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Date:	Fri, 22 May 2015 13:28:54 +0200
From:	Jan Kara <jack@...e.cz>
To:	linux-ext4@...r.kernel.org
Cc:	Jan Kara <jack@...e.cz>
Subject: [PATCH 1/4] libext2fs: Support for orphan file feature

Add support for creating and deleting orphan file and a couple of
utility functions that will be used in other tools.

Signed-off-by: Jan Kara <jack@...e.cz>
---
 lib/e2p/feature.c      |   4 +
 lib/ext2fs/Makefile.in |   2 +
 lib/ext2fs/ext2_fs.h   |  11 +++
 lib/ext2fs/ext2fs.h    |  35 +++++++-
 lib/ext2fs/orphan.c    | 217 +++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 267 insertions(+), 2 deletions(-)
 create mode 100644 lib/ext2fs/orphan.c

diff --git a/lib/e2p/feature.c b/lib/e2p/feature.c
index 73884f2cf5bf..a8e0d4a4644a 100644
--- a/lib/e2p/feature.c
+++ b/lib/e2p/feature.c
@@ -45,6 +45,8 @@ static struct feature feature_list[] = {
 			"snapshot_bitmap" },
 	{	E2P_FEATURE_COMPAT, EXT4_FEATURE_COMPAT_SPARSE_SUPER2,
 			"sparse_super2" },
+	{	E2P_FEATURE_COMPAT, EXT4_FEATURE_COMPAT_ORPHAN_FILE,
+			"orphan_file" },
 
 	{	E2P_FEATURE_RO_INCOMPAT, EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER,
 			"sparse_super" },
@@ -70,6 +72,8 @@ static struct feature feature_list[] = {
 			"replica" },
 	{	E2P_FEATURE_RO_INCOMPAT, EXT4_FEATURE_RO_COMPAT_READONLY,
 			"read-only" },
+	{	E2P_FEATURE_RO_INCOMPAT, EXT4_FEATURE_RO_COMPAT_ORPHAN_PRESENT,
+			"orphan_file_used" },
 
 	{	E2P_FEATURE_INCOMPAT, EXT2_FEATURE_INCOMPAT_COMPRESSION,
 			"compression" },
diff --git a/lib/ext2fs/Makefile.in b/lib/ext2fs/Makefile.in
index 8a7f8ca52902..67120b10438c 100644
--- a/lib/ext2fs/Makefile.in
+++ b/lib/ext2fs/Makefile.in
@@ -109,6 +109,7 @@ OBJS= $(DEBUGFS_LIB_OBJS) $(RESIZE_LIB_OBJS) $(E2IMAGE_LIB_OBJS) \
 	native.o \
 	newdir.o \
 	openfs.o \
+	orphan.o \
 	progress.o \
 	punch.o \
 	qcow2.o \
@@ -189,6 +190,7 @@ SRCS= ext2_err.c \
 	$(srcdir)/native.c \
 	$(srcdir)/newdir.c \
 	$(srcdir)/openfs.c \
+	$(srcdir)/orphan.c \
 	$(srcdir)/progress.c \
 	$(srcdir)/punch.c \
 	$(srcdir)/qcow2.c \
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index a755cfac8eae..a77c8fa09938 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -52,6 +52,7 @@
 #define EXT2_JOURNAL_INO	 8	/* Journal inode */
 #define EXT2_EXCLUDE_INO	 9	/* The "exclude" inode, for snapshots */
 #define EXT4_REPLICA_INO	10	/* Used by non-upstream feature */
+#define EXT4_ORPHAN_INO		 9	/* Inode with orphan entries */
 
 /* First non-reserved inode for old ext2 filesystems */
 #define EXT2_GOOD_OLD_FIRST_INO	11
@@ -769,6 +770,7 @@ struct ext2_super_block {
 /* #define EXT2_FEATURE_COMPAT_EXCLUDE_INODE	0x0080 not used, legacy */
 #define EXT2_FEATURE_COMPAT_EXCLUDE_BITMAP	0x0100
 #define EXT4_FEATURE_COMPAT_SPARSE_SUPER2	0x0200
+#define EXT4_FEATURE_COMPAT_ORPHAN_FILE		0x0400
 
