xfs: Read Block directories

Block directories can now be read.
Change-Id: I9aa898638e6ac39cb903f2dd58cd184785e1a06b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2992
Reviewed-by: Adrien Destugues <[email protected]>

src/add-ons/kernel/file_systems/xfs/Debug.h

@@ -9,7 +9,7 @@
 #ifndef _DEBUG_H_
 #define _DEBUG_H_
 
-#define TRACE_XFS
+// #define TRACE_XFS
 #ifdef TRACE_XFS
 #define TRACE(x...) dprintf("\n\33[34mxfs:\33[0m " x)
 #define ASSERT(x) \

src/add-ons/kernel/file_systems/xfs/Directory.cpp

@@ -62,15 +62,17 @@ DirectoryIterator::Init()
 status_t
 DirectoryIterator::GetNext(char* name, size_t* length, xfs_ino_t* ino)
 {
+	status_t status;
 	if (fInode->Format() == XFS_DINODE_FMT_LOCAL) {
-		status_t status = fShortDir->GetNext(name, length, ino);
+		status = fShortDir->GetNext(name, length, ino);
 		return status;
 	}
 
 	//TODO: Reading from extent based directories
 	if (fInode->Format() == XFS_DINODE_FMT_EXTENTS) {
 		TRACE("Iterator:GetNext: EXTENTS");
-		return B_NOT_SUPPORTED;
+		status = fExtentDir->GetNext(name, length, ino);
+		return status;
 	}
 
 	//TODO: Reading from B+Trees based directories
@@ -87,19 +89,17 @@ DirectoryIterator::GetNext(char* name, size_t* length, xfs_ino_t* ino)
 status_t
 DirectoryIterator::Lookup(const char* name, size_t length, xfs_ino_t* ino)
 {
+	status_t status;
 	if (fInode->Format() == XFS_DINODE_FMT_LOCAL) {
-		status_t status = fShortDir->Lookup(name, length, ino);
+		status = fShortDir->Lookup(name, length, ino);
 		return status;
 	}
 
 	//TODO: Reading from extent based dirs
 	if (fInode->Format() == XFS_DINODE_FMT_EXTENTS) {
 		TRACE("Iterator:Lookup: EXTENTS");
-		#if 0
-			status_t status = fExtentDir->Lookup(name, length, ino);
-			return status;
-		#endif
-		return B_NOT_SUPPORTED;
+		status = fExtentDir->Lookup(name, length, ino);
+		return status;
 	}
 
 	//TODO: Reading from B+Tree based dirs

src/add-ons/kernel/file_systems/xfs/Extent.cpp

@@ -9,7 +9,8 @@
 
 Extent::Extent(Inode* inode)
 	:
-	fInode(inode)
+	fInode(inode),
+	fOffset(0)
 {
 }
 
