fs/erofs/internal.h - linux/kernel/git/paulmck/linux-rcu - 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/dcache.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 #include <linux/bio.h>
 #include <linux/buffer_head.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 erofs_dbg(x, ...)       pr_debug(x "\n", ##__VA_ARGS__)
 #define DBG_BUGON               BUG_ON
 #else
 #define erofs_dbg(x, ...)       ((void)0)
 #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_fs_context {
 #ifdef CONFIG_EROFS_FS_ZIP
 	/* current strategy of how to use managed cache */
 	unsigned char cache_strategy;
 	/* strategy of sync decompression (false - auto, true - force on) */
 	bool readahead_sync_decompress;

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

 /* 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_sb_info {
 #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 dax_device *dax_dev;
 	u32 blocks;
 	u32 meta_blkaddr;
 #ifdef CONFIG_EROFS_FS_XATTR
 	u32 xattr_blkaddr;
 #endif

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

 	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;
 	/* 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;

 	struct erofs_fs_context ctx;	/* options */
 };

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

 enum {
 	EROFS_ZIP_CACHE_DISABLED,
 	EROFS_ZIP_CACHE_READAHEAD,
 	EROFS_ZIP_CACHE_READAROUND
 };

 #ifdef CONFIG_EROFS_FS_ZIP
 #define EROFS_LOCKED_MAGIC     (INT_MIN | 0xE0F510CCL)

 /* basic unit of the workstation of a super_block */
 struct erofs_workgroup {
 	/* the workgroup index in the workstation */
 	pgoff_t index;

 	/* overall workgroup reference count */
 	atomic_t refcount;
 };

 #if defined(CONFIG_SMP)
 static inline bool erofs_workgroup_try_to_freeze(struct erofs_workgroup *grp,
 						 int val)
 {
 	preempt_disable();
 	if (val != atomic_cmpxchg(&grp->refcount, val, EROFS_LOCKED_MAGIC)) {
 		preempt_enable();
 		return false;
 	}
 	return true;
 }

 static inline void erofs_workgroup_unfreeze(struct erofs_workgroup *grp,
 					    int orig_val)
 {
 	/*
 	 * other observers should notice all modifications
 	 * in the freezing period.
 	 */
 	smp_mb();
 	atomic_set(&grp->refcount, orig_val);
 	preempt_enable();
 }

 static inline int erofs_wait_on_workgroup_freezed(struct erofs_workgroup *grp)
 {
 	return atomic_cond_read_relaxed(&grp->refcount,
 					VAL != EROFS_LOCKED_MAGIC);
 }
 #else
 static inline bool erofs_workgroup_try_to_freeze(struct erofs_workgroup *grp,
 						 int val)
 {
 	preempt_disable();
 	/* no need to spin on UP platforms, let's just disable preemption. */
 	if (val != atomic_read(&grp->refcount)) {
 		preempt_enable();
 		return false;
 	}
 	return true;
 }

 static inline void erofs_workgroup_unfreeze(struct erofs_workgroup *grp,
 					    int orig_val)
 {
 	preempt_enable();
 }

 static inline int erofs_wait_on_workgroup_freezed(struct erofs_workgroup *grp)
 {
 	int v = atomic_read(&grp->refcount);

 	/* workgroup is never freezed on uniprocessor systems */
 	DBG_BUGON(v == EROFS_LOCKED_MAGIC);
 	return v;
 }
 #endif	/* !CONFIG_SMP */
 #endif	/* !CONFIG_EROFS_FS_ZIP */

 /* we strictly follow PAGE_SIZE and no buffer head yet */
 #define LOG_BLOCK_SIZE		PAGE_SHIFT

 #undef LOG_SECTORS_PER_BLOCK
 #define LOG_SECTORS_PER_BLOCK	(PAGE_SHIFT - 9)

 #undef SECTORS_PER_BLOCK
 #define SECTORS_PER_BLOCK	(1 << SECTORS_PER_BLOCK)

 #define EROFS_BLKSIZ		(1 << LOG_BLOCK_SIZE)

 #if (EROFS_BLKSIZ % 4096 || !EROFS_BLKSIZ)
 #error erofs cannot be used in this platform
 #endif

 #define ROOT_NID(sb)		((sb)->root_nid)

