lib/ext2fs/rw_bitmaps.c - pub/scm/fs/ext2/e2fsprogs - Git at Google

 /*
  * rw_bitmaps.c --- routines to read and write the  inode and block bitmaps.
  *
  * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
  *
  * %Begin-Header%
  * This file may be redistributed under the terms of the GNU Library
  * General Public License, version 2.
  * %End-Header%
  */

 #include "config.h"
 #include <stdio.h>
 #include <string.h>
 #if HAVE_UNISTD_H
 #include <unistd.h>
 #endif
 #include <fcntl.h>
 #include <time.h>
 #ifdef HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
 #ifdef HAVE_PTHREAD_H
 #include <pthread.h>
 #endif

 #include "ext2_fs.h"
 #include "ext2fs.h"
 #include "e2image.h"

 #ifdef HAVE_PTHREAD
 typedef pthread_mutex_t mutex_t;

 static void unix_pthread_mutex_lock(mutex_t *mutex)
 {
 	if (mutex)
 		pthread_mutex_lock(mutex);
 }
 static void unix_pthread_mutex_unlock(mutex_t *mutex)
 {
 	if (mutex)
 		pthread_mutex_unlock(mutex);
 }
 #else
 typedef int mutex_t;
 #define unix_pthread_mutex_lock(mutex_t) do {} while (0)
 #define unix_pthread_mutex_unlock(mutex_t) do {} while (0)
 #endif

 static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 {
 	dgrp_t 		i;
 	unsigned int	j;
 	int		block_nbytes, inode_nbytes;
 	unsigned int	nbits;
 	errcode_t	retval;
 	char		*block_buf = NULL, *inode_buf = NULL;
 	int		csum_flag;
 	blk64_t		blk;
 	blk64_t		blk_itr = EXT2FS_B2C(fs, fs->super->s_first_data_block);
 	ext2_ino_t	ino_itr = 1;

 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

 	if (!(fs->flags & EXT2_FLAG_RW))
 		return EXT2_ET_RO_FILSYS;

 	csum_flag = ext2fs_has_group_desc_csum(fs);

 	inode_nbytes = block_nbytes = 0;
 	if (do_block) {
 		block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
 		retval = io_channel_alloc_buf(fs->io, 0, &block_buf);
 		if (retval)
 			goto errout;
 		memset(block_buf, 0xff, fs->blocksize);
 	}
 	if (do_inode) {
 		inode_nbytes = (size_t)
 			((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
 		retval = io_channel_alloc_buf(fs->io, 0, &inode_buf);
 		if (retval)
 			goto errout;
 		memset(inode_buf, 0xff, fs->blocksize);
 	}

 	for (i = 0; i < fs->group_desc_count; i++) {
 		if (!do_block)
 			goto skip_block_bitmap;

 		if (csum_flag && ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT)
 		    )
 			goto skip_this_block_bitmap;

 		retval = ext2fs_get_block_bitmap_range2(fs->block_map,
 				blk_itr, block_nbytes << 3, block_buf);
 		if (retval)
 			goto errout;

 		if (i == fs->group_desc_count - 1) {
 			/* Force bitmap padding for the last group */
 			nbits = EXT2FS_NUM_B2C(fs,
 				((ext2fs_blocks_count(fs->super)
 				  - (__u64) fs->super->s_first_data_block)
 				 % (__u64) EXT2_BLOCKS_PER_GROUP(fs->super)));
 			if (nbits)
 				for (j = nbits; j < fs->blocksize * 8; j++)
 					ext2fs_set_bit(j, block_buf);
 		}

 		retval = ext2fs_block_bitmap_csum_set(fs, i, block_buf,
 						      block_nbytes);
 		if (retval)
 			return retval;
 		ext2fs_group_desc_csum_set(fs, i);
 		fs->flags |= EXT2_FLAG_DIRTY;

 		blk = ext2fs_block_bitmap_loc(fs, i);
 		if (blk && blk < ext2fs_blocks_count(fs->super)) {
 			retval = io_channel_write_blk64(fs->io, blk, 1,
 							block_buf);
 			if (retval) {
 				retval = EXT2_ET_BLOCK_BITMAP_WRITE;
 				goto errout;
 			}
 		}
 	skip_this_block_bitmap:
 		blk_itr += block_nbytes << 3;
 	skip_block_bitmap:

 		if (!do_inode)
 			continue;

 		if (csum_flag && ext2fs_bg_flags_test(fs, i, EXT2_BG_INODE_UNINIT)
 		    )
 			goto skip_this_inode_bitmap;

 		retval = ext2fs_get_inode_bitmap_range2(fs->inode_map,
 				ino_itr, inode_nbytes << 3, inode_buf);
 		if (retval)
 			goto errout;

 		retval = ext2fs_inode_bitmap_csum_set(fs, i, inode_buf,
 						      inode_nbytes);
 		if (retval)
 			goto errout;
 		ext2fs_group_desc_csum_set(fs, i);
 		fs->flags |= EXT2_FLAG_DIRTY;

 		blk = ext2fs_inode_bitmap_loc(fs, i);
 		if (blk && blk < ext2fs_blocks_count(fs->super)) {
 			retval = io_channel_write_blk64(fs->io, blk, 1,
 						      inode_buf);
 			if (retval) {
 				retval = EXT2_ET_INODE_BITMAP_WRITE;
 				goto errout;
 			}
 		}
 	skip_this_inode_bitmap:
 		ino_itr += inode_nbytes << 3;

 	}
 	if (do_block) {
 		fs->flags &= ~EXT2_FLAG_BB_DIRTY;
 		ext2fs_free_mem(&block_buf);
 	}
 	if (do_inode) {
 		fs->flags &= ~EXT2_FLAG_IB_DIRTY;
 		ext2fs_free_mem(&inode_buf);
 	}
 	return 0;
 errout:
 	if (inode_buf)
 		ext2fs_free_mem(&inode_buf);
 	if (block_buf)
 		ext2fs_free_mem(&block_buf);
 	return retval;
 }

 static errcode_t mark_uninit_bg_group_blocks(ext2_filsys fs)
 {
 	dgrp_t			i;
 	blk64_t			blk;
 	ext2fs_block_bitmap	bmap = fs->block_map;

 	for (i = 0; i < fs->group_desc_count; i++) {
 		if (!ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT))
 			continue;

 		ext2fs_reserve_super_and_bgd(fs, i, bmap);

