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Diffstat (limited to 'include/linux/buffer_head.h')
| -rw-r--r-- | include/linux/buffer_head.h | 480 |
1 files changed, 480 insertions, 0 deletions
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h new file mode 100644 index 000000000..33fa5e94a --- /dev/null +++ b/include/linux/buffer_head.h @@ -0,0 +1,480 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * include/linux/buffer_head.h + * + * Everything to do with buffer_heads. + */ + +#ifndef _LINUX_BUFFER_HEAD_H +#define _LINUX_BUFFER_HEAD_H + +#include <linux/types.h> +#include <linux/blk_types.h> +#include <linux/fs.h> +#include <linux/linkage.h> +#include <linux/pagemap.h> +#include <linux/wait.h> +#include <linux/atomic.h> + +#ifdef CONFIG_BLOCK + +enum bh_state_bits { + BH_Uptodate, /* Contains valid data */ + BH_Dirty, /* Is dirty */ + BH_Lock, /* Is locked */ + BH_Req, /* Has been submitted for I/O */ + + BH_Mapped, /* Has a disk mapping */ + BH_New, /* Disk mapping was newly created by get_block */ + BH_Async_Read, /* Is under end_buffer_async_read I/O */ + BH_Async_Write, /* Is under end_buffer_async_write I/O */ + BH_Delay, /* Buffer is not yet allocated on disk */ + BH_Boundary, /* Block is followed by a discontiguity */ + BH_Write_EIO, /* I/O error on write */ + BH_Unwritten, /* Buffer is allocated on disk but not written */ + BH_Quiet, /* Buffer Error Prinks to be quiet */ + BH_Meta, /* Buffer contains metadata */ + BH_Prio, /* Buffer should be submitted with REQ_PRIO */ + BH_Defer_Completion, /* Defer AIO completion to workqueue */ + + BH_PrivateStart,/* not a state bit, but the first bit available + * for private allocation by other entities + */ +}; + +#define MAX_BUF_PER_PAGE (PAGE_SIZE / 512) + +struct page; +struct buffer_head; +struct address_space; +typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); + +/* + * Historically, a buffer_head was used to map a single block + * within a page, and of course as the unit of I/O through the + * filesystem and block layers. Nowadays the basic I/O unit + * is the bio, and buffer_heads are used for extracting block + * mappings (via a get_block_t call), for tracking state within + * a page (via a page_mapping) and for wrapping bio submission + * for backward compatibility reasons (e.g. submit_bh). + */ +struct buffer_head { + unsigned long b_state; /* buffer state bitmap (see above) */ + struct buffer_head *b_this_page;/* circular list of page's buffers */ + struct page *b_page; /* the page this bh is mapped to */ + + sector_t b_blocknr; /* start block number */ + size_t b_size; /* size of mapping */ + char *b_data; /* pointer to data within the page */ + + struct block_device *b_bdev; + bh_end_io_t *b_end_io; /* I/O completion */ + void *b_private; /* reserved for b_end_io */ + struct list_head b_assoc_buffers; /* associated with another mapping */ + struct address_space *b_assoc_map; /* mapping this buffer is + associated with */ + atomic_t b_count; /* users using this buffer_head */ + spinlock_t b_uptodate_lock; /* Used by the first bh in a page, to + * serialise IO completion of other + * buffers in the page */ +}; + +/* + * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() + * and buffer_foo() functions. + * To avoid reset buffer flags that are already set, because that causes + * a costly cache line transition, check the flag first. + */ +#define BUFFER_FNS(bit, name) \ +static __always_inline void set_buffer_##name(struct buffer_head *bh) \ +{ \ + if (!test_bit(BH_##bit, &(bh)->b_state)) \ + set_bit(BH_##bit, &(bh)->b_state); \ +} \ +static __always_inline void clear_buffer_##name(struct buffer_head *bh) \ +{ \ + clear_bit(BH_##bit, &(bh)->b_state); \ +} \ +static __always_inline int buffer_##name(const struct buffer_head *bh) \ +{ \ + return test_bit(BH_##bit, &(bh)->b_state); \ +} + +/* + * test_set_buffer_foo() and test_clear_buffer_foo() + */ +#define TAS_BUFFER_FNS(bit, name) \ +static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \ +{ \ + return test_and_set_bit(BH_##bit, &(bh)->b_state); \ +} \ +static __always_inline int test_clear_buffer_##name(struct buffer_head *bh) \ +{ \ + return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ +} \ + +/* + * Emit the buffer bitops functions. Note that there are also functions + * of the form "mark_buffer_foo()". These are higher-level functions which + * do something in addition to setting a b_state bit. + */ +BUFFER_FNS(Dirty, dirty) +TAS_BUFFER_FNS(Dirty, dirty) +BUFFER_FNS(Lock, locked) +BUFFER_FNS(Req, req) +TAS_BUFFER_FNS(Req, req) +BUFFER_FNS(Mapped, mapped) +BUFFER_FNS(New, new) +BUFFER_FNS(Async_Read, async_read) +BUFFER_FNS(Async_Write, async_write) +BUFFER_FNS(Delay, delay) +BUFFER_FNS(Boundary, boundary) +BUFFER_FNS(Write_EIO, write_io_error) +BUFFER_FNS(Unwritten, unwritten) +BUFFER_FNS(Meta, meta) +BUFFER_FNS(Prio, prio) +BUFFER_FNS(Defer_Completion, defer_completion) + +static __always_inline void set_buffer_uptodate(struct buffer_head *bh) +{ + /* + * If somebody else already set this uptodate, they will + * have done the memory barrier, and a reader will thus + * see *some* valid buffer state. + * + * Any other serialization (with IO errors or whatever that + * might clear the bit) has to come from other state (eg BH_Lock). + */ + if (test_bit(BH_Uptodate, &bh->b_state)) + return; + + /* + * make it consistent with folio_mark_uptodate + * pairs with smp_load_acquire in buffer_uptodate + */ + smp_mb__before_atomic(); + set_bit(BH_Uptodate, &bh->b_state); +} + +static __always_inline void clear_buffer_uptodate(struct buffer_head *bh) +{ + clear_bit(BH_Uptodate, &bh->b_state); +} + +static __always_inline int buffer_uptodate(const struct buffer_head *bh) +{ + /* + * make it consistent with folio_test_uptodate + * pairs with smp_mb__before_atomic in set_buffer_uptodate + */ + return test_bit_acquire(BH_Uptodate, &bh->b_state); +} + +#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) + +/* If we *know* page->private refers to buffer_heads */ +#define page_buffers(page) \ + ({ \ + BUG_ON(!PagePrivate(page)); \ + ((struct buffer_head *)page_private(page)); \ + }) +#define page_has_buffers(page) PagePrivate(page) +#define folio_buffers(folio) folio_get_private(folio) + +void buffer_check_dirty_writeback(struct folio *folio, + bool *dirty, bool *writeback); + +/* + * Declarations + */ + +void mark_buffer_dirty(struct buffer_head *bh); +void mark_buffer_write_io_error(struct buffer_head *bh); +void touch_buffer(struct buffer_head *bh); +void set_bh_page(struct buffer_head *bh, + struct page *page, unsigned long offset); +bool try_to_free_buffers(struct folio *); +struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, + bool retry); +void create_empty_buffers(struct page *, unsigned long, + unsigned long b_state); +void end_buffer_read_sync(struct buffer_head *bh, int uptodate); +void end_buffer_write_sync(struct buffer_head *bh, int uptodate); +void end_buffer_async_write(struct buffer_head *bh, int uptodate); + +/* Things to do with buffers at mapping->private_list */ +void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); +int inode_has_buffers(struct inode *); +void invalidate_inode_buffers(struct inode *); +int remove_inode_buffers(struct inode *inode); +int sync_mapping_buffers(struct address_space *mapping); +void clean_bdev_aliases(struct block_device *bdev, sector_t block, + sector_t len); +static inline void clean_bdev_bh_alias(struct buffer_head *bh) +{ + clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1); +} + +void mark_buffer_async_write(struct buffer_head *bh); +void __wait_on_buffer(struct buffer_head *); +wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); +struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block, + unsigned size); +struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block, + unsigned size, gfp_t gfp); +void __brelse(struct buffer_head *); +void __bforget(struct buffer_head *); +void __breadahead(struct block_device *, sector_t block, unsigned int size); +struct buffer_head *__bread_gfp(struct block_device *, + sector_t block, unsigned size, gfp_t gfp); +void invalidate_bh_lrus(void); +void invalidate_bh_lrus_cpu(void); +bool has_bh_in_lru(int cpu, void *dummy); +struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); +void free_buffer_head(struct buffer_head * bh); +void unlock_buffer(struct buffer_head *bh); +void __lock_buffer(struct buffer_head *bh); +int sync_dirty_buffer(struct buffer_head *bh); +int __sync_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags); +void write_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags); +void submit_bh(blk_opf_t, struct buffer_head *); +void write_boundary_block(struct block_device *bdev, + sector_t bblock, unsigned blocksize); +int bh_uptodate_or_lock(struct buffer_head *bh); +int __bh_read(struct buffer_head *bh, blk_opf_t op_flags, bool wait); +void __bh_read_batch(int nr, struct buffer_head *bhs[], + blk_opf_t op_flags, bool force_lock); + +extern int buffer_heads_over_limit; + +/* + * Generic address_space_operations implementations for buffer_head-backed + * address_spaces. + */ +void block_invalidate_folio(struct folio *folio, size_t offset, size_t length); +int block_write_full_page(struct page *page, get_block_t *get_block, + struct writeback_control *wbc); +int __block_write_full_page(struct inode *inode, struct page *page, + get_block_t *get_block, struct writeback_control *wbc, + bh_end_io_t *handler); +int block_read_full_folio(struct folio *, get_block_t *); +bool block_is_partially_uptodate(struct folio *, size_t from, size_t count); +int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, + struct page **pagep, get_block_t *get_block); +int __block_write_begin(struct page *page, loff_t pos, unsigned len, + get_block_t *get_block); +int block_write_end(struct file *, struct address_space *, + loff_t, unsigned, unsigned, + struct page *, void *); +int generic_write_end(struct file *, struct address_space *, + loff_t, unsigned, unsigned, + struct page *, void *); +void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); +void clean_page_buffers(struct page *page); +int cont_write_begin(struct file *, struct address_space *, loff_t, + unsigned, struct page **, void **, + get_block_t *, loff_t *); +int generic_cont_expand_simple(struct inode *inode, loff_t size); +int block_commit_write(struct page *page, unsigned from, unsigned to); +int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, + get_block_t get_block); +/* Convert errno to return value from ->page_mkwrite() call */ +static inline vm_fault_t block_page_mkwrite_return(int err) +{ + if (err == 0) + return VM_FAULT_LOCKED; + if (err == -EFAULT || err == -EAGAIN) + return VM_FAULT_NOPAGE; + if (err == -ENOMEM) + return VM_FAULT_OOM; + /* -ENOSPC, -EDQUOT, -EIO ... */ + return VM_FAULT_SIGBUS; +} +sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); +int block_truncate_page(struct address_space *, loff_t, get_block_t *); + +#ifdef CONFIG_MIGRATION +extern int buffer_migrate_folio(struct address_space *, + struct folio *dst, struct folio *src, enum migrate_mode); +extern int buffer_migrate_folio_norefs(struct address_space *, + struct folio *dst, struct folio *src, enum migrate_mode); +#else +#define buffer_migrate_folio NULL +#define buffer_migrate_folio_norefs NULL +#endif + +void buffer_init(void); + +/* + * inline definitions + */ + +static inline void get_bh(struct buffer_head *bh) +{ + atomic_inc(&bh->b_count); +} + +static inline void put_bh(struct buffer_head *bh) +{ + smp_mb__before_atomic(); + atomic_dec(&bh->b_count); +} + +static inline void brelse(struct buffer_head *bh) +{ + if (bh) + __brelse(bh); +} + +static inline void bforget(struct buffer_head *bh) +{ + if (bh) + __bforget(bh); +} + +static inline struct buffer_head * +sb_bread(struct super_block *sb, sector_t block) +{ + return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE); +} + +static inline struct buffer_head * +sb_bread_unmovable(struct super_block *sb, sector_t block) +{ + return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0); +} + +static inline void +sb_breadahead(struct super_block *sb, sector_t block) +{ + __breadahead(sb->s_bdev, block, sb->s_blocksize); +} + +static inline struct buffer_head * +sb_getblk(struct super_block *sb, sector_t block) +{ + return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE); +} + + +static inline struct buffer_head * +sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp) +{ + return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp); +} + +static inline struct buffer_head * +sb_find_get_block(struct super_block *sb, sector_t block) +{ + return __find_get_block(sb->s_bdev, block, sb->s_blocksize); +} + +static inline void +map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) +{ + set_buffer_mapped(bh); + bh->b_bdev = sb->s_bdev; + bh->b_blocknr = block; + bh->b_size = sb->s_blocksize; +} + +static inline void wait_on_buffer(struct buffer_head *bh) +{ + might_sleep(); + if (buffer_locked(bh)) + __wait_on_buffer(bh); +} + +static inline int trylock_buffer(struct buffer_head *bh) +{ + return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state)); +} + +static inline void lock_buffer(struct buffer_head *bh) +{ + might_sleep(); + if (!trylock_buffer(bh)) + __lock_buffer(bh); +} + +static inline struct buffer_head *getblk_unmovable(struct block_device *bdev, + sector_t block, + unsigned size) +{ + return __getblk_gfp(bdev, block, size, 0); +} + +static inline struct buffer_head *__getblk(struct block_device *bdev, + sector_t block, + unsigned size) +{ + return __getblk_gfp(bdev, block, size, __GFP_MOVABLE); +} + +static inline void bh_readahead(struct buffer_head *bh, blk_opf_t op_flags) +{ + if (!buffer_uptodate(bh) && trylock_buffer(bh)) { + if (!buffer_uptodate(bh)) + __bh_read(bh, op_flags, false); + else + unlock_buffer(bh); + } +} + +static inline void bh_read_nowait(struct buffer_head *bh, blk_opf_t op_flags) +{ + if (!bh_uptodate_or_lock(bh)) + __bh_read(bh, op_flags, false); +} + +/* Returns 1 if buffer uptodated, 0 on success, and -EIO on error. */ +static inline int bh_read(struct buffer_head *bh, blk_opf_t op_flags) +{ + if (bh_uptodate_or_lock(bh)) + return 1; + return __bh_read(bh, op_flags, true); +} + +static inline void bh_read_batch(int nr, struct buffer_head *bhs[]) +{ + __bh_read_batch(nr, bhs, 0, true); +} + +static inline void bh_readahead_batch(int nr, struct buffer_head *bhs[], + blk_opf_t op_flags) +{ + __bh_read_batch(nr, bhs, op_flags, false); +} + +/** + * __bread() - reads a specified block and returns the bh + * @bdev: the block_device to read from + * @block: number of block + * @size: size (in bytes) to read + * + * Reads a specified block, and returns buffer head that contains it. + * The page cache is allocated from movable area so that it can be migrated. + * It returns NULL if the block was unreadable. + */ +static inline struct buffer_head * +__bread(struct block_device *bdev, sector_t block, unsigned size) +{ + return __bread_gfp(bdev, block, size, __GFP_MOVABLE); +} + +bool block_dirty_folio(struct address_space *mapping, struct folio *folio); + +#else /* CONFIG_BLOCK */ + +static inline void buffer_init(void) {} +static inline bool try_to_free_buffers(struct folio *folio) { return true; } +static inline int inode_has_buffers(struct inode *inode) { return 0; } +static inline void invalidate_inode_buffers(struct inode *inode) {} +static inline int remove_inode_buffers(struct inode *inode) { return 1; } +static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; } +static inline void invalidate_bh_lrus_cpu(void) {} +static inline bool has_bh_in_lru(int cpu, void *dummy) { return false; } +#define buffer_heads_over_limit 0 + +#endif /* CONFIG_BLOCK */ +#endif /* _LINUX_BUFFER_HEAD_H */ |