1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __SHMEM_FS_H
3#define __SHMEM_FS_H
4
5#include <linux/file.h>
6#include <linux/swap.h>
7#include <linux/mempolicy.h>
8#include <linux/pagemap.h>
9#include <linux/percpu_counter.h>
10#include <linux/xattr.h>
11#include <linux/fs_parser.h>
12
13/* inode in-kernel data */
14
15struct shmem_inode_info {
16 spinlock_t lock;
17 unsigned int seals; /* shmem seals */
18 unsigned long flags;
19 unsigned long alloced; /* data pages alloced to file */
20 unsigned long swapped; /* subtotal assigned to swap */
21 pgoff_t fallocend; /* highest fallocate endindex */
22 struct list_head shrinklist; /* shrinkable hpage inodes */
23 struct list_head swaplist; /* chain of maybes on swap */
24 struct shared_policy policy; /* NUMA memory alloc policy */
25 struct simple_xattrs xattrs; /* list of xattrs */
26 atomic_t stop_eviction; /* hold when working on inode */
27 struct timespec64 i_crtime; /* file creation time */
28 unsigned int fsflags; /* flags for FS_IOC_[SG]ETFLAGS */
29 struct inode vfs_inode;
30};
31
32#define SHMEM_FL_USER_VISIBLE FS_FL_USER_VISIBLE
33#define SHMEM_FL_USER_MODIFIABLE FS_FL_USER_MODIFIABLE
34#define SHMEM_FL_INHERITED FS_FL_USER_MODIFIABLE
35
36/* Flags that are appropriate for regular files (all but dir-specific ones). */
37#define SHMEM_REG_FLMASK (~(FS_DIRSYNC_FL | FS_TOPDIR_FL))
38
39/* Flags that are appropriate for non-directories/regular files. */
40#define SHMEM_OTHER_FLMASK (FS_NODUMP_FL | FS_NOATIME_FL)
41
42struct shmem_sb_info {
43 unsigned long max_blocks; /* How many blocks are allowed */
44 struct percpu_counter used_blocks; /* How many are allocated */
45 unsigned long max_inodes; /* How many inodes are allowed */
46 unsigned long free_inodes; /* How many are left for allocation */
47 raw_spinlock_t stat_lock; /* Serialize shmem_sb_info changes */
48 umode_t mode; /* Mount mode for root directory */
49 unsigned char huge; /* Whether to try for hugepages */
50 kuid_t uid; /* Mount uid for root directory */
51 kgid_t gid; /* Mount gid for root directory */
52 bool full_inums; /* If i_ino should be uint or ino_t */
53 ino_t next_ino; /* The next per-sb inode number to use */
54 ino_t __percpu *ino_batch; /* The next per-cpu inode number to use */
55 struct mempolicy *mpol; /* default memory policy for mappings */
56 spinlock_t shrinklist_lock; /* Protects shrinklist */
57 struct list_head shrinklist; /* List of shinkable inodes */
58 unsigned long shrinklist_len; /* Length of shrinklist */
59};
60
61static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
62{
63 return container_of(inode, struct shmem_inode_info, vfs_inode);
64}
65
66/*
67 * Functions in mm/shmem.c called directly from elsewhere:
68 */
69extern const struct fs_parameter_spec shmem_fs_parameters[];
70extern void shmem_init(void);
71extern int shmem_init_fs_context(struct fs_context *fc);
72extern struct file *shmem_file_setup(const char *name,
73 loff_t size, unsigned long flags);
74extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
75 unsigned long flags);
76extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
77 const char *name, loff_t size, unsigned long flags);
78extern int shmem_zero_setup(struct vm_area_struct *);
79extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
80 unsigned long len, unsigned long pgoff, unsigned long flags);
81extern int shmem_lock(struct file *file, int lock, struct ucounts *ucounts);
82#ifdef CONFIG_SHMEM
83extern const struct address_space_operations shmem_aops;
84static inline bool shmem_mapping(struct address_space *mapping)
85{
86 return mapping->a_ops == &shmem_aops;
87}
88#else
89static inline bool shmem_mapping(struct address_space *mapping)
90{
91 return false;
92}
93#endif /* CONFIG_SHMEM */
94extern void shmem_unlock_mapping(struct address_space *mapping);
95extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
96 pgoff_t index, gfp_t gfp_mask);
97extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
98int shmem_unuse(unsigned int type);
99
100extern bool shmem_is_huge(struct vm_area_struct *vma,
101 struct inode *inode, pgoff_t index);
102static inline bool shmem_huge_enabled(struct vm_area_struct *vma)
103{
104 return shmem_is_huge(vma, file_inode(vma->vm_file), vma->vm_pgoff);
105}
106extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
107extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
108 pgoff_t start, pgoff_t end);
109
110/* Flag allocation requirements to shmem_getpage */
111enum sgp_type {
112 SGP_READ, /* don't exceed i_size, don't allocate page */
113 SGP_NOALLOC, /* similar, but fail on hole or use fallocated page */
114 SGP_CACHE, /* don't exceed i_size, may allocate page */
115 SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */
116 SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
117};
118
119extern int shmem_getpage(struct inode *inode, pgoff_t index,
120 struct page **pagep, enum sgp_type sgp);
121
122static inline struct page *shmem_read_mapping_page(
123 struct address_space *mapping, pgoff_t index)
124{
125 return shmem_read_mapping_page_gfp(mapping, index,
126 mapping_gfp_mask(mapping));
127}
128
129static inline bool shmem_file(struct file *file)
130{
131 if (!IS_ENABLED(CONFIG_SHMEM))
132 return false;
133 if (!file || !file->f_mapping)
134 return false;
135 return shmem_mapping(file->f_mapping);
136}
137
138/*
139 * If fallocate(FALLOC_FL_KEEP_SIZE) has been used, there may be pages
140 * beyond i_size's notion of EOF, which fallocate has committed to reserving:
141 * which split_huge_page() must therefore not delete. This use of a single
142 * "fallocend" per inode errs on the side of not deleting a reservation when
143 * in doubt: there are plenty of cases when it preserves unreserved pages.
144 */
145static inline pgoff_t shmem_fallocend(struct inode *inode, pgoff_t eof)
146{
147 return max(eof, SHMEM_I(inode)->fallocend);
148}
149
150extern bool shmem_charge(struct inode *inode, long pages);
151extern void shmem_uncharge(struct inode *inode, long pages);
152
153#ifdef CONFIG_USERFAULTFD
154#ifdef CONFIG_SHMEM
155extern int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
156 struct vm_area_struct *dst_vma,
157 unsigned long dst_addr,
158 unsigned long src_addr,
159 bool zeropage, bool wp_copy,
160 struct page **pagep);
161#else /* !CONFIG_SHMEM */
162#define shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, \
163 src_addr, zeropage, wp_copy, pagep) ({ BUG(); 0; })
164#endif /* CONFIG_SHMEM */
165#endif /* CONFIG_USERFAULTFD */
166
167#endif
168

source code of linux/include/linux/shmem_fs.h