fs: btrfs: Add single-device read-only BTRFS implementation

This adds the proper implementation for the BTRFS filesystem.
The implementation currently supports only read-only mode and
the filesystem can be only on a single device.

Checksums of data chunks is unimplemented.

Compression is implemented (ZLIB + LZO).

Signed-off-by: Marek Behun <marek.behun@nic.cz>

 create mode 100644 fs/btrfs/btrfs.h
 create mode 100644 fs/btrfs/chunk-map.c
 create mode 100644 fs/btrfs/compression.c
 create mode 100644 fs/btrfs/ctree.c
 create mode 100644 fs/btrfs/dev.c
 create mode 100644 fs/btrfs/dir-item.c
 create mode 100644 fs/btrfs/extent-io.c
 create mode 100644 fs/btrfs/hash.c
 create mode 100644 fs/btrfs/inode.c
 create mode 100644 fs/btrfs/root.c
 create mode 100644 fs/btrfs/subvolume.c
 create mode 100644 fs/btrfs/super.c

1 files changed, 120 insertions, 0 deletions

diff --git a/fs/btrfs/extent-io.c b/fs/btrfs/extent-io.c
new file mode 100644
index 0000000000..feb91432e9
--- /dev/null
+++ b/fs/btrfs/extent-io.c
@@ -0,0 +1,120 @@
+/*
+ * BTRFS filesystem implementation for U-Boot
+ *
+ * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include "btrfs.h"
+#include <malloc.h>
+
+u64 btrfs_read_extent_inline(struct btrfs_path *path,
+			     struct btrfs_file_extent_item *extent, u64 offset,
+			     u64 size, char *out)
+{
+	u32 clen, dlen, orig_size = size, res;
+	const char *cbuf;
+	char *dbuf;
+	const int data_off = offsetof(struct btrfs_file_extent_item,
+				      disk_bytenr);
+
+	clen = btrfs_path_item_size(path) - data_off;
+	cbuf = (const char *) extent + data_off;
+	dlen = extent->ram_bytes;
+
+	if (offset > dlen)
+		return -1ULL;
+
+	if (size > dlen - offset)
+		size = dlen - offset;
+
+	if (extent->compression == BTRFS_COMPRESS_NONE) {
+		memcpy(out, cbuf + offset, size);
+		return size;
+	}
+
+	if (dlen > orig_size) {
+		dbuf = malloc(dlen);
+		if (!dbuf)
+			return -1ULL;
+	} else {
+		dbuf = out;
+	}
+
+	res = btrfs_decompress(extent->compression, cbuf, clen, dbuf, dlen);
+	if (res == -1 || res != dlen)
+		goto err;
+
+	if (dlen > orig_size) {
+		memcpy(out, dbuf + offset, size);
+		free(dbuf);
+	} else if (offset) {
+		memmove(out, dbuf + offset, size);
+	}
+
+	return size;
+
+err:
+	if (dlen > orig_size)
+		free(dbuf);
+	return -1ULL;
+}
+
+u64 btrfs_read_extent_reg(struct btrfs_path *path,
+			  struct btrfs_file_extent_item *extent, u64 offset,
+			  u64 size, char *out)
+{
+	u64 physical, clen, dlen, orig_size = size;
+	u32 res;
+	char *cbuf, *dbuf;
+
+	clen = extent->disk_num_bytes;
+	dlen = extent->num_bytes;
+
+	if (offset > dlen)
+		return -1ULL;
+
+	if (size > dlen - offset)
+		size = dlen - offset;
+
+	physical = btrfs_map_logical_to_physical(extent->disk_bytenr);
+	if (physical == -1ULL)
+		return -1ULL;
+
+	if (extent->compression == BTRFS_COMPRESS_NONE) {
+		physical += extent->offset + offset;
+		if (!btrfs_devread(physical, size, out))
+			return -1ULL;
+
+		return size;
+	}
+
+	cbuf = malloc(dlen > size ? clen + dlen : clen);
+	if (!cbuf)
+		return -1ULL;
+
+	if (dlen > orig_size)
+		dbuf = cbuf + clen;
+	else
+		dbuf = out;
+
+	if (!btrfs_devread(physical, clen, cbuf))
+		goto err;
+
+	res = btrfs_decompress(extent->compression, cbuf, clen, dbuf, dlen);
+	if (res == -1)
+		goto err;
+
+	if (dlen > orig_size)
+		memcpy(out, dbuf + offset, size);
+	else
+		memmove(out, dbuf + offset, size);
+
+	free(cbuf);
+	return res;
+
+err:
+	free(cbuf);
+	return -1ULL;
+}