@@ -36,6 +37,37 @@ Extent::FillMapEntry(void* pointerToMap)
 }
 
 
+status_t
+Extent::FillBlockBuffer()
+{
+	if (fMap->br_state != 0)
+		return B_BAD_VALUE;
+
+	int len = fInode->DirBlockSize();
+	fBlockBuffer = new(std::nothrow) char[len];
+	if (fBlockBuffer == NULL)
+		return B_NO_MEMORY;
+
+	Volume* volume = fInode->GetVolume();
+	xfs_agblock_t numberOfBlocksInAg = volume->AgBlocks();
+
+	uint64 agNo = FSBLOCKS_TO_AGNO(fMap->br_startblock, volume);
+	uint64 agBlockNo = FSBLOCKS_TO_AGBLOCKNO(fMap->br_startblock, volume);
+	xfs_fsblock_t blockToRead = FSBLOCKS_TO_BASICBLOCKS(volume->BlockLog(),
+		((uint64)(agNo * numberOfBlocksInAg) + agBlockNo));
+
+	xfs_daddr_t readPos = blockToRead * (BASICBLOCKSIZE) + fMap->br_startoff;
+
+	TRACE("blockToRead: (%ld), readPos: (%ld)\n", blockToRead, readPos);
+	if (read_pos(volume->Device(), readPos, fBlockBuffer, len) != len) {
+		ERROR("Extent::FillBlockBuffer(): IO Error");
+		return B_IO_ERROR;
+	}
+
+	return B_OK;
+}
+
+
 status_t
 Extent::Init()
 {
@@ -46,16 +78,38 @@ Extent::Init()
 	ASSERT(BlockType() == true);
 	void* pointerToMap = DIR_DFORK_PTR(fInode->Buffer());
 	FillMapEntry(pointerToMap);
+	ASSERT(fMap->br_blockcount == 1);
+		//TODO: This is always true for block directories
+		//If we use this implementation for leaf directories, this is not
+		//always true
+	status_t status = FillBlockBuffer();
+	ExtentDataHeader* header = (ExtentDataHeader*)fBlockBuffer;
+	if (B_BENDIAN_TO_HOST_INT32(header->magic) == DIR2_BLOCK_HEADER_MAGIC) {
+		status = B_OK;
+		TRACE("Extent:Init(): Block read successfully\n");
+	} else {
+		status = B_BAD_VALUE;
+		TRACE("Extent:Init(): Bad Block!\n");
+	}
 
-	return B_NOT_SUPPORTED;
+	return status;
 }
 
 
 ExtentBlockTail*
-Extent::BlockTail(ExtentDataHeader* header)
+Extent::BlockTail()
 {
 	return (ExtentBlockTail*)
-		((char*)header + fInode->DirBlockSize() - sizeof(ExtentBlockTail));
+		(fBlockBuffer + fInode->DirBlockSize() - sizeof(ExtentBlockTail));
+}
+
+
+uint32
+Extent::GetOffsetFromAddress(uint32 address)
+{
+	address = address * 8;
+		// block offset in eight bytes, hence multiple with 8
+	return address & (fInode->DirBlockSize() - 1);
 }
 
