ANDROID: Incremental fs: Create mapped file

Bug: 160634482
Test: incfs_test passes
Signed-off-by: Paul Lawrence <[email protected]>
Change-Id: Ic2ac8dfccd60f6c9c72c38bf323997fce7546c1c

Author: PaulLawrenceGoogle

fs/incfs/data_mgmt.c

@@ -8,6 +8,7 @@
 #include <linux/ktime.h>
 #include <linux/lz4.h>
 #include <linux/mm.h>
+#include <linux/namei.h>
 #include <linux/pagemap.h>
 #include <linux/slab.h>
 #include <linux/types.h>
@@ -123,6 +124,86 @@ static void data_file_segment_init(struct data_file_segment *segment)
 	INIT_LIST_HEAD(&segment->reads_list_head);
 }
 
+char *file_id_to_str(incfs_uuid_t id)
+{
+	char *result = kmalloc(1 + sizeof(id.bytes) * 2, GFP_NOFS);
+	char *end;
+
+	if (!result)
+		return NULL;
+
+	end = bin2hex(result, id.bytes, sizeof(id.bytes));
+	*end = 0;
+	return result;
+}
+
+struct dentry *incfs_lookup_dentry(struct dentry *parent, const char *name)
+{
+	struct inode *inode;
+	struct dentry *result = NULL;
+
+	if (!parent)
+		return ERR_PTR(-EFAULT);
+
+	inode = d_inode(parent);
+	inode_lock_nested(inode, I_MUTEX_PARENT);
+	result = lookup_one_len(name, parent, strlen(name));
+	inode_unlock(inode);
+
+	if (IS_ERR(result))
+		pr_warn("%s err:%ld\n", __func__, PTR_ERR(result));
+
+	return result;
+}
+
+static struct data_file *handle_mapped_file(struct mount_info *mi,
+					    struct data_file *df)
+{
+	char *file_id_str;
+	struct dentry *index_file_dentry;
+	struct path path;
+	struct file *bf;
+	struct data_file *result = NULL;
+
+	file_id_str = file_id_to_str(df->df_id);
+	if (!file_id_str)
+		return ERR_PTR(-ENOENT);
+
+	index_file_dentry = incfs_lookup_dentry(mi->mi_index_dir,
+						file_id_str);
+	kfree(file_id_str);
+	if (!index_file_dentry)
+		return ERR_PTR(-ENOENT);
+	if (IS_ERR(index_file_dentry))
+		return (struct data_file *)index_file_dentry;
+	if (!d_really_is_positive(index_file_dentry)) {
+		result = ERR_PTR(-ENOENT);
+		goto out;
+	}
+
+	path = (struct path) {
+		.mnt = mi->mi_backing_dir_path.mnt,
+		.dentry = index_file_dentry
+	};
+
+	bf = dentry_open(&path, O_RDWR | O_NOATIME | O_LARGEFILE, mi->mi_owner);
+	if (IS_ERR(bf)) {
+		result = (struct data_file *)bf;
+		goto out;
+	}
+
+	result = incfs_open_data_file(mi, bf);
+	fput(bf);
+	if (IS_ERR(result))
+		goto out;
+
+	result->df_mapped_offset = df->df_metadata_off;
+
+out:
+	dput(index_file_dentry);
+	return result;
+}
+
 struct data_file *incfs_open_data_file(struct mount_info *mi, struct file *bf)
 {
 	struct data_file *df = NULL;
@@ -167,6 +248,13 @@ struct data_file *incfs_open_data_file(struct mount_info *mi, struct file *bf)
 	if (size > 0)
 		df->df_data_block_count = get_blocks_count_for_size(size);
 
+	if (df->df_header_flags & INCFS_FILE_MAPPED) {
+		struct data_file *mapped_df = handle_mapped_file(mi, df);
+
+		incfs_free_data_file(df);
+		return mapped_df;
+	}
+
 	md_records = incfs_scan_metadata_chain(df);
 	if (md_records < 0)
 		error = md_records;

fs/incfs/data_mgmt.h

@@ -235,6 +235,9 @@ struct data_file {
 	/* Total number of blocks, data + hash */
 	int df_total_block_count;
 
+	/* For mapped files, the offset into the actual file */
+	loff_t df_mapped_offset;
+
 	struct file_attr n_attr;
 
 	struct mtree *df_hash_tree;
@@ -271,6 +274,8 @@ int incfs_realloc_mount_info(struct mount_info *mi,
 
 void incfs_free_mount_info(struct mount_info *mi);
 
+char *file_id_to_str(incfs_uuid_t id);
+struct dentry *incfs_lookup_dentry(struct dentry *parent, const char *name);
 struct data_file *incfs_open_data_file(struct mount_info *mi, struct file *bf);
 void incfs_free_data_file(struct data_file *df);
 

fs/incfs/format.c

@@ -233,8 +233,7 @@ int incfs_write_file_header_flags(struct backing_file_context *bfc, u32 flags)
 		return -EFAULT;
 
 	return write_to_bf(bfc, &flags, sizeof(flags),
-			   offsetof(struct incfs_file_header,
-				    fh_file_header_flags));
+			   offsetof(struct incfs_file_header, fh_flags));
 }
 
