inode.c

linux 内核源代码

			brelse(prev_epos.bh);
			get_bh(cur_epos.bh);
			prev_epos.bh = cur_epos.bh;
		}
		if (cur_epos.bh != next_epos.bh) {
			brelse(cur_epos.bh);
			get_bh(next_epos.bh);
			cur_epos.bh = next_epos.bh;
		}

		lbcount += elen;

		prev_epos.block = cur_epos.block;
		cur_epos.block = next_epos.block;

		prev_epos.offset = cur_epos.offset;
		cur_epos.offset = next_epos.offset;

		if ((etype = udf_next_aext(inode, &next_epos, &eloc, &elen, 1)) == -1)
			break;

		c = !c;

		laarr[c].extLength = (etype << 30) | elen;
		laarr[c].extLocation = eloc;

		if (etype != (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
			pgoal = eloc.logicalBlockNum +
				((elen + inode->i_sb->s_blocksize - 1) >>
				 inode->i_sb->s_blocksize_bits);

		count++;
	} while (lbcount + elen <= b_off);

	b_off -= lbcount;
	offset = b_off >> inode->i_sb->s_blocksize_bits;
	/*
	 * Move prev_epos and cur_epos into indirect extent if we are at
	 * the pointer to it
	 */
	udf_next_aext(inode, &prev_epos, &tmpeloc, &tmpelen, 0);
	udf_next_aext(inode, &cur_epos, &tmpeloc, &tmpelen, 0);

	/* if the extent is allocated and recorded, return the block
	   if the extent is not a multiple of the blocksize, round up */

	if (etype == (EXT_RECORDED_ALLOCATED >> 30)) {
		if (elen & (inode->i_sb->s_blocksize - 1)) {
			elen = EXT_RECORDED_ALLOCATED |
				((elen + inode->i_sb->s_blocksize - 1) &
				 ~(inode->i_sb->s_blocksize - 1));
			etype = udf_write_aext(inode, &cur_epos, eloc, elen, 1);
		}
		brelse(prev_epos.bh);
		brelse(cur_epos.bh);
		brelse(next_epos.bh);
		newblock = udf_get_lb_pblock(inode->i_sb, eloc, offset);
		*phys = newblock;
		return NULL;
	}

	last_block = block;
	/* Are we beyond EOF? */
	if (etype == -1) {
		int ret;

		if (count) {
			if (c)
				laarr[0] = laarr[1];
			startnum = 1;
		} else {
			/* Create a fake extent when there's not one */
			memset(&laarr[0].extLocation, 0x00, sizeof(kernel_lb_addr));
			laarr[0].extLength = EXT_NOT_RECORDED_NOT_ALLOCATED;
			/* Will udf_extend_file() create real extent from a fake one? */
			startnum = (offset > 0);
		}
		/* Create extents for the hole between EOF and offset */
		ret = udf_extend_file(inode, &prev_epos, laarr, offset);
		if (ret == -1) {
			brelse(prev_epos.bh);
			brelse(cur_epos.bh);
			brelse(next_epos.bh);
			/* We don't really know the error here so we just make
			 * something up */
			*err = -ENOSPC;
			return NULL;
		}
		c = 0;
		offset = 0;
		count += ret;
		/* We are not covered by a preallocated extent? */
		if ((laarr[0].extLength & UDF_EXTENT_FLAG_MASK) != EXT_NOT_RECORDED_ALLOCATED) {
			/* Is there any real extent? - otherwise we overwrite
			 * the fake one... */
			if (count)
				c = !c;
			laarr[c].extLength = EXT_NOT_RECORDED_NOT_ALLOCATED |
				inode->i_sb->s_blocksize;
			memset(&laarr[c].extLocation, 0x00, sizeof(kernel_lb_addr));
			count++;
			endnum++;
		}
		endnum = c + 1;
		lastblock = 1;
	} else {
		endnum = startnum = ((count > 2) ? 2 : count);

		/* if the current extent is in position 0, swap it with the previous */
		if (!c && count != 1) {
			laarr[2] = laarr[0];
			laarr[0] = laarr[1];
			laarr[1] = laarr[2];
			c = 1;
		}

		/* if the current block is located in an extent, read the next extent */
		if ((etype = udf_next_aext(inode, &next_epos, &eloc, &elen, 0)) != -1) {
			laarr[c + 1].extLength = (etype << 30) | elen;
			laarr[c + 1].extLocation = eloc;
			count++;
			startnum++;
			endnum++;
		} else {
			lastblock = 1;
		}
	}