 
@@ -75,5 +129,128 @@ Extent::BlockType()
 	if (fInode->Size() != fInode->DirBlockSize())
 		status = false;
 	return status;
+	//TODO: Checks: Fileoffset must be 0 and
+	//length = directory block size / filesystem block size
+}
+
+
+int
+Extent::EntrySize(int len) const
+{
+	int entrySize= sizeof(xfs_ino_t) + sizeof(uint8) + len + sizeof(uint16);
+			// uint16 is for the tag
+	if (fInode->HasFileTypeField())
+		entrySize += sizeof(uint8);
+
+	return (entrySize + 7) & -8;
+			// rounding off to closest multiple of 8
+}
+
+
+status_t
+Extent::GetNext(char* name, size_t* length, xfs_ino_t* ino)
+{
+	TRACE("Extend::GetNext\n");
+	void* entry = (void*)((ExtentDataHeader*)fBlockBuffer + 1);
+		// This could be an unused entry so we should check
+
+	int numberOfEntries = B_BENDIAN_TO_HOST_INT32(BlockTail()->count);
+	TRACE("numberOfEntries:(%d)\n", numberOfEntries);
+
+	for (int i = 0; i < numberOfEntries; i++) {
+		TRACE("i:(%d)\n", i);
+		ExtentUnusedEntry* unusedEntry = (ExtentUnusedEntry*)entry;
+
+		if (B_BENDIAN_TO_HOST_INT16(unusedEntry->freetag) == DIR2_FREE_TAG) {
+			TRACE("Unused entry found\n");
+			entry = (void*)
+				((char*)entry + B_BENDIAN_TO_HOST_INT16(unusedEntry->length));
+			continue;
+		}
+		ExtentDataEntry* dataEntry = (ExtentDataEntry*) entry;
+
+		uint16 currentOffset = (char*)dataEntry - fBlockBuffer;
+		TRACE("GetNext: fOffset:(%d), currentOffset:(%d)\n",
+			fOffset, currentOffset);
+
+		if (fOffset >= currentOffset) {
+			entry = (void*)((char*)entry + EntrySize(dataEntry->namelen));
+			continue;
+		}
+
+		if (dataEntry->namelen > *length)
+				return B_BUFFER_OVERFLOW;
+
+		fOffset = currentOffset;
+		memcpy(name, dataEntry->name, dataEntry->namelen);
+		name[dataEntry->namelen] = '\0';
+		*length = dataEntry->namelen + 1;
+		*ino = B_BENDIAN_TO_HOST_INT64(dataEntry->inumber);
+
+		TRACE("Entry found. Name: (%s), Length: (%ld),ino: (%ld)\n", name,
+			*length, *ino);
+		return B_OK;
+	}
+
+	return B_ENTRY_NOT_FOUND;
+}
+
+
+status_t
+Extent::Lookup(const char* name, size_t length, xfs_ino_t* ino)
+{
+	TRACE("Extent: Lookup\n");
+	TRACE("Name: %s\n", name);
+	uint32 hashValueOfRequest = hashfunction(name, length);
+	TRACE("Hashval:(%ld)\n", hashValueOfRequest);
+	ExtentBlockTail* blockTail = BlockTail();
+	ExtentLeafEntry* leafEntry = BlockFirstLeaf(blockTail);
+
+	int numberOfLeafEntries = B_BENDIAN_TO_HOST_INT32(blockTail->count);
+	int left = 0;
+	int mid;
+	int right = numberOfLeafEntries - 1;
+
+	/*
+	* Trying to find the lowerbound of hashValueOfRequest
+	* This is slightly different from bsearch(), as we want the first
+	* instance of hashValueOfRequest and not any instance.
+	*/
+	while (left < right) {
+		mid = (left+right)/2;
+		uint32 hashval = B_BENDIAN_TO_HOST_INT32(leafEntry[mid].hashval);
+		if (hashval >= hashValueOfRequest) {
+			right = mid;
+			continue;
+		}
+		if (hashval < hashValueOfRequest) {
+			left = mid+1;
+		}
+	}
+	TRACE("left:(%d), right:(%d)\n", left, right);
+
+	while (B_BENDIAN_TO_HOST_INT32(leafEntry[left].hashval)
+			== hashValueOfRequest) {
+
+		uint32 address = B_BENDIAN_TO_HOST_INT32(leafEntry[left].address);
+		if (address == 0) {
+			left++;
+			continue;
+		}
+
+		uint32 offset = GetOffsetFromAddress(address);
+		TRACE("offset:(%d)\n", offset);
+		ExtentDataEntry* entry = (ExtentDataEntry*)(fBlockBuffer + offset);
+
+		int retVal = strncmp(name, (char*)entry->name, entry->namelen);
+		if (retVal == 0) {
+			*ino = B_BENDIAN_TO_HOST_INT64(entry->inumber);
+			TRACE("ino:(%d)\n", *ino);
+			return B_OK;
+		}
+		left++;
+	}
+
+	return B_ENTRY_NOT_FOUND;
 }
 

src/add-ons/kernel/file_systems/xfs/Extent.h

@@ -12,9 +12,13 @@
 
 #define DIR2_BLOCK_HEADER_MAGIC 0x58443242
 	// for v4 system
+#define DIR2_FREE_TAG 0xffff
 #define XFS_DIR2_DATA_FD_COUNT 3
 #define EXTENT_REC_SIZE		128
 #define MASK(n) ((1UL << n) - 1)
+#define FSBLOCKS_TO_AGNO(n, volume) (n >> volume->AgBlocksLog())
+#define FSBLOCKS_TO_AGBLOCKNO(n, volume) (n & MASK(volume->AgBlocksLog()))
+
 