 
 #define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER	0x0001
@@ -789,6 +791,7 @@ struct ext2_super_block {
 #define EXT4_FEATURE_RO_COMPAT_METADATA_CSUM	0x0400
 #define EXT4_FEATURE_RO_COMPAT_REPLICA		0x0800
 #define EXT4_FEATURE_RO_COMPAT_READONLY		0x1000
+#define EXT4_FEATURE_RO_COMPAT_ORPHAN_PRESENT	0x2000
 
 
 #define EXT2_FEATURE_INCOMPAT_COMPRESSION	0x0001
@@ -838,6 +841,14 @@ struct ext2_super_block {
 #define EXT4_DEFM_DISCARD	0x0400
 #define EXT4_DEFM_NODELALLOC	0x0800
 
+#define EXT4_ORPHAN_BLOCK_MAGIC 0x0b10ca04
+
+/* Structure at the tail of orphan block */
+struct ext4_orphan_block_tail {
+	__u32 ob_magic;
+	__u32 ob_checksum;
+};
+
 /*
  * Structure of a directory entry
  */
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 28c46701da29..1e303d5d59ca 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -555,7 +555,8 @@ typedef struct ext2_icount *ext2_icount_t;
 					 EXT2_FEATURE_COMPAT_RESIZE_INODE|\
 					 EXT2_FEATURE_COMPAT_DIR_INDEX|\
 					 EXT2_FEATURE_COMPAT_EXT_ATTR|\
-					 EXT4_FEATURE_COMPAT_SPARSE_SUPER2)
+					 EXT4_FEATURE_COMPAT_SPARSE_SUPER2|\
+					 EXT4_FEATURE_COMPAT_ORPHAN_FILE)
 
 #ifdef CONFIG_MMP
 #define EXT4_LIB_INCOMPAT_MMP		EXT4_FEATURE_INCOMPAT_MMP
@@ -589,7 +590,8 @@ typedef struct ext2_icount *ext2_icount_t;
 					 EXT4_FEATURE_RO_COMPAT_BIGALLOC|\
 					 EXT4_LIB_RO_COMPAT_QUOTA|\
 					 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM|\
-					 EXT4_FEATURE_RO_COMPAT_READONLY)
+					 EXT4_FEATURE_RO_COMPAT_READONLY|\
+					 EXT4_FEATURE_RO_COMPAT_ORPHAN_PRESENT)
 
 /*
  * These features are only allowed if EXT2_FLAG_SOFTSUPP_FEATURES is passed
@@ -1512,6 +1514,19 @@ errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io);
 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io);
 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io);
 
+/* orphan.c */
+/*
+ * Minimum orphan file size (it must be at least 1 block and smaller one isn't
+ * very useful).
+ */
+#define EXT4_MIN_ORPHAN_FILE_SIZE 16384
+
+extern errcode_t ext2fs_create_orphan_file(ext2_filsys fs, blk_t num_blocks);
+extern errcode_t ext2fs_truncate_orphan_file(ext2_filsys fs);
+extern e2_blkcnt_t ext2fs_default_orphan_file_blocks(__u64 num_blocks);
+extern errcode_t ext2fs_orphan_file_block_csum_set(ext2_filsys fs, char *buf);
+extern int ext2fs_orphan_file_block_csum_verify(ext2_filsys fs, char *buf);
+
 /* get_pathname.c */
 extern errcode_t ext2fs_get_pathname(ext2_filsys fs, ext2_ino_t dir, ext2_ino_t ino,
 			       char **name);
@@ -1645,6 +1660,9 @@ extern int ext2fs_dirent_name_len(const struct ext2_dir_entry *entry);
 extern void ext2fs_dirent_set_name_len(struct ext2_dir_entry *entry, int len);
 extern int ext2fs_dirent_file_type(const struct ext2_dir_entry *entry);
 extern void ext2fs_dirent_set_file_type(struct ext2_dir_entry *entry, int type);
+extern int ext2fs_inodes_per_orphan_block(ext2_filsys fs);
+extern struct ext4_orphan_block_tail *ext2fs_orphan_block_tail(ext2_filsys fs,
+							       char *buf)
 
 #endif
 
@@ -1915,6 +1933,19 @@ _INLINE_ void ext2fs_dirent_set_file_type(struct ext2_dir_entry *entry, int type
 	entry->name_len = (entry->name_len & 0xff) | (type << 8);
 }
 
