fs/erofs/internal.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             https://www.huawei.com/
  * Copyright (C) 2021, Alibaba Cloud
  */
 #ifndef __EROFS_INTERNAL_H
 #define __EROFS_INTERNAL_H

 #include <linux/fs.h>
 #include <linux/dax.h>
 #include <linux/dcache.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/pagemap.h>
 #include <linux/bio.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/iomap.h>
 #include "erofs_fs.h"

 /* redefine pr_fmt "erofs: " */
 #undef pr_fmt
 #define pr_fmt(fmt) "erofs: " fmt

 __printf(3, 4) void _erofs_err(struct super_block *sb,
 			       const char *function, const char *fmt, ...);
 #define erofs_err(sb, fmt, ...)	\
 	_erofs_err(sb, __func__, fmt "\n", ##__VA_ARGS__)
 __printf(3, 4) void _erofs_info(struct super_block *sb,
 			       const char *function, const char *fmt, ...);
 #define erofs_info(sb, fmt, ...) \
 	_erofs_info(sb, __func__, fmt "\n", ##__VA_ARGS__)
 #ifdef CONFIG_EROFS_FS_DEBUG
 #define DBG_BUGON               BUG_ON
 #else
 #define DBG_BUGON(x)            ((void)(x))
 #endif	/* !CONFIG_EROFS_FS_DEBUG */

 /* EROFS_SUPER_MAGIC_V1 to represent the whole file system */
 #define EROFS_SUPER_MAGIC   EROFS_SUPER_MAGIC_V1

 typedef u64 erofs_nid_t;
 typedef u64 erofs_off_t;
 /* data type for filesystem-wide blocks number */
 typedef u32 erofs_blk_t;

 struct erofs_device_info {
 	char *path;
 	struct erofs_fscache *fscache;
 	struct bdev_handle *bdev_handle;
 	struct dax_device *dax_dev;
 	u64 dax_part_off;

 	u32 blocks;
 	u32 mapped_blkaddr;
 };

 enum {
 	EROFS_SYNC_DECOMPRESS_AUTO,
 	EROFS_SYNC_DECOMPRESS_FORCE_ON,
 	EROFS_SYNC_DECOMPRESS_FORCE_OFF
 };

 struct erofs_mount_opts {
 #ifdef CONFIG_EROFS_FS_ZIP
 	/* current strategy of how to use managed cache */
 	unsigned char cache_strategy;
 	/* strategy of sync decompression (0 - auto, 1 - force on, 2 - force off) */
 	unsigned int sync_decompress;

 	/* threshold for decompression synchronously */
 	unsigned int max_sync_decompress_pages;
 #endif
 	unsigned int mount_opt;
 };

 struct erofs_dev_context {
 	struct idr tree;
 	struct rw_semaphore rwsem;

 	unsigned int extra_devices;
 	bool flatdev;
 };

 struct erofs_fs_context {
 	struct erofs_mount_opts opt;
 	struct erofs_dev_context *devs;
 	char *fsid;
 	char *domain_id;
 };

 /* all filesystem-wide lz4 configurations */
 struct erofs_sb_lz4_info {
 	/* # of pages needed for EROFS lz4 rolling decompression */
 	u16 max_distance_pages;
 	/* maximum possible blocks for pclusters in the filesystem */
 	u16 max_pclusterblks;
 };

 struct erofs_domain {
 	refcount_t ref;
 	struct list_head list;
 	struct fscache_volume *volume;
 	char *domain_id;
 };

 struct erofs_fscache {
 	struct fscache_cookie *cookie;
 	struct inode *inode;	/* anonymous inode for the blob */

 	/* used for share domain mode */
 	struct erofs_domain *domain;
 	struct list_head node;
 	refcount_t ref;
 	char *name;
 };

 struct erofs_xattr_prefix_item {
 	struct erofs_xattr_long_prefix *prefix;
 	u8 infix_len;
 };

 struct erofs_sb_info {
 	struct erofs_mount_opts opt;	/* options */
 #ifdef CONFIG_EROFS_FS_ZIP
 	/* list for all registered superblocks, mainly for shrinker */
 	struct list_head list;
 	struct mutex umount_mutex;

 	/* managed XArray arranged in physical block number */
 	struct xarray managed_pslots;

 	unsigned int shrinker_run_no;
 	u16 available_compr_algs;

 	/* pseudo inode to manage cached pages */
 	struct inode *managed_cache;

 	struct erofs_sb_lz4_info lz4;
 #endif	/* CONFIG_EROFS_FS_ZIP */
 	struct inode *packed_inode;
 	struct erofs_dev_context *devs;
 	struct dax_device *dax_dev;
 	u64 dax_part_off;
 	u64 total_blocks;
 	u32 primarydevice_blocks;

 	u32 meta_blkaddr;
 #ifdef CONFIG_EROFS_FS_XATTR
 	u32 xattr_blkaddr;
 	u32 xattr_prefix_start;
 	u8 xattr_prefix_count;
 	struct erofs_xattr_prefix_item *xattr_prefixes;
 	unsigned int xattr_filter_reserved;
 #endif
 	u16 device_id_mask;	/* valid bits of device id to be used */

 	unsigned char islotbits;	/* inode slot unit size in bit shift */
 	unsigned char blkszbits;	/* filesystem block size in bit shift */

 	u32 sb_size;			/* total superblock size */
 	u32 build_time_nsec;
 	u64 build_time;

