2007-08-01 02:05:37

by Aneesh Kumar K.V

[permalink] [raw]
Subject: [PATCH 1/4] e2fsprogs: Add 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,
&current_fs);

Signed-off-by: Aneesh Kumar K.V <[email protected]>
---
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 <[email protected]>
+ *
+ * %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++) {
+
+ 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


2007-08-01 02:04:24

by Aneesh Kumar K.V

[permalink] [raw]
Subject: [PATCH 2/4] e2fsprogs: Add undoe2fs

From: Aneesh Kumar K.V <[email protected]>

undoe2fs can be used to replay the transaction saved
in the transaction file using undo I/O Manager

Signed-off-by: Aneesh Kumar K.V <[email protected]>
---
misc/Makefile.in | 10 +++++-
misc/undoe2fs.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 85 insertions(+), 2 deletions(-)
create mode 100644 misc/undoe2fs.c

diff --git a/misc/Makefile.in b/misc/Makefile.in
index ccad78c..51bb17a 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -15,7 +15,7 @@ INSTALL = @[email protected]
@[email protected]_MAN= e2image.8

SPROGS= mke2fs badblocks tune2fs dumpe2fs blkid logsave \
- $(E2IMAGE_PROG) @[email protected]
+ $(E2IMAGE_PROG) @[email protected] undoe2fs
USPROGS= mklost+found filefrag
SMANPAGES= tune2fs.8 mklost+found.8 mke2fs.8 dumpe2fs.8 badblocks.8 \
e2label.8 findfs.8 blkid.8 $(E2IMAGE_MAN) \
@@ -39,6 +39,7 @@ E2IMAGE_OBJS= e2image.o
FSCK_OBJS= fsck.o base_device.o
BLKID_OBJS= blkid.o
FILEFRAG_OBJS= filefrag.o
+UNDOE2FS_OBJS= undoe2fs.o

XTRA_CFLAGS= -I$(srcdir)/../e2fsck -I.

@@ -47,7 +48,7 @@ SRCS= $(srcdir)/tune2fs.c $(srcdir)/mklost+found.c $(srcdir)/mke2fs.c \
$(srcdir)/badblocks.c $(srcdir)/fsck.c $(srcdir)/util.c \
$(srcdir)/uuidgen.c $(srcdir)/blkid.c $(srcdir)/logsave.c \
$(srcdir)/filefrag.c $(srcdir)/base_device.c \
- $(srcdir)/../e2fsck/profile.c
+ $(srcdir)/../e2fsck/profile.c $(srcdir)/undoe2fs.c

LIBS= $(LIBEXT2FS) $(LIBCOM_ERR)
DEPLIBS= $(LIBEXT2FS) $(LIBCOM_ERR)
@@ -108,6 +109,10 @@ e2image: $(E2IMAGE_OBJS) $(DEPLIBS)
@echo " LD $@"
@$(CC) $(ALL_LDFLAGS) -o e2image $(E2IMAGE_OBJS) $(LIBS) $(LIBINTL)