+_INLINE_ int ext2fs_inodes_per_orphan_block(ext2_filsys fs)
+{
+	return (fs->blocksize - sizeof(struct ext4_orphan_block_tail)) /
+		sizeof(__u32);
+}
+
+_INLINE_ struct ext4_orphan_block_tail *
+ext2fs_orphan_block_tail(ext2_filsys fs, char *buf)
+{
+	return (struct ext4_orphan_block_tail *)(buf + fs->blocksize -
+		sizeof(struct ext4_orphan_block_tail));
+}
+
 #undef _INLINE_
 #endif
 
diff --git a/lib/ext2fs/orphan.c b/lib/ext2fs/orphan.c
new file mode 100644
index 000000000000..1fd5c0688218
--- /dev/null
+++ b/lib/ext2fs/orphan.c
@@ -0,0 +1,217 @@
+/*
+ * orphan.c --- utility function to handle orphan file
+ *
+ * Copyright (C) 2015 Jan Kara.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Library
+ * General Public License, version 2.
+ * %End-Header%
+ */
+
+#include "config.h"
+#include <string.h>
+
+#include "ext2_fs.h"
+#include "ext2fsP.h"
+
+errcode_t ext2fs_truncate_orphan_file(ext2_filsys fs)
+{
+	struct ext2_inode inode;
+	errcode_t err;
+
+	err = ext2fs_read_inode(fs, EXT4_ORPHAN_INO, &inode);
+	if (err)
+		return err;
+
+	err = ext2fs_punch(fs, EXT4_ORPHAN_INO, &inode, NULL, 0, ~0ULL);
+	if (err)
+		return err;
+
+	fs->flags &= ~EXT2_FLAG_SUPER_ONLY;
+	memset(&inode, 0, sizeof(struct ext2_inode));
+	err = ext2fs_write_inode(fs, EXT4_ORPHAN_INO, &inode);
+
+	fs->super->s_feature_compat &= ~EXT4_FEATURE_COMPAT_ORPHAN_FILE;
+	ext2fs_mark_super_dirty(fs);
+
+	return err;
+}
+
+struct mkorphan_info {
+	char *buf;
+	char *zerobuf;
+	blk_t num_blocks;
+	blk_t alloc_blocks;
+	errcode_t err;
+};
+
+static int mkorphan_proc(ext2_filsys	fs,
+			 blk64_t	*blocknr,
+			 e2_blkcnt_t	blockcnt,
+			 blk64_t	ref_block EXT2FS_ATTR((unused)),
+			 int		ref_offset EXT2FS_ATTR((unused)),
+			 void		*priv_data)
+{
+	struct mkorphan_info *oi = (struct mkorphan_info *)priv_data;
+	blk64_t new_blk;
+	errcode_t err;
+
+	err = ext2fs_new_block2(fs, 0, 0, &new_blk);
+	if (err) {
+		oi->err = err;
+		return BLOCK_ABORT;
+	}
+	ext2fs_block_alloc_stats2(fs, new_blk, +1);
+	if (blockcnt >= 0)
+		err = io_channel_write_blk64(fs->io, new_blk, 1, oi->buf);
+	else
+		err = io_channel_write_blk64(fs->io, new_blk, 1, oi->zerobuf);
+	if (err) {
+		oi->err = err;
+		return BLOCK_ABORT;
+	}
+	oi->alloc_blocks++;
+	*blocknr = new_blk;
+	if (blockcnt >= 0 && --oi->num_blocks == 0)
+		return BLOCK_CHANGED | BLOCK_ABORT;
+	return BLOCK_CHANGED;
+}
+
+errcode_t ext2fs_create_orphan_file(ext2_filsys fs, blk_t num_blocks)
+{
+	struct ext2_inode inode;
+	errcode_t err;
+	char *buf = NULL, *zerobuf = NULL;
+	struct mkorphan_info oi;
+	struct ext4_orphan_block_tail *ob_tail;
+
+	err = ext2fs_read_inode(fs, EXT4_ORPHAN_INO, &inode);
+	if (err)
+		return err;
+	if (EXT2_I_SIZE(&inode)) {
+		err = ext2fs_truncate_orphan_file(fs);
+		if (err)
+			return err;
+	}
+
+	memset(&inode, 0, sizeof(struct ext2_inode));
+	if (fs->super->s_feature_incompat & EXT3_FEATURE_INCOMPAT_EXTENTS) {
+		inode.i_flags |= EXT4_EXTENTS_FL;
+		err = ext2fs_write_inode(fs, EXT4_ORPHAN_INO, &inode);
+		if (err)
+			return err;
+	}
+
+	err = ext2fs_get_mem(fs->blocksize, &buf);
+	if (err)
+		return err;
