Theodore Ts'o wrote:
The hg repository located at:
http://thunk.org/hg/e2fsprogs
... contains what I hope to be the e2fsprogs 1.40 release. If folks
could test it and let me know if they find any embarassing bugs, I would
greatly appreciate it. It can also be found at:
ftp://ftp.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/e2fsprogs-1.40-rc1.tar.gz
Over the next few days, I'll be working on converting e2fsprogs SCM from
hg to git. Assuming no one finds any problems, I'll be releasing
e2fsprogs 1.40 by the end of the week.
What about undo I/O manager ?
This I/O manager saves the contents of the location being overwritten
to a tdb database. This helps in undoing the changes done to the
file system.
The call sequence involve
set_undo_io_backing_manager(unix_io_manager);
set_undo_io_backup_file("/tmp/test.tdb");
retval = ext2fs_open2(dev_name, 0, flags,
superblock, block_size, undo_io_manager,
¤t_fs);
The patch is on top of e2fsprogs-upstream mercurial repo
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
----
diff -r fe55db3e508c lib/ext2fs/Makefile.in
--- a/lib/ext2fs/Makefile.in Sun Jun 24 17:32:47 2007 -0400
+++ b/lib/ext2fs/Makefile.in Mon Jun 25 20:59:36 2007 +0530
@@ -66,7 +66,8 @@ OBJS= $(DEBUGFS_LIB_OBJS) $(RESIZE_LIB_O
unix_io.o \
unlink.o \
valid_blk.o \
- version.o
+ version.o \
+ undo_io.o
SRCS= ext2_err.c \
$(srcdir)/alloc.c \
@@ -134,7 +135,8 @@ SRCS= ext2_err.c \
$(srcdir)/tst_bitops.c \
$(srcdir)/tst_byteswap.c \
$(srcdir)/tst_getsize.c \
- $(srcdir)/tst_iscan.c
+ $(srcdir)/tst_iscan.c \
+ $(srcdir)/undo_io.c
HFILES= bitops.h ext2fs.h ext2_io.h ext2_fs.h ext2_ext_attr.h ext3_extents.h \
tdb.h
@@ -583,3 +585,4 @@ tst_iscan.o: $(srcdir)/tst_iscan.c $(src
$(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h \
$(srcdir)/ext2_fs.h $(srcdir)/ext3_extents.h $(top_srcdir)/lib/et/com_err.h \
$(srcdir)/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h $(srcdir)/bitops.h
+undo_io.o: $(srcdir)/undo_io.c $(srcdir)/ext2_fs.h $(srcdir)/ext2fs.h
diff -r fe55db3e508c lib/ext2fs/ext2_io.h
--- a/lib/ext2fs/ext2_io.h Sun Jun 24 17:32:47 2007 -0400
+++ b/lib/ext2fs/ext2_io.h Mon Jun 25 20:59:36 2007 +0530
@@ -96,6 +96,11 @@ extern errcode_t io_channel_write_byte(i
/* unix_io.c */
extern io_manager unix_io_manager;
+/* undo_io.c */
+extern io_manager undo_io_manager;
+extern errcode_t set_undo_io_backing_manager(io_manager manager);
+extern errcode_t set_undo_io_backup_file(char *file_name);
+
/* test_io.c */
extern io_manager test_io_manager, test_io_backing_manager;
extern void (*test_io_cb_read_blk)
diff -r fe55db3e508c lib/ext2fs/undo_io.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/ext2fs/undo_io.c Mon Jun 25 21:02:24 2007 +0530
@@ -0,0 +1,478 @@
+/*
+ * undo_io.c --- This is the undo io manager that copies the old data that
+ * copies the old data being overwritten into a tdb database
+ *
+ * Copyright IBM Corporation, 2007
+ * Author Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#define _LARGEFILE_SOURCE
+#define _LARGEFILE64_SOURCE
+
+#include <stdio.h>
+#include <string.h>
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#if HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <fcntl.h>
+#include <time.h>
+#ifdef __linux__
+#include <sys/utsname.h>
+#endif
+#if HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#if HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#if HAVE_SYS_RESOURCE_H
+#include <sys/resource.h>
+#endif
+
+#include "tdb.h"
+
+#include "ext2_fs.h"
+#include "ext2fs.h"
+
+/*
+ * For checking structure magic numbers...