+undoe2fs: $(UNDOE2FS_OBJS) $(DEPLIBS)
+ @echo " LD [email protected]"
+ @$(CC) $(ALL_LDFLAGS) -o undoe2fs $(UNDOE2FS_OBJS) $(LIBS)
+
base_device: base_device.c
@echo " LD [email protected]"
@$(CC) $(ALL_CFLAGS) $(ALL_LDFLAGS) $(srcdir)/base_device.c \
@@ -434,3 +439,4 @@ filefrag.o: $(srcdir)/filefrag.c
base_device.o: $(srcdir)/base_device.c $(srcdir)/fsck.h
profile.o: $(srcdir)/../e2fsck/profile.c $(top_srcdir)/lib/et/com_err.h \
$(srcdir)/../e2fsck/profile.h prof_err.h
+undoe2fs.o: $(srcdir)/undoe2fs.c $(top_srcdir)/lib/ext2fs/tdb.h
diff --git a/misc/undoe2fs.c b/misc/undoe2fs.c
new file mode 100644
index 0000000..d14d44a
--- /dev/null
+++ b/misc/undoe2fs.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright IBM Corporation, 2007
+ * Author Aneesh Kumar K.V <[email protected]>
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#if HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include "ext2fs/tdb.h"
+
+void usage(char *prg_name)
+{
+ fprintf(stderr,
+ "Usage: %s <transaction file> <filesystem>\n", prg_name);
+ exit(1);
+
+}
+
+
+main(int argc, char *argv[])
+{
+ TDB_CONTEXT *tdb;
+ TDB_DATA key, data;
+ unsigned long blk_num;
+ unsigned long long int location;
+ int fd, retval;
+
+ if (argc != 3)
+ usage(argv[0]);
+
+ tdb = tdb_open(argv[1], 0, 0, O_RDONLY, 0600);
+
+ if (!tdb) {
+ fprintf(stderr, "Failed tdb_open %s\n", strerror(errno));
+ exit(1);
+ }
+
+ fd = open(argv[2], O_WRONLY);
+ if (fd == -1) {
+ fprintf(stderr, "Failed open %s\n", strerror(errno));
+ exit(1);
+ }
+
+ for (key = tdb_firstkey(tdb); key.dptr; key = tdb_nextkey(tdb, key)) {
+ data = tdb_fetch(tdb, key);
+ if (!data.dptr) {
+ fprintf(stderr,
+ "Failed tdb_fetch %s\n", tdb_errorstr(tdb));
+ exit(1);
+ }
+ blk_num = *(unsigned long *)key.dptr;
+ location = blk_num * data.dsize;
+ printf("Replayed transaction of size %d at location %ld\n",
+ data.dsize, blk_num);
+ retval = lseek(fd, location, SEEK_SET);
+ if (retval == -1) {
+ fprintf(stderr, "Failed lseek %s\n", strerror(errno));
+ exit(1);
+ }
+ retval = write(fd, data.dptr, data.dsize);
+ if (retval == -1) {
+ fprintf(stderr, "Failed write %s\n", strerror(errno));
+ exit(1);
+ }
+ }
+ close(fd);
+ tdb_close(tdb);
+
+}
--
1.5.3.rc2.22.g69a9b-dirty

2007-08-01 02:04:27

by Aneesh Kumar K.V

[permalink] [raw]
Subject: [PATCH 3/4] e2fsprogs: Make mke2fs use undo I/O manager.

From: Aneesh Kumar K.V <[email protected]>

When running mke2fs, if a file system is detected
on the device, we use Undo I/O manager as the io manager.
This helps in reverting the changes made to the filesystem
in case we wrongly selected the device.

The environment variable MKE2FS_SCRATCH_DIR
is used to indicate the directory within which the tdb
file need to be created. The file will be named mke2fs-XXXXXX
If MKE2FS_SCRATCH_DIR is not set /var/lib/e2fsprogs is used


Signed-off-by: Aneesh Kumar K.V <[email protected]>
---
misc/mke2fs.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 97 insertions(+), 1 deletions(-)

diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 0c6d4f3..5e02b2e 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -1521,6 +1521,92 @@ static void PRS(int argc, char *argv[])
fs_param.s_blocks_count);
}