 
 // xfs_exntst_t
@@ -97,10 +101,12 @@ public:
 			status_t			Init();
 			bool				BlockType();
 			void				FillMapEntry(void* pointerToMap);
-			ExtentDataHeader*	BlockHeader();
-			ExtentBlockTail*	BlockTail(ExtentDataHeader* header);
+			status_t			FillBlockBuffer();
+			ExtentBlockTail*	BlockTail();
 			ExtentLeafEntry*	BlockFirstLeaf(ExtentBlockTail* tail);
 			xfs_ino_t			GetIno();
+			uint32				GetOffsetFromAddress(uint32 address);
+			int					EntrySize(int len) const;
 			status_t			GetNext(char* name, size_t* length,
 									xfs_ino_t* ino);
 			status_t			Lookup(const char* name, size_t length,
@@ -108,6 +114,7 @@ public:
 private:
 			Inode*				fInode;
 			ExtentMapEntry*		fMap;
+			uint32				fOffset;
 			char*				fBlockBuffer;
 				// This isn't inode data. It holds the directory block.
 };

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

@@ -160,6 +160,13 @@ Inode::Init()
 }
 
 
+bool
+Inode::HasFileTypeField() const
+{
+	return fVolume->SuperBlockFeatures2() & XFS_SB_VERSION2_FTYPE;
+}
+
+
 status_t
 Inode::GetFromDisk()
 {
@@ -209,17 +216,21 @@ Inode::~Inode()
 }
 
 
+/*
+ * Basically take 4 characters at a time as long as you can, and xor with
+ * previous hashVal after rotating 4 bits of hashVal. Likewise, continue
+ * xor and rotating. This is quite a generic hash function.
+*/
 uint32
 hashfunction(const char* name, int length)
 {
 	uint32 hashVal = 0;
-
 	int lengthCovered = 0;
 	int index = 0;
 	if (length >= 4) {
-		for (; index <= length; index+=4)
+		for (;index < length && (length - index) >= 4; index += 4)
 		{
-			lengthCovered = index;
+			lengthCovered += 4;
 			hashVal = (name[index] << 21) ^ (name[index+1] << 14)
 				^ (name[index+2] << 7) ^ (name[index+3] << 0)
 				^ ((hashVal << 28) | (hashVal >> (4)));

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

@@ -178,6 +178,7 @@ public:
 
 			uint32				UserId() const { return fNode->UserId(); }
 			uint32				GroupId() const { return fNode->GroupId(); }
+			bool				HasFileTypeField() const;
 
 private:
 			status_t			GetFromDisk();

src/add-ons/kernel/file_systems/xfs/ShortDirectory.cpp

@@ -22,20 +22,10 @@ ShortDirectory::~ShortDirectory()
 }
 
 
-bool
-ShortDirectory::HasFileTypeField()
-{
-	if (fInode->GetVolume()->SuperBlockFeatures2() & XFS_SB_VERSION2_FTYPE)
-		return true;
-	else
-		return false;
-}
-
-
 uint8
 ShortDirectory::GetFileType(ShortFormEntry* entry)
 {
-	ASSERT(HasFileTypeField() == true);
+	ASSERT(fInode->HasFileTypeField() == true);
 	return entry->name[entry->namelen];
 }
 
@@ -70,7 +60,7 @@ ShortDirectory::GetIno(ShortFormInodeUnion* inum)
 xfs_ino_t
 ShortDirectory::GetEntryIno(ShortFormEntry* entry)
 {
-	if (HasFileTypeField())
+	if (fInode->HasFileTypeField())
 		return GetIno((ShortFormInodeUnion*)(entry->name
 				+ entry->namelen + sizeof(uint8)));
 	else
@@ -82,7 +72,7 @@ size_t
 ShortDirectory::EntrySize(int namelen)
 {
 	return sizeof(ShortFormEntry) + namelen
-			+ (HasFileTypeField()? sizeof(uint8) : 0)
+			+ (fInode->HasFileTypeField()? sizeof(uint8) : 0)
 			+ (fHeader->i8count? sizeof(uint64):sizeof(uint32));
 }
 

src/add-ons/kernel/file_systems/xfs/ShortDirectory.h

@@ -56,7 +56,6 @@ public:
 								ShortDirectory(Inode* inode);
 								~ShortDirectory();
 			size_t				HeaderSize();
-			bool				HasFileTypeField();
 			uint8				GetFileType(ShortFormEntry* entry);
 			ShortFormEntry*		FirstEntry();
 			xfs_ino_t			GetIno(ShortFormInodeUnion* inum);