 #define erofs_blknr(addr)       ((addr) / EROFS_BLKSIZ)
 #define erofs_blkoff(addr)      ((addr) % EROFS_BLKSIZ)
 #define blknr_to_addr(nr)       ((erofs_off_t)(nr) * EROFS_BLKSIZ)

 static inline erofs_off_t iloc(struct erofs_sb_info *sbi, erofs_nid_t nid)
 {
 	return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits);
 }

 #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(lz4_0padding, incompat, INCOMPAT_LZ4_0PADDING)
 EROFS_FEATURE_FUNCS(compr_cfgs, incompat, INCOMPAT_COMPR_CFGS)
 EROFS_FEATURE_FUNCS(big_pcluster, incompat, INCOMPAT_BIG_PCLUSTER)
 EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)

 /* 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 short xattr_isize;

 	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;
 		};
 #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 unsigned long erofs_inode_datablocks(struct inode *inode)
 {
 	/* since i_size cannot be changed */
 	return DIV_ROUND_UP(inode->i_size, EROFS_BLKSIZ);
 }

 static inline unsigned int erofs_bitrange(unsigned int value, unsigned int bit,
 					  unsigned int bits)
 {

 	return (value >> bit) & ((1 << bits) - 1);
 }


 static inline unsigned int erofs_inode_version(unsigned int value)
 {
 	return erofs_bitrange(value, EROFS_I_VERSION_BIT,
 			      EROFS_I_VERSION_BITS);
 }

 static inline unsigned int erofs_inode_datalayout(unsigned int value)
 {
 	return erofs_bitrange(value, EROFS_I_DATALAYOUT_BIT,
 			      EROFS_I_DATALAYOUT_BITS);
 }

 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;

 /*
  * Logical to physical block mapping
  *
  * Different with other file systems, it is used for 2 access modes:
  *
  * 1) RAW access mode:
  *
  * Users pass a valid (m_lblk, m_lofs -- usually 0) pair,
  * and get the valid m_pblk, m_pofs and the longest m_len(in bytes).
  *
  * Note that m_lblk in the RAW access mode refers to the number of
  * the compressed ondisk block rather than the uncompressed
  * in-memory block for the compressed file.
  *
  * m_pofs equals to m_lofs except for the inline data page.
  *
  * 2) Normal access mode:
  *
  * If the inode is not compressed, it has no difference with
  * the RAW access mode. However, if the inode is compressed,
  * users should pass a valid (m_lblk, m_lofs) pair, and get
  * the needed m_pblk, m_pofs, m_len to get the compressed data
  * and the updated m_lblk, m_lofs which indicates the start
  * of the corresponding uncompressed data in the file.
  */
 enum {
 	BH_Zipped = BH_PrivateStart,
 	BH_FullMapped,
 };

 /* Has a disk mapping */
 #define EROFS_MAP_MAPPED	(1 << BH_Mapped)
 /* Located in metadata (could be copied from bd_inode) */
 #define EROFS_MAP_META		(1 << BH_Meta)
 /* The extent has been compressed */
 #define EROFS_MAP_ZIPPED	(1 << BH_Zipped)
 /* The length of extent is full */
 #define EROFS_MAP_FULL_MAPPED	(1 << BH_FullMapped)

 struct erofs_map_blocks {
 	erofs_off_t m_pa, m_la;
 	u64 m_plen, m_llen;

 	unsigned int m_flags;

 	struct page *mpage;
 };

 /* Flags used by erofs_map_blocks_flatmode() */
 #define EROFS_GET_BLOCKS_RAW    0x0001
 /*
  * 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	0x0002

 /* zmap.c */
 extern const struct iomap_ops z_erofs_iomap_report_ops;

 #ifdef CONFIG_EROFS_FS_ZIP
 int z_erofs_fill_inode(struct inode *inode);
 int z_erofs_map_blocks_iter(struct inode *inode,
 			    struct erofs_map_blocks *map,
 			    int flags);
 #else
 static inline int z_erofs_fill_inode(struct inode *inode) { return -EOPNOTSUPP; }
 static inline int z_erofs_map_blocks_iter(struct inode *inode,
 					  struct erofs_map_blocks *map,
 					  int flags)
 {
 	return -EOPNOTSUPP;
 }
 #endif	/* !CONFIG_EROFS_FS_ZIP */