+static int fileystem_exist(const char *name)
+{
+ errcode_t retval;
+ io_channel channel;
+ __u16 s_magic;
+ struct ext2_super_block super;
+ io_manager manager = unix_io_manager;
+
+ retval = manager->open(name, IO_FLAG_EXCLUSIVE, &channel);
+ if (retval) {
+ /*
+ * We don't handle error cases instead we
+ * declare that the file system doesn't exist
+ * and let the rest of mke2fs take care of
+ * error
+ */
+ retval = 0;
+ goto open_err_out;
+ }
+
+ io_channel_set_blksize(channel, SUPERBLOCK_OFFSET);
+ retval = io_channel_read_blk(channel, 1, -SUPERBLOCK_SIZE, &super);
+ if (retval) {
+ retval = 0;
+ goto err_out;
+ }
+
+#if defined(WORDS_BIGENDIAN)
+ s_magic = ext2fs_swab16(super.s_magic);
+#else
+ s_magic = super.s_magic;
+#endif
+
+ if (s_magic == EXT2_SUPER_MAGIC)
+ retval = 1;
+
+err_out:
+ io_channel_close(channel);
+
+open_err_out:
+
+ return retval;
+}
+
+static int mke2fs_setup_tdb(const char *name)
+{
+ char *tdb_dir, tdb_file[PATH_MAX];
+#if 0 /* FIXME!! */
+ /*
+ * Configuration via a conf file would be
+ * nice
+ */
+ profile_get_string(profile, "scratch_files",
+ "directory", 0, 0,
+ &tdb_dir);
+#endif
+ tdb_dir = getenv("MKE2FS_SCRATCH_DIR");
+ if (!tdb_dir) {
+ printf(_("MKE2FS_SCRATCH_DIR not configured\n"));
+ printf(_("Using /var/lib/e2fsprogs\n"));
+ tdb_dir="/var/lib/e2fsprogs";
+ }
+ if (access(tdb_dir, W_OK)) {
+ fprintf(stderr,
+ _("Cannot create file under %s\n"),
+ tdb_dir);
+ return EXT2_ET_INVALID_ARGUMENT;
+
+ }
+
+ /* FIXME!! Should we generate Unique file name ?? */
+ sprintf(tdb_file, "%s/mke2fs-XXXXXX", tdb_dir);
+
+ if (!access(tdb_file, F_OK)) {
+ fprintf(stderr,
+ _("File exist %s\n"), tdb_file);
+ return EXT2_ET_INVALID_ARGUMENT;
+ }
+
+ set_undo_io_backup_file(tdb_file);
+ printf(_("previous filesystem detected; to undo "
+ "the mke2fs operation, please run the "
+ "command \n'undoe2fs %s %s' in order to recover\n\n"),
+ tdb_file, name);
+ return 0;
+}
int main (int argc, char *argv[])
{
errcode_t retval = 0;
@@ -1543,7 +1629,17 @@ int main (int argc, char *argv[])
io_ptr = test_io_manager;
test_io_backing_manager = unix_io_manager;
#else
- io_ptr = unix_io_manager;
+ if (fileystem_exist(device_name)) {
+
+ io_ptr = undo_io_manager;
+ set_undo_io_backing_manager(unix_io_manager);
+ retval = mke2fs_setup_tdb(device_name);
+ if (retval)
+ exit(1);
+
+ } else {
+ io_ptr = unix_io_manager;
+ }
#endif

/*
--
1.5.3.rc2.22.g69a9b-dirty

2007-08-01 02:04:36

by Aneesh Kumar K.V

[permalink] [raw]
Subject: [PATCH 4/4] e2fsprogs: Support for large inode migration.

From: Aneesh Kumar K.V <[email protected]>

Add new option -I <inode_size> to tune2fs.
This is used to change the inode size. The size
need to be multiple of 2 and we don't allow to
decrease the inode size.

As a part of increasing the inode size we increase the
inode table size. We also move the used data blocks around
and update the respective inodes to point to the new block


tune2fs use undo I/O manager when migrating to large
inode. This helps in reverting the changes if end results
are not correct.The environment variable TUNE2FS_SCRATCH_DIR
is used to indicate the directory within which the tdb
file need to be created. The file will be named tune2fs-XXXXXX
If TUNE2FS_SCRATCH_DIR is not set /var/lib/e2fsprogs is used

