shmem_fs.h

  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#include <linux/userfaultfd_k.h>
 13#include <linux/bits.h>
 14
 15struct swap_iocb;
 16
 17/* inode in-kernel data */
 18
 19#ifdef CONFIG_TMPFS_QUOTA
 20#define SHMEM_MAXQUOTAS 2
 21#endif
 22
 23/* Suppress pre-accounting of the entire object size. */
 24#define SHMEM_F_NORESERVE	BIT(0)
 25/* Disallow swapping. */
 26#define SHMEM_F_LOCKED		BIT(1)
 27/*
 28 * Disallow growing, shrinking, or hole punching in the inode. Combined with
 29 * folio pinning, makes sure the inode's mapping stays fixed.
 30 *
 31 * In some ways similar to F_SEAL_GROW | F_SEAL_SHRINK, but can be removed and
 32 * isn't directly visible to userspace.
 33 */
 34#define SHMEM_F_MAPPING_FROZEN	BIT(2)
 35
 36struct shmem_inode_info {
 37	spinlock_t		lock;
 38	unsigned int		seals;		/* shmem seals */
 39	unsigned long		flags;
 40	unsigned long		alloced;	/* data pages alloced to file */
 41	unsigned long		swapped;	/* subtotal assigned to swap */
 42	union {
 43	    struct offset_ctx	dir_offsets;	/* stable directory offsets */
 44	    struct {
 45		struct list_head shrinklist;	/* shrinkable hpage inodes */
 46		struct list_head swaplist;	/* chain of maybes on swap */
 47	    };
 48	};
 49	struct timespec64	i_crtime;	/* file creation time */
 50	struct shared_policy	policy;		/* NUMA memory alloc policy */
 51	struct simple_xattrs	xattrs;		/* list of xattrs */
 52	pgoff_t			fallocend;	/* highest fallocate endindex */
 53	unsigned int		fsflags;	/* for FS_IOC_[SG]ETFLAGS */
 54	atomic_t		stop_eviction;	/* hold when working on inode */
 55#ifdef CONFIG_TMPFS_QUOTA
 56	struct dquot __rcu	*i_dquot[MAXQUOTAS];
 57#endif
 58	struct inode		vfs_inode;
 59};
 60
 61#define SHMEM_FL_USER_VISIBLE		(FS_FL_USER_VISIBLE | FS_CASEFOLD_FL)
 62#define SHMEM_FL_USER_MODIFIABLE \
 63	(FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NODUMP_FL | FS_NOATIME_FL | FS_CASEFOLD_FL)
 64#define SHMEM_FL_INHERITED		(FS_NODUMP_FL | FS_NOATIME_FL | FS_CASEFOLD_FL)
 65
 66struct shmem_quota_limits {
 67	qsize_t usrquota_bhardlimit; /* Default user quota block hard limit */
 68	qsize_t usrquota_ihardlimit; /* Default user quota inode hard limit */
 69	qsize_t grpquota_bhardlimit; /* Default group quota block hard limit */
 70	qsize_t grpquota_ihardlimit; /* Default group quota inode hard limit */
 71};
 72
 73struct shmem_sb_info {
 74	unsigned long max_blocks;   /* How many blocks are allowed */
 75	struct percpu_counter used_blocks;  /* How many are allocated */
 76	unsigned long max_inodes;   /* How many inodes are allowed */
 77	unsigned long free_ispace;  /* How much ispace left for allocation */
 78	raw_spinlock_t stat_lock;   /* Serialize shmem_sb_info changes */
 79	umode_t mode;		    /* Mount mode for root directory */
 80	unsigned char huge;	    /* Whether to try for hugepages */
 81	kuid_t uid;		    /* Mount uid for root directory */
 82	kgid_t gid;		    /* Mount gid for root directory */
 83	bool full_inums;	    /* If i_ino should be uint or ino_t */
 84	bool noswap;		    /* ignores VM reclaim / swap requests */
 85	ino_t next_ino;		    /* The next per-sb inode number to use */
 86	ino_t __percpu *ino_batch;  /* The next per-cpu inode number to use */
 87	struct mempolicy *mpol;     /* default memory policy for mappings */
 88	spinlock_t shrinklist_lock;   /* Protects shrinklist */
 89	struct list_head shrinklist;  /* List of shinkable inodes */
 90	unsigned long shrinklist_len; /* Length of shrinklist */
 91	struct shmem_quota_limits qlimits; /* Default quota limits */
 92};
 93
 94static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
 95{
 96	return container_of(inode, struct shmem_inode_info, vfs_inode);
 97}
 98
 99/*
100 * Functions in mm/shmem.c called directly from elsewhere:
101 */
102extern const struct fs_parameter_spec shmem_fs_parameters[];
103extern void shmem_init(void);
104extern int shmem_init_fs_context(struct fs_context *fc);
105extern struct file *shmem_file_setup(const char *name,
106					loff_t size, unsigned long flags);
107extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
108					    unsigned long flags);
109extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
110		const char *name, loff_t size, unsigned long flags);
111int shmem_zero_setup(struct vm_area_struct *vma);
112int shmem_zero_setup_desc(struct vm_area_desc *desc);
113extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
114		unsigned long len, unsigned long pgoff, unsigned long flags);
115extern int shmem_lock(struct file *file, int lock, struct ucounts *ucounts);
116#ifdef CONFIG_SHMEM
117bool shmem_mapping(const struct address_space *mapping);
