From: "Aneesh Kumar K.V" Subject: [PATCH 1/4] e2fsprogs: Add undo I/O manager Date: Wed, 1 Aug 2007 07:34:06 +0530 Message-ID: <11859338491592-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: linux-ext4@vger.kernel.org, "Aneesh Kumar K.V" To: tytso@mit.edu Return-path: Received: from ausmtp04.au.ibm.com ([202.81.18.152]:53915 "EHLO ausmtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753449AbXHACFh (ORCPT ); Tue, 31 Jul 2007 22:05:37 -0400 Received: from d23relay01.au.ibm.com (d23relay01.au.ibm.com [202.81.18.232]) by ausmtp04.au.ibm.com (8.13.8/8.13.8) with ESMTP id l7128K6V279602 for ; Wed, 1 Aug 2007 12:08:20 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.250.237]) by d23relay01.au.ibm.com (8.13.8/8.13.8/NCO v8.4) with ESMTP id l7123WXI241864 for ; Wed, 1 Aug 2007 12:03:32 +1000 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l7124ISQ008535 for ; Wed, 1 Aug 2007 12:04:18 +1000 Message-Id: Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org 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); Signed-off-by: Aneesh Kumar K.V --- lib/ext2fs/Makefile.in | 7 +- lib/ext2fs/ext2_io.h | 5 + lib/ext2fs/undo_io.c | 500 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 510 insertions(+), 2 deletions(-) create mode 100644 lib/ext2fs/undo_io.c diff --git a/lib/ext2fs/Makefile.in b/lib/ext2fs/Makefile.in index 70e18e7..7afd5eb 100644 --- a/lib/ext2fs/Makefile.in +++ b/lib/ext2fs/Makefile.in @@ -66,7 +66,8 @@ OBJS= $(DEBUGFS_LIB_OBJS) $(RESIZE_LIB_OBJS) $(E2IMAGE_LIB_OBJS) \ unix_io.o \ unlink.o \ valid_blk.o \ - version.o + version.o \ + undo_io.o SRCS= ext2_err.c \ $(srcdir)/alloc.c \ @@ -132,7 +133,8 @@ 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 @@ -573,3 +575,4 @@ tst_iscan.o: $(srcdir)/tst_iscan.c $(srcdir)/ext2_fs.h \ $(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 --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h index eada278..476eb4d 100644 --- a/lib/ext2fs/ext2_io.h +++ b/lib/ext2fs/ext2_io.h @@ -96,6 +96,11 @@ extern errcode_t io_channel_write_byte(io_channel channel, /* 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 --git a/lib/ext2fs/undo_io.c b/lib/ext2fs/undo_io.c new file mode 100644 index 0000000..320428c --- /dev/null +++ b/lib/ext2fs/undo_io.c @@ -0,0 +1,500 @@ +/* + * 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 + * + * %Begin-Header% + * This file may be redistributed under the terms of the GNU Public + * License. + * %End-Header% + */ + +#define _LARGEFILE_SOURCE +#define _LARGEFILE64_SOURCE + +#include +#include +#if HAVE_UNISTD_H +#include +#endif +#if HAVE_ERRNO_H +#include +#endif +#include +#include +#ifdef __linux__ +#include +#endif +#if HAVE_SYS_STAT_H +#include +#endif +#if HAVE_SYS_TYPES_H +#include +#endif +#if HAVE_SYS_RESOURCE_H +#include +#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++) { + + 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 */ + block_num++; + 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) { + tdb_transaction_cancel(data->tdb); + 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); + tdb_transaction_cancel(data->tdb); + 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); + /* Next block */ + block_num++; + } + + 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 | O_EXCL, 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 ) { + /* + * This retval results in the below + * string in com_err + * "TDB: Record exists". This helps + * in finding out that the error is + * with respect to TDB + */ + retval = EXT2_ET_TDB_ERR_EXISTS; + 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 retval; +} + + +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) +{ + errcode_t retval = 0; + 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 (data->real && data->real->manager->set_option) { + + retval = data->real->manager->set_option(data->real, + option, arg); + } + + if (!retval && !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 retval; +} -- 1.5.3.rc2.22.g69a9b-dirty