 /* data.c */
 extern const struct file_operations erofs_file_fops;
 struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr);
 int erofs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		 u64 start, u64 len);

 /* inode.c */
 static inline unsigned long erofs_inode_hash(erofs_nid_t nid)
 {
 #if BITS_PER_LONG == 32
 	return (nid >> 32) ^ (nid & 0xffffffff);
 #else
 	return nid;
 #endif
 }

 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;

 struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid, bool dir);
 int erofs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 		  struct kstat *stat, u32 request_mask,
 		  unsigned int query_flags);

 /* namei.c */
 extern const struct inode_operations erofs_dir_iops;

 int erofs_namei(struct inode *dir, struct qstr *name,
 		erofs_nid_t *nid, unsigned int *d_type);

 /* dir.c */
 extern const struct file_operations erofs_dir_fops;

 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;
 }

 /* pcpubuf.c */
 void *erofs_get_pcpubuf(unsigned int requiredpages);
 void erofs_put_pcpubuf(void *ptr);
 int erofs_pcpubuf_growsize(unsigned int nrpages);
 void erofs_pcpubuf_init(void);
 void erofs_pcpubuf_exit(void);

 /* utils.c / zdata.c */
 struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp);

 #ifdef CONFIG_EROFS_FS_ZIP
 int 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 erofs_try_to_free_cached_page(struct page *page);
 int z_erofs_load_lz4_config(struct super_block *sb,
 			    struct erofs_super_block *dsb,
 			    struct z_erofs_lz4_cfgs *lz4, int len);
 #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 int z_erofs_load_lz4_config(struct super_block *sb,
 				  struct erofs_super_block *dsb,
 				  struct z_erofs_lz4_cfgs *lz4, int len)
 {
 	if (lz4 || dsb->u1.lz4_max_distance) {
 		erofs_err(sb, "lz4 algorithm isn't enabled");
 		return -EINVAL;
 	}
 	return 0;
 }
 #endif	/* !CONFIG_EROFS_FS_ZIP */

 #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/dcache.h>
	#include <linux/mm.h>
	#include <linux/pagemap.h>
	#include <linux/bio.h>
	#include <linux/buffer_head.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 erofs_dbg(x, ...) pr_debug(x "\n", ##__VA_ARGS__)
	#define DBG_BUGON BUG_ON
	#else
	#define erofs_dbg(x, ...) ((void)0)
	#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_fs_context {
	#ifdef CONFIG_EROFS_FS_ZIP
	/* current strategy of how to use managed cache */
	unsigned char cache_strategy;
	/* strategy of sync decompression (false - auto, true - force on) */
	bool readahead_sync_decompress;

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

	/* 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_sb_info {
	#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 dax_device *dax_dev;
	u32 blocks;
	u32 meta_blkaddr;
	#ifdef CONFIG_EROFS_FS_XATTR
	u32 xattr_blkaddr;
	#endif

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

	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;
	/* 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;

	struct erofs_fs_context ctx; /* options */
	};

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

	enum {
	EROFS_ZIP_CACHE_DISABLED,
	EROFS_ZIP_CACHE_READAHEAD,
	EROFS_ZIP_CACHE_READAROUND
	};

	#ifdef CONFIG_EROFS_FS_ZIP
	#define EROFS_LOCKED_MAGIC (INT_MIN \| 0xE0F510CCL)

	/* basic unit of the workstation of a super_block */
	struct erofs_workgroup {
	/* the workgroup index in the workstation */
	pgoff_t index;

	/* overall workgroup reference count */
	atomic_t refcount;
	};

	#if defined(CONFIG_SMP)
	static inline bool erofs_workgroup_try_to_freeze(struct erofs_workgroup *grp,
	int val)
	{
	preempt_disable();
	if (val != atomic_cmpxchg(&grp->refcount, val, EROFS_LOCKED_MAGIC)) {
	preempt_enable();
	return false;
	}
	return true;
	}

	static inline void erofs_workgroup_unfreeze(struct erofs_workgroup *grp,
	int orig_val)
	{
	/*
	* other observers should notice all modifications
	* in the freezing period.
	*/
	smp_mb();
	atomic_set(&grp->refcount, orig_val);
	preempt_enable();
	}