Signed-off-by: Aneesh Kumar K.V <[email protected]>
---
misc/tune2fs.c | 525 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 522 insertions(+), 3 deletions(-)

diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 833b994..8cfb05a 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -61,6 +61,7 @@ char * new_label, *new_last_mounted, *new_UUID;
char * io_options;
static int c_flag, C_flag, e_flag, f_flag, g_flag, i_flag, l_flag, L_flag;
static int m_flag, M_flag, r_flag, s_flag = -1, u_flag, U_flag, T_flag;
+static int I_flag;
static time_t last_check_time;
static int print_label;
static int max_mount_count, mount_count, mount_flags;
@@ -71,10 +72,20 @@ static unsigned short errors;
static int open_flag;
static char *features_cmd;
static char *mntopts_cmd;
+static unsigned long int new_inode_size;

int journal_size, journal_flags;
char *journal_device;

+static struct list_head blk_move_list;
+
+struct blk_move {
+ struct list_head list;
+ blk_t old_loc;
+ blk_t new_loc;
+};
+
+
static const char *please_fsck = N_("Please run e2fsck on the filesystem.\n");

void do_findfs(int argc, char **argv);
@@ -89,7 +100,8 @@ static void usage(void)
"\t[-o [^]mount_options[,...]] [-r reserved_blocks_count]\n"
"\t[-u user] [-C mount_count] [-L volume_label] "
"[-M last_mounted_dir]\n"
- "\t[-O [^]feature[,...]] [-T last_check_time] [-U UUID]"
+ "\t[-O [^]feature[,...]] [-T last_check_time] [-U UUID]\n"
+ "\t[ -I new_inode_size ]"
" device\n"), program_name);
exit (1);
}
@@ -505,7 +517,7 @@ static void parse_tune2fs_options(int argc, char **argv)
struct passwd * pw;

printf("tune2fs %s (%s)\n", E2FSPROGS_VERSION, E2FSPROGS_DATE);
- while ((c = getopt(argc, argv, "c:e:fg:i:jlm:o:r:s:u:C:J:L:M:O:T:U:")) != EOF)
+ while ((c = getopt(argc, argv, "c:e:fg:i:jlm:o:r:s:u:C:J:L:M:O:T:U:I:")) != EOF)
switch (c)
{
case 'c':
@@ -702,6 +714,25 @@ static void parse_tune2fs_options(int argc, char **argv)
open_flag = EXT2_FLAG_RW |
EXT2_FLAG_JOURNAL_DEV_OK;
break;
+ case 'I':
+ new_inode_size = strtoul (optarg, &tmp, 0);
+ if (*tmp) {
+ com_err (program_name, 0,
+ _("bad Inode size - %s"),
+ optarg);
+ usage();
+ }
+ if (!((new_inode_size &
+ (new_inode_size - 1)) == 0)) {
+ com_err (program_name, 0,
+ _("Inode size must be a "
+ "power of two- %s"),
+ optarg);
+ usage();
+ }
+ open_flag = EXT2_FLAG_RW;
+ I_flag = 1;
+ break;
default:
usage();
}
@@ -739,6 +770,460 @@ void do_findfs(int argc, char **argv)
exit(0);
}