 	/* what we really care is nid, rather than ino.. */
 	erofs_nid_t root_nid;
 	erofs_nid_t packed_nid;
 	/* used for statfs, f_files - f_favail */
 	u64 inos;

 	u8 uuid[16];                    /* 128-bit uuid for volume */
 	u8 volume_name[16];             /* volume name */
 	u32 feature_compat;
 	u32 feature_incompat;

 	/* sysfs support */
 	struct kobject s_kobj;		/* /sys/fs/erofs/<devname> */
 	struct completion s_kobj_unregister;

 	/* fscache support */
 	struct fscache_volume *volume;
 	struct erofs_fscache *s_fscache;
 	struct erofs_domain *domain;
 	char *fsid;
 	char *domain_id;
 };

 #define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info)
 #define EROFS_I_SB(inode) ((struct erofs_sb_info *)(inode)->i_sb->s_fs_info)

 /* Mount flags set via mount options or defaults */
 #define EROFS_MOUNT_XATTR_USER		0x00000010
 #define EROFS_MOUNT_POSIX_ACL		0x00000020
 #define EROFS_MOUNT_DAX_ALWAYS		0x00000040
 #define EROFS_MOUNT_DAX_NEVER		0x00000080

 #define clear_opt(opt, option)	((opt)->mount_opt &= ~EROFS_MOUNT_##option)
 #define set_opt(opt, option)	((opt)->mount_opt |= EROFS_MOUNT_##option)
 #define test_opt(opt, option)	((opt)->mount_opt & EROFS_MOUNT_##option)

 static inline bool erofs_is_fscache_mode(struct super_block *sb)
 {
 	return IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && !sb->s_bdev;
 }

 enum {
 	EROFS_ZIP_CACHE_DISABLED,
 	EROFS_ZIP_CACHE_READAHEAD,
 	EROFS_ZIP_CACHE_READAROUND
 };

 /* basic unit of the workstation of a super_block */
 struct erofs_workgroup {
 	pgoff_t index;
 	struct lockref lockref;
 };

 enum erofs_kmap_type {
 	EROFS_NO_KMAP,		/* don't map the buffer */
 	EROFS_KMAP,		/* use kmap_local_page() to map the buffer */
 };

 struct erofs_buf {
 	struct inode *inode;
 	struct page *page;
 	void *base;
 	enum erofs_kmap_type kmap_type;
 };
 #define __EROFS_BUF_INITIALIZER	((struct erofs_buf){ .page = NULL })

 #define erofs_blknr(sb, addr)	((addr) >> (sb)->s_blocksize_bits)
 #define erofs_blkoff(sb, addr)	((addr) & ((sb)->s_blocksize - 1))
 #define erofs_pos(sb, blk)	((erofs_off_t)(blk) << (sb)->s_blocksize_bits)
 #define erofs_iblks(i)	(round_up((i)->i_size, i_blocksize(i)) >> (i)->i_blkbits)

 #define EROFS_FEATURE_FUNCS(name, compat, feature) \
 static inline bool erofs_sb_has_##name(struct erofs_sb_info *sbi) \
 { \
 	return sbi->feature_##compat & EROFS_FEATURE_##feature; \
 }

 EROFS_FEATURE_FUNCS(zero_padding, incompat, INCOMPAT_ZERO_PADDING)
 EROFS_FEATURE_FUNCS(compr_cfgs, incompat, INCOMPAT_COMPR_CFGS)
 EROFS_FEATURE_FUNCS(big_pcluster, incompat, INCOMPAT_BIG_PCLUSTER)
 EROFS_FEATURE_FUNCS(chunked_file, incompat, INCOMPAT_CHUNKED_FILE)
 EROFS_FEATURE_FUNCS(device_table, incompat, INCOMPAT_DEVICE_TABLE)
 EROFS_FEATURE_FUNCS(compr_head2, incompat, INCOMPAT_COMPR_HEAD2)
 EROFS_FEATURE_FUNCS(ztailpacking, incompat, INCOMPAT_ZTAILPACKING)
 EROFS_FEATURE_FUNCS(fragments, incompat, INCOMPAT_FRAGMENTS)
 EROFS_FEATURE_FUNCS(dedupe, incompat, INCOMPAT_DEDUPE)
 EROFS_FEATURE_FUNCS(xattr_prefixes, incompat, INCOMPAT_XATTR_PREFIXES)
 EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)
 EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)

 /* atomic flag definitions */
 #define EROFS_I_EA_INITED_BIT	0
 #define EROFS_I_Z_INITED_BIT	1

 /* bitlock definitions (arranged in reverse order) */
 #define EROFS_I_BL_XATTR_BIT	(BITS_PER_LONG - 1)
 #define EROFS_I_BL_Z_BIT	(BITS_PER_LONG - 2)

 struct erofs_inode {
 	erofs_nid_t nid;

