int nilfs_get_block(struct inode *inode, sector_t blkoff,
		    struct buffer_head *bh_result, int create)
{
	struct nilfs_inode_info *ii = NILFS_I(inode);
	struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
	__u64 blknum = 0;
	int err = 0, ret;
	unsigned maxblocks = bh_result->b_size >> inode->i_blkbits;

	down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
	ret = nilfs_bmap_lookup_contig(ii->i_bmap, blkoff, &blknum, maxblocks);
	up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
	if (ret >= 0) {	
		map_bh(bh_result, inode->i_sb, blknum);
		if (ret > 0)
			bh_result->b_size = (ret << inode->i_blkbits);
		goto out;
	}
	
	if (ret == -ENOENT && create) {
		struct nilfs_transaction_info ti;

		bh_result->b_blocknr = 0;
		err = nilfs_transaction_begin(inode->i_sb, &ti, 1);
		if (unlikely(err))
			goto out;
		err = nilfs_bmap_insert(ii->i_bmap, (unsigned long)blkoff,
					(unsigned long)bh_result);
		if (unlikely(err != 0)) {
			if (err == -EEXIST) {
				printk(KERN_WARNING
				       "nilfs_get_block: a race condition "
				       "while inserting a data block. "
				       "(inode number=%lu, file block "
				       "offset=%llu)\n",
				       inode->i_ino,
				       (unsigned long long)blkoff);
				err = 0;
			}
			nilfs_transaction_abort(inode->i_sb);
			goto out;
		}
		nilfs_mark_inode_dirty(inode);
		nilfs_transaction_commit(inode->i_sb); 
		
		set_buffer_new(bh_result);
		set_buffer_delay(bh_result);
		map_bh(bh_result, inode->i_sb, 0); 
	} else if (ret == -ENOENT) {
		;
	} else {
		err = ret;
	}

 out:
	return err;
}
Exemple #2
0
/**
 * nilfs_get_block() - get a file block on the filesystem (callback function)
 * @inode - inode struct of the target file
 * @blkoff - file block number
 * @bh_result - buffer head to be mapped on
 * @create - indicate whether allocating the block or not when it has not
 *      been allocated yet.
 *
 * This function does not issue actual read request of the specified data
 * block. It is done by VFS.
 */
int nilfs_get_block(struct inode *inode, sector_t blkoff,
		    struct buffer_head *bh_result, int create)
{
	struct nilfs_inode_info *ii = NILFS_I(inode);
	struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
	__u64 blknum = 0;
	int err = 0, ret;
	unsigned maxblocks = bh_result->b_size >> inode->i_blkbits;

	down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
	ret = nilfs_bmap_lookup_contig(ii->i_bmap, blkoff, &blknum, maxblocks);
	up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
	if (ret >= 0) {	/* found */
		map_bh(bh_result, inode->i_sb, blknum);
		if (ret > 0)
			bh_result->b_size = (ret << inode->i_blkbits);
		goto out;
	}
	/* data block was not found */
	if (ret == -ENOENT && create) {
		struct nilfs_transaction_info ti;

		bh_result->b_blocknr = 0;
		err = nilfs_transaction_begin(inode->i_sb, &ti, 1);
		if (unlikely(err))
			goto out;
		err = nilfs_bmap_insert(ii->i_bmap, (unsigned long)blkoff,
					(unsigned long)bh_result);
		if (unlikely(err != 0)) {
			if (err == -EEXIST) {
				/*
				 * The get_block() function could be called
				 * from multiple callers for an inode.
				 * However, the page having this block must
				 * be locked in this case.
				 */
				printk(KERN_WARNING
				       "nilfs_get_block: a race condition "
				       "while inserting a data block. "
				       "(inode number=%lu, file block "
				       "offset=%llu)\n",
				       inode->i_ino,
				       (unsigned long long)blkoff);
				err = 0;
			}
			nilfs_transaction_abort(inode->i_sb);
			goto out;
		}
		nilfs_mark_inode_dirty(inode);
		nilfs_transaction_commit(inode->i_sb); /* never fails */
		/* Error handling should be detailed */
		set_buffer_new(bh_result);
		set_buffer_delay(bh_result);
		map_bh(bh_result, inode->i_sb, 0); /* dbn must be changed
						      to proper value */
	} else if (ret == -ENOENT) {
		/* not found is not error (e.g. hole); must return without
		   the mapped state flag. */
		;
	} else {
		err = ret;
	}

 out:
	return err;
}