	/* if the current extent is not recorded but allocated, get the
	 * block in the extent corresponding to the requested block */
	if ((laarr[c].extLength >> 30) == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
		newblocknum = laarr[c].extLocation.logicalBlockNum + offset;
	} else { /* otherwise, allocate a new block */
		if (UDF_I_NEXT_ALLOC_BLOCK(inode) == block)
			goal = UDF_I_NEXT_ALLOC_GOAL(inode);

		if (!goal) {
			if (!(goal = pgoal))
				goal = UDF_I_LOCATION(inode).logicalBlockNum + 1;
		}

		if (!(newblocknum = udf_new_block(inode->i_sb, inode,
						  UDF_I_LOCATION(inode).partitionReferenceNum,
						  goal, err))) {
			brelse(prev_epos.bh);
			*err = -ENOSPC;
			return NULL;
		}
		UDF_I_LENEXTENTS(inode) += inode->i_sb->s_blocksize;
	}

	/* if the extent the requsted block is located in contains multiple blocks,
	 * split the extent into at most three extents. blocks prior to requested
	 * block, requested block, and blocks after requested block */
	udf_split_extents(inode, &c, offset, newblocknum, laarr, &endnum);

#ifdef UDF_PREALLOCATE
	/* preallocate blocks */
	udf_prealloc_extents(inode, c, lastblock, laarr, &endnum);
#endif

	/* merge any continuous blocks in laarr */
	udf_merge_extents(inode, laarr, &endnum);

	/* write back the new extents, inserting new extents if the new number
	 * of extents is greater than the old number, and deleting extents if
	 * the new number of extents is less than the old number */
	udf_update_extents(inode, laarr, startnum, endnum, &prev_epos);

	brelse(prev_epos.bh);

	if (!(newblock = udf_get_pblock(inode->i_sb, newblocknum,
					UDF_I_LOCATION(inode).partitionReferenceNum, 0))) {
		return NULL;
	}
	*phys = newblock;
	*err = 0;
	*new = 1;
	UDF_I_NEXT_ALLOC_BLOCK(inode) = block;
	UDF_I_NEXT_ALLOC_GOAL(inode) = newblocknum;
	inode->i_ctime = current_fs_time(inode->i_sb);

	if (IS_SYNC(inode))
		udf_sync_inode(inode);
	else
		mark_inode_dirty(inode);

	return result;
}

static void udf_split_extents(struct inode *inode, int *c, int offset,
			      int newblocknum,
			      kernel_long_ad laarr[EXTENT_MERGE_SIZE],
			      int *endnum)
{
	if ((laarr[*c].extLength >> 30) == (EXT_NOT_RECORDED_ALLOCATED >> 30) ||
	    (laarr[*c].extLength >> 30) == (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30)) {
		int curr = *c;
		int blen = ((laarr[curr].extLength & UDF_EXTENT_LENGTH_MASK) +
			    inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits;
		int8_t etype = (laarr[curr].extLength >> 30);

		if (blen == 1) {
			;
		} else if (!offset || blen == offset + 1) {
			laarr[curr + 2] = laarr[curr + 1];
			laarr[curr + 1] = laarr[curr];
		} else {
			laarr[curr + 3] = laarr[curr + 1];
			laarr[curr + 2] = laarr[curr + 1] = laarr[curr];
		}

		if (offset) {
			if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
				udf_free_blocks(inode->i_sb, inode, laarr[curr].extLocation, 0, offset);
				laarr[curr].extLength = EXT_NOT_RECORDED_NOT_ALLOCATED |
					(offset << inode->i_sb->s_blocksize_bits);
				laarr[curr].extLocation.logicalBlockNum = 0;
				laarr[curr].extLocation.partitionReferenceNum = 0;
			} else {
				laarr[curr].extLength = (etype << 30) |
					(offset << inode->i_sb->s_blocksize_bits);
			}
			curr++;
			(*c)++;
			(*endnum)++;
		}

		laarr[curr].extLocation.logicalBlockNum = newblocknum;
		if (etype == (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
			laarr[curr].extLocation.partitionReferenceNum =
				UDF_I_LOCATION(inode).partitionReferenceNum;
		laarr[curr].extLength = EXT_RECORDED_ALLOCATED |
			inode->i_sb->s_blocksize;
		curr++;

		if (blen != offset + 1) {
			if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30))
				laarr[curr].extLocation.logicalBlockNum += (offset + 1);
			laarr[curr].extLength = (etype << 30) |
				((blen - (offset + 1)) << inode->i_sb->s_blocksize_bits);
			curr++;
			(*endnum)++;
		}
	}
}

static void udf_prealloc_extents(struct inode *inode, int c, int lastblock,
				 kernel_long_ad laarr[EXTENT_MERGE_SIZE],
				 int *endnum)
{
	int start, length = 0, currlength = 0, i;