 	/* atomic flags (including bitlocks) */
 	unsigned long flags;

 	unsigned char datalayout;
 	unsigned char inode_isize;
 	unsigned int xattr_isize;

 	unsigned int xattr_name_filter;
 	unsigned int xattr_shared_count;
 	unsigned int *xattr_shared_xattrs;

 	union {
 		erofs_blk_t raw_blkaddr;
 		struct {
 			unsigned short	chunkformat;
 			unsigned char	chunkbits;
 		};
 #ifdef CONFIG_EROFS_FS_ZIP
 		struct {
 			unsigned short z_advise;
 			unsigned char  z_algorithmtype[2];
 			unsigned char  z_logical_clusterbits;
 			unsigned long  z_tailextent_headlcn;
 			union {
 				struct {
 					erofs_off_t    z_idataoff;
 					unsigned short z_idata_size;
 				};
 				erofs_off_t z_fragmentoff;
 			};
 		};
 #endif	/* CONFIG_EROFS_FS_ZIP */
 	};
 	/* the corresponding vfs inode */
 	struct inode vfs_inode;
 };

 #define EROFS_I(ptr)	container_of(ptr, struct erofs_inode, vfs_inode)

 static inline erofs_off_t erofs_iloc(struct inode *inode)
 {
 	struct erofs_sb_info *sbi = EROFS_I_SB(inode);

 	return erofs_pos(inode->i_sb, sbi->meta_blkaddr) +
 		(EROFS_I(inode)->nid << sbi->islotbits);
 }

 static inline unsigned int erofs_inode_version(unsigned int ifmt)
 {
 	return (ifmt >> EROFS_I_VERSION_BIT) & EROFS_I_VERSION_MASK;
 }

 static inline unsigned int erofs_inode_datalayout(unsigned int ifmt)
 {
 	return (ifmt >> EROFS_I_DATALAYOUT_BIT) & EROFS_I_DATALAYOUT_MASK;
 }

 /*
  * Different from grab_cache_page_nowait(), reclaiming is never triggered
  * when allocating new pages.
  */
 static inline
 struct page *erofs_grab_cache_page_nowait(struct address_space *mapping,
 					  pgoff_t index)
 {
 	return pagecache_get_page(mapping, index,
 			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
 			readahead_gfp_mask(mapping) & ~__GFP_RECLAIM);
 }

 /* Has a disk mapping */
 #define EROFS_MAP_MAPPED	0x0001
 /* Located in metadata (could be copied from bd_inode) */
 #define EROFS_MAP_META		0x0002
 /* The extent is encoded */
 #define EROFS_MAP_ENCODED	0x0004
 /* The length of extent is full */
 #define EROFS_MAP_FULL_MAPPED	0x0008
 /* Located in the special packed inode */
 #define EROFS_MAP_FRAGMENT	0x0010
 /* The extent refers to partial decompressed data */
 #define EROFS_MAP_PARTIAL_REF	0x0020

 struct erofs_map_blocks {
 	struct erofs_buf buf;

 	erofs_off_t m_pa, m_la;
 	u64 m_plen, m_llen;

 	unsigned short m_deviceid;
 	char m_algorithmformat;
 	unsigned int m_flags;
 };

 /*
  * Used to get the exact decompressed length, e.g. fiemap (consider lookback
  * approach instead if possible since it's more metadata lightweight.)
  */
 #define EROFS_GET_BLOCKS_FIEMAP		0x0001
 /* Used to map the whole extent if non-negligible data is requested for LZMA */
 #define EROFS_GET_BLOCKS_READMORE	0x0002
 /* Used to map tail extent for tailpacking inline or fragment pcluster */
 #define EROFS_GET_BLOCKS_FINDTAIL	0x0004

 enum {
 	Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX,
 	Z_EROFS_COMPRESSION_INTERLACED,
 	Z_EROFS_COMPRESSION_RUNTIME_MAX
 };

 struct erofs_map_dev {
 	struct erofs_fscache *m_fscache;
 	struct block_device *m_bdev;
 	struct dax_device *m_daxdev;
 	u64 m_dax_part_off;

 	erofs_off_t m_pa;
 	unsigned int m_deviceid;
 };

 extern struct file_system_type erofs_fs_type;
 extern const struct super_operations erofs_sops;

 extern const struct address_space_operations erofs_raw_access_aops;
 extern const struct address_space_operations z_erofs_aops;
 extern const struct address_space_operations erofs_fscache_access_aops;

 extern const struct inode_operations erofs_generic_iops;
 extern const struct inode_operations erofs_symlink_iops;
 extern const struct inode_operations erofs_fast_symlink_iops;
 extern const struct inode_operations erofs_dir_iops;

 extern const struct file_operations erofs_file_fops;
 extern const struct file_operations erofs_dir_fops;

 extern const struct iomap_ops z_erofs_iomap_report_ops;

