335 lines
11 KiB
C
335 lines
11 KiB
C
/*
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* include/linux/buffer_head.h
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*
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* Everything to do with buffer_heads.
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*/
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#ifndef _LINUX_BUFFER_HEAD_H
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#define _LINUX_BUFFER_HEAD_H
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/linkage.h>
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#include <linux/pagemap.h>
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#include <linux/wait.h>
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#include <asm/atomic.h>
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#ifdef CONFIG_BLOCK
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enum bh_state_bits {
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BH_Uptodate, /* Contains valid data */
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BH_Dirty, /* Is dirty */
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BH_Lock, /* Is locked */
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BH_Req, /* Has been submitted for I/O */
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BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
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* IO completion of other buffers in the page
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*/
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BH_Mapped, /* Has a disk mapping */
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BH_New, /* Disk mapping was newly created by get_block */
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BH_Async_Read, /* Is under end_buffer_async_read I/O */
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BH_Async_Write, /* Is under end_buffer_async_write I/O */
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BH_Delay, /* Buffer is not yet allocated on disk */
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BH_Boundary, /* Block is followed by a discontiguity */
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BH_Write_EIO, /* I/O error on write */
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BH_Unwritten, /* Buffer is allocated on disk but not written */
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BH_Quiet, /* Buffer Error Prinks to be quiet */
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BH_PrivateStart,/* not a state bit, but the first bit available
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* for private allocation by other entities
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*/
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};
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#define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
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struct page;
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struct buffer_head;
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struct address_space;
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typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
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/*
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* Historically, a buffer_head was used to map a single block
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* within a page, and of course as the unit of I/O through the
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* filesystem and block layers. Nowadays the basic I/O unit
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* is the bio, and buffer_heads are used for extracting block
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* mappings (via a get_block_t call), for tracking state within
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* a page (via a page_mapping) and for wrapping bio submission
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* for backward compatibility reasons (e.g. submit_bh).
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*/
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struct buffer_head {
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unsigned long b_state; /* buffer state bitmap (see above) */
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struct buffer_head *b_this_page;/* circular list of page's buffers */
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struct page *b_page; /* the page this bh is mapped to */
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sector_t b_blocknr; /* start block number */
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size_t b_size; /* size of mapping */
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char *b_data; /* pointer to data within the page */
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struct block_device *b_bdev;
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bh_end_io_t *b_end_io; /* I/O completion */
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void *b_private; /* reserved for b_end_io */
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struct list_head b_assoc_buffers; /* associated with another mapping */
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struct address_space *b_assoc_map; /* mapping this buffer is
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associated with */
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atomic_t b_count; /* users using this buffer_head */
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};
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/*
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* macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
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* and buffer_foo() functions.
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*/
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#define BUFFER_FNS(bit, name) \
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static inline void set_buffer_##name(struct buffer_head *bh) \
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{ \
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set_bit(BH_##bit, &(bh)->b_state); \
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} \
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static inline void clear_buffer_##name(struct buffer_head *bh) \
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{ \
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clear_bit(BH_##bit, &(bh)->b_state); \
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} \
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static inline int buffer_##name(const struct buffer_head *bh) \
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{ \
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return test_bit(BH_##bit, &(bh)->b_state); \
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}
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/*
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* test_set_buffer_foo() and test_clear_buffer_foo()
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*/
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#define TAS_BUFFER_FNS(bit, name) \
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static inline int test_set_buffer_##name(struct buffer_head *bh) \
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{ \
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return test_and_set_bit(BH_##bit, &(bh)->b_state); \
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} \
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static inline int test_clear_buffer_##name(struct buffer_head *bh) \
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{ \
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return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
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} \
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/*
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* Emit the buffer bitops functions. Note that there are also functions
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* of the form "mark_buffer_foo()". These are higher-level functions which
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* do something in addition to setting a b_state bit.
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*/
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BUFFER_FNS(Uptodate, uptodate)
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BUFFER_FNS(Dirty, dirty)
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TAS_BUFFER_FNS(Dirty, dirty)
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BUFFER_FNS(Lock, locked)
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BUFFER_FNS(Req, req)
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TAS_BUFFER_FNS(Req, req)
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BUFFER_FNS(Mapped, mapped)
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BUFFER_FNS(New, new)
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BUFFER_FNS(Async_Read, async_read)
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BUFFER_FNS(Async_Write, async_write)
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BUFFER_FNS(Delay, delay)
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BUFFER_FNS(Boundary, boundary)
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BUFFER_FNS(Write_EIO, write_io_error)
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BUFFER_FNS(Unwritten, unwritten)
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#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
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#define touch_buffer(bh) mark_page_accessed(bh->b_page)
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/* If we *know* page->private refers to buffer_heads */
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#define page_buffers(page) \
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({ \
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BUG_ON(!PagePrivate(page)); \
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((struct buffer_head *)page_private(page)); \
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})
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#define page_has_buffers(page) PagePrivate(page)
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/*
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* Declarations
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*/
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void mark_buffer_dirty(struct buffer_head *bh);
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void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
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void set_bh_page(struct buffer_head *bh,
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struct page *page, unsigned long offset);
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int try_to_free_buffers(struct page *);
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struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
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int retry);
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void create_empty_buffers(struct page *, unsigned long,
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unsigned long b_state);
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void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
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void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
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void end_buffer_async_write(struct buffer_head *bh, int uptodate);
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/* Things to do with buffers at mapping->private_list */
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void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
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int inode_has_buffers(struct inode *);
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void invalidate_inode_buffers(struct inode *);
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int remove_inode_buffers(struct inode *inode);
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int sync_mapping_buffers(struct address_space *mapping);
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void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
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void mark_buffer_async_write(struct buffer_head *bh);
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void __wait_on_buffer(struct buffer_head *);
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wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
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struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
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unsigned size);
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struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
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unsigned size);
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void __brelse(struct buffer_head *);
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void __bforget(struct buffer_head *);
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void __breadahead(struct block_device *, sector_t block, unsigned int size);
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struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
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void invalidate_bh_lrus(void);
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struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
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void free_buffer_head(struct buffer_head * bh);
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void unlock_buffer(struct buffer_head *bh);
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void __lock_buffer(struct buffer_head *bh);
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void ll_rw_block(int, int, struct buffer_head * bh[]);
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int sync_dirty_buffer(struct buffer_head *bh);
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int __sync_dirty_buffer(struct buffer_head *bh, int rw);
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void write_dirty_buffer(struct buffer_head *bh, int rw);
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int submit_bh(int, struct buffer_head *);
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void write_boundary_block(struct block_device *bdev,
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sector_t bblock, unsigned blocksize);
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int bh_uptodate_or_lock(struct buffer_head *bh);
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int bh_submit_read(struct buffer_head *bh);
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extern int buffer_heads_over_limit;
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/*
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* Generic address_space_operations implementations for buffer_head-backed
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* address_spaces.