	if (*endnum >= (c + 1)) {
		if (!lastblock)
			return;
		else
			start = c;
	} else {
		if ((laarr[c + 1].extLength >> 30) == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
			start = c + 1;
			length = currlength = (((laarr[c + 1].extLength & UDF_EXTENT_LENGTH_MASK) +
						inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits);
		} else {
			start = c;
		}
	}

	for (i = start + 1; i <= *endnum; i++) {
		if (i == *endnum) {
			if (lastblock)
				length += UDF_DEFAULT_PREALLOC_BLOCKS;
		} else if ((laarr[i].extLength >> 30) == (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30)) {
			length += (((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
				    inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits);
		} else {
			break;
		}
	}

	if (length) {
		int next = laarr[start].extLocation.logicalBlockNum +
			(((laarr[start].extLength & UDF_EXTENT_LENGTH_MASK) +
			  inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits);
		int numalloc = udf_prealloc_blocks(inode->i_sb, inode,
						   laarr[start].extLocation.partitionReferenceNum,
						   next, (UDF_DEFAULT_PREALLOC_BLOCKS > length ? length :
							  UDF_DEFAULT_PREALLOC_BLOCKS) - currlength);
		if (numalloc) 	{
			if (start == (c + 1)) {
				laarr[start].extLength +=
					(numalloc << inode->i_sb->s_blocksize_bits);
			} else {
				memmove(&laarr[c + 2], &laarr[c + 1],
					sizeof(long_ad) * (*endnum - (c + 1)));
				(*endnum)++;
				laarr[c + 1].extLocation.logicalBlockNum = next;
				laarr[c + 1].extLocation.partitionReferenceNum =
					laarr[c].extLocation.partitionReferenceNum;
				laarr[c + 1].extLength = EXT_NOT_RECORDED_ALLOCATED |
					(numalloc << inode->i_sb->s_blocksize_bits);
				start = c + 1;
			}

			for (i = start + 1; numalloc && i < *endnum; i++) {
				int elen = ((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
					    inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits;

				if (elen > numalloc) {
					laarr[i].extLength -=
						(numalloc << inode->i_sb->s_blocksize_bits);
					numalloc = 0;
				} else {
					numalloc -= elen;
					if (*endnum > (i + 1))
						memmove(&laarr[i], &laarr[i + 1],
							sizeof(long_ad) * (*endnum - (i + 1)));
					i--;
					(*endnum)--;
				}
			}
			UDF_I_LENEXTENTS(inode) += numalloc << inode->i_sb->s_blocksize_bits;
		}
	}
}

static void udf_merge_extents(struct inode *inode,
			      kernel_long_ad laarr[EXTENT_MERGE_SIZE],
			      int *endnum)
{
	int i;

	for (i = 0; i < (*endnum - 1); i++) {
		if ((laarr[i].extLength >> 30) == (laarr[i + 1].extLength >> 30)) {
			if (((laarr[i].extLength >> 30) == (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30)) ||
			    ((laarr[i + 1].extLocation.logicalBlockNum - laarr[i].extLocation.logicalBlockNum) ==
			     (((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
			       inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits))) {
				if (((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
				     (laarr[i + 1].extLength & UDF_EXTENT_LENGTH_MASK) +
				     inode->i_sb->s_blocksize - 1) & ~UDF_EXTENT_LENGTH_MASK) {
					laarr[i + 1].extLength = (laarr[i + 1].extLength -
								  (laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
								  UDF_EXTENT_LENGTH_MASK) & ~(inode->i_sb->s_blocksize - 1);
					laarr[i].extLength = (laarr[i].extLength & UDF_EXTENT_FLAG_MASK) +
						(UDF_EXTENT_LENGTH_MASK + 1) - inode->i_sb->s_blocksize;
					laarr[i + 1].extLocation.logicalBlockNum =
						laarr[i].extLocation.logicalBlockNum +
						((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) >>
						 inode->i_sb->s_blocksize_bits);
				} else {
					laarr[i].extLength = laarr[i + 1].extLength +
						(((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
						  inode->i_sb->s_blocksize - 1) & ~(inode->i_sb->s_blocksize - 1));
					if (*endnum > (i + 2))
						memmove(&laarr[i + 1], &laarr[i + 2],
							sizeof(long_ad) * (*endnum - (i + 2)));
					i--;
					(*endnum)--;
				}
			}
		} else if (((laarr[i].extLength >> 30) == (EXT_NOT_RECORDED_ALLOCATED >> 30)) &&
			   ((laarr[i + 1].extLength >> 30) == (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))) {
			udf_free_blocks(inode->i_sb, inode, laarr[i].extLocation, 0,
					((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
					 inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits);
			laarr[i].extLocation.logicalBlockNum = 0;
			laarr[i].extLocation.partitionReferenceNum = 0;