+static int get_move_bitmap(ext2_filsys fs, int new_ino_blks_per_grp,
+ ext2fs_block_bitmap bmap)
+{
+ dgrp_t i;
+ blk_t j, needed_blocks = 0;
+ blk_t start_blk, end_blk;
+
+ for (i = 0; i < fs->group_desc_count; i++) {
+
+ start_blk = fs->group_desc[i].bg_inode_table +
+ fs->inode_blocks_per_group;
+
+ end_blk = fs->group_desc[i].bg_inode_table +
+ new_ino_blks_per_grp;
+
+ for (j = start_blk; j < end_blk; j++) {
+
+ if (ext2fs_test_block_bitmap(fs->block_map, j)) {
+ /* FIXME!!
+ * What happens if the block is marked
+ * as a bad block
+ */
+ ext2fs_mark_block_bitmap(bmap, j);
+ needed_blocks++;
+ } else {
+ /*
+ * We are going to use this block for
+ * inode table. So mark them used.
+ */
+ ext2fs_mark_block_bitmap(fs->block_map, j);
+ }
+ }
+ }
+
+ if (needed_blocks > fs->super->s_free_blocks_count ) {
+ return ENOSPC;
+ }
+
+ return 0;
+}
+
+static int move_block(ext2_filsys fs, ext2fs_block_bitmap bmap)
+{
+ char *buf;
+ errcode_t retval;
+ blk_t blk, new_blk;
+ struct blk_move *bmv;
+
+
+ retval = ext2fs_get_mem(fs->blocksize, &buf);
+ if (retval)
+ return retval;
+
+ for (blk = fs->super->s_first_data_block;
+ blk < fs->super->s_blocks_count; blk++) {
+
+ if (!ext2fs_test_block_bitmap(bmap, blk))
+ continue;
+
+ retval = ext2fs_new_block(fs, blk, NULL, &new_blk);
+ if (retval)
+ goto err_out;
+
+ /* Mark this block as allocated */
+ ext2fs_mark_block_bitmap(fs->block_map, new_blk);
+
+ /* Add it to block move list */
+ retval = ext2fs_get_mem(sizeof(struct blk_move), &bmv);
+ if (retval)
+ goto err_out;
+
+ bmv->old_loc = blk;
+ bmv->new_loc = new_blk;
+
+ list_add(&(bmv->list), &blk_move_list);
+
+ retval = io_channel_read_blk(fs->io, blk, 1, buf);
+ if (retval)
+ goto err_out;
+
+ retval = io_channel_write_blk(fs->io, new_blk, 1, buf);
+ if (retval)
+ goto err_out;
+ }
+
+err_out:
+ ext2fs_free_mem(&buf);
+ return retval;
+}
+static blk_t transalate_block(blk_t blk)
+{
+ struct list_head *entry;
+ struct blk_move *bmv;
+
+ list_for_each(entry, &blk_move_list) {
+
+ bmv = list_entry(entry, struct blk_move, list);
+ if (bmv->old_loc == blk)
+ return bmv->new_loc;
+ }
+
+ return 0;
+}
+
+static int process_block(ext2_filsys fs, blk_t *block_nr,
+ e2_blkcnt_t blockcnt,
+ blk_t ref_block EXT2FS_ATTR((unused)),
+ int ref_offset EXT2FS_ATTR((unused)),
+ void *priv_data EXT2FS_ATTR((unused)))
+{
+ int ret = 0;
+ blk_t new_blk;
+
+
+ new_blk = transalate_block(*block_nr);
+ if (new_blk) {
+ *block_nr = new_blk;
+ /*
+ * This will force the ext2fs_write_inode in the iterator
+ */
+ ret |= BLOCK_CHANGED;
+ }
+
+ return ret;
+}
+
+static int inode_scan_and_fix(ext2_filsys fs)
+{
+ errcode_t retval = 0;
+ ext2_ino_t ino;
+ blk_t blk;
+ char *block_buf = 0;
+ struct ext2_inode inode;
+ ext2_inode_scan scan = NULL;
+
+ retval = ext2fs_get_mem(fs->blocksize * 3, &block_buf);
+ if (retval)
+ return retval;
+
+ retval = ext2fs_open_inode_scan(fs, 0, &scan);
+ if (retval)
