ext2: use st_blocks from the disk inode structure

* this lets cp from coreutils use lseek to find the data chunks in a
  sparse file.
* fix endian conversion macro used for num_blocks_high

Change-Id: I221d6316002b1c491ae987aeef3f25e8721b5ab9
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5218
Reviewed-by: Adrien Destugues <[email protected]>
Tested-by: Commit checker robot <[email protected]>

src/add-ons/kernel/file_systems/ext2/Inode.cpp

@@ -857,7 +857,7 @@ Inode::_EnlargeDataStream(Transaction& transaction, off_t size)
 	fNode.SetSize(size);
 	TRACE("Inode::_EnlargeDataStream(): Setting allocated block count to %"
 		B_PRIdOFF "\n", end);
-	return _SetNumBlocks(_NumBlocks() + end * (fVolume->BlockSize() / 512));
+	return _SetNumBlocks(NumBlocks() + end * (fVolume->BlockSize() / 512));
 }
 
 
@@ -895,12 +895,12 @@ Inode::_ShrinkDataStream(Transaction& transaction, off_t size)
 	}
 
 	fNode.SetSize(size);
-	return _SetNumBlocks(_NumBlocks() - end * (fVolume->BlockSize() / 512));
+	return _SetNumBlocks(NumBlocks() - end * (fVolume->BlockSize() / 512));
 }
 
 
 uint64
-Inode::_NumBlocks()
+Inode::NumBlocks()
 {
 	if (fVolume->HugeFiles()) {
 		if (fNode.Flags() & EXT2_INODE_HUGE_FILE)

src/add-ons/kernel/file_systems/ext2/Inode.h

@@ -59,6 +59,7 @@ public:
 			int32		Flags() const { return fNode.Flags(); }
 
 			off_t		Size() const { return fNode.Size(); }
+			uint64		NumBlocks();
 			void		GetChangeTime(struct timespec *timespec) const
 						{ fNode.GetChangeTime(timespec, fHasExtraAttributes); }
 			void		GetModificationTime(struct timespec *timespec) const
@@ -142,7 +143,6 @@ private:
 			status_t	_ShrinkDataStream(Transaction& transaction,
 							off_t size);
 	
-			uint64		_NumBlocks();
 			status_t	_SetNumBlocks(uint64 numBlocks);
 
 			uint32		_InodeChecksum(ext2_inode* inode);

src/add-ons/kernel/file_systems/ext2/ext2.h

@@ -490,7 +490,7 @@ struct ext2_inode {
 	uint16 NumLinks() const { return B_LENDIAN_TO_HOST_INT16(num_links); }
 	uint32 NumBlocks() const { return B_LENDIAN_TO_HOST_INT32(num_blocks); }
 	uint64 NumBlocks64() const { return B_LENDIAN_TO_HOST_INT32(num_blocks)
-		| ((uint64)B_LENDIAN_TO_HOST_INT32(num_blocks_high) << 32); }
+		| ((uint64)B_LENDIAN_TO_HOST_INT16(num_blocks_high) << 32); }
 
 	static void _DecodeTime(struct timespec *timespec, uint32 time,
 		uint32 time_extra, bool extra)
@@ -631,7 +631,7 @@ struct ext2_inode {
 	void SetNumBlocks64(uint64 numBlocks)
 	{
 		num_blocks = B_HOST_TO_LENDIAN_INT32(numBlocks & 0xffffffff);
-		num_blocks_high = B_HOST_TO_LENDIAN_INT32(numBlocks >> 32);
+		num_blocks_high = B_HOST_TO_LENDIAN_INT16(numBlocks >> 32);
 	}
 
 	void SetNextOrphan(ino_t id)

src/add-ons/kernel/file_systems/ext2/kernel_interface.cpp

@@ -587,7 +587,7 @@ ext2_read_stat(fs_volume* _volume, fs_vnode* _node, struct stat* stat)
 	inode->GetCreationTime(&stat->st_crtim);
 
 	stat->st_size = inode->Size();
-	stat->st_blocks = (inode->Size() + 511) / 512;
+	stat->st_blocks = inode->NumBlocks();
 
 	return B_OK;
 }