1 // SPDX-License-Identifier: GPL-2.0
7  * Based on portions of file.c by Makoto Kato <m_kato@ga2.so-net.ne.jp>
39  * befs_read_datastream - get buffer_head containing data, starting from pos.
43  * @off: offset of data in buffer_head->b_data
45  * Returns pointer to buffer_head containing data starting with offset @off,
46  * if you don't need to know offset just set @off = NULL.
54 	befs_blocknr_t block;	/* block coresponding to pos */  in befs_read_datastream()  local
56 	befs_debug(sb, "---> %s %llu", __func__, pos);  in befs_read_datastream()
57 	block = pos >> BEFS_SB(sb)->block_shift;  in befs_read_datastream()
59 		*off = pos - (block << BEFS_SB(sb)->block_shift);  in befs_read_datastream()
61 	if (befs_fblock2brun(sb, ds, block, &run) != BEFS_OK) {  in befs_read_datastream()
62 		befs_error(sb, "BeFS: Error finding disk addr of block %lu",  in befs_read_datastream()
63 			   (unsigned long)block);  in befs_read_datastream()
64 		befs_debug(sb, "<--- %s ERROR", __func__);  in befs_read_datastream()
69 		befs_error(sb, "BeFS: Error reading block %lu from datastream",  in befs_read_datastream()
70 			   (unsigned long)block);  in befs_read_datastream()
74 	befs_debug(sb, "<--- %s read data, starting at %llu", __func__, pos);  in befs_read_datastream()
80  * befs_fblock2brun - give back block run for fblock
86  * Takes a file position and gives back a brun who's starting block
87  * is block number fblock of the file.
99 	befs_off_t pos = fblock << BEFS_SB(sb)->block_shift;  in befs_fblock2brun()
101 	if (pos < data->max_direct_range) {  in befs_fblock2brun()
104 	} else if (pos < data->max_indirect_range) {  in befs_fblock2brun()
107 	} else if (pos < data->max_double_indirect_range) {  in befs_fblock2brun()
112 			   "befs_fblock2brun() was asked to find block %lu, "  in befs_fblock2brun()
121  * befs_read_lsmylink - read long symlink from datastream.
137 	befs_debug(sb, "---> %s length: %llu", __func__, len);  in befs_read_lsymlink()
142 			befs_error(sb, "BeFS: Error reading datastream block "  in befs_read_lsymlink()
144 			befs_debug(sb, "<--- %s ERROR", __func__);  in befs_read_lsymlink()
148 		plen = ((bytes_read + BEFS_SB(sb)->block_size) < len) ?  in befs_read_lsymlink()
149 		    BEFS_SB(sb)->block_size : len - bytes_read;  in befs_read_lsymlink()
150 		memcpy(buff + bytes_read, bh->b_data, plen);  in befs_read_lsymlink()
155 	befs_debug(sb, "<--- %s read %u bytes", __func__, (unsigned int)  in befs_read_lsymlink()
161  * befs_count_blocks - blocks used by a file
179 	befs_debug(sb, "---> %s", __func__);  in befs_count_blocks()
181 	datablocks = ds->size >> befs_sb->block_shift;  in befs_count_blocks()
182 	if (ds->size & (befs_sb->block_size - 1))  in befs_count_blocks()
185 	metablocks = 1;		/* Start with 1 block for inode */  in befs_count_blocks()
187 	/* Size of indirect block */  in befs_count_blocks()
188 	if (ds->size > ds->max_direct_range)  in befs_count_blocks()
189 		metablocks += ds->indirect.len;  in befs_count_blocks()
192 	 * Double indir block, plus all the indirect blocks it maps.  in befs_count_blocks()
193 	 * In the double-indirect range, all block runs of data are  in befs_count_blocks()
195 	 * how many data block runs are in the double-indirect region,  in befs_count_blocks()
200 	if (ds->size > ds->max_indirect_range && ds->max_indirect_range != 0) {  in befs_count_blocks()
206 		    ds->max_double_indirect_range - ds->max_indirect_range;  in befs_count_blocks()
208 		    dbl_bytes / (befs_sb->block_size * BEFS_DBLINDIR_BRUN_LEN);  in befs_count_blocks()
211 		metablocks += ds->double_indirect.len;  in befs_count_blocks()
216 	befs_debug(sb, "<--- %s %u blocks", __func__, (unsigned int)blocks);  in befs_count_blocks()
222  * befs_find_brun_direct - find a direct block run in the datastream
228  * Finds the block run that starts at file block number blockno
237  * contains the blockno-th filesystem block. This is necessary
238  * because the block runs map variable amounts of data. Simply
240  * incrementing this by the length of each block run as we come
245  * When/if blockno is found, if blockno is inside of a block
246  * run as stored on disk, we offset the start and length members
247  * of the block run, so that blockno is the start and len is
255 	const befs_block_run *array = data->direct;  in befs_find_brun_direct()
258 	befs_debug(sb, "---> %s, find %lu", __func__, (unsigned long)blockno);  in befs_find_brun_direct()
263 			int offset = blockno - sum;  in befs_find_brun_direct()  local
265 			run->allocation_group = array[i].allocation_group;  in befs_find_brun_direct()
266 			run->start = array[i].start + offset;  in befs_find_brun_direct()
267 			run->len = array[i].len - offset;  in befs_find_brun_direct()
269 			befs_debug(sb, "---> %s, "  in befs_find_brun_direct()
276 	befs_error(sb, "%s failed to find file block %lu", __func__,  in befs_find_brun_direct()