+ */
+
+#define EXT2_CHECK_MAGIC(struct, code) \
+ if ((struct)->magic != (code)) return (code)
+
+
+
+struct undo_private_data {
+ int magic;
+ TDB_CONTEXT *tdb;
+ char *tdb_file;
+
+ /* The backing io channel */
+ io_channel real;
+
+ /* to support offset in unix I/O manager */
+ ext2_loff_t offset;
+};
+
+static errcode_t undo_open(const char *name, int flags, io_channel *channel);
+static errcode_t undo_close(io_channel channel);
+static errcode_t undo_set_blksize(io_channel channel, int blksize);
+static errcode_t undo_read_blk(io_channel channel, unsigned long block,
+ int count, void *data);
+static errcode_t undo_write_blk(io_channel channel, unsigned long block,
+ int count, const void *data);
+static errcode_t undo_flush(io_channel channel);
+static errcode_t undo_write_byte(io_channel channel, unsigned long offset,
+ int size, const void *data);
+static errcode_t undo_set_option(io_channel channel, const char *option,
+ const char *arg);
+
+static struct struct_io_manager struct_undo_manager = {
+ EXT2_ET_MAGIC_IO_MANAGER,
+ "Undo I/O Manager",
+ undo_open,
+ undo_close,
+ undo_set_blksize,
+ undo_read_blk,
+ undo_write_blk,
+ undo_flush,
+ undo_write_byte,
+ undo_set_option
+};
+
+io_manager undo_io_manager = &struct_undo_manager;
+static io_manager undo_io_backing_manager ;
+static char *tdb_file ;
+static int tdb_data_size = 0;
+
+errcode_t set_undo_io_backing_manager(io_manager manager)
+{
+ /*
+ * We may want to do some validation later
+ */
+ undo_io_backing_manager = manager;
+ return 0;
+}
+
+errcode_t set_undo_io_backup_file(char *file_name)
+{
+ tdb_file = strdup(file_name);
+
+ if (tdb_file == NULL) {
+ return EXT2_ET_NO_MEMORY;
+ }
+
+ return 0;
+}
+
+
+static errcode_t undo_write_tdb(io_channel channel,
+ unsigned long block, int count)
+
+{
+ int size, loop_count = 0, i;
+ unsigned long block_num, backing_blk_num;
+ errcode_t retval = 0;
+ ext2_loff_t offset;
+ struct undo_private_data *data;
+ TDB_DATA tdb_key, tdb_data;
+ char *read_ptr;
+
+ data = (struct undo_private_data *) channel->private_data;
+
+
+ if (data->tdb == NULL) {
+ /*
+ * Transaction database not initialized
+ */
+ return 0;
+ }
+
+ /*
+ * Set the block size used to read for tdb
+ */
+ if (!tdb_data_size)
+ tdb_data_size = channel->block_size;
+
+ if (count == 1)
+ size = channel->block_size;
+ else {
+ if (count < 0)
+ size = -count;
+ else
+ size = count * channel->block_size;
+ }
+
+ /*
+ * Data is stored in tdb database as blocks of tdb_data_size size
+ * This helps in efficient lookup further.
+ *
+ * We divide the disk to blocks of tdb_data_size.
+ */
+
+ block_num = ((block*channel->block_size)+data->offset)/tdb_data_size;
+
+
+ loop_count = (size + tdb_data_size -1)/tdb_data_size;
+
+ tdb_transaction_start(data->tdb);
+ for (i = 0; i < loop_count; i++) {
+
+ block_num += i;
+ tdb_key.dptr = (unsigned char *)&block_num;
+ tdb_key.dsize = sizeof(block_num);
+
+ /*
+ * Check if we have the record already
+ */
+ if (tdb_exists(data->tdb, tdb_key)) {
+
+ /* Try the next block */
+ continue;
+ }
+
+ /*
+ * Read one block using the backing I/O manager
+ * The backing I/O manager block size may be
+ * different from the tdb_data_size.
+ * Also we need to recalcuate the block number with respect
+ * to the backing I/O manager.
+ */
+
+ offset = block_num * tdb_data_size;
+ backing_blk_num = (offset - data->offset) / channel->block_size;
+
+ count = tdb_data_size +
+ ((offset - data->offset) % channel->block_size);
+
+ retval = ext2fs_get_mem(count, &read_ptr);
+ if (retval)
+ return retval;
+
+ memset(read_ptr, 0, count);
+
+ retval = io_channel_read_blk(data->real,
+ backing_blk_num,
+ -count, read_ptr);
+ if (retval) {
+ free(read_ptr);
+ return retval;
+ }
+
+
+ tdb_data.dptr = read_ptr +
+ ((offset - data->offset) % channel->block_size);
+
+ tdb_data.dsize = tdb_data_size;
+
+#ifdef DEBUG
+ printf("Printing with key %ld data %x and size %d\n",
+ block_num,
+ tdb_data.dptr, tdb_data_size);
+#endif
+
+ retval = tdb_store(data->tdb, tdb_key, tdb_data, TDB_INSERT);
+ if (retval == -1) {
+ /*
+ * TDB_ERR_EXISTS cannot happen because we
+ * have already verified it doesn't exist
+ */
+ tdb_transaction_cancel(data->tdb);
+ retval = EXT2_ET_TDB_ERR_IO;
+ free(read_ptr);
+ return retval;
+
+ }
+ free(read_ptr);
+ }
+
+ tdb_transaction_commit(data->tdb);
+
+ return retval;
+
+}
+
+static TDB_CONTEXT *undo_setup_tdb(char *tdb_file,
+ struct undo_private_data *data)
+{
+ errcode_t retval;
+
+ data->tdb = tdb_open(tdb_file, 0, TDB_CLEAR_IF_FIRST,
+ O_RDWR | O_CREAT | O_TRUNC, 0600);
+ return data->tdb;
+
+}
+static errcode_t undo_open(const char *name, int flags, io_channel *channel)