			if (((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
			     (laarr[i + 1].extLength & UDF_EXTENT_LENGTH_MASK) +
			     inode->i_sb->s_blocksize - 1) & ~UDF_EXTENT_LENGTH_MASK) {
				laarr[i + 1].extLength = (laarr[i + 1].extLength -
							  (laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
							  UDF_EXTENT_LENGTH_MASK) & ~(inode->i_sb->s_blocksize - 1);
				laarr[i].extLength = (laarr[i].extLength & UDF_EXTENT_FLAG_MASK) +
					(UDF_EXTENT_LENGTH_MASK + 1) - inode->i_sb->s_blocksize;
			} else {
				laarr[i].extLength = laarr[i + 1].extLength +
					(((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
					  inode->i_sb->s_blocksize - 1) & ~(inode->i_sb->s_blocksize - 1));
				if (*endnum > (i + 2))
					memmove(&laarr[i + 1], &laarr[i + 2],
						sizeof(long_ad) * (*endnum - (i + 2)));
				i--;
				(*endnum)--;
			}
		} else if ((laarr[i].extLength >> 30) == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
			udf_free_blocks(inode->i_sb, inode, laarr[i].extLocation, 0,
					((laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) +
					 inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits);
			laarr[i].extLocation.logicalBlockNum = 0;
			laarr[i].extLocation.partitionReferenceNum = 0;
			laarr[i].extLength = (laarr[i].extLength & UDF_EXTENT_LENGTH_MASK) |
				EXT_NOT_RECORDED_NOT_ALLOCATED;
		}
	}
}

static void udf_update_extents(struct inode *inode,
			       kernel_long_ad laarr[EXTENT_MERGE_SIZE],
			       int startnum, int endnum,
			       struct extent_position *epos)
{
	int start = 0, i;
	kernel_lb_addr tmploc;
	uint32_t tmplen;

	if (startnum > endnum) {
		for (i = 0; i < (startnum - endnum); i++)
			udf_delete_aext(inode, *epos, laarr[i].extLocation,
					laarr[i].extLength);
	} else if (startnum < endnum) {
		for (i = 0; i < (endnum - startnum); i++) {
			udf_insert_aext(inode, *epos, laarr[i].extLocation,
					laarr[i].extLength);
			udf_next_aext(inode, epos, &laarr[i].extLocation,
				      &laarr[i].extLength, 1);
			start++;
		}
	}

	for (i = start; i < endnum; i++) {
		udf_next_aext(inode, epos, &tmploc, &tmplen, 0);
		udf_write_aext(inode, epos, laarr[i].extLocation,
			       laarr[i].extLength, 1);
	}
}

struct buffer_head *udf_bread(struct inode *inode, int block,
			      int create, int *err)
{
	struct buffer_head *bh = NULL;

	bh = udf_getblk(inode, block, create, err);
	if (!bh)
		return NULL;

	if (buffer_uptodate(bh))
		return bh;

	ll_rw_block(READ, 1, &bh);

	wait_on_buffer(bh);
	if (buffer_uptodate(bh))
		return bh;

	brelse(bh);
	*err = -EIO;
	return NULL;
}

void udf_truncate(struct inode *inode)
{
	int offset;
	int err;

	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
	      S_ISLNK(inode->i_mode)))
		return;
	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
		return;

	lock_kernel();
	if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB) {
		if (inode->i_sb->s_blocksize < (udf_file_entry_alloc_offset(inode) +
						inode->i_size)) {
			udf_expand_file_adinicb(inode, inode->i_size, &err);
			if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB) {
				inode->i_size = UDF_I_LENALLOC(inode);
				unlock_kernel();
				return;
			} else {
				udf_truncate_extents(inode);
			}
		} else {
			offset = inode->i_size & (inode->i_sb->s_blocksize - 1);
			memset(UDF_I_DATA(inode) + UDF_I_LENEATTR(inode) + offset, 0x00,
			       inode->i_sb->s_blocksize - offset - udf_file_entry_alloc_offset(inode));
			UDF_I_LENALLOC(inode) = inode->i_size;
		}
	} else {
		block_truncate_page(inode->i_mapping, inode->i_size, udf_get_block);
		udf_truncate_extents(inode);
	}

	inode->i_mtime = inode->i_ctime = current_fs_time(inode->i_sb);
	if (IS_SYNC(inode))
		udf_sync_inode(inode);
	else
		mark_inode_dirty(inode);
	unlock_kernel();
}

static void __udf_read_inode(struct inode *inode)
{
	struct buffer_head *bh = NULL;
	struct fileEntry *fe;
	uint16_t ident;