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*/
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void block_invalidatepage(struct page *page, unsigned long offset);
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int block_write_full_page(struct page *page, get_block_t *get_block,
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struct writeback_control *wbc);
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int block_write_full_page_endio(struct page *page, get_block_t *get_block,
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struct writeback_control *wbc, bh_end_io_t *handler);
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int block_read_full_page(struct page*, get_block_t*);
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int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
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unsigned long from);
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int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
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unsigned flags, struct page **pagep, get_block_t *get_block);
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int __block_write_begin(struct page *page, loff_t pos, unsigned len,
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get_block_t *get_block);
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int block_write_end(struct file *, struct address_space *,
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loff_t, unsigned, unsigned,
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struct page *, void *);
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int generic_write_end(struct file *, struct address_space *,
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loff_t, unsigned, unsigned,
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struct page *, void *);
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void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
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int cont_write_begin(struct file *, struct address_space *, loff_t,
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unsigned, unsigned, struct page **, void **,
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get_block_t *, loff_t *);
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int generic_cont_expand_simple(struct inode *inode, loff_t size);
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int block_commit_write(struct page *page, unsigned from, unsigned to);
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int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
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get_block_t get_block);
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sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
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int block_truncate_page(struct address_space *, loff_t, get_block_t *);
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int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
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struct page **, void **, get_block_t*);
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int nobh_write_end(struct file *, struct address_space *,
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loff_t, unsigned, unsigned,
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struct page *, void *);
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int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
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int nobh_writepage(struct page *page, get_block_t *get_block,
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struct writeback_control *wbc);
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void buffer_init(void);
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/*
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* inline definitions
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*/
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static inline void attach_page_buffers(struct page *page,
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struct buffer_head *head)
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{
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page_cache_get(page);
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SetPagePrivate(page);
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set_page_private(page, (unsigned long)head);
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}
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static inline void get_bh(struct buffer_head *bh)
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{
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atomic_inc(&bh->b_count);
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}
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static inline void put_bh(struct buffer_head *bh)
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{
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smp_mb__before_atomic_dec();
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atomic_dec(&bh->b_count);
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}
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static inline void brelse(struct buffer_head *bh)
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{
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if (bh)
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__brelse(bh);
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}
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static inline void bforget(struct buffer_head *bh)
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{
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if (bh)
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__bforget(bh);
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}
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static inline struct buffer_head *
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sb_bread(struct super_block *sb, sector_t block)
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{
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return __bread(sb->s_bdev, block, sb->s_blocksize);
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}
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static inline void
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sb_breadahead(struct super_block *sb, sector_t block)
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{
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__breadahead(sb->s_bdev, block, sb->s_blocksize);
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}
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static inline struct buffer_head *
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sb_getblk(struct super_block *sb, sector_t block)
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{
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return __getblk(sb->s_bdev, block, sb->s_blocksize);
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}
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static inline struct buffer_head *
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sb_find_get_block(struct super_block *sb, sector_t block)
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{
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return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
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}
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static inline void
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map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
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{
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set_buffer_mapped(bh);
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bh->b_bdev = sb->s_bdev;
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bh->b_blocknr = block;
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bh->b_size = sb->s_blocksize;
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}
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static inline void wait_on_buffer(struct buffer_head *bh)
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{
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might_sleep();
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if (buffer_locked(bh))
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__wait_on_buffer(bh);
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}
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static inline int trylock_buffer(struct buffer_head *bh)
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{
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return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
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}
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static inline void lock_buffer(struct buffer_head *bh)
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{
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might_sleep();
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if (!trylock_buffer(bh))
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__lock_buffer(bh);
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}
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extern int __set_page_dirty_buffers(struct page *page);
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#else /* CONFIG_BLOCK */
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static inline void buffer_init(void) {}
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static inline int try_to_free_buffers(struct page *page) { return 1; }
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static inline int inode_has_buffers(struct inode *inode) { return 0; }
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static inline void invalidate_inode_buffers(struct inode *inode) {}
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static inline int remove_inode_buffers(struct inode *inode) { return 1; }
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static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
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#endif /* CONFIG_BLOCK */
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#endif /* _LINUX_BUFFER_HEAD_H */
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