hfsplus: implement attributes file's header node initialization code

Implement functionality of AttributesFile's header node initialization.

Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 65 insertions, 0 deletions

diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index bd8471fb9a6a..568a45cb1145 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -127,6 +127,71 @@ static int can_set_xattr(struct inode *inode, const char *name,
         return 0;
 }
 
+static void hfsplus_init_header_node(struct inode *attr_file,
+                                        u32 clump_size,
+                                        char *buf, size_t node_size)
+{
+        struct hfs_bnode_desc *desc;
+        struct hfs_btree_header_rec *head;
+        u16 offset;
+        __be16 *rec_offsets;
+        u32 hdr_node_map_rec_bits;
+        char *bmp;
+        u32 used_nodes;
+        u32 used_bmp_bytes;
+
+        hfs_dbg(ATTR_MOD, "init_hdr_attr_file: clump %u, node_size %zu\n",
+                                clump_size, node_size);
+
+        /* The end of the node contains list of record offsets */
+        rec_offsets = (__be16 *)(buf + node_size);
+
+        desc = (struct hfs_bnode_desc *)buf;
+        desc->type = HFS_NODE_HEADER;
+        desc->num_recs = cpu_to_be16(HFSPLUS_BTREE_HDR_NODE_RECS_COUNT);
+        offset = sizeof(struct hfs_bnode_desc);
+        *--rec_offsets = cpu_to_be16(offset);
+
+        head = (struct hfs_btree_header_rec *)(buf + offset);
+        head->node_size = cpu_to_be16(node_size);
+        head->node_count = cpu_to_be32(i_size_read(attr_file) / node_size);
+        head->free_nodes = cpu_to_be32(be32_to_cpu(head->node_count) - 1);
+        head->clump_size = cpu_to_be32(clump_size);
+        head->attributes |= cpu_to_be32(HFS_TREE_BIGKEYS | HFS_TREE_VARIDXKEYS);
+        head->max_key_len = cpu_to_be16(HFSPLUS_ATTR_KEYLEN - sizeof(u16));
+        offset += sizeof(struct hfs_btree_header_rec);
+        *--rec_offsets = cpu_to_be16(offset);
+        offset += HFSPLUS_BTREE_HDR_USER_BYTES;
+        *--rec_offsets = cpu_to_be16(offset);
+
+        hdr_node_map_rec_bits = 8 * (node_size - offset - (4 * sizeof(u16)));
+        if (be32_to_cpu(head->node_count) > hdr_node_map_rec_bits) {
+                u32 map_node_bits;
+                u32 map_nodes;
+
+                desc->next = cpu_to_be32(be32_to_cpu(head->leaf_tail) + 1);
+                map_node_bits = 8 * (node_size - sizeof(struct hfs_bnode_desc) -
+                                        (2 * sizeof(u16)) - 2);
+                map_nodes = (be32_to_cpu(head->node_count) -
+                                hdr_node_map_rec_bits +
+                                (map_node_bits - 1)) / map_node_bits;
+                be32_add_cpu(&head->free_nodes, 0 - map_nodes);
+        }
+
+        bmp = buf + offset;
+        used_nodes =
+                be32_to_cpu(head->node_count) - be32_to_cpu(head->free_nodes);
+        used_bmp_bytes = used_nodes / 8;
+        if (used_bmp_bytes) {
+                memset(bmp, 0xFF, used_bmp_bytes);
+                bmp += used_bmp_bytes;
+                used_nodes %= 8;
+        }
+        *bmp = ~(0xFF >> used_nodes);
+        offset += hdr_node_map_rec_bits / 8;
+        *--rec_offsets = cpu_to_be16(offset);
+}
+
 int __hfsplus_setxattr(struct inode *inode, const char *name,
                         const void *value, size_t size, int flags)
 {