 /* flags for erofs_fscache_register_cookie() */
 #define EROFS_REG_COOKIE_SHARE		0x0001
 #define EROFS_REG_COOKIE_NEED_NOEXIST	0x0002

 void *erofs_read_metadata(struct super_block *sb, struct erofs_buf *buf,
 			  erofs_off_t *offset, int *lengthp);
 void erofs_unmap_metabuf(struct erofs_buf *buf);
 void erofs_put_metabuf(struct erofs_buf *buf);
 void *erofs_bread(struct erofs_buf *buf, erofs_blk_t blkaddr,
 		  enum erofs_kmap_type type);
 void erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb);
 void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
 			 erofs_blk_t blkaddr, enum erofs_kmap_type type);
 int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *dev);
 int erofs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		 u64 start, u64 len);
 int erofs_map_blocks(struct inode *inode, struct erofs_map_blocks *map);
 struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid);
 int erofs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		  struct kstat *stat, u32 request_mask,
 		  unsigned int query_flags);
 int erofs_namei(struct inode *dir, const struct qstr *name,
 		erofs_nid_t *nid, unsigned int *d_type);

 static inline void *erofs_vm_map_ram(struct page **pages, unsigned int count)
 {
 	int retried = 0;

 	while (1) {
 		void *p = vm_map_ram(pages, count, -1);

 		/* retry two more times (totally 3 times) */
 		if (p || ++retried >= 3)
 			return p;
 		vm_unmap_aliases();
 	}
 	return NULL;
 }

 int erofs_register_sysfs(struct super_block *sb);
 void erofs_unregister_sysfs(struct super_block *sb);
 int __init erofs_init_sysfs(void);
 void erofs_exit_sysfs(void);

 struct page *erofs_allocpage(struct page **pagepool, gfp_t gfp);
 static inline void erofs_pagepool_add(struct page **pagepool, struct page *page)
 {
 	set_page_private(page, (unsigned long)*pagepool);
 	*pagepool = page;
 }
 void erofs_release_pages(struct page **pagepool);

 #ifdef CONFIG_EROFS_FS_ZIP
 void erofs_workgroup_put(struct erofs_workgroup *grp);
 struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
 					     pgoff_t index);
 struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
 					       struct erofs_workgroup *grp);
 void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
 void erofs_shrinker_register(struct super_block *sb);
 void erofs_shrinker_unregister(struct super_block *sb);
 int __init erofs_init_shrinker(void);
 void erofs_exit_shrinker(void);
 int __init z_erofs_init_zip_subsystem(void);
 void z_erofs_exit_zip_subsystem(void);
 int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 				       struct erofs_workgroup *egrp);
 int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map,
 			    int flags);
 void *erofs_get_pcpubuf(unsigned int requiredpages);
 void erofs_put_pcpubuf(void *ptr);
 int erofs_pcpubuf_growsize(unsigned int nrpages);
 void __init erofs_pcpubuf_init(void);
 void erofs_pcpubuf_exit(void);
 int erofs_init_managed_cache(struct super_block *sb);
 int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb);
 #else
 static inline void erofs_shrinker_register(struct super_block *sb) {}
 static inline void erofs_shrinker_unregister(struct super_block *sb) {}
 static inline int erofs_init_shrinker(void) { return 0; }
 static inline void erofs_exit_shrinker(void) {}
 static inline int z_erofs_init_zip_subsystem(void) { return 0; }
 static inline void z_erofs_exit_zip_subsystem(void) {}
 static inline void erofs_pcpubuf_init(void) {}
 static inline void erofs_pcpubuf_exit(void) {}
 static inline int erofs_init_managed_cache(struct super_block *sb) { return 0; }
 #endif	/* !CONFIG_EROFS_FS_ZIP */

 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
 int __init z_erofs_lzma_init(void);
 void z_erofs_lzma_exit(void);
 #else
 static inline int z_erofs_lzma_init(void) { return 0; }
 static inline int z_erofs_lzma_exit(void) { return 0; }
 #endif	/* !CONFIG_EROFS_FS_ZIP_LZMA */

 #ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
 int __init z_erofs_deflate_init(void);
 void z_erofs_deflate_exit(void);
 #else
 static inline int z_erofs_deflate_init(void) { return 0; }
 static inline int z_erofs_deflate_exit(void) { return 0; }
 #endif	/* !CONFIG_EROFS_FS_ZIP_DEFLATE */

 #ifdef CONFIG_EROFS_FS_ONDEMAND
 int erofs_fscache_register_fs(struct super_block *sb);
 void erofs_fscache_unregister_fs(struct super_block *sb);

 struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
 					char *name, unsigned int flags);
 void erofs_fscache_unregister_cookie(struct erofs_fscache *fscache);
 #else
 static inline int erofs_fscache_register_fs(struct super_block *sb)
 {
 	return -EOPNOTSUPP;
 }
 static inline void erofs_fscache_unregister_fs(struct super_block *sb) {}

 static inline
 struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
 					char *name, unsigned int flags)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }

 static inline void erofs_fscache_unregister_cookie(struct erofs_fscache *fscache)
 {
 }
 #endif

 #define EFSCORRUPTED    EUCLEAN         /* Filesystem is corrupted */

 #endif	/* __EROFS_INTERNAL_H */
	/* SPDX-License-Identifier: GPL-2.0-only */
	/*
	* Copyright (C) 2017-2018 HUAWEI, Inc.
	* https://www.huawei.com/
	* Copyright (C) 2021, Alibaba Cloud
	*/
	#ifndef __EROFS_INTERNAL_H
	#define __EROFS_INTERNAL_H