+ goto err_out;
+
+ while (1) {
+
+ retval = ext2fs_get_next_inode(scan, &ino, &inode);
+ if (retval)
+ goto err_out;
+
+ if (!ino)
+ break;
+
+ if (inode.i_links_count == 0)
+ continue; /* inode not in use */
+
+ /* FIXME!!
+ * If we end up modifying the journal inode
+ * the sb->s_jnl_blocks will differ. But a
+ * subsequent e2fsck fixes that.
+ * Do we need to fix this ??
+ */
+
+ if (inode.i_file_acl) {
+
+ blk = transalate_block(inode.i_file_acl);
+ if (!blk)
+ continue;
+
+ inode.i_file_acl = blk;
+
+ /*
+ * Write the inode to disk so that inode table
+ * resizing can work
+ */
+ retval = ext2fs_write_inode(fs, ino, &inode);
+ if (retval)
+ goto err_out;
+ }
+
+ if (!ext2fs_inode_has_valid_blocks(&inode))
+ continue;
+
+ retval = ext2fs_block_iterate2(fs, ino, 0,
+ block_buf, process_block,
+ 0);
+ if (retval)
+ goto err_out;
+
+ }
+
+err_out:
+ ext2fs_free_mem(&block_buf);
+
+ return retval;
+
+}
+
+
+static int expand_inode_table(ext2_filsys fs, unsigned long int new_inode_size)
+{
+ dgrp_t i;
+ blk_t blk;
+ errcode_t retval;
+ int new_ino_blks_per_grp, j;
+ char *old_itable = NULL, *new_itable = NULL;
+ char *tmp_old_itable = NULL, *tmp_new_itable = NULL;
+ unsigned long int old_inode_size;
+ int old_itable_size, new_itable_size;
+
+ old_itable_size = fs->inode_blocks_per_group * fs->blocksize;
+ old_inode_size = EXT2_INODE_SIZE(fs->super);
+
+ new_ino_blks_per_grp = ext2fs_div_ceil(
+ EXT2_INODES_PER_GROUP(fs->super) *
+ new_inode_size,
+ fs->blocksize);
+
+ new_itable_size = new_ino_blks_per_grp * fs->blocksize;
+
+ retval = ext2fs_get_mem(old_itable_size, &old_itable);
+ if (retval)
+ return retval;
+
+ retval = ext2fs_get_mem(new_itable_size, &new_itable);
+ if (retval)
+ goto err_out;
+
+ tmp_old_itable = old_itable;
+ tmp_new_itable = new_itable;
+
+ for (i = 0; i < fs->group_desc_count; i++) {
+
+ blk = fs->group_desc[i].bg_inode_table;
+ retval = io_channel_read_blk(fs->io, blk,
+ fs->inode_blocks_per_group, old_itable);
+ if (retval)
+ goto err_out;
+
+ for (j = 0; j < EXT2_INODES_PER_GROUP(fs->super); j++) {
+
+ memcpy(new_itable, old_itable, old_inode_size);
+
+ memset(new_itable+old_inode_size, 0,
+ new_inode_size - old_inode_size);
+
+ new_itable += new_inode_size;
+ old_itable += old_inode_size;
+ }
+
+ /* reset the pointer */
+ old_itable = tmp_old_itable;
+ new_itable = tmp_new_itable;
+
+ retval = io_channel_write_blk(fs->io, blk,
+ new_ino_blks_per_grp, new_itable);
+ if (retval)
+ goto err_out;
+ }
+
+ /* Update the meta data */
+ fs->inode_blocks_per_group = new_ino_blks_per_grp;
+ fs->super->s_inode_size = new_inode_size;
+
+err_out:
+ if (old_itable)
+ ext2fs_free_mem(&old_itable);
+
+ if (new_itable)
+ ext2fs_free_mem(&new_itable);
+
+ return retval;
+
+}
+
+static errcode_t ext2fs_calculate_summary_stats(ext2_filsys fs)
+{
+ blk_t blk;
+ ext2_ino_t ino;
+ unsigned int group = 0;
+ unsigned int count = 0;
+ int total_free = 0;
+ int group_free = 0;
