C++ put_bh函数代码示例

static int update_dind_extent_range(handle_t *handle, struct inode *inode,
				    ext4_fsblk_t pblock,
				    struct migrate_struct *lb)
{
	struct buffer_head *bh;
	__le32 *i_data;
	int i, retval = 0;
	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

	bh = sb_bread(inode->i_sb, pblock);
	if (!bh)
		return -EIO;

	i_data = (__le32 *)bh->b_data;
	for (i = 0; i < max_entries; i++) {
		if (i_data[i]) {
			retval = update_ind_extent_range(handle, inode,
						le32_to_cpu(i_data[i]), lb);
			if (retval)
				break;
		} else {
			/* Only update the file block number */
			lb->curr_block += max_entries;
		}
	}
	put_bh(bh);
	return retval;

}

static int free_dind_blocks(handle_t *handle,
				struct inode *inode, __le32 i_data)
{
	int i;
	__le32 *tmp_idata;
	struct buffer_head *bh;
	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

	bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
	if (!bh)
		return -EIO;

	tmp_idata = (__le32 *)bh->b_data;
	for (i = 0; i < max_entries; i++) {
		if (tmp_idata[i]) {
			extend_credit_for_blkdel(handle, inode);
			ext4_free_blocks(handle, inode,
					le32_to_cpu(tmp_idata[i]), 1, 1);
		}
	}
	put_bh(bh);
	extend_credit_for_blkdel(handle, inode);
	ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
	return 0;
}

static int free_ext_idx(handle_t *handle, struct inode *inode,
					struct ext4_extent_idx *ix)
{
	int i, retval = 0;
	ext4_fsblk_t block;
	struct buffer_head *bh;
	struct ext4_extent_header *eh;

	block = idx_pblock(ix);
	bh = sb_bread(inode->i_sb, block);
	if (!bh)
		return -EIO;

	eh = (struct ext4_extent_header *)bh->b_data;
	if (eh->eh_depth != 0) {
		ix = EXT_FIRST_INDEX(eh);
		for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
			retval = free_ext_idx(handle, inode, ix);
			if (retval)
				break;
		}
	}
	put_bh(bh);
	extend_credit_for_blkdel(handle, inode);
	ext4_free_blocks(handle, inode, block, 1, 1);
	return retval;
}

/*
 * Read the metadata block length, this is stored in the first two
 * bytes of the metadata block.
 */
static struct buffer_head *get_block_length(struct super_block *sb,
			u64 *cur_index, int *offset, int *length)
{
	struct squashfs_sb_info *msblk = sb->s_fs_info;
	struct buffer_head *bh;

	bh = sb_bread(sb, *cur_index);
	if (bh == NULL)
		return NULL;

	if (msblk->devblksize - *offset == 1) {
		*length = (unsigned char) bh->b_data[*offset];
		put_bh(bh);
		bh = sb_bread(sb, ++(*cur_index));
		if (bh == NULL)
			return NULL;
		*length |= (unsigned char) bh->b_data[0] << 8;
		*offset = 1;
	} else {
		*length = (unsigned char) bh->b_data[*offset] |
			(unsigned char) bh->b_data[*offset + 1] << 8;
		*offset += 2;
	}

	return bh;
}

/* Done it all: now write the commit record.  We should have
 * cleaned up our previous buffers by now, so if we are in abort
 * mode we can now just skip the rest of the journal write
 * entirely.
 *
 * Returns 1 if the journal needs to be aborted or 0 on success
 */
static int journal_write_commit_record(journal_t *journal,
					transaction_t *commit_transaction)
{
	struct journal_head *descriptor;
	struct buffer_head *bh;
	journal_header_t *header;
	int ret;

	if (is_journal_aborted(journal))
		return 0;

	descriptor = journal_get_descriptor_buffer(journal);
	if (!descriptor)
		return 1;

	bh = jh2bh(descriptor);

	header = (journal_header_t *)(bh->b_data);
	header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
	header->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK);
	header->h_sequence = cpu_to_be32(commit_transaction->t_tid);