	#include <linux/fs.h>
	#include <linux/dax.h>
	#include <linux/dcache.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/pagemap.h>
	#include <linux/bio.h>
	#include <linux/magic.h>
	#include <linux/slab.h>
	#include <linux/vmalloc.h>
	#include <linux/iomap.h>
	#include "erofs_fs.h"

	/* redefine pr_fmt "erofs: " */
	#undef pr_fmt
	#define pr_fmt(fmt) "erofs: " fmt

	__printf(3, 4) void _erofs_err(struct super_block *sb,
	const char function, const char fmt, ...);
	#define erofs_err(sb, fmt, ...) \
	_erofs_err(sb, __func__, fmt "\n", ##__VA_ARGS__)
	__printf(3, 4) void _erofs_info(struct super_block *sb,
	const char function, const char fmt, ...);
	#define erofs_info(sb, fmt, ...) \
	_erofs_info(sb, __func__, fmt "\n", ##__VA_ARGS__)
	#ifdef CONFIG_EROFS_FS_DEBUG
	#define DBG_BUGON BUG_ON
	#else
	#define DBG_BUGON(x) ((void)(x))
	#endif /* !CONFIG_EROFS_FS_DEBUG */

	/* EROFS_SUPER_MAGIC_V1 to represent the whole file system */
	#define EROFS_SUPER_MAGIC EROFS_SUPER_MAGIC_V1

	typedef u64 erofs_nid_t;
	typedef u64 erofs_off_t;
	/* data type for filesystem-wide blocks number */
	typedef u32 erofs_blk_t;

	struct erofs_device_info {
	char *path;
	struct erofs_fscache *fscache;
	struct bdev_handle *bdev_handle;
	struct dax_device *dax_dev;
	u64 dax_part_off;

	u32 blocks;
	u32 mapped_blkaddr;
	};

	enum {
	EROFS_SYNC_DECOMPRESS_AUTO,
	EROFS_SYNC_DECOMPRESS_FORCE_ON,
	EROFS_SYNC_DECOMPRESS_FORCE_OFF
	};

	struct erofs_mount_opts {
	#ifdef CONFIG_EROFS_FS_ZIP
	/* current strategy of how to use managed cache */
	unsigned char cache_strategy;
	/* strategy of sync decompression (0 - auto, 1 - force on, 2 - force off) */
	unsigned int sync_decompress;

	/* threshold for decompression synchronously */
	unsigned int max_sync_decompress_pages;
	#endif
	unsigned int mount_opt;
	};

	struct erofs_dev_context {
	struct idr tree;
	struct rw_semaphore rwsem;

	unsigned int extra_devices;
	bool flatdev;
	};

	struct erofs_fs_context {
	struct erofs_mount_opts opt;
	struct erofs_dev_context *devs;
	char *fsid;
	char *domain_id;
	};

	/* all filesystem-wide lz4 configurations */
	struct erofs_sb_lz4_info {
	/* # of pages needed for EROFS lz4 rolling decompression */
	u16 max_distance_pages;
	/* maximum possible blocks for pclusters in the filesystem */
	u16 max_pclusterblks;
	};

	struct erofs_domain {
	refcount_t ref;
	struct list_head list;
	struct fscache_volume *volume;
	char *domain_id;
	};

	struct erofs_fscache {
	struct fscache_cookie *cookie;
	struct inode inode; / anonymous inode for the blob */

	/* used for share domain mode */
	struct erofs_domain *domain;
	struct list_head node;
	refcount_t ref;
	char *name;
	};

	struct erofs_xattr_prefix_item {
	struct erofs_xattr_long_prefix *prefix;
	u8 infix_len;
	};

	struct erofs_sb_info {
	struct erofs_mount_opts opt; /* options */
	#ifdef CONFIG_EROFS_FS_ZIP
	/* list for all registered superblocks, mainly for shrinker */
	struct list_head list;
	struct mutex umount_mutex;

	/* managed XArray arranged in physical block number */
	struct xarray managed_pslots;

	unsigned int shrinker_run_no;
	u16 available_compr_algs;

	/* pseudo inode to manage cached pages */
	struct inode *managed_cache;

	struct erofs_sb_lz4_info lz4;
	#endif /* CONFIG_EROFS_FS_ZIP */
	struct inode *packed_inode;
	struct erofs_dev_context *devs;
	struct dax_device *dax_dev;
	u64 dax_part_off;
	u64 total_blocks;
	u32 primarydevice_blocks;

	u32 meta_blkaddr;
	#ifdef CONFIG_EROFS_FS_XATTR
	u32 xattr_blkaddr;
	u32 xattr_prefix_start;
	u8 xattr_prefix_count;
	struct erofs_xattr_prefix_item *xattr_prefixes;
	unsigned int xattr_filter_reserved;
	#endif
	u16 device_id_mask; /* valid bits of device id to be used */

	unsigned char islotbits; /* inode slot unit size in bit shift */
	unsigned char blkszbits; /* filesystem block size in bit shift */

	u32 sb_size; /* total superblock size */
	u32 build_time_nsec;
	u64 build_time;