278 	befs_debug(sb, "---> %s ERROR", __func__);  in befs_find_brun_direct()
283  * befs_find_brun_indirect - find a block run in the datastream
289  * Finds the block run that starts at file block number blockno
297  * For each block in the indirect run of the datastream, read
317 	befs_block_run indirect = data->indirect;  in befs_find_brun_indirect()
321 	befs_debug(sb, "---> %s, find %lu", __func__, (unsigned long)blockno);  in befs_find_brun_indirect()
323 	indir_start_blk = data->max_direct_range >> BEFS_SB(sb)->block_shift;  in befs_find_brun_indirect()
324 	search_blk = blockno - indir_start_blk;  in befs_find_brun_indirect()
330 			befs_error(sb, "---> %s failed to read "  in befs_find_brun_indirect()
331 				   "disk block %lu from the indirect brun",  in befs_find_brun_indirect()
333 			befs_debug(sb, "<--- %s ERROR", __func__);  in befs_find_brun_indirect()
337 		array = (befs_disk_block_run *) indirblock->b_data;  in befs_find_brun_indirect()
343 				int offset = search_blk - sum;  in befs_find_brun_indirect()  local
344 				run->allocation_group =  in befs_find_brun_indirect()
346 				run->start =  in befs_find_brun_indirect()
347 				    fs16_to_cpu(sb, array[j].start) + offset;  in befs_find_brun_indirect()
348 				run->len =  in befs_find_brun_indirect()
349 				    fs16_to_cpu(sb, array[j].len) - offset;  in befs_find_brun_indirect()
353 					   "<--- %s found file block "  in befs_find_brun_indirect()
367 		   "file block %lu", __func__, (unsigned long)blockno);  in befs_find_brun_indirect()
369 	befs_debug(sb, "<--- %s ERROR", __func__);  in befs_find_brun_indirect()
374  * befs_find_brun_dblindirect - find a block run in the datastream
380  * Finds the block run that starts at file block number blockno
382  * blockno is in the double-indirect region of the datastream.
388  * The block runs in the double-indirect region are different.
390  * block run maps a constant amount of file data. This means
391  * that we can directly calculate how many block runs into the
392  * double-indirect region we need to go to get to the one that
393  * maps a particular filesystem block.
396  * inode addresses in the double-indirect block will point us
397  * to the indirect block that contains the mapping for the data,
399  * indirect block maps the data block we are after.
403  * though the double-indirect run may be several blocks long,
406  * the indirect block and perform a similar process to find
407  * the actual block run that maps the data block we are interested
410  * Then we offset the run as in befs_find_brun_array() and we are
421 	int offset;  in befs_find_brun_dblindirect()  local
434 	    data->max_indirect_range >> BEFS_SB(sb)->block_shift;  in befs_find_brun_dblindirect()
436 	off_t dbl_indir_off = blockno - indir_start_blk;  in befs_find_brun_dblindirect()
439 	 * the indirect block pointed to by the double indirect block  in befs_find_brun_dblindirect()
444 	 * the double indirect block  in befs_find_brun_dblindirect()
449 	befs_debug(sb, "---> %s find %lu", __func__, (unsigned long)blockno);  in befs_find_brun_dblindirect()
451 	/* First, discover which of the double_indir->indir blocks  in befs_find_brun_dblindirect()
454 	 * the indirect block contains pos.  in befs_find_brun_dblindirect()
461 	/* Read double indirect block */  in befs_find_brun_dblindirect()
463 	if (dbl_which_block > data->double_indirect.len) {  in befs_find_brun_dblindirect()
464 		befs_error(sb, "The double-indirect index calculated by "  in befs_find_brun_dblindirect()
466 			   "of the double-indirect block", __func__,  in befs_find_brun_dblindirect()
472 	    sb_bread(sb, iaddr2blockno(sb, &data->double_indirect) +  in befs_find_brun_dblindirect()
476 			   "double-indirect block at blockno %lu", __func__,  in befs_find_brun_dblindirect()
478 			   iaddr2blockno(sb, &data->double_indirect) +  in befs_find_brun_dblindirect()
484 	    dblindir_indx - (dbl_which_block * befs_iaddrs_per_block(sb));  in befs_find_brun_dblindirect()
485 	iaddr_array = (befs_disk_inode_addr *) dbl_indir_block->b_data;  in befs_find_brun_dblindirect()
489 	/* Read indirect block */  in befs_find_brun_dblindirect()
494 			   "of the indirect block", __func__, indir_indx);  in befs_find_brun_dblindirect()
501 		befs_error(sb, "%s couldn't read the indirect block "  in befs_find_brun_dblindirect()
507 	block_indx = indir_indx - (which_block * befs_iaddrs_per_block(sb));  in befs_find_brun_dblindirect()
508 	iaddr_array = (befs_disk_inode_addr *) indir_block->b_data;  in befs_find_brun_dblindirect()
515 	offset = blockno - blockno_at_run_start;  in befs_find_brun_dblindirect()
517 	run->start += offset;  in befs_find_brun_dblindirect()
518 	run->len -= offset;  in befs_find_brun_dblindirect()
520 	befs_debug(sb, "Found file block %lu in double_indirect[%d][%d],"  in befs_find_brun_dblindirect()