	JBUFFER_TRACE(descriptor, "write commit block");
	set_buffer_dirty(bh);

	if (journal->j_flags & JFS_BARRIER) {
		ret = __sync_dirty_buffer(bh, WRITE_SYNC | WRITE_BARRIER);

		/*
		 * Is it possible for another commit to fail at roughly
		 * the same time as this one?  If so, we don't want to
		 * trust the barrier flag in the super, but instead want
		 * to remember if we sent a barrier request
		 */
		if (ret == -EOPNOTSUPP) {
			char b[BDEVNAME_SIZE];

			printk(KERN_WARNING
				"JBD: barrier-based sync failed on %s - "
				"disabling barriers\n",
				bdevname(journal->j_dev, b));
			spin_lock(&journal->j_state_lock);
			journal->j_flags &= ~JFS_BARRIER;
			spin_unlock(&journal->j_state_lock);

			/* And try again, without the barrier */
			set_buffer_uptodate(bh);
			set_buffer_dirty(bh);
			ret = sync_dirty_buffer(bh);
		}
	} else {
		ret = sync_dirty_buffer(bh);
	}

	put_bh(bh);		/* One for getblk() */
	journal_put_journal_head(descriptor);

	return (ret == -EIO);
}

/* Done it all: now write the commit record.  We should have
 * cleaned up our previous buffers by now, so if we are in abort
 * mode we can now just skip the rest of the journal write
 * entirely.
 *
 * Returns 1 if the journal needs to be aborted or 0 on success
 */
static int journal_write_commit_record(journal_t *journal,
					transaction_t *commit_transaction)
{
	struct journal_head *descriptor;
	struct buffer_head *bh;
	int i, ret;
	int barrier_done = 0;

	if (is_journal_aborted(journal))
		return 0;

	descriptor = jbd2_journal_get_descriptor_buffer(journal);
	if (!descriptor)
		return 1;

	bh = jh2bh(descriptor);

	/* AKPM: buglet - add `i' to tmp! */
	for (i = 0; i < bh->b_size; i += 512) {
		journal_header_t *tmp = (journal_header_t*)bh->b_data;
		tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
		tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK);
		tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
	}

	JBUFFER_TRACE(descriptor, "write commit block");
	set_buffer_dirty(bh);
	if (journal->j_flags & JBD2_BARRIER) {
		set_buffer_ordered(bh);
		barrier_done = 1;
	}
	ret = sync_dirty_buffer(bh);
	/* is it possible for another commit to fail at roughly
	 * the same time as this one?  If so, we don't want to
	 * trust the barrier flag in the super, but instead want
	 * to remember if we sent a barrier request
	 */
	if (ret == -EOPNOTSUPP && barrier_done) {
		char b[BDEVNAME_SIZE];

		printk(KERN_WARNING
			"JBD: barrier-based sync failed on %s - "
			"disabling barriers\n",
			bdevname(journal->j_dev, b));
		spin_lock(&journal->j_state_lock);
		journal->j_flags &= ~JBD2_BARRIER;
		spin_unlock(&journal->j_state_lock);

		/* And try again, without the barrier */
		clear_buffer_ordered(bh);
		set_buffer_uptodate(bh);
		set_buffer_dirty(bh);
		ret = sync_dirty_buffer(bh);
	}
	put_bh(bh);		/* One for getblk() */
	jbd2_journal_put_journal_head(descriptor);

	return (ret == -EIO);
}

/*
 * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
 * The caller must restart a list walk.  Wait for someone else to run
 * jbd_unlock_bh_state().
 */
static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
{
	get_bh(bh);
	spin_unlock(&journal->j_list_lock);
	jbd_lock_bh_state(bh);
	jbd_unlock_bh_state(bh);
	put_bh(bh);
}

