v4.19.13 snapshot.
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
new file mode 100644
index 0000000..96225a7
--- /dev/null
+++ b/include/linux/buffer_head.h
@@ -0,0 +1,411 @@
+/* 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_Uptodate_Lock,/* Used by the first bh in a page, to serialise
+ * IO completion of other buffers in the page
+ */
+
+ 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 */
+};
+
+/*
+ * 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);
+struct buffer_head *__bread_gfp(struct block_device *,
+ sector_t block, unsigned size, gfp_t gfp);
+void invalidate_bh_lrus(void);
+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 int 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 attach_page_buffers(struct page *page,
+ struct buffer_head *head)
+{
+ get_page(page);
+ SetPagePrivate(page);
+ set_page_private(page, (unsigned long)head);
+}
+
+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);
+}
+
+/**
+ * __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; }
+
+#endif /* CONFIG_BLOCK */
+#endif /* _LINUX_BUFFER_HEAD_H */