	/* what we really care is nid, rather than ino.. */
	erofs_nid_t root_nid;
	erofs_nid_t packed_nid;
	/* used for statfs, f_files - f_favail */
	u64 inos;

	u8 uuid[16]; /* 128-bit uuid for volume */
	u8 volume_name[16]; /* volume name */
	u32 feature_compat;
	u32 feature_incompat;

	/* sysfs support */
	struct kobject s_kobj; /* /sys/fs/erofs/<devname> */
	struct completion s_kobj_unregister;

	/* fscache support */
	struct fscache_volume *volume;
	struct erofs_fscache *s_fscache;
	struct erofs_domain *domain;
	char *fsid;
	char *domain_id;
	};

	#define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info)
	#define EROFS_I_SB(inode) ((struct erofs_sb_info *)(inode)->i_sb->s_fs_info)

	/* Mount flags set via mount options or defaults */
	#define EROFS_MOUNT_XATTR_USER 0x00000010
	#define EROFS_MOUNT_POSIX_ACL 0x00000020
	#define EROFS_MOUNT_DAX_ALWAYS 0x00000040
	#define EROFS_MOUNT_DAX_NEVER 0x00000080

	#define clear_opt(opt, option) ((opt)->mount_opt &= ~EROFS_MOUNT_##option)
	#define set_opt(opt, option) ((opt)->mount_opt \|= EROFS_MOUNT_##option)
	#define test_opt(opt, option) ((opt)->mount_opt & EROFS_MOUNT_##option)

	static inline bool erofs_is_fscache_mode(struct super_block *sb)
	{
	return IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && !sb->s_bdev;
	}

	enum {
	EROFS_ZIP_CACHE_DISABLED,
	EROFS_ZIP_CACHE_READAHEAD,
	EROFS_ZIP_CACHE_READAROUND
	};

	/* basic unit of the workstation of a super_block */
	struct erofs_workgroup {
	pgoff_t index;
	struct lockref lockref;
	};

	enum erofs_kmap_type {
	EROFS_NO_KMAP, /* don't map the buffer */
	EROFS_KMAP, /* use kmap_local_page() to map the buffer */
	};

	struct erofs_buf {
	struct inode *inode;
	struct page *page;
	void *base;
	enum erofs_kmap_type kmap_type;
	};
	#define __EROFS_BUF_INITIALIZER ((struct erofs_buf){ .page = NULL })

	#define erofs_blknr(sb, addr) ((addr) >> (sb)->s_blocksize_bits)
	#define erofs_blkoff(sb, addr) ((addr) & ((sb)->s_blocksize - 1))
	#define erofs_pos(sb, blk) ((erofs_off_t)(blk) << (sb)->s_blocksize_bits)
	#define erofs_iblks(i) (round_up((i)->i_size, i_blocksize(i)) >> (i)->i_blkbits)

	#define EROFS_FEATURE_FUNCS(name, compat, feature) \
	static inline bool erofs_sb_has_##name(struct erofs_sb_info *sbi) \
	{ \
	return sbi->feature_##compat & EROFS_FEATURE_##feature; \
	}

	EROFS_FEATURE_FUNCS(zero_padding, incompat, INCOMPAT_ZERO_PADDING)
	EROFS_FEATURE_FUNCS(compr_cfgs, incompat, INCOMPAT_COMPR_CFGS)
	EROFS_FEATURE_FUNCS(big_pcluster, incompat, INCOMPAT_BIG_PCLUSTER)
	EROFS_FEATURE_FUNCS(chunked_file, incompat, INCOMPAT_CHUNKED_FILE)
	EROFS_FEATURE_FUNCS(device_table, incompat, INCOMPAT_DEVICE_TABLE)
	EROFS_FEATURE_FUNCS(compr_head2, incompat, INCOMPAT_COMPR_HEAD2)
	EROFS_FEATURE_FUNCS(ztailpacking, incompat, INCOMPAT_ZTAILPACKING)
	EROFS_FEATURE_FUNCS(fragments, incompat, INCOMPAT_FRAGMENTS)
	EROFS_FEATURE_FUNCS(dedupe, incompat, INCOMPAT_DEDUPE)
	EROFS_FEATURE_FUNCS(xattr_prefixes, incompat, INCOMPAT_XATTR_PREFIXES)
	EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)
	EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)

	/* atomic flag definitions */
	#define EROFS_I_EA_INITED_BIT 0
	#define EROFS_I_Z_INITED_BIT 1

	/* bitlock definitions (arranged in reverse order) */
	#define EROFS_I_BL_XATTR_BIT (BITS_PER_LONG - 1)
	#define EROFS_I_BL_Z_BIT (BITS_PER_LONG - 2)

	struct erofs_inode {
	erofs_nid_t nid;

	/* atomic flags (including bitlocks) */
	unsigned long flags;

	unsigned char datalayout;
	unsigned char inode_isize;
	unsigned int xattr_isize;

	unsigned int xattr_name_filter;
	unsigned int xattr_shared_count;
	unsigned int *xattr_shared_xattrs;

	union {
	erofs_blk_t raw_blkaddr;
	struct {
	unsigned short chunkformat;
	unsigned char chunkbits;
	};
	#ifdef CONFIG_EROFS_FS_ZIP
	struct {
	unsigned short z_advise;
	unsigned char z_algorithmtype[2];
	unsigned char z_logical_clusterbits;
	unsigned long z_tailextent_headlcn;
	union {
	struct {
	erofs_off_t z_idataoff;
	unsigned short z_idata_size;
	};
	erofs_off_t z_fragmentoff;
	};
	};
	#endif /* CONFIG_EROFS_FS_ZIP */
	};
	/* the corresponding vfs inode */
	struct inode vfs_inode;
	};