118#else
119static inline bool shmem_mapping(const struct address_space *mapping)
120{
121	return false;
122}
123#endif /* CONFIG_SHMEM */
124void shmem_unlock_mapping(struct address_space *mapping);
125struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
126					pgoff_t index, gfp_t gfp_mask);
127int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
128		struct list_head *folio_list);
129void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end);
130int shmem_unuse(unsigned int type);
131
132#ifdef CONFIG_TRANSPARENT_HUGEPAGE
133unsigned long shmem_allowable_huge_orders(struct inode *inode,
134				struct vm_area_struct *vma, pgoff_t index,
135				loff_t write_end, bool shmem_huge_force);
136bool shmem_hpage_pmd_enabled(void);
137#else
138static inline unsigned long shmem_allowable_huge_orders(struct inode *inode,
139				struct vm_area_struct *vma, pgoff_t index,
140				loff_t write_end, bool shmem_huge_force)
141{
142	return 0;
143}
144
145static inline bool shmem_hpage_pmd_enabled(void)
146{
147	return false;
148}
149#endif
150
151#ifdef CONFIG_SHMEM
152extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
153extern void shmem_uncharge(struct inode *inode, long pages);
154#else
155static inline unsigned long shmem_swap_usage(struct vm_area_struct *vma)
156{
157	return 0;
158}
159
160static inline void shmem_uncharge(struct inode *inode, long pages)
161{
162}
163#endif
164extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
165						pgoff_t start, pgoff_t end);
166
167/* Flag allocation requirements to shmem_get_folio */
168enum sgp_type {
169	SGP_READ,	/* don't exceed i_size, don't allocate page */
170	SGP_NOALLOC,	/* similar, but fail on hole or use fallocated page */
171	SGP_CACHE,	/* don't exceed i_size, may allocate page */
172	SGP_WRITE,	/* may exceed i_size, may allocate !Uptodate page */
173	SGP_FALLOC,	/* like SGP_WRITE, but make existing page Uptodate */
174};
175
176int shmem_get_folio(struct inode *inode, pgoff_t index, loff_t write_end,
177		struct folio **foliop, enum sgp_type sgp);
178struct folio *shmem_read_folio_gfp(struct address_space *mapping,
179		pgoff_t index, gfp_t gfp);
180
181static inline struct folio *shmem_read_folio(struct address_space *mapping,
182		pgoff_t index)
183{
184	return shmem_read_folio_gfp(mapping, index, mapping_gfp_mask(mapping));
185}
186
187static inline struct page *shmem_read_mapping_page(
188				struct address_space *mapping, pgoff_t index)
189{
190	return shmem_read_mapping_page_gfp(mapping, index,
191					mapping_gfp_mask(mapping));
192}
193
194static inline bool shmem_file(struct file *file)
195{
196	if (!IS_ENABLED(CONFIG_SHMEM))
197		return false;
198	if (!file || !file->f_mapping)
199		return false;
200	return shmem_mapping(file->f_mapping);
201}
202
203/* Must be called with inode lock taken exclusive. */
204static inline void shmem_freeze(struct inode *inode, bool freeze)
205{
206	if (freeze)
207		SHMEM_I(inode)->flags |= SHMEM_F_MAPPING_FROZEN;
208	else
209		SHMEM_I(inode)->flags &= ~SHMEM_F_MAPPING_FROZEN;
210}
211
212/*
213 * If fallocate(FALLOC_FL_KEEP_SIZE) has been used, there may be pages
214 * beyond i_size's notion of EOF, which fallocate has committed to reserving:
215 * which split_huge_page() must therefore not delete.  This use of a single
216 * "fallocend" per inode errs on the side of not deleting a reservation when
217 * in doubt: there are plenty of cases when it preserves unreserved pages.
218 */
219static inline pgoff_t shmem_fallocend(struct inode *inode, pgoff_t eof)
220{
221	return max(eof, SHMEM_I(inode)->fallocend);
222}
223
224extern bool shmem_charge(struct inode *inode, long pages);
225
226#ifdef CONFIG_USERFAULTFD
227#ifdef CONFIG_SHMEM
228extern int shmem_mfill_atomic_pte(pmd_t *dst_pmd,
229				  struct vm_area_struct *dst_vma,
230				  unsigned long dst_addr,
231				  unsigned long src_addr,
232				  uffd_flags_t flags,
233				  struct folio **foliop);
234#else /* !CONFIG_SHMEM */
235#define shmem_mfill_atomic_pte(dst_pmd, dst_vma, dst_addr, \
236			       src_addr, flags, foliop) ({ BUG(); 0; })
237#endif /* CONFIG_SHMEM */
238#endif /* CONFIG_USERFAULTFD */
239
240/*
241 * Used space is stored as unsigned 64-bit value in bytes but
242 * quota core supports only signed 64-bit values so use that
243 * as a limit
244 */
245#define SHMEM_QUOTA_MAX_SPC_LIMIT 0x7fffffffffffffffLL /* 2^63-1 */
246#define SHMEM_QUOTA_MAX_INO_LIMIT 0x7fffffffffffffffLL
247
248#ifdef CONFIG_TMPFS_QUOTA
249extern const struct dquot_operations shmem_quota_operations;
250extern struct quota_format_type shmem_quota_format;
251#endif /* CONFIG_TMPFS_QUOTA */
252
253#endif