1 files changed, 164 insertions, 0 deletions
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
new file mode 100644
index 000000000..d500ea967
--- /dev/null
+++ b/include/linux/shmem_fs.h
@@ -0,0 +1,164 @@
+/* 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 */
+	pgoff_t			fallocend;	/* highest fallocate endindex */
+	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 timespec64	i_crtime;	/* file creation time */
+	unsigned int		fsflags;	/* flags for FS_IOC_[SG]ETFLAGS */
+	struct inode		vfs_inode;
+};
+
+#define SHMEM_FL_USER_VISIBLE		FS_FL_USER_VISIBLE
+#define SHMEM_FL_USER_MODIFIABLE \
+	(FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NODUMP_FL | FS_NOATIME_FL)
+#define SHMEM_FL_INHERITED		(FS_NODUMP_FL | FS_NOATIME_FL)
+
+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 */
+	raw_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 void 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 ucounts *ucounts);
+#ifdef CONFIG_SHMEM
+extern const struct address_space_operations shmem_aops;
+static inline bool shmem_mapping(struct address_space *mapping)
+{
+	return mapping->a_ops == &shmem_aops;
+}
+#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);
+int shmem_unuse(unsigned int type);
+
+extern bool shmem_is_huge(struct vm_area_struct *vma, struct inode *inode,
+			  pgoff_t index, bool shmem_huge_force);
+static inline bool shmem_huge_enabled(struct vm_area_struct *vma,
+				      bool shmem_huge_force)
+{
+	return shmem_is_huge(vma, file_inode(vma->vm_file), vma->vm_pgoff,
+			     shmem_huge_force);
+}
+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_get_folio */
+enum sgp_type {
+	SGP_READ,	/* don't exceed i_size, don't allocate page */
+	SGP_NOALLOC,	/* similar, but fail on hole or use fallocated page */
+	SGP_CACHE,	/* don't exceed i_size, may allocate page */
+	SGP_WRITE,	/* may exceed i_size, may allocate !Uptodate page */
+	SGP_FALLOC,	/* like SGP_WRITE, but make existing page Uptodate */
+};
+
+int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
+		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);
+}
+
+/*
+ * If fallocate(FALLOC_FL_KEEP_SIZE) has been used, there may be pages
+ * beyond i_size's notion of EOF, which fallocate has committed to reserving:
+ * which split_huge_page() must therefore not delete.  This use of a single
+ * "fallocend" per inode errs on the side of not deleting a reservation when
+ * in doubt: there are plenty of cases when it preserves unreserved pages.
+ */
+static inline pgoff_t shmem_fallocend(struct inode *inode, pgoff_t eof)
+{
+	return max(eof, SHMEM_I(inode)->fallocend);
+}
+
+extern bool shmem_charge(struct inode *inode, long pages);
+extern void shmem_uncharge(struct inode *inode, long pages);
+
+#ifdef CONFIG_USERFAULTFD
+#ifdef CONFIG_SHMEM
+extern int shmem_mfill_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,
+				  bool zeropage, bool wp_copy,
+				  struct page **pagep);
+#else /* !CONFIG_SHMEM */
+#define shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, \
+			       src_addr, zeropage, wp_copy, pagep) ({ BUG(); 0; })
+#endif /* CONFIG_SHMEM */
+#endif /* CONFIG_USERFAULTFD */
+
+#endif