/*
 * Decrement reference counter for data buffer. If it has been marked
 * 'BH_Freed', release it and the page to which it belongs if possible.
 */
static void release_data_buffer(struct buffer_head *bh)
{
	if (buffer_freed(bh)) {
		clear_buffer_freed(bh);
		release_buffer_page(bh);
	} else
		put_bh(bh);
}

static int ufs_fmp_run(struct device *dev, uint32_t mode, uint8_t *data,
			uint32_t len, uint32_t write)
{
	int ret = 0;
	struct ufs_hba *hba;
	struct ufs_fmp_work *work;
	struct Scsi_Host *host;
	static struct buffer_head *bh;

	work = dev_get_drvdata(dev);
	if (!work) {
		dev_err(dev, "Fail to get work from platform device\n");
		return -ENODEV;
	}
	host = work->host;
	hba = shost_priv(host);
	hba->self_test_mode = mode;

	bh = __getblk(work->bdev, work->sector, FMP_BLK_SIZE);
	if (!bh) {
		dev_err(dev, "Fail to get block from bdev\n");
		return -ENODEV;
	}
	hba->self_test_bh = bh;

	get_bh(bh);
	if (write == WRITE_MODE) {
		memcpy(bh->b_data, data, len);
		set_buffer_dirty(bh);
		sync_dirty_buffer(bh);
		if (buffer_req(bh) && !buffer_uptodate(bh)) {
			dev_err(dev, "IO error syncing for FMP fips write\n");
			ret = -EIO;
			goto out;
		}
		memset(bh->b_data, 0, FMP_BLK_SIZE);
	} else {
		lock_buffer(bh);
		bh->b_end_io = end_buffer_read_sync;
		submit_bh(READ_SYNC, bh);
		wait_on_buffer(bh);
		if (unlikely(!buffer_uptodate(bh))) {
			ret = -EIO;
			goto out;
		}
		memcpy(data, bh->b_data, len);
	}
out:
	hba->self_test_mode = 0;
	hba->self_test_bh = NULL;
	put_bh(bh);

	return ret;
}

/* XXX Il ne semble pas y avoir de compteur de référence dans struct buf */
inline void
decrement_bcount(struct buf *p_s_bp)
{

	if (p_s_bp) {
		if (atomic_read(&(p_s_bp->b_count))) {
			put_bh(p_s_bp);
			return;
		}
	}
}

/*
 * Decrement reference counter for data buffer. If it has been marked
 * 'BH_Freed', release it and the page to which it belongs if possible.
 */
static void release_data_buffer(struct buffer_head *bh)
{
    if (buffer_freed(bh)) {
        WARN_ON_ONCE(buffer_dirty(bh));
        clear_buffer_freed(bh);
        clear_buffer_mapped(bh);
        clear_buffer_new(bh);
        clear_buffer_req(bh);
        bh->b_bdev = NULL;
        release_buffer_page(bh);
    } else
        put_bh(bh);
}

/*
 * Returns 0 if the caller should continue scanning, 1 if the scan must end
 * and -ve on error.
 */
static int rock_continue(struct rock_state *rs)
{
	int ret = 1;
	int blocksize = 1 << rs->inode->i_blkbits;
	const int min_de_size = offsetof(struct rock_ridge, u);

	kfree(rs->buffer);
	rs->buffer = NULL;

	if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
	    (unsigned)rs->cont_size > blocksize ||
	    (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
		printk(KERN_NOTICE "rock: corrupted directory entry. "
			"extent=%d, offset=%d, size=%d\n",
			rs->cont_extent, rs->cont_offset, rs->cont_size);
		ret = -EIO;
		goto out;
	}

	if (rs->cont_extent) {
		struct buffer_head *bh;

		rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
		if (!rs->buffer) {
			ret = -ENOMEM;
			goto out;
		}
		ret = -EIO;
		if (++rs->cont_loops >= RR_MAX_CE_ENTRIES)
			goto out;
		bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
		if (bh) {
			memcpy(rs->buffer, bh->b_data + rs->cont_offset,
					rs->cont_size);
			put_bh(bh);
			rs->chr = rs->buffer;
			rs->len = rs->cont_size;
			rs->cont_extent = 0;
			rs->cont_size = 0;
			rs->cont_offset = 0;
			return 0;
		}
		printk("Unable to read rock-ridge attributes\n");
	}
out:
	kfree(rs->buffer);
	rs->buffer = NULL;
	return ret;
}

int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
		      struct inode *inode)
{
	int ret = 0;

	mlog_entry("(bh->b_blocknr = %llu, inode=%p)\n",
		   (unsigned long long)bh->b_blocknr, inode);

	BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
	BUG_ON(buffer_jbd(bh));

	/* No need to check for a soft readonly file system here. non
	 * journalled writes are only ever done on system files which
	 * can get modified during recovery even if read-only. */
	if (ocfs2_is_hard_readonly(osb)) {
		ret = -EROFS;
		goto out;
	}

	mutex_lock(&OCFS2_I(inode)->ip_io_mutex);

	lock_buffer(bh);
	set_buffer_uptodate(bh);

	/* remove from dirty list before I/O. */
	clear_buffer_dirty(bh);

	get_bh(bh); /* for end_buffer_write_sync() */
	bh->b_end_io = end_buffer_write_sync;
	submit_bh(WRITE, bh);

	wait_on_buffer(bh);

	if (buffer_uptodate(bh)) {
		ocfs2_set_buffer_uptodate(inode, bh);
	} else {
		/* We don't need to remove the clustered uptodate
		 * information for this bh as it's not marked locally
		 * uptodate. */
		ret = -EIO;
		put_bh(bh);
	}

	mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
out:
	mlog_exit(ret);
	return ret;
}

static int ufs_fmp_run(struct device *dev, uint32_t mode, uint8_t *data,
			uint32_t len, uint32_t write)
{
	struct ufs_hba *hba;
	struct ufs_fmp_work *work;
	struct Scsi_Host *host;
	static struct buffer_head *bh;

	work = dev_get_drvdata(dev);
	if (!work) {
		dev_err(dev, "Fail to get work from platform device\n");
		return -ENODEV;
	}
	host = work->host;
	hba = shost_priv(host);
	hba->self_test_mode = mode;

	bh = __getblk(work->bdev, work->sector, FMP_BLK_SIZE);
	if (!bh) {
		dev_err(dev, "Fail to get block from bdev\n");
		return -ENODEV;
	}
	hba->self_test_bh = bh;

	get_bh(bh);
	if (write == WRITE_MODE) {
		memcpy(bh->b_data, data, len);
		bh->b_state &= ~(1 << BH_Uptodate);
		bh->b_state &= ~(1 << BH_Lock);
		ll_rw_block(WRITE_FLUSH_FUA, 1, &bh);
		wait_on_buffer(bh);

		memset(bh->b_data, 0, FMP_BLK_SIZE);
	} else {
		bh->b_state &= ~(1 << BH_Uptodate);
		bh->b_state &= ~(1 << BH_Lock);
		ll_rw_block(READ_SYNC, 1, &bh);
		wait_on_buffer(bh);

		memcpy(data, bh->b_data, len);
	}
	put_bh(bh);

	hba->self_test_mode = 0;
	hba->self_test_bh = NULL;

	return 0;
}

static void flush_descriptor(journal_t *journal,
			     struct journal_head *descriptor,
			     int offset)
{
	jbd2_journal_revoke_header_t *header;
	struct buffer_head *bh = jh2bh(descriptor);

	if (is_journal_aborted(journal)) {
		put_bh(bh);
		return;
	}

	header = (jbd2_journal_revoke_header_t *) jh2bh(descriptor)->b_data;
	header->r_count = cpu_to_be32(offset);
	set_buffer_jwrite(bh);
	BUFFER_TRACE(bh, "write");
	set_buffer_dirty(bh);
	ll_rw_block(SWRITE, 1, &bh);
}