 		/*
 		 * Mark the blocks used for the inode table
 		 */
 		blk = ext2fs_inode_table_loc(fs, i);
 		if (blk)
 			ext2fs_mark_block_bitmap_range2(bmap, blk,
 						fs->inode_blocks_per_group);

 		/*
 		 * Mark block used for the block bitmap
 		 */
 		blk = ext2fs_block_bitmap_loc(fs, i);
 		if (blk && blk < ext2fs_blocks_count(fs->super))
 			ext2fs_mark_block_bitmap2(bmap, blk);

 		/*
 		 * Mark block used for the inode bitmap
 		 */
 		blk = ext2fs_inode_bitmap_loc(fs, i);
 		if (blk && blk < ext2fs_blocks_count(fs->super))
 			ext2fs_mark_block_bitmap2(bmap, blk);
 	}
 	return 0;
 }

 static int bitmap_tail_verify(unsigned char *bitmap, int first, int last)
 {
 	int i;

 	for (i = first; i <= last; i++)
 		if (bitmap[i] != 0xff)
 			return 0;
 	return 1;
 }

 static errcode_t read_bitmaps_range_prepare(ext2_filsys fs, int flags)
 {
 	errcode_t retval;
 	int block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
 	int inode_nbytes = EXT2_INODES_PER_GROUP(fs->super) / 8;
 	char *buf;

 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

 	if ((block_nbytes > (int) fs->blocksize) ||
 	    (inode_nbytes > (int) fs->blocksize))
 		return EXT2_ET_CORRUPT_SUPERBLOCK;

 	fs->write_bitmaps = ext2fs_write_bitmaps;

 	retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
 	if (retval)
 		return retval;

 	if (flags & EXT2FS_BITMAPS_BLOCK) {
 		if (fs->block_map)
 			ext2fs_free_block_bitmap(fs->block_map);
 		strcpy(buf, "block bitmap for ");
 		strcat(buf, fs->device_name);
 		retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
 		if (retval)
 			goto cleanup;
 	}

 	if (flags & EXT2FS_BITMAPS_INODE) {
 		if (fs->inode_map)
 			ext2fs_free_inode_bitmap(fs->inode_map);
 		strcpy(buf, "inode bitmap for ");
 		strcat(buf, fs->device_name);
 		retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 		if (retval)
 			goto cleanup;
 	}
 	ext2fs_free_mem(&buf);
 	return retval;

 cleanup:
 	if (flags & EXT2FS_BITMAPS_BLOCK) {
 		ext2fs_free_block_bitmap(fs->block_map);
 		fs->block_map = 0;
 	}
 	if (flags & EXT2FS_BITMAPS_INODE) {
 		ext2fs_free_inode_bitmap(fs->inode_map);
 		fs->inode_map = 0;
 	}
 	ext2fs_free_mem(&buf);
 	return retval;
 }

 static errcode_t read_bitmaps_range_start(ext2_filsys fs, int flags,
 					  dgrp_t start, dgrp_t end,
 					  mutex_t *mutex,
 					  int *tail_flags)
 {
 	dgrp_t i;
 	char *block_bitmap = 0, *inode_bitmap = 0;
 	errcode_t retval = 0;
 	int block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
 	int inode_nbytes = EXT2_INODES_PER_GROUP(fs->super) / 8;
 	int csum_flag;
 	unsigned int	cnt;
 	blk64_t	blk;
 	blk64_t	blk_itr = EXT2FS_B2C(fs, fs->super->s_first_data_block);
 	blk64_t   blk_cnt;
 	ext2_ino_t ino_itr = 1;
 	ext2_ino_t ino_cnt;

 	csum_flag = ext2fs_has_group_desc_csum(fs);

 	if (flags & EXT2FS_BITMAPS_BLOCK) {
 		retval = io_channel_alloc_buf(fs->io, 0, &block_bitmap);
 		if (retval)
 			goto cleanup;
 	} else {
 		block_nbytes = 0;
 	}

 	if (flags & EXT2FS_BITMAPS_INODE) {
 		retval = io_channel_alloc_buf(fs->io, 0, &inode_bitmap);
 		if (retval)
 			goto cleanup;
 	} else {
 		inode_nbytes = 0;
 	}

 	/* io should be null */
 	if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
 		blk = (ext2fs_le32_to_cpu(fs->image_header->offset_inodemap) / fs->blocksize);
 		ino_cnt = fs->super->s_inodes_count;
 		while (inode_bitmap && ino_cnt > 0) {
 			retval = io_channel_read_blk64(fs->image_io, blk++,
 						     1, inode_bitmap);
 			if (retval)
 				goto cleanup;
 			cnt = fs->blocksize << 3;
 			if (cnt > ino_cnt)
 				cnt = ino_cnt;
 			retval = ext2fs_set_inode_bitmap_range2(fs->inode_map,
 					       ino_itr, cnt, inode_bitmap);
 			if (retval)
 				goto cleanup;
 			ino_itr += cnt;
 			ino_cnt -= cnt;
 		}
 		blk = (ext2fs_le32_to_cpu(fs->image_header->offset_blockmap) /
 		       fs->blocksize);
 		blk_cnt = EXT2_GROUPS_TO_CLUSTERS(fs->super,
 						  fs->group_desc_count);
 		while (block_bitmap && blk_cnt > 0) {
 			retval = io_channel_read_blk64(fs->image_io, blk++,
 						     1, block_bitmap);
 			if (retval)
 				goto cleanup;
 			cnt = fs->blocksize << 3;
 			if (cnt > blk_cnt)
 				cnt = blk_cnt;
 			retval = ext2fs_set_block_bitmap_range2(fs->block_map,
 				       blk_itr, cnt, block_bitmap);
 			if (retval)
 				goto cleanup;
 			blk_itr += cnt;
 			blk_cnt -= cnt;
 		}
 		goto cleanup;
 	}