+
+ /*
+ * First calculate the block statistics
+ */
+ for (blk = fs->super->s_first_data_block;
+ blk < fs->super->s_blocks_count; blk++) {
+ if (!ext2fs_fast_test_block_bitmap(fs->block_map, blk)) {
+ group_free++;
+ total_free++;
+ }
+ count++;
+ if ((count == fs->super->s_blocks_per_group) ||
+ (blk == fs->super->s_blocks_count-1)) {
+ fs->group_desc[group++].bg_free_blocks_count =
+ group_free;
+ count = 0;
+ group_free = 0;
+ }
+ }
+ fs->super->s_free_blocks_count = total_free;
+
+ /*
+ * Next, calculate the inode statistics
+ */
+ group_free = 0;
+ total_free = 0;
+ count = 0;
+ group = 0;
+
+ /* Protect loop from wrap-around if s_inodes_count maxed */
+ for (ino = 1; ino <= fs->super->s_inodes_count && ino > 0; ino++) {
+ if (!ext2fs_fast_test_inode_bitmap(fs->inode_map, ino)) {
+ group_free++;
+ total_free++;
+ }
+ count++;
+ if ((count == fs->super->s_inodes_per_group) ||
+ (ino == fs->super->s_inodes_count)) {
+ fs->group_desc[group++].bg_free_inodes_count =
+ group_free;
+ count = 0;
+ group_free = 0;
+ }
+ }
+ fs->super->s_free_inodes_count = total_free;
+ ext2fs_mark_super_dirty(fs);
+ return 0;
+}
+
+#define list_for_each_safe(pos, pnext, head) \
+ for (pos = (head)->next, pnext = pos->next; pos != (head); \
+ pos = pnext, pnext = pos->next)
+
+static void free_blk_move_list()
+{
+ struct list_head *entry, *tmp;
+ struct blk_move *bmv;
+
+ list_for_each_safe(entry, tmp, &blk_move_list) {
+
+ bmv = list_entry(entry, struct blk_move, list);
+ list_del(entry);
+ ext2fs_free_mem(&bmv);
+ }
+
+ return ;
+}
+static int resize_inode(ext2_filsys fs, unsigned long int new_inode_size)
+{
+ errcode_t retval;
+ int new_ino_blks_per_grp;
+ ext2fs_block_bitmap bmap;
+
+ if (new_inode_size <= EXT2_INODE_SIZE(fs->super)) {
+ fprintf(stderr, _("New Inode size too small\n"));
+ return EXT2_ET_INVALID_ARGUMENT;
+ }
+
+ ext2fs_read_inode_bitmap(fs);
+ ext2fs_read_block_bitmap(fs);
+ INIT_LIST_HEAD(&blk_move_list);
+
+
+ new_ino_blks_per_grp = ext2fs_div_ceil(
+ EXT2_INODES_PER_GROUP(fs->super)*
+ new_inode_size,
+ fs->blocksize);
+
+ /* We may change the file system.
+ * Mark the file system as invalid so that
+ * the user is prompted to run fsck.
+ */
+ fs->super->s_state &= ~EXT2_VALID_FS;
+
+ retval = ext2fs_allocate_block_bitmap(fs, _("blocks to be moved"),
+ &bmap);
+ if (retval)
+ return retval;
+
+ retval = get_move_bitmap(fs, new_ino_blks_per_grp, bmap);
+ if (retval)
+ goto err_out;
+
+ retval = move_block(fs, bmap);
+ if (retval)
+ goto err_out;
+
+ retval = inode_scan_and_fix(fs);
+ if (retval)
+ goto err_out;
+
+ retval = expand_inode_table(fs, new_inode_size);
+ if (retval)
+ goto err_out;
+
+ ext2fs_calculate_summary_stats(fs);
+
+ fs->super->s_state |= EXT2_VALID_FS;
+ /* mark super block and block bitmap as dirty */
+ ext2fs_mark_super_dirty(fs);
+ ext2fs_mark_bb_dirty(fs);
+
+err_out:
+ free_blk_move_list();
+ ext2fs_free_block_bitmap(bmap);
+
+