+{
+ io_channel io = NULL;
+ struct undo_private_data *data = NULL;
+ errcode_t retval;
+ int open_flags;
+ struct stat st;
+
+ if (name == 0)
+ return EXT2_ET_BAD_DEVICE_NAME;
+ retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
+ if (retval)
+ return retval;
+ memset(io, 0, sizeof(struct struct_io_channel));
+ io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
+ retval = ext2fs_get_mem(sizeof(struct undo_private_data), &data);
+ if (retval)
+ goto cleanup;
+
+ io->manager = undo_io_manager;
+ retval = ext2fs_get_mem(strlen(name)+1, &io->name);
+ if (retval)
+ goto cleanup;
+
+ strcpy(io->name, name);
+ io->private_data = data;
+ io->block_size = 1024;
+ io->read_error = 0;
+ io->write_error = 0;
+ io->refcount = 1;
+
+ memset(data, 0, sizeof(struct undo_private_data));
+ data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
+
+ if (undo_io_backing_manager) {
+ retval = undo_io_backing_manager->open(name, flags,
+ &data->real);
+ if (retval)
+ goto cleanup;
+ } else {
+ data->real = 0;
+ }
+
+ /* setup the tdb file */
+ if (undo_setup_tdb(tdb_file, data) == NULL )
+ goto cleanup;
+
+ *channel = io;
+ return 0;
+
+cleanup:
+ if (data->real)
+ io_channel_close(data->real);
+
+ if (data)
+ ext2fs_free_mem(&data);
+
+ if (io)
+ ext2fs_free_mem(&io);
+
+ return retval;
+}
+
+static errcode_t undo_close(io_channel channel)
+{
+ struct undo_private_data *data;
+ errcode_t retval = 0;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ if (--channel->refcount > 0)
+ return 0;
+
+ if (data->real)
+ retval = io_channel_close(data->real);
+
+ if (data->tdb)
+ tdb_close(data->tdb);
+
+ ext2fs_free_mem(&channel->private_data);
+ if (channel->name)
+ ext2fs_free_mem(&channel->name);
+ ext2fs_free_mem(&channel);
+
+ return retval;
+}
+
+static errcode_t undo_set_blksize(io_channel channel, int blksize)
+{
+ struct undo_private_data *data;
+ errcode_t retval;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ if (data->real)
+ retval = io_channel_set_blksize(data->real, blksize);
+
+ channel->block_size = blksize;
+ return 0;
+}
+
+
+static errcode_t undo_read_blk(io_channel channel, unsigned long block,
+ int count, void *buf)
+{
+ errcode_t retval;
+ struct undo_private_data *data;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ if (data->real)
+ retval = io_channel_read_blk(data->real, block, count, buf);
+
+ return retval;
+}
+
+static errcode_t undo_write_blk(io_channel channel, unsigned long block,
+ int count, const void *buf)
+{
+ struct undo_private_data *data;
+ errcode_t retval = 0;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ /*
+ * First write the existing content into database
+ */
+ retval = undo_write_tdb(channel, block, count);
+ if (retval)
+ return retval;
+
+
+ if (data->real)
+ retval = io_channel_write_blk(data->real, block, count, buf);
+
+ return retval;
+
+}
+
+static errcode_t undo_write_byte(io_channel channel, unsigned long offset,
+ int size, const void *buf)
+{
+ struct undo_private_data *data;
+ errcode_t retval = 0;
+ ssize_t actual;
+ ext2_loff_t location;
+ unsigned long blk_num, count;;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ location = offset + data->offset;
+ blk_num = location/channel->block_size;
+ /*
+ * the size specified may spread across multiple blocks
+ * also make sure we account for the fact that block start
+ * offset for tdb is different from the backing I/O manager
+ * due to possible different block size
+ */
+ count = (size + (location % channel->block_size) +
+ channel->block_size -1)/channel->block_size;
+
+ retval = undo_write_tdb(channel, blk_num, count);
+ if (retval)
+ return retval;
+
+ if (data->real && data->real->manager->write_byte)
+ retval = io_channel_write_byte(data->real, offset, size, buf);
+
+ return retval;
+}
+
+/*
+ * Flush data buffers to disk.
+ */
+static errcode_t undo_flush(io_channel channel)
+{
+ errcode_t retval = 0;
+ struct undo_private_data *data;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ if (data->real)
+ retval = io_channel_flush(data->real);
+
+ return retval;
+}
+
+static errcode_t undo_set_option(io_channel channel, const char *option,
+ const char *arg)
+{
+ struct undo_private_data *data;
+ unsigned long tmp;
+ char *end;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ /*
+ * Need to support offset option to work with
+ * Unix I/O manager
+ */
+ if (!strcmp(option, "offset")) {
+ if (!arg)
+ return EXT2_ET_INVALID_ARGUMENT;
+
+ tmp = strtoul(arg, &end, 0);
+ if (*end)
+ return EXT2_ET_INVALID_ARGUMENT;
+ data->offset = tmp;
+ return 0;
+ }
+}
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