	static inline int erofs_wait_on_workgroup_freezed(struct erofs_workgroup *grp)
	{
	return atomic_cond_read_relaxed(&grp->refcount,
	VAL != EROFS_LOCKED_MAGIC);
	}
	#else
	static inline bool erofs_workgroup_try_to_freeze(struct erofs_workgroup *grp,
	int val)
	{
	preempt_disable();
	/* no need to spin on UP platforms, let's just disable preemption. */
	if (val != atomic_read(&grp->refcount)) {
	preempt_enable();
	return false;
	}
	return true;
	}

	static inline void erofs_workgroup_unfreeze(struct erofs_workgroup *grp,
	int orig_val)
	{
	preempt_enable();
	}

	static inline int erofs_wait_on_workgroup_freezed(struct erofs_workgroup *grp)
	{
	int v = atomic_read(&grp->refcount);

	/* workgroup is never freezed on uniprocessor systems */
	DBG_BUGON(v == EROFS_LOCKED_MAGIC);
	return v;
	}
	#endif /* !CONFIG_SMP */
	#endif /* !CONFIG_EROFS_FS_ZIP */

	/* we strictly follow PAGE_SIZE and no buffer head yet */
	#define LOG_BLOCK_SIZE PAGE_SHIFT

	#undef LOG_SECTORS_PER_BLOCK
	#define LOG_SECTORS_PER_BLOCK (PAGE_SHIFT - 9)

	#undef SECTORS_PER_BLOCK
	#define SECTORS_PER_BLOCK (1 << SECTORS_PER_BLOCK)

	#define EROFS_BLKSIZ (1 << LOG_BLOCK_SIZE)

	#if (EROFS_BLKSIZ % 4096 \|\| !EROFS_BLKSIZ)
	#error erofs cannot be used in this platform
	#endif

	#define ROOT_NID(sb) ((sb)->root_nid)

	#define erofs_blknr(addr) ((addr) / EROFS_BLKSIZ)
	#define erofs_blkoff(addr) ((addr) % EROFS_BLKSIZ)
	#define blknr_to_addr(nr) ((erofs_off_t)(nr) * EROFS_BLKSIZ)

	static inline erofs_off_t iloc(struct erofs_sb_info *sbi, erofs_nid_t nid)
	{
	return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits);
	}

	#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(lz4_0padding, incompat, INCOMPAT_LZ4_0PADDING)
	EROFS_FEATURE_FUNCS(compr_cfgs, incompat, INCOMPAT_COMPR_CFGS)
	EROFS_FEATURE_FUNCS(big_pcluster, incompat, INCOMPAT_BIG_PCLUSTER)
	EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)

	/* 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 short xattr_isize;

	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;
	};
	#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 unsigned long erofs_inode_datablocks(struct inode *inode)
	{
	/* since i_size cannot be changed */
	return DIV_ROUND_UP(inode->i_size, EROFS_BLKSIZ);
	}

	static inline unsigned int erofs_bitrange(unsigned int value, unsigned int bit,
	unsigned int bits)
	{

	return (value >> bit) & ((1 << bits) - 1);
	}


	static inline unsigned int erofs_inode_version(unsigned int value)
	{
	return erofs_bitrange(value, EROFS_I_VERSION_BIT,
	EROFS_I_VERSION_BITS);
	}

	static inline unsigned int erofs_inode_datalayout(unsigned int value)
	{
	return erofs_bitrange(value, EROFS_I_DATALAYOUT_BIT,
	EROFS_I_DATALAYOUT_BITS);
	}

	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;

	/*
	* Logical to physical block mapping
	*
	* Different with other file systems, it is used for 2 access modes:
	*
	* 1) RAW access mode:
	*
	* Users pass a valid (m_lblk, m_lofs -- usually 0) pair,
	* and get the valid m_pblk, m_pofs and the longest m_len(in bytes).
	*
	* Note that m_lblk in the RAW access mode refers to the number of
	* the compressed ondisk block rather than the uncompressed
	* in-memory block for the compressed file.
	*
	* m_pofs equals to m_lofs except for the inline data page.
	*
	* 2) Normal access mode:
	*
	* If the inode is not compressed, it has no difference with
	* the RAW access mode. However, if the inode is compressed,
	* users should pass a valid (m_lblk, m_lofs) pair, and get
	* the needed m_pblk, m_pofs, m_len to get the compressed data
	* and the updated m_lblk, m_lofs which indicates the start
	* of the corresponding uncompressed data in the file.
	*/
	enum {
	BH_Zipped = BH_PrivateStart,
	BH_FullMapped,
	};