	#define EROFS_I(ptr) container_of(ptr, struct erofs_inode, vfs_inode)

	static inline erofs_off_t erofs_iloc(struct inode *inode)
	{
	struct erofs_sb_info *sbi = EROFS_I_SB(inode);

	return erofs_pos(inode->i_sb, sbi->meta_blkaddr) +
	(EROFS_I(inode)->nid << sbi->islotbits);
	}

	static inline unsigned int erofs_inode_version(unsigned int ifmt)
	{
	return (ifmt >> EROFS_I_VERSION_BIT) & EROFS_I_VERSION_MASK;
	}

	static inline unsigned int erofs_inode_datalayout(unsigned int ifmt)
	{
	return (ifmt >> EROFS_I_DATALAYOUT_BIT) & EROFS_I_DATALAYOUT_MASK;
	}

	/*
	* Different from grab_cache_page_nowait(), reclaiming is never triggered
	* when allocating new pages.
	*/
	static inline
	struct page erofs_grab_cache_page_nowait(struct address_space mapping,
	pgoff_t index)
	{
	return pagecache_get_page(mapping, index,
	FGP_LOCK\|FGP_CREAT\|FGP_NOFS\|FGP_NOWAIT,
	readahead_gfp_mask(mapping) & ~__GFP_RECLAIM);
	}

	/* Has a disk mapping */
	#define EROFS_MAP_MAPPED 0x0001
	/* Located in metadata (could be copied from bd_inode) */
	#define EROFS_MAP_META 0x0002
	/* The extent is encoded */
	#define EROFS_MAP_ENCODED 0x0004
	/* The length of extent is full */
	#define EROFS_MAP_FULL_MAPPED 0x0008
	/* Located in the special packed inode */
	#define EROFS_MAP_FRAGMENT 0x0010
	/* The extent refers to partial decompressed data */
	#define EROFS_MAP_PARTIAL_REF 0x0020

	struct erofs_map_blocks {
	struct erofs_buf buf;

	erofs_off_t m_pa, m_la;
	u64 m_plen, m_llen;

	unsigned short m_deviceid;
	char m_algorithmformat;
	unsigned int m_flags;
	};

	/*
	* Used to get the exact decompressed length, e.g. fiemap (consider lookback
	* approach instead if possible since it's more metadata lightweight.)
	*/
	#define EROFS_GET_BLOCKS_FIEMAP 0x0001
	/* Used to map the whole extent if non-negligible data is requested for LZMA */
	#define EROFS_GET_BLOCKS_READMORE 0x0002
	/* Used to map tail extent for tailpacking inline or fragment pcluster */
	#define EROFS_GET_BLOCKS_FINDTAIL 0x0004

	enum {
	Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX,
	Z_EROFS_COMPRESSION_INTERLACED,
	Z_EROFS_COMPRESSION_RUNTIME_MAX
	};

	struct erofs_map_dev {
	struct erofs_fscache *m_fscache;
	struct block_device *m_bdev;
	struct dax_device *m_daxdev;
	u64 m_dax_part_off;

	erofs_off_t m_pa;
	unsigned int m_deviceid;
	};

	extern struct file_system_type erofs_fs_type;
	extern const struct super_operations erofs_sops;

	extern const struct address_space_operations erofs_raw_access_aops;
	extern const struct address_space_operations z_erofs_aops;
	extern const struct address_space_operations erofs_fscache_access_aops;

	extern const struct inode_operations erofs_generic_iops;
	extern const struct inode_operations erofs_symlink_iops;
	extern const struct inode_operations erofs_fast_symlink_iops;
	extern const struct inode_operations erofs_dir_iops;

	extern const struct file_operations erofs_file_fops;
	extern const struct file_operations erofs_dir_fops;

	extern const struct iomap_ops z_erofs_iomap_report_ops;

	/* flags for erofs_fscache_register_cookie() */
	#define EROFS_REG_COOKIE_SHARE 0x0001
	#define EROFS_REG_COOKIE_NEED_NOEXIST 0x0002

	void erofs_read_metadata(struct super_block sb, struct erofs_buf *buf,
	erofs_off_t offset, int lengthp);
	void erofs_unmap_metabuf(struct erofs_buf *buf);
	void erofs_put_metabuf(struct erofs_buf *buf);
	void erofs_bread(struct erofs_buf buf, erofs_blk_t blkaddr,
	enum erofs_kmap_type type);
	void erofs_init_metabuf(struct erofs_buf buf, struct super_block sb);
	void erofs_read_metabuf(struct erofs_buf buf, struct super_block *sb,
	erofs_blk_t blkaddr, enum erofs_kmap_type type);
	int erofs_map_dev(struct super_block sb, struct erofs_map_dev dev);
	int erofs_fiemap(struct inode inode, struct fiemap_extent_info fieinfo,
	u64 start, u64 len);
	int erofs_map_blocks(struct inode inode, struct erofs_map_blocks map);
	struct inode erofs_iget(struct super_block sb, erofs_nid_t nid);
	int erofs_getattr(struct mnt_idmap idmap, const struct path path,
	struct kstat *stat, u32 request_mask,
	unsigned int query_flags);
	int erofs_namei(struct inode dir, const struct qstr name,
	erofs_nid_t nid, unsigned int d_type);

	static inline void erofs_vm_map_ram(struct page *pages, unsigned int count)
	{
	int retried = 0;

	while (1) {
	void *p = vm_map_ram(pages, count, -1);