+	err = ext2fs_get_mem(fs->blocksize, &zerobuf);
+	if (err)
+		goto out;
+	memset(buf, 0, fs->blocksize);
+	memset(zerobuf, 0, fs->blocksize);
+	ob_tail = ext2fs_orphan_block_tail(fs, buf);
+	ob_tail->ob_magic = ext2fs_cpu_to_le32(EXT4_ORPHAN_BLOCK_MAGIC);
+	ext2fs_orphan_file_block_csum_set(fs, buf);
+	oi.num_blocks = num_blocks;
+	oi.alloc_blocks = 0;
+	oi.buf = buf;
+	oi.zerobuf = zerobuf;
+	oi.err = 0;
+	err = ext2fs_block_iterate3(fs, EXT4_ORPHAN_INO, BLOCK_FLAG_APPEND,
+				    0, mkorphan_proc, &oi);
+	if (err)
+		goto out;
+
+	/* Reread inode after blocks were allocated */
+	err = ext2fs_read_inode(fs, EXT4_ORPHAN_INO, &inode);
+	if (err)
+		goto out;
+	ext2fs_iblk_set(fs, &inode, 0);
+	inode.i_atime = inode.i_mtime =
+		inode.i_ctime = fs->now ? fs->now : time(0);
+	inode.i_links_count = 1;
+	inode.i_mode = LINUX_S_IFREG | 0600;
+	ext2fs_iblk_add_blocks(fs, &inode, oi.alloc_blocks);
+	err = ext2fs_inode_size_set(fs, &inode,
+			(unsigned long long)fs->blocksize * num_blocks);
+	if (err)
+		goto out;
+	err = ext2fs_write_new_inode(fs, EXT4_ORPHAN_INO, &inode);
+	if (err)
+		goto out;
+
+	fs->super->s_feature_compat |= EXT4_FEATURE_COMPAT_ORPHAN_FILE;
+	ext2fs_mark_super_dirty(fs);
+out:
+	if (buf)
+		ext2fs_free_mem(&buf);
+	if (zerobuf)
+		ext2fs_free_mem(&zerobuf);
+	return err;
+}
+
+/*
+ * Find reasonable size for orphan file. We choose orphan file size to be
+ * between 32 and 512 filesystem blocks and not more than 1/4096 of the
+ * filesystem unless it is really small.
+ */
+e2_blkcnt_t ext2fs_default_orphan_file_blocks(__u64 num_blocks)
+{
+	if (num_blocks < 128 * 1024)
+		return 32;
+	if (num_blocks < 2 * 1024 * 1024)
+		return num_blocks / 4096;
+	return 512;
+}
+
+static errcode_t ext2fs_orphan_file_block_csum(ext2_filsys fs, char *buf,
+					       __u32 *crc)
+{
+	int inodes_per_ob = ext2fs_inodes_per_orphan_block(fs);
+	__u32 gen;
+	ext2_ino_t inum;
+	struct ext2_inode inode;
+	errcode_t retval;
+
+	retval = ext2fs_read_inode(fs, EXT4_ORPHAN_INO, &inode);
+	if (retval)
+		return retval;
+	inum = ext2fs_cpu_to_le32(EXT4_ORPHAN_INO);
+	gen = ext2fs_cpu_to_le32(inode.i_generation);
+	*crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
+			       sizeof(inum));
+	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
+	*crc = ext2fs_crc32c_le(*crc, buf, inodes_per_ob * sizeof(__u32));
+
+	return 0;
+}
+
+errcode_t ext2fs_orphan_file_block_csum_set(ext2_filsys fs, char *buf)
+{
+	struct ext4_orphan_block_tail *tail;
+
+	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return 0;
+
+	tail = ext2fs_orphan_block_tail(fs, buf);
+	return ext2fs_orphan_file_block_csum(fs, buf, &tail->ob_checksum);
+}
+
+int ext2fs_orphan_file_block_csum_verify(ext2_filsys fs, char *buf)
+{
+	struct ext4_orphan_block_tail *tail;
+	__u32 crc;
+	errcode_t retval;
+
+	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return 1;
+	retval = ext2fs_orphan_file_block_csum(fs, buf, &crc);
+	if (retval)
+		return 0;
+	tail = ext2fs_orphan_block_tail(fs, buf);
+	return ext2fs_le32_to_cpu(tail->ob_checksum) == crc;
+}
-- 
2.1.4

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