 	blk_itr += ((blk64_t)start * (block_nbytes << 3));
 	ino_itr += ((blk64_t)start * (inode_nbytes << 3));
 	for (i = start; i <= end; i++) {
 		if (block_bitmap) {
 			blk = ext2fs_block_bitmap_loc(fs, i);
 			if ((csum_flag &&
 			     ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT) &&
 			     ext2fs_group_desc_csum_verify(fs, i)) ||
 			    (blk >= ext2fs_blocks_count(fs->super)))
 				blk = 0;
 			if (blk) {
 				retval = io_channel_read_blk64(fs->io, blk,
 							       1, block_bitmap);
 				if (retval) {
 					retval = EXT2_ET_BLOCK_BITMAP_READ;
 					goto cleanup;
 				}
 				/* verify block bitmap checksum */
 				if (!(fs->flags &
 				      EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
 				    !ext2fs_block_bitmap_csum_verify(fs, i,
 						block_bitmap, block_nbytes)) {
 					retval =
 					EXT2_ET_BLOCK_BITMAP_CSUM_INVALID;
 					goto cleanup;
 				}
 				if (!bitmap_tail_verify((unsigned char *) block_bitmap,
 							block_nbytes, fs->blocksize - 1))
 					*tail_flags |= EXT2_FLAG_BBITMAP_TAIL_PROBLEM;
 			} else
 				memset(block_bitmap, 0, block_nbytes);
 			cnt = block_nbytes << 3;
 			unix_pthread_mutex_lock(mutex);
 			retval = ext2fs_set_block_bitmap_range2(fs->block_map,
 					       blk_itr, cnt, block_bitmap);
 			unix_pthread_mutex_unlock(mutex);
 			if (retval)
 				goto cleanup;
 			blk_itr += block_nbytes << 3;
 		}
 		if (inode_bitmap) {
 			blk = ext2fs_inode_bitmap_loc(fs, i);
 			if ((csum_flag &&
 			     ext2fs_bg_flags_test(fs, i, EXT2_BG_INODE_UNINIT) &&
 			     ext2fs_group_desc_csum_verify(fs, i)) ||
 			    (blk >= ext2fs_blocks_count(fs->super)))
 				blk = 0;
 			if (blk) {
 				retval = io_channel_read_blk64(fs->io, blk,
 							       1, inode_bitmap);
 				if (retval) {
 					retval = EXT2_ET_INODE_BITMAP_READ;
 					goto cleanup;
 				}

 				/* verify inode bitmap checksum */
 				if (!(fs->flags &
 				      EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
 				    !ext2fs_inode_bitmap_csum_verify(fs, i,
 						inode_bitmap, inode_nbytes)) {
 					retval =
 					EXT2_ET_INODE_BITMAP_CSUM_INVALID;
 					goto cleanup;
 				}
 				if (!bitmap_tail_verify((unsigned char *) inode_bitmap,
 							inode_nbytes, fs->blocksize - 1))
 					*tail_flags |= EXT2_FLAG_IBITMAP_TAIL_PROBLEM;
 			} else
 				memset(inode_bitmap, 0, inode_nbytes);
 			cnt = inode_nbytes << 3;
 			unix_pthread_mutex_lock(mutex);
 			retval = ext2fs_set_inode_bitmap_range2(fs->inode_map,
 					       ino_itr, cnt, inode_bitmap);
 			unix_pthread_mutex_unlock(mutex);
 			if (retval)
 				goto cleanup;
 			ino_itr += inode_nbytes << 3;
 		}
 	}

 cleanup:
 	if (inode_bitmap)
 		ext2fs_free_mem(&inode_bitmap);
 	if (block_bitmap)
 		ext2fs_free_mem(&block_bitmap);
 	return retval;
 }

 static errcode_t read_bitmaps_range_end(ext2_filsys fs, int flags,
 					int tail_flags)
 {
 	errcode_t retval;

 	/* Mark group blocks for any BLOCK_UNINIT groups */
 	if (flags & EXT2FS_BITMAPS_BLOCK) {
 		retval = mark_uninit_bg_group_blocks(fs);
 		if (retval)
 			return retval;
 		fs->flags &= ~EXT2_FLAG_BBITMAP_TAIL_PROBLEM;
 	}
 	if (flags & EXT2FS_BITMAPS_INODE)
 		fs->flags &= ~EXT2_FLAG_IBITMAP_TAIL_PROBLEM;
 	fs->flags |= tail_flags;

 	return 0;
 }

 static void read_bitmaps_cleanup_on_error(ext2_filsys fs, int flags)
 {
 	if (flags & EXT2FS_BITMAPS_BLOCK) {
 		ext2fs_free_block_bitmap(fs->block_map);
 		fs->block_map = 0;
 	}
 	if (flags & EXT2FS_BITMAPS_INODE) {
 		ext2fs_free_inode_bitmap(fs->inode_map);
 		fs->inode_map = 0;
 	}
 }

 static errcode_t read_bitmaps_range(ext2_filsys fs, int flags,
 				    dgrp_t start, dgrp_t end)
 {
 	errcode_t retval;
 	int tail_flags = 0;

 	retval = read_bitmaps_range_prepare(fs, flags);
 	if (retval)
 		return retval;

 	retval = read_bitmaps_range_start(fs, flags, start, end,
 					  NULL, &tail_flags);
 	if (retval == 0)
 		retval = read_bitmaps_range_end(fs, flags, tail_flags);
 	if (retval)
 		read_bitmaps_cleanup_on_error(fs, flags);
 	return retval;
 }