	/* retry two more times (totally 3 times) */
	if (p \|\| ++retried >= 3)
	return p;
	vm_unmap_aliases();
	}
	return NULL;
	}

	int erofs_register_sysfs(struct super_block *sb);
	void erofs_unregister_sysfs(struct super_block *sb);
	int __init erofs_init_sysfs(void);
	void erofs_exit_sysfs(void);

	struct page erofs_allocpage(struct page *pagepool, gfp_t gfp);
	static inline void erofs_pagepool_add(struct page *pagepool, struct page page)
	{
	set_page_private(page, (unsigned long)*pagepool);
	*pagepool = page;
	}
	void erofs_release_pages(struct page **pagepool);

	#ifdef CONFIG_EROFS_FS_ZIP
	void erofs_workgroup_put(struct erofs_workgroup *grp);
	struct erofs_workgroup erofs_find_workgroup(struct super_block sb,
	pgoff_t index);
	struct erofs_workgroup erofs_insert_workgroup(struct super_block sb,
	struct erofs_workgroup *grp);
	void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
	void erofs_shrinker_register(struct super_block *sb);
	void erofs_shrinker_unregister(struct super_block *sb);
	int __init erofs_init_shrinker(void);
	void erofs_exit_shrinker(void);
	int __init z_erofs_init_zip_subsystem(void);
	void z_erofs_exit_zip_subsystem(void);
	int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
	struct erofs_workgroup *egrp);
	int z_erofs_map_blocks_iter(struct inode inode, struct erofs_map_blocks map,
	int flags);
	void *erofs_get_pcpubuf(unsigned int requiredpages);
	void erofs_put_pcpubuf(void *ptr);
	int erofs_pcpubuf_growsize(unsigned int nrpages);
	void __init erofs_pcpubuf_init(void);
	void erofs_pcpubuf_exit(void);
	int erofs_init_managed_cache(struct super_block *sb);
	int z_erofs_parse_cfgs(struct super_block sb, struct erofs_super_block dsb);
	#else
	static inline void erofs_shrinker_register(struct super_block *sb) {}
	static inline void erofs_shrinker_unregister(struct super_block *sb) {}
	static inline int erofs_init_shrinker(void) { return 0; }
	static inline void erofs_exit_shrinker(void) {}
	static inline int z_erofs_init_zip_subsystem(void) { return 0; }
	static inline void z_erofs_exit_zip_subsystem(void) {}
	static inline void erofs_pcpubuf_init(void) {}
	static inline void erofs_pcpubuf_exit(void) {}
	static inline int erofs_init_managed_cache(struct super_block *sb) { return 0; }
	#endif /* !CONFIG_EROFS_FS_ZIP */

	#ifdef CONFIG_EROFS_FS_ZIP_LZMA
	int __init z_erofs_lzma_init(void);
	void z_erofs_lzma_exit(void);
	#else
	static inline int z_erofs_lzma_init(void) { return 0; }
	static inline int z_erofs_lzma_exit(void) { return 0; }
	#endif /* !CONFIG_EROFS_FS_ZIP_LZMA */

	#ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
	int __init z_erofs_deflate_init(void);
	void z_erofs_deflate_exit(void);
	#else
	static inline int z_erofs_deflate_init(void) { return 0; }
	static inline int z_erofs_deflate_exit(void) { return 0; }
	#endif /* !CONFIG_EROFS_FS_ZIP_DEFLATE */

	#ifdef CONFIG_EROFS_FS_ONDEMAND
	int erofs_fscache_register_fs(struct super_block *sb);
	void erofs_fscache_unregister_fs(struct super_block *sb);

	struct erofs_fscache erofs_fscache_register_cookie(struct super_block sb,
	char *name, unsigned int flags);
	void erofs_fscache_unregister_cookie(struct erofs_fscache *fscache);
	#else
	static inline int erofs_fscache_register_fs(struct super_block *sb)
	{
	return -EOPNOTSUPP;
	}
	static inline void erofs_fscache_unregister_fs(struct super_block *sb) {}

	static inline
	struct erofs_fscache erofs_fscache_register_cookie(struct super_block sb,
	char *name, unsigned int flags)
	{
	return ERR_PTR(-EOPNOTSUPP);
	}

	static inline void erofs_fscache_unregister_cookie(struct erofs_fscache *fscache)
	{
	}
	#endif

	#define EFSCORRUPTED EUCLEAN /* Filesystem is corrupted */

	#endif /* __EROFS_INTERNAL_H */