	/* Has a disk mapping */
	#define EROFS_MAP_MAPPED (1 << BH_Mapped)
	/* Located in metadata (could be copied from bd_inode) */
	#define EROFS_MAP_META (1 << BH_Meta)
	/* The extent has been compressed */
	#define EROFS_MAP_ZIPPED (1 << BH_Zipped)
	/* The length of extent is full */
	#define EROFS_MAP_FULL_MAPPED (1 << BH_FullMapped)

	struct erofs_map_blocks {
	erofs_off_t m_pa, m_la;
	u64 m_plen, m_llen;

	unsigned int m_flags;

	struct page *mpage;
	};

	/* Flags used by erofs_map_blocks_flatmode() */
	#define EROFS_GET_BLOCKS_RAW 0x0001
	/*
	* 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 0x0002

	/* zmap.c */
	extern const struct iomap_ops z_erofs_iomap_report_ops;

	#ifdef CONFIG_EROFS_FS_ZIP
	int z_erofs_fill_inode(struct inode *inode);
	int z_erofs_map_blocks_iter(struct inode *inode,
	struct erofs_map_blocks *map,
	int flags);
	#else
	static inline int z_erofs_fill_inode(struct inode *inode) { return -EOPNOTSUPP; }
	static inline int z_erofs_map_blocks_iter(struct inode *inode,
	struct erofs_map_blocks *map,
	int flags)
	{
	return -EOPNOTSUPP;
	}
	#endif /* !CONFIG_EROFS_FS_ZIP */

	/* data.c */
	extern const struct file_operations erofs_file_fops;
	struct page erofs_get_meta_page(struct super_block sb, erofs_blk_t blkaddr);
	int erofs_fiemap(struct inode inode, struct fiemap_extent_info fieinfo,
	u64 start, u64 len);

	/* inode.c */
	static inline unsigned long erofs_inode_hash(erofs_nid_t nid)
	{
	#if BITS_PER_LONG == 32
	return (nid >> 32) ^ (nid & 0xffffffff);
	#else
	return nid;
	#endif
	}

	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;

	struct inode erofs_iget(struct super_block sb, erofs_nid_t nid, bool dir);
	int erofs_getattr(struct user_namespace mnt_userns, const struct path path,
	struct kstat *stat, u32 request_mask,
	unsigned int query_flags);

	/* namei.c */
	extern const struct inode_operations erofs_dir_iops;

	int erofs_namei(struct inode dir, struct qstr name,
	erofs_nid_t nid, unsigned int d_type);

	/* dir.c */
	extern const struct file_operations erofs_dir_fops;

	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;
	}

	/* pcpubuf.c */
	void *erofs_get_pcpubuf(unsigned int requiredpages);
	void erofs_put_pcpubuf(void *ptr);
	int erofs_pcpubuf_growsize(unsigned int nrpages);
	void erofs_pcpubuf_init(void);
	void erofs_pcpubuf_exit(void);

	/* utils.c / zdata.c */
	struct page erofs_allocpage(struct list_head pool, gfp_t gfp);

	#ifdef CONFIG_EROFS_FS_ZIP
	int 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 erofs_try_to_free_cached_page(struct page *page);
	int z_erofs_load_lz4_config(struct super_block *sb,
	struct erofs_super_block *dsb,
	struct z_erofs_lz4_cfgs *lz4, int len);
	#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 int z_erofs_load_lz4_config(struct super_block *sb,
	struct erofs_super_block *dsb,
	struct z_erofs_lz4_cfgs *lz4, int len)
	{
	if (lz4 \|\| dsb->u1.lz4_max_distance) {
	erofs_err(sb, "lz4 algorithm isn't enabled");
	return -EINVAL;
	}
	return 0;
	}
	#endif /* !CONFIG_EROFS_FS_ZIP */

	#define EFSCORRUPTED EUCLEAN /* Filesystem is corrupted */

	#endif /* __EROFS_INTERNAL_H */