 #ifdef HAVE_PTHREAD
 struct read_bitmaps_thread_info {
 	ext2_filsys	rbt_fs;
 	int		rbt_flags;
 	dgrp_t		rbt_grp_start;
 	dgrp_t		rbt_grp_end;
 	errcode_t	rbt_retval;
 	pthread_mutex_t *rbt_mutex;
 	int		rbt_tail_flags;
 };

 static void *read_bitmaps_thread(void *data)
 {
 	struct read_bitmaps_thread_info *rbt = data;

 	rbt->rbt_retval = read_bitmaps_range_start(rbt->rbt_fs, rbt->rbt_flags,
 				rbt->rbt_grp_start, rbt->rbt_grp_end,
 				rbt->rbt_mutex, &rbt->rbt_tail_flags);
 	return NULL;
 }
 #endif

 errcode_t ext2fs_rw_bitmaps(ext2_filsys fs, int flags, int num_threads)
 {
 #ifdef HAVE_PTHREAD
 	pthread_attr_t	attr;
 	pthread_t *thread_ids = NULL;
 	struct read_bitmaps_thread_info *thread_infos = NULL;
 	pthread_mutex_t rbt_mutex = PTHREAD_MUTEX_INITIALIZER;
 	errcode_t retval;
 	errcode_t rc;
 	unsigned flexbg_size = 1U << fs->super->s_log_groups_per_flex;
 	dgrp_t average_group;
 	int i, tail_flags = 0;
 #endif

 	if (flags & ~EXT2FS_BITMAPS_VALID_FLAGS)
 		return EXT2_ET_INVALID_ARGUMENT;

 	if (ext2fs_has_feature_journal_dev(fs->super))
 		return EXT2_ET_EXTERNAL_JOURNAL_NOSUPP;

 	if (flags & EXT2FS_BITMAPS_WRITE)
 		return write_bitmaps(fs, flags & EXT2FS_BITMAPS_INODE,
 				     flags & EXT2FS_BITMAPS_BLOCK);

 #ifdef HAVE_PTHREAD
 	if (((fs->io->flags & CHANNEL_FLAGS_THREADS) == 0) ||
 	    (num_threads == 1) || (fs->flags & EXT2_FLAG_IMAGE_FILE))
 		goto fallback;

 #if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_CONF)
 	if (num_threads < 0)
 		num_threads = sysconf(_SC_NPROCESSORS_CONF);
 #endif
 	/*
 	 * Guess for now; eventually we should probably define
 	 * ext2fs_get_num_cpus() and teach it how to get this info on
 	 * MacOS, FreeBSD, etc.
 	 * ref: https://stackoverflow.com/questions/150355
 	 */
 	if (num_threads <= 0)
 		num_threads = 4;

 	if ((unsigned) num_threads > fs->group_desc_count)
 		num_threads = fs->group_desc_count;
 	average_group = fs->group_desc_count / num_threads;
 	if (ext2fs_has_feature_flex_bg(fs->super)) {
 		average_group = (average_group / flexbg_size) * flexbg_size;
 	}
 	if ((num_threads <= 1) || (average_group == 0))
 		goto fallback;

 	io_channel_set_options(fs->io, "cache=off");
 	retval = pthread_attr_init(&attr);
 	if (retval)
 		return retval;

 	thread_ids = calloc(sizeof(pthread_t), num_threads);
 	if (!thread_ids)
 		return ENOMEM;

 	thread_infos = calloc(sizeof(struct read_bitmaps_thread_info),
 				num_threads);
 	if (!thread_infos)
 		goto out;

 	retval = read_bitmaps_range_prepare(fs, flags);
 	if (retval)
 		goto out;

 //	fprintf(stdout, "Multiple threads triggered to read bitmaps\n");
 	for (i = 0; i < num_threads; i++) {
 		thread_infos[i].rbt_fs = fs;
 		thread_infos[i].rbt_flags = flags;
 		thread_infos[i].rbt_mutex = &rbt_mutex;
 		thread_infos[i].rbt_tail_flags = 0;
 		if (i == 0)
 			thread_infos[i].rbt_grp_start = 0;
 		else
 			thread_infos[i].rbt_grp_start = average_group * i + 1;

 		if (i == num_threads - 1)
 			thread_infos[i].rbt_grp_end = fs->group_desc_count - 1;
 		else
 			thread_infos[i].rbt_grp_end = average_group * (i + 1);
 		retval = pthread_create(&thread_ids[i], &attr,
 					&read_bitmaps_thread, &thread_infos[i]);
 		if (retval)
 			break;
 	}
 	for (i = 0; i < num_threads; i++) {
 		if (!thread_ids[i])
 			break;
 		rc = pthread_join(thread_ids[i], NULL);
 		if (rc && !retval)
 			retval = rc;
 		rc = thread_infos[i].rbt_retval;
 		if (rc && !retval)
 			retval = rc;
 		tail_flags |= thread_infos[i].rbt_tail_flags;
 	}
 out:
 	rc = pthread_attr_destroy(&attr);
 	if (rc && !retval)
 		retval = rc;
 	free(thread_infos);
 	free(thread_ids);

 	if (retval == 0)
 		retval = read_bitmaps_range_end(fs, flags, tail_flags);
 	if (retval)
 		read_bitmaps_cleanup_on_error(fs, flags);
 	/* XXX should save and restore cache setting */
 	io_channel_set_options(fs->io, "cache=on");
 	return retval;
 fallback:
 #endif /* HAVE_PTHREAD */
 	return read_bitmaps_range(fs, flags, 0, fs->group_desc_count - 1);
 }

 errcode_t ext2fs_read_inode_bitmap(ext2_filsys fs)
 {
 	return ext2fs_rw_bitmaps(fs, EXT2FS_BITMAPS_INODE, -1);
 }

 errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
 {
 	return ext2fs_rw_bitmaps(fs, EXT2FS_BITMAPS_BLOCK, -1);
 }

 errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
 {
 	return write_bitmaps(fs, 1, 0);
 }

 errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
 {
 	return write_bitmaps(fs, 0, 1);
 }

 errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
 {
 	int flags = 0;

 	if (!fs->inode_map)
 		flags |= EXT2FS_BITMAPS_INODE;
 	if (!fs->block_map)
 		flags |= EXT2FS_BITMAPS_BLOCK;
 	if (flags == 0)
 		return 0;
 	return ext2fs_rw_bitmaps(fs, flags, -1);
 }

 errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
 {
 	int do_inode = fs->inode_map && ext2fs_test_ib_dirty(fs);
 	int do_block = fs->block_map && ext2fs_test_bb_dirty(fs);

 	if (!do_inode && !do_block)
 		return 0;

 	return write_bitmaps(fs, do_inode, do_block);
 }
	/*
	* rw_bitmaps.c --- routines to read and write the inode and block bitmaps.
	*
	* Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
	*
	* %Begin-Header%
	* This file may be redistributed under the terms of the GNU Library
	* General Public License, version 2.
	* %End-Header%
	*/

	#include "config.h"
	#include <stdio.h>
	#include <string.h>
	#if HAVE_UNISTD_H
	#include <unistd.h>
	#endif
	#include <fcntl.h>
	#include <time.h>
	#ifdef HAVE_SYS_STAT_H
	#include <sys/stat.h>
	#endif
	#ifdef HAVE_SYS_TYPES_H
	#include <sys/types.h>
	#endif
	#ifdef HAVE_PTHREAD_H
	#include <pthread.h>
	#endif

	#include "ext2_fs.h"
	#include "ext2fs.h"
	#include "e2image.h"

	#ifdef HAVE_PTHREAD
	typedef pthread_mutex_t mutex_t;

	static void unix_pthread_mutex_lock(mutex_t *mutex)
	{
	if (mutex)
	pthread_mutex_lock(mutex);
	}
	static void unix_pthread_mutex_unlock(mutex_t *mutex)
	{
	if (mutex)
	pthread_mutex_unlock(mutex);
	}
	#else
	typedef int mutex_t;
	#define unix_pthread_mutex_lock(mutex_t) do {} while (0)
	#define unix_pthread_mutex_unlock(mutex_t) do {} while (0)
	#endif

	static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block)
	{
	dgrp_t i;
	unsigned int j;
	int block_nbytes, inode_nbytes;
	unsigned int nbits;
	errcode_t retval;
	char block_buf = NULL, inode_buf = NULL;
	int csum_flag;
	blk64_t blk;
	blk64_t blk_itr = EXT2FS_B2C(fs, fs->super->s_first_data_block);
	ext2_ino_t ino_itr = 1;

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	if (!(fs->flags & EXT2_FLAG_RW))
	return EXT2_ET_RO_FILSYS;

	csum_flag = ext2fs_has_group_desc_csum(fs);

	inode_nbytes = block_nbytes = 0;
	if (do_block) {
	block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
	retval = io_channel_alloc_buf(fs->io, 0, &block_buf);
	if (retval)
	goto errout;
	memset(block_buf, 0xff, fs->blocksize);
	}
	if (do_inode) {
	inode_nbytes = (size_t)
	((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
	retval = io_channel_alloc_buf(fs->io, 0, &inode_buf);
	if (retval)
	goto errout;
	memset(inode_buf, 0xff, fs->blocksize);
	}

	for (i = 0; i < fs->group_desc_count; i++) {
	if (!do_block)
	goto skip_block_bitmap;

	if (csum_flag && ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT)
	)
	goto skip_this_block_bitmap;

	retval = ext2fs_get_block_bitmap_range2(fs->block_map,
	blk_itr, block_nbytes << 3, block_buf);
	if (retval)
	goto errout;

	if (i == fs->group_desc_count - 1) {
	/* Force bitmap padding for the last group */
	nbits = EXT2FS_NUM_B2C(fs,
	((ext2fs_blocks_count(fs->super)
	- (__u64) fs->super->s_first_data_block)
	% (__u64) EXT2_BLOCKS_PER_GROUP(fs->super)));
	if (nbits)
	for (j = nbits; j < fs->blocksize * 8; j++)
	ext2fs_set_bit(j, block_buf);
	}

	retval = ext2fs_block_bitmap_csum_set(fs, i, block_buf,
	block_nbytes);
	if (retval)
	return retval;
	ext2fs_group_desc_csum_set(fs, i);
	fs->flags \|= EXT2_FLAG_DIRTY;

	blk = ext2fs_block_bitmap_loc(fs, i);
	if (blk && blk < ext2fs_blocks_count(fs->super)) {
	retval = io_channel_write_blk64(fs->io, blk, 1,
	block_buf);
	if (retval) {
	retval = EXT2_ET_BLOCK_BITMAP_WRITE;
	goto errout;
	}
	}
	skip_this_block_bitmap:
	blk_itr += block_nbytes << 3;
	skip_block_bitmap:

	if (!do_inode)
	continue;

	if (csum_flag && ext2fs_bg_flags_test(fs, i, EXT2_BG_INODE_UNINIT)
	)
	goto skip_this_inode_bitmap;

	retval = ext2fs_get_inode_bitmap_range2(fs->inode_map,
	ino_itr, inode_nbytes << 3, inode_buf);
	if (retval)
	goto errout;

	retval = ext2fs_inode_bitmap_csum_set(fs, i, inode_buf,
	inode_nbytes);
	if (retval)
	goto errout;
	ext2fs_group_desc_csum_set(fs, i);
	fs->flags \|= EXT2_FLAG_DIRTY;

	blk = ext2fs_inode_bitmap_loc(fs, i);
	if (blk && blk < ext2fs_blocks_count(fs->super)) {
	retval = io_channel_write_blk64(fs->io, blk, 1,
	inode_buf);
	if (retval) {
	retval = EXT2_ET_INODE_BITMAP_WRITE;
	goto errout;
	}
	}
	skip_this_inode_bitmap:
	ino_itr += inode_nbytes << 3;