 /*
@@ -385,7 +384,7 @@ int incfs_write_signature_to_backing_file(struct backing_file_context *bfc,
 /*
  * Write a backing file header
  * It should always be called only on empty file.
- * incfs_super_block.s_first_md_offset is 0 for now, but will be updated
+ * fh.fh_first_md_offset is 0 for now, but will be updated
  * once first metadata record is added.
  */
 int incfs_write_fh_to_backing_file(struct backing_file_context *bfc,
@@ -415,6 +414,38 @@ int incfs_write_fh_to_backing_file(struct backing_file_context *bfc,
 	return write_to_bf(bfc, &fh, sizeof(fh), file_pos);
 }
 
+/*
+ * Write a backing file header for a mapping file
+ * It should always be called only on empty file.
+ */
+int incfs_write_mapping_fh_to_backing_file(struct backing_file_context *bfc,
+				incfs_uuid_t *uuid, u64 file_size, u64 offset)
+{
+	struct incfs_file_header fh = {};
+	loff_t file_pos = 0;
+
+	if (!bfc)
+		return -EFAULT;
+
+	fh.fh_magic = cpu_to_le64(INCFS_MAGIC_NUMBER);
+	fh.fh_version = cpu_to_le64(INCFS_FORMAT_CURRENT_VER);
+	fh.fh_header_size = cpu_to_le16(sizeof(fh));
+	fh.fh_original_offset = cpu_to_le64(offset);
+	fh.fh_data_block_size = cpu_to_le16(INCFS_DATA_FILE_BLOCK_SIZE);
+
+	fh.fh_mapped_file_size = cpu_to_le64(file_size);
+	fh.fh_original_uuid = *uuid;
+	fh.fh_flags = INCFS_FILE_MAPPED;
+
+	LOCK_REQUIRED(bfc->bc_mutex);
+
+	file_pos = incfs_get_end_offset(bfc->bc_file);
+	if (file_pos != 0)
+		return -EEXIST;
+
+	return write_to_bf(bfc, &fh, sizeof(fh), file_pos);
+}
+
 /* Write a given data block and update file's blockmap to point it. */
 int incfs_write_data_block_to_backing_file(struct backing_file_context *bfc,
 				     struct mem_range block, int block_index,
@@ -598,7 +629,7 @@ int incfs_read_file_header(struct backing_file_context *bfc,
 	if (file_size)
 		*file_size = le64_to_cpu(fh.fh_file_size);
 	if (flags)
-		*flags = le32_to_cpu(fh.fh_file_header_flags);
+		*flags = le32_to_cpu(fh.fh_flags);
 	return 0;
 }
 

fs/incfs/format.h

@@ -72,7 +72,7 @@
  *
  *
  *              +-------------------------------------------+
- *              |            incfs_super_block              |]---+
+ *              |            incfs_file_header              |]---+
  *              +-------------------------------------------+    |
  *              |                 metadata                  |<---+
  *              |           incfs_file_signature            |]---+
@@ -123,6 +123,7 @@ enum incfs_metadata_type {
 
 enum incfs_file_header_flags {
 	INCFS_FILE_COMPLETE = 1 << 0,
+	INCFS_FILE_MAPPED = 1 << 1,
 };
 
 /* Header included at the beginning of all metadata records on the disk. */
@@ -164,20 +165,33 @@ struct incfs_file_header {
 	__le16 fh_data_block_size;
 
 	/* File flags, from incfs_file_header_flags */
-	__le32 fh_file_header_flags;
+	__le32 fh_flags;
 
-	/* Offset of the first metadata record */
-	__le64 fh_first_md_offset;
-
-	/*
-	 * Put file specific information after this point
-	 */
-
-	/* Full size of the file's content */
-	__le64 fh_file_size;
-
-	/* File uuid */
-	incfs_uuid_t fh_uuid;
+	union {
+		/* Standard incfs file */
+		struct {
+			/* Offset of the first metadata record */
+			__le64 fh_first_md_offset;
+
+			/* Full size of the file's content */
+			__le64 fh_file_size;
+
+			/* File uuid */
+			incfs_uuid_t fh_uuid;
+		};
+
+		/* Mapped file - INCFS_FILE_MAPPED set in fh_flags */
+		struct {
+			/* Offset in original file */
+			__le64 fh_original_offset;
+
+			/* Full size of the file's content */
+			__le64 fh_mapped_file_size;
+
+			/* Original file's uuid */
+			incfs_uuid_t fh_original_uuid;
+		};
+	};
 } __packed;
 
 enum incfs_block_map_entry_flags {
@@ -294,6 +308,9 @@ int incfs_write_blockmap_to_backing_file(struct backing_file_context *bfc,
 int incfs_write_fh_to_backing_file(struct backing_file_context *bfc,
 				   incfs_uuid_t *uuid, u64 file_size);
 
+int incfs_write_mapping_fh_to_backing_file(struct backing_file_context *bfc,
+				incfs_uuid_t *uuid, u64 file_size, u64 offset);
+
 int incfs_write_data_block_to_backing_file(struct backing_file_context *bfc,
 					   struct mem_range block,
 					   int block_index, loff_t bm_base_off,