| /* 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/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(Uptodate, uptodate) |
| 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) |
| |
| #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) |
| |
| void buffer_check_dirty_writeback(struct page *page, |
| 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); |
| int try_to_free_buffers(struct page *); |
| 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); |
| void __breadahead_gfp(struct block_device *, sector_t block, unsigned int size, |
| gfp_t gfp); |
| 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); |
| void ll_rw_block(int, int, int, struct buffer_head * bh[]); |
| int sync_dirty_buffer(struct buffer_head *bh); |
| int __sync_dirty_buffer(struct buffer_head *bh, int op_flags); |
| void write_dirty_buffer(struct buffer_head *bh, int op_flags); |
| int submit_bh(int, int, 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_submit_read(struct buffer_head *bh); |
| |
| extern int buffer_heads_over_limit; |
| |
| /* |
| * Generic address_space_operations implementations for buffer_head-backed |
| * address_spaces. |
| */ |
| void block_invalidatepage(struct page *page, unsigned int offset, |
| unsigned int 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_page(struct page*, get_block_t*); |
| int block_is_partially_uptodate(struct page *page, unsigned long from, |
| unsigned long count); |
| int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, |
| unsigned flags, 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, 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 *); |
| int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned, |
| struct page **, void **, get_block_t*); |
| int nobh_write_end(struct file *, struct address_space *, |
| loff_t, unsigned, unsigned, |
| struct page *, void *); |
| int nobh_truncate_page(struct address_space *, loff_t, get_block_t *); |
| int nobh_writepage(struct page *page, get_block_t *get_block, |
| struct writeback_control *wbc); |
| |
| 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 void |
| sb_breadahead_unmovable(struct super_block *sb, sector_t block) |
| { |
| __breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0); |
| } |
| |
| 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); |
| } |
| |
| /** |
| * __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); |
| } |
| |
| extern int __set_page_dirty_buffers(struct page *page); |
| |
| #else /* CONFIG_BLOCK */ |
| |
| static inline void buffer_init(void) {} |
| static inline int try_to_free_buffers(struct page *page) { return 1; } |
| 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 */ |