	}
	if (do_block) {
	fs->flags &= ~EXT2_FLAG_BB_DIRTY;
	ext2fs_free_mem(&block_buf);
	}
	if (do_inode) {
	fs->flags &= ~EXT2_FLAG_IB_DIRTY;
	ext2fs_free_mem(&inode_buf);
	}
	return 0;
	errout:
	if (inode_buf)
	ext2fs_free_mem(&inode_buf);
	if (block_buf)
	ext2fs_free_mem(&block_buf);
	return retval;
	}

	static errcode_t mark_uninit_bg_group_blocks(ext2_filsys fs)
	{
	dgrp_t i;
	blk64_t blk;
	ext2fs_block_bitmap bmap = fs->block_map;

	for (i = 0; i < fs->group_desc_count; i++) {
	if (!ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT))
	continue;

	ext2fs_reserve_super_and_bgd(fs, i, bmap);

	/*
	* Mark the blocks used for the inode table
	*/
	blk = ext2fs_inode_table_loc(fs, i);
	if (blk)
	ext2fs_mark_block_bitmap_range2(bmap, blk,
	fs->inode_blocks_per_group);

	/*
	* Mark block used for the block bitmap
	*/
	blk = ext2fs_block_bitmap_loc(fs, i);
	if (blk && blk < ext2fs_blocks_count(fs->super))
	ext2fs_mark_block_bitmap2(bmap, blk);

	/*
	* Mark block used for the inode bitmap
	*/
	blk = ext2fs_inode_bitmap_loc(fs, i);
	if (blk && blk < ext2fs_blocks_count(fs->super))
	ext2fs_mark_block_bitmap2(bmap, blk);
	}
	return 0;
	}

	static int bitmap_tail_verify(unsigned char *bitmap, int first, int last)
	{
	int i;

	for (i = first; i <= last; i++)
	if (bitmap[i] != 0xff)
	return 0;
	return 1;
	}

	static errcode_t read_bitmaps_range_prepare(ext2_filsys fs, int flags)
	{
	errcode_t retval;
	int block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
	int inode_nbytes = EXT2_INODES_PER_GROUP(fs->super) / 8;
	char *buf;

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	if ((block_nbytes > (int) fs->blocksize) \|\|
	(inode_nbytes > (int) fs->blocksize))
	return EXT2_ET_CORRUPT_SUPERBLOCK;

	fs->write_bitmaps = ext2fs_write_bitmaps;

	retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
	if (retval)
	return retval;

	if (flags & EXT2FS_BITMAPS_BLOCK) {
	if (fs->block_map)
	ext2fs_free_block_bitmap(fs->block_map);
	strcpy(buf, "block bitmap for ");
	strcat(buf, fs->device_name);
	retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
	if (retval)
	goto cleanup;
	}

	if (flags & EXT2FS_BITMAPS_INODE) {
	if (fs->inode_map)
	ext2fs_free_inode_bitmap(fs->inode_map);
	strcpy(buf, "inode bitmap for ");
	strcat(buf, fs->device_name);
	retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
	if (retval)
	goto cleanup;
	}
	ext2fs_free_mem(&buf);
	return retval;

	cleanup:
	if (flags & EXT2FS_BITMAPS_BLOCK) {
	ext2fs_free_block_bitmap(fs->block_map);
	fs->block_map = 0;
	}
	if (flags & EXT2FS_BITMAPS_INODE) {
	ext2fs_free_inode_bitmap(fs->inode_map);
	fs->inode_map = 0;
	}
	ext2fs_free_mem(&buf);
	return retval;
	}

	static errcode_t read_bitmaps_range_start(ext2_filsys fs, int flags,
	dgrp_t start, dgrp_t end,
	mutex_t *mutex,
	int *tail_flags)
	{
	dgrp_t i;
	char block_bitmap = 0, inode_bitmap = 0;
	errcode_t retval = 0;
	int block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
	int inode_nbytes = EXT2_INODES_PER_GROUP(fs->super) / 8;
	int csum_flag;
	unsigned int cnt;
	blk64_t blk;
	blk64_t blk_itr = EXT2FS_B2C(fs, fs->super->s_first_data_block);
	blk64_t blk_cnt;
	ext2_ino_t ino_itr = 1;
	ext2_ino_t ino_cnt;

	csum_flag = ext2fs_has_group_desc_csum(fs);

	if (flags & EXT2FS_BITMAPS_BLOCK) {
	retval = io_channel_alloc_buf(fs->io, 0, &block_bitmap);
	if (retval)
	goto cleanup;
	} else {
	block_nbytes = 0;
	}

	if (flags & EXT2FS_BITMAPS_INODE) {
	retval = io_channel_alloc_buf(fs->io, 0, &inode_bitmap);
	if (retval)
	goto cleanup;
	} else {
	inode_nbytes = 0;
	}

	/* io should be null */
	if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
	blk = (ext2fs_le32_to_cpu(fs->image_header->offset_inodemap) / fs->blocksize);
	ino_cnt = fs->super->s_inodes_count;
	while (inode_bitmap && ino_cnt > 0) {
	retval = io_channel_read_blk64(fs->image_io, blk++,
	1, inode_bitmap);
	if (retval)
	goto cleanup;
	cnt = fs->blocksize << 3;
	if (cnt > ino_cnt)
	cnt = ino_cnt;
	retval = ext2fs_set_inode_bitmap_range2(fs->inode_map,
	ino_itr, cnt, inode_bitmap);
	if (retval)
	goto cleanup;
	ino_itr += cnt;
	ino_cnt -= cnt;
	}
	blk = (ext2fs_le32_to_cpu(fs->image_header->offset_blockmap) /
	fs->blocksize);
	blk_cnt = EXT2_GROUPS_TO_CLUSTERS(fs->super,
	fs->group_desc_count);
	while (block_bitmap && blk_cnt > 0) {
	retval = io_channel_read_blk64(fs->image_io, blk++,
	1, block_bitmap);
	if (retval)
	goto cleanup;
	cnt = fs->blocksize << 3;
	if (cnt > blk_cnt)
	cnt = blk_cnt;
	retval = ext2fs_set_block_bitmap_range2(fs->block_map,
	blk_itr, cnt, block_bitmap);
	if (retval)
	goto cleanup;
	blk_itr += cnt;
	blk_cnt -= cnt;
	}
	goto cleanup;
	}

