;
+	if (!file || !file->f_mapping)
+		return false;
+	return shmem_mapping(file->f_mapping);
+}
+
+extern bool shmem_charge(struct inode *inode, long pages);
+extern void shmem_uncharge(struct inode *inode, long pages);
+
+#ifdef CONFIG_SHMEM
+extern int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
+				  struct vm_area_struct *dst_vma,
+				  unsigned long dst_addr,
+				  unsigned long src_addr,
+				  struct page **pagep);
+extern int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
+				    pmd_t *dst_pmd,
+				    struct vm_area_struct *dst_vma,
+				    unsigned long dst_addr);
+#else
+#define shmem_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \
+			       src_addr, pagep)        ({ BUG(); 0; })
+#define shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, \
+				 dst_addr)      ({ BUG(); 0; })
+#endif
+
+#endif