text: /*
   * ext4_jbd2.h
   *
   * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
   *
   * Copyright 1998--1999 Red Hat corp --- All Rights Reserved
   *
   * This file is part of the Linux kernel and is made available under
   * the terms of the GNU General Public License, version 2, or at your
   * option, any later version, incorporated herein by reference.
   *
   * Ext4-specific journaling extensions.
   */
  
  #ifndef _EXT4_JBD2_H
  #define _EXT4_JBD2_H
  
  #include <linux/fs.h>
  #include <linux/jbd2.h>
  #include "ext4.h"
  
  #define EXT4_JOURNAL(inode)	(EXT4_SB((inode)->i_sb)->s_journal)
  
  /* Define the number of blocks we need to account to a transaction to
   * modify one block of data.
   *
   * We may have to touch one inode, one bitmap buffer, up to three
   * indirection blocks, the group and superblock summaries, and the data
   * block to complete the transaction.
   *
   * For extents-enabled fs we may have to allocate and modify up to
   * 5 levels of tree + root which are stored in the inode. */
  
  #define EXT4_SINGLEDATA_TRANS_BLOCKS(sb)				\
  	(EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)   \
  	 ? 27U : 8U)
  
  /* Extended attribute operations touch at most two data buffers,
   * two bitmap buffers, and two group summaries, in addition to the inode
   * and the superblock, which are already accounted for. */
  
  #define EXT4_XATTR_TRANS_BLOCKS		6U
  
  /* Define the minimum size for a transaction which modifies data.  This
   * needs to take into account the fact that we may end up modifying two
   * quota files too (one for the group, one for the user quota).  The
   * superblock only gets updated once, of course, so don't bother
   * counting that again for the quota updates. */
  
  #define EXT4_DATA_TRANS_BLOCKS(sb)	(EXT4_SINGLEDATA_TRANS_BLOCKS(sb) + \
  					 EXT4_XATTR_TRANS_BLOCKS - 2 + \
  					 EXT4_MAXQUOTAS_TRANS_BLOCKS(sb))
  
  /*
   * Define the number of metadata blocks we need to account to modify data.
   *
   * This include super block, inode block, quota blocks and xattr blocks
   */
  #define EXT4_META_TRANS_BLOCKS(sb)	(EXT4_XATTR_TRANS_BLOCKS + \
  					EXT4_MAXQUOTAS_TRANS_BLOCKS(sb))
  
  /* Delete operations potentially hit one directory's namespace plus an
   * entire inode, plus arbitrary amounts of bitmap/indirection data.  Be
   * generous.  We can grow the delete transaction later if necessary. */
  
  #define EXT4_DELETE_TRANS_BLOCKS(sb)	(2 * EXT4_DATA_TRANS_BLOCKS(sb) + 64)
  
  /* Define an arbitrary limit for the amount of data we will anticipate
   * writing to any given transaction.  For unbounded transactions such as
   * write(2) and truncate(2) we can write more than this, but we always
   * start off at the maximum transaction size and grow the transaction
   * optimistically as we go. */
  
  #define EXT4_MAX_TRANS_DATA		64U
  
  /* We break up a large truncate or write transaction once the handle's
   * buffer credits gets this low, we need either to extend the
   * transaction or to start a new one.  Reserve enough space here for
   * inode, bitmap, superblock, group and indirection updates for at least
   * one block, plus two quota updates.  Quota allocations are not
   * needed. */
  
  #define EXT4_RESERVE_TRANS_BLOCKS	12U
  
  #define EXT4_INDEX_EXTRA_TRANS_BLOCKS	8
  
  #ifdef CONFIG_QUOTA
  /* Amount of blocks needed for quota update - we know that the structure was
   * allocated so we need to update only inode+data */
  #define EXT4_QUOTA_TRANS_BLOCKS(sb) (test_opt(sb, QUOTA) ? 2 : 0)
  /* Amount of blocks needed for quota insert/delete - we do some block writes
   * but inode, sb and group updates are done only once */
  #define EXT4_QUOTA_INIT_BLOCKS(sb) (test_opt(sb, QUOTA) ? (DQUOT_INIT_ALLOC*\
  		(EXT4_SINGLEDATA_TRANS_BLOCKS(sb)-3)+3+DQUOT_INIT_REWRITE) : 0)
  