	blk_itr += ((blk64_t)start * (block_nbytes << 3));
	ino_itr += ((blk64_t)start * (inode_nbytes << 3));
	for (i = start; i <= end; i++) {
	if (block_bitmap) {
	blk = ext2fs_block_bitmap_loc(fs, i);
	if ((csum_flag &&
	ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT) &&
	ext2fs_group_desc_csum_verify(fs, i)) \|\|
	(blk >= ext2fs_blocks_count(fs->super)))
	blk = 0;
	if (blk) {
	retval = io_channel_read_blk64(fs->io, blk,
	1, block_bitmap);
	if (retval) {
	retval = EXT2_ET_BLOCK_BITMAP_READ;
	goto cleanup;
	}
	/* verify block bitmap checksum */
	if (!(fs->flags &
	EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
	!ext2fs_block_bitmap_csum_verify(fs, i,
	block_bitmap, block_nbytes)) {
	retval =
	EXT2_ET_BLOCK_BITMAP_CSUM_INVALID;
	goto cleanup;
	}
	if (!bitmap_tail_verify((unsigned char *) block_bitmap,
	block_nbytes, fs->blocksize - 1))
	*tail_flags \|= EXT2_FLAG_BBITMAP_TAIL_PROBLEM;
	} else
	memset(block_bitmap, 0, block_nbytes);
	cnt = block_nbytes << 3;
	unix_pthread_mutex_lock(mutex);
	retval = ext2fs_set_block_bitmap_range2(fs->block_map,
	blk_itr, cnt, block_bitmap);
	unix_pthread_mutex_unlock(mutex);
	if (retval)
	goto cleanup;
	blk_itr += block_nbytes << 3;
	}
	if (inode_bitmap) {
	blk = ext2fs_inode_bitmap_loc(fs, i);
	if ((csum_flag &&
	ext2fs_bg_flags_test(fs, i, EXT2_BG_INODE_UNINIT) &&
	ext2fs_group_desc_csum_verify(fs, i)) \|\|
	(blk >= ext2fs_blocks_count(fs->super)))
	blk = 0;
	if (blk) {
	retval = io_channel_read_blk64(fs->io, blk,
	1, inode_bitmap);
	if (retval) {
	retval = EXT2_ET_INODE_BITMAP_READ;
	goto cleanup;
	}

	/* verify inode bitmap checksum */
	if (!(fs->flags &
	EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
	!ext2fs_inode_bitmap_csum_verify(fs, i,
	inode_bitmap, inode_nbytes)) {
	retval =
	EXT2_ET_INODE_BITMAP_CSUM_INVALID;
	goto cleanup;
	}
	if (!bitmap_tail_verify((unsigned char *) inode_bitmap,
	inode_nbytes, fs->blocksize - 1))
	*tail_flags \|= EXT2_FLAG_IBITMAP_TAIL_PROBLEM;
	} else
	memset(inode_bitmap, 0, inode_nbytes);
	cnt = inode_nbytes << 3;
	unix_pthread_mutex_lock(mutex);
	retval = ext2fs_set_inode_bitmap_range2(fs->inode_map,
	ino_itr, cnt, inode_bitmap);
	unix_pthread_mutex_unlock(mutex);
	if (retval)
	goto cleanup;
	ino_itr += inode_nbytes << 3;
	}
	}

	cleanup:
	if (inode_bitmap)
	ext2fs_free_mem(&inode_bitmap);
	if (block_bitmap)
	ext2fs_free_mem(&block_bitmap);
	return retval;
	}

	static errcode_t read_bitmaps_range_end(ext2_filsys fs, int flags,
	int tail_flags)
	{
	errcode_t retval;

	/* Mark group blocks for any BLOCK_UNINIT groups */
	if (flags & EXT2FS_BITMAPS_BLOCK) {
	retval = mark_uninit_bg_group_blocks(fs);
	if (retval)
	return retval;
	fs->flags &= ~EXT2_FLAG_BBITMAP_TAIL_PROBLEM;
	}
	if (flags & EXT2FS_BITMAPS_INODE)
	fs->flags &= ~EXT2_FLAG_IBITMAP_TAIL_PROBLEM;
	fs->flags \|= tail_flags;

	return 0;
	}

	static void read_bitmaps_cleanup_on_error(ext2_filsys fs, int flags)
	{
	if (flags & EXT2FS_BITMAPS_BLOCK) {
	ext2fs_free_block_bitmap(fs->block_map);
	fs->block_map = 0;
	}
	if (flags & EXT2FS_BITMAPS_INODE) {
	ext2fs_free_inode_bitmap(fs->inode_map);
	fs->inode_map = 0;
	}
	}

	static errcode_t read_bitmaps_range(ext2_filsys fs, int flags,
	dgrp_t start, dgrp_t end)
	{
	errcode_t retval;
	int tail_flags = 0;

	retval = read_bitmaps_range_prepare(fs, flags);
	if (retval)
	return retval;

	retval = read_bitmaps_range_start(fs, flags, start, end,
	NULL, &tail_flags);
	if (retval == 0)
	retval = read_bitmaps_range_end(fs, flags, tail_flags);
	if (retval)
	read_bitmaps_cleanup_on_error(fs, flags);
	return retval;
	}

	#ifdef HAVE_PTHREAD
	struct read_bitmaps_thread_info {
	ext2_filsys rbt_fs;
	int rbt_flags;
	dgrp_t rbt_grp_start;
	dgrp_t rbt_grp_end;
	errcode_t rbt_retval;
	pthread_mutex_t *rbt_mutex;
	int rbt_tail_flags;
	};

	static void read_bitmaps_thread(void data)
	{
	struct read_bitmaps_thread_info *rbt = data;

	rbt->rbt_retval = read_bitmaps_range_start(rbt->rbt_fs, rbt->rbt_flags,
	rbt->rbt_grp_start, rbt->rbt_grp_end,
	rbt->rbt_mutex, &rbt->rbt_tail_flags);
	return NULL;
	}
	#endif

	errcode_t ext2fs_rw_bitmaps(ext2_filsys fs, int flags, int num_threads)
	{
	#ifdef HAVE_PTHREAD
	pthread_attr_t attr;
	pthread_t *thread_ids = NULL;
	struct read_bitmaps_thread_info *thread_infos = NULL;
	pthread_mutex_t rbt_mutex = PTHREAD_MUTEX_INITIALIZER;
	errcode_t retval;
	errcode_t rc;
	unsigned flexbg_size = 1U << fs->super->s_log_groups_per_flex;
	dgrp_t average_group;
	int i, tail_flags = 0;
	#endif

	if (flags & ~EXT2FS_BITMAPS_VALID_FLAGS)
	return EXT2_ET_INVALID_ARGUMENT;

	if (ext2fs_has_feature_journal_dev(fs->super))
	return EXT2_ET_EXTERNAL_JOURNAL_NOSUPP;

	if (flags & EXT2FS_BITMAPS_WRITE)
	return write_bitmaps(fs, flags & EXT2FS_BITMAPS_INODE,
	flags & EXT2FS_BITMAPS_BLOCK);

	#ifdef HAVE_PTHREAD
	if (((fs->io->flags & CHANNEL_FLAGS_THREADS) == 0) \|\|
	(num_threads == 1) \|\| (fs->flags & EXT2_FLAG_IMAGE_FILE))
	goto fallback;

	#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_CONF)
	if (num_threads < 0)
	num_threads = sysconf(_SC_NPROCESSORS_CONF);
	#endif
	/*
	* Guess for now; eventually we should probably define
	* ext2fs_get_num_cpus() and teach it how to get this info on
	* MacOS, FreeBSD, etc.
	* ref: https://stackoverflow.com/questions/150355
	*/
	if (num_threads <= 0)
	num_threads = 4;

	if ((unsigned) num_threads > fs->group_desc_count)
	num_threads = fs->group_desc_count;
	average_group = fs->group_desc_count / num_threads;
	if (ext2fs_has_feature_flex_bg(fs->super)) {
	average_group = (average_group / flexbg_size) * flexbg_size;
	}
	if ((num_threads <= 1) \|\| (average_group == 0))
	goto fallback;

	io_channel_set_options(fs->io, "cache=off");
	retval = pthread_attr_init(&attr);
	if (retval)
	return retval;

	thread_ids = calloc(sizeof(pthread_t), num_threads);
	if (!thread_ids)
	return ENOMEM;

	thread_infos = calloc(sizeof(struct read_bitmaps_thread_info),
	num_threads);
	if (!thread_infos)
	goto out;

	retval = read_bitmaps_range_prepare(fs, flags);
	if (retval)
	goto out;

	// fprintf(stdout, "Multiple threads triggered to read bitmaps\n");
	for (i = 0; i < num_threads; i++) {
	thread_infos[i].rbt_fs = fs;
	thread_infos[i].rbt_flags = flags;
	thread_infos[i].rbt_mutex = &rbt_mutex;
	thread_infos[i].rbt_tail_flags = 0;
	if (i == 0)
	thread_infos[i].rbt_grp_start = 0;
	else
	thread_infos[i].rbt_grp_start = average_group * i + 1;

	if (i == num_threads - 1)
	thread_infos[i].rbt_grp_end = fs->group_desc_count - 1;
	else
	thread_infos[i].rbt_grp_end = average_group * (i + 1);
	retval = pthread_create(&thread_ids[i], &attr,
	&read_bitmaps_thread, &thread_infos[i]);
	if (retval)
	break;
	}
	for (i = 0; i < num_threads; i++) {
	if (!thread_ids[i])
	break;
	rc = pthread_join(thread_ids[i], NULL);
	if (rc && !retval)
	retval = rc;
	rc = thread_infos[i].rbt_retval;
	if (rc && !retval)
	retval = rc;
	tail_flags \|= thread_infos[i].rbt_tail_flags;
	}
	out:
	rc = pthread_attr_destroy(&attr);
	if (rc && !retval)
	retval = rc;
	free(thread_infos);
	free(thread_ids);

	if (retval == 0)
	retval = read_bitmaps_range_end(fs, flags, tail_flags);
	if (retval)
	read_bitmaps_cleanup_on_error(fs, flags);
	/* XXX should save and restore cache setting */
	io_channel_set_options(fs->io, "cache=on");
	return retval;
	fallback:
	#endif /* HAVE_PTHREAD */
	return read_bitmaps_range(fs, flags, 0, fs->group_desc_count - 1);
	}

	errcode_t ext2fs_read_inode_bitmap(ext2_filsys fs)
	{
	return ext2fs_rw_bitmaps(fs, EXT2FS_BITMAPS_INODE, -1);
	}

	errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
	{
	return ext2fs_rw_bitmaps(fs, EXT2FS_BITMAPS_BLOCK, -1);
	}

	errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
	{
	return write_bitmaps(fs, 1, 0);
	}

	errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
	{
	return write_bitmaps(fs, 0, 1);
	}

	errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
	{
	int flags = 0;

	if (!fs->inode_map)
	flags \|= EXT2FS_BITMAPS_INODE;
	if (!fs->block_map)
	flags \|= EXT2FS_BITMAPS_BLOCK;
	if (flags == 0)
	return 0;
	return ext2fs_rw_bitmaps(fs, flags, -1);
	}

	errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
	{
	int do_inode = fs->inode_map && ext2fs_test_ib_dirty(fs);
	int do_block = fs->block_map && ext2fs_test_bb_dirty(fs);

	if (!do_inode && !do_block)
	return 0;

	return write_bitmaps(fs, do_inode, do_block);
	}