  #define EXT4_QUOTA_DEL_BLOCKS(sb) (test_opt(sb, QUOTA) ? (DQUOT_DEL_ALLOC*\
  		(EXT4_SINGLEDATA_TRANS_BLOCKS(sb)-3)+3+DQUOT_DEL_REWRITE) : 0)
  #else
  #define EXT4_QUOTA_TRANS_BLOCKS(sb) 0
  #define EXT4_QUOTA_INIT_BLOCKS(sb) 0
  #define EXT4_QUOTA_DEL_BLOCKS(sb) 0
  #endif
  #define EXT4_MAXQUOTAS_TRANS_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_TRANS_BLOCKS(sb))
  #define EXT4_MAXQUOTAS_INIT_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_INIT_BLOCKS(sb))
  #define EXT4_MAXQUOTAS_DEL_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_DEL_BLOCKS(sb))
  
  int
  ext4_mark_iloc_dirty(handle_t *handle,
  		     struct inode *inode,
  		     struct ext4_iloc *iloc);
  
  /*
   * On success, We end up with an outstanding reference count against
   * iloc->bh.  This _must_ be cleaned up later.
   */
  
  int ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
  			struct ext4_iloc *iloc);
  
  int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode);
  
  /*
   * Wrapper functions with which ext4 calls into JBD.
   */
  void ext4_journal_abort_handle(const char *caller, const char *err_fn,
  		struct buffer_head *bh, handle_t *handle, int err);
  
  int __ext4_journal_get_undo_access(const char *where, handle_t *handle,
  				struct buffer_head *bh);
  
  int __ext4_journal_get_write_access(const char *where, handle_t *handle,
  				struct buffer_head *bh);
  
  int __ext4_forget(const char *where, handle_t *handle, int is_metadata,
  		  struct inode *inode, struct buffer_head *bh,
  		  ext4_fsblk_t blocknr);
  
  int __ext4_journal_get_create_access(const char *where,
  				handle_t *handle, struct buffer_head *bh);
  
  int __ext4_handle_dirty_metadata(const char *where, handle_t *handle,
  				 struct inode *inode, struct buffer_head *bh);
  
  #define ext4_journal_get_undo_access(handle, bh) \
  	__ext4_journal_get_undo_access(__func__, (handle), (bh))
  #define ext4_journal_get_write_access(handle, bh) \
  	__ext4_journal_get_write_access(__func__, (handle), (bh))
  #define ext4_forget(handle, is_metadata, inode, bh, block_nr) \
  	__ext4_forget(__func__, (handle), (is_metadata), (inode), (bh),\
  		      (block_nr))
  #define ext4_journal_get_create_access(handle, bh) \
  	__ext4_journal_get_create_access(__func__, (handle), (bh))
  #define ext4_handle_dirty_metadata(handle, inode, bh) \
  	__ext4_handle_dirty_metadata(__func__, (handle), (inode), (bh))
  
  handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
  int __ext4_journal_stop(const char *where, handle_t *handle);
  
  #define EXT4_NOJOURNAL_MAX_REF_COUNT ((unsigned long) 4096)
  
  /* Note:  Do not use this for NULL handles.  This is only to determine if
   * a properly allocated handle is using a journal or not. */
  static inline int ext4_handle_valid(handle_t *handle)
  {
  	if ((unsigned long)handle < EXT4_NOJOURNAL_MAX_REF_COUNT)
  		return 0;
  	return 1;
  }
  
  static inline void ext4_handle_sync(handle_t *handle)
  {
  	if (ext4_handle_valid(handle))
  		handle->h_sync = 1;
  }
  
  static inline void ext4_handle_release_buffer(handle_t *handle,
  						struct buffer_head *bh)
  {
  	if (ext4_handle_valid(handle))
  		jbd2_journal_release_buffer(handle, bh);
  }
  
  static inline int ext4_handle_is_aborted(handle_t *handle)
  {
  	if (ext4_handle_valid(handle))
  		return is_handle_aborted(handle);
  	return 0;
  }
  
  static inline int ext4_handle_has_enough_credits(handle_t *handle, int needed)
  {
  	if (ext4_handle_valid(handle) && handle->h_buffer_credits < needed)
  		return 0;
  	return 1;
  }
  
  static inline void ext4_journal_release_buffer(handle_t *handle,
  						struct buffer_head *bh)
  {
  	if (ext4_handle_valid(handle))
  		jbd2_journal_release_buffer(handle, bh);
  }
  
  static inline handle_t *ext4_journal_start(struct inode *inode, int nblocks)
  {
  	return ext4_journal_start_sb(inode->i_sb, nblocks);
  }
  
  #define ext4_journal_stop(handle) \
  	__ext4_journal_stop(__func__, (handle))
  
  static inline handle_t *ext4_journal_current_handle(void)
  {
  	return journal_current_handle();
  }
  
  static inline int ext4_journal_extend(handle_t *handle, int nblocks)
  {
  	if (ext4_handle_valid(handle))
  		return jbd2_journal_extend(handle, nblocks);
  	return 0;
  }
  
  static inline int ext4_journal_restart(handle_t *handle, int nblocks)
  {
  	if (ext4_handle_valid(handle))
  		return jbd2_journal_restart(handle, nblocks);
  	return 0;
  }
  
  static inline int ext4_journal_blocks_per_page(struct inode *inode)
  {
  	if (EXT4_JOURNAL(inode) != NULL)
  		return jbd2_journal_blocks_per_page(inode);
  	return 0;
  }
  
  static inline int ext4_journal_force_commit(journal_t *journal)
  {
  	if (journal)
  		return jbd2_journal_force_commit(journal);
  	return 0;
  }
  
  static inline int ext4_jbd2_file_inode(handle_t *handle, struct inode *inode)
  {
  	if (ext4_handle_valid(handle))
  		return jbd2_journal_file_inode(handle, &EXT4_I(inode)->jinode);
  	return 0;
  }
  
  static inline void ext4_update_inode_fsync_trans(handle_t *handle,
  						 struct inode *inode,
  						 int datasync)
  {
  	struct ext4_inode_info *ei = EXT4_I(inode);
  
  	if (ext4_handle_valid(handle)) {
  		ei->i_sync_tid = handle->h_transaction->t_tid;
  		if (datasync)
  			ei->i_datasync_tid = handle->h_transaction->t_tid;
  	}
  }
  
  /* super.c */
  int ext4_force_commit(struct super_block *sb);
  
  static inline int ext4_should_journal_data(struct inode *inode)
  {
  	if (EXT4_JOURNAL(inode) == NULL)
  		return 0;
  	if (!S_ISREG(inode->i_mode))
  		return 1;
  	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
  		return 1;
  	if (EXT4_I(inode)->i_flags & EXT4_JOURNAL_DATA_FL)
  		return 1;
  	return 0;
  }
  
  static inline int ext4_should_order_data(struct inode *inode)
  {
  	if (EXT4_JOURNAL(inode) == NULL)
  		return 0;
  	if (!S_ISREG(inode->i_mode))
  		return 0;
  	if (EXT4_I(inode)->i_flags & EXT4_JOURNAL_DATA_FL)
  		return 0;
  	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA)
  		return 1;
  	return 0;
  }
  
  static inline int ext4_should_writeback_data(struct inode *inode)
  {
  	if (!S_ISREG(inode->i_mode))
  		return 0;
  	if (EXT4_JOURNAL(inode) == NULL)
  		return 1;
  	if (EXT4_I(inode)->i_flags & EXT4_JOURNAL_DATA_FL)
  		return 0;
  	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)
  		return 1;
  	return 0;
  }
  
  /*
   * This function controls whether or not we should try to go down the
   * dioread_nolock code paths, which makes it safe to avoid taking
   * i_mutex for direct I/O reads.  This only works for extent-based
   * files, and it doesn't work for nobh or if data journaling is
   * enabled, since the dioread_nolock code uses b_private to pass
   * information back to the I/O completion handler, and this conflicts
   * with the jbd's use of b_private.
   */
  static inline int ext4_should_dioread_nolock(struct inode *inode)
  {
  	if (!test_opt(inode->i_sb, DIOREAD_NOLOCK))
  		return 0;
  	if (test_opt(inode->i_sb, NOBH))
  		return 0;
  	if (!S_ISREG(inode->i_mode))
  		return 0;
  	if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
  		return 0;
  	if (ext4_should_journal_data(inode))
  		return 0;
  	return 1;
  }
  
  #endif	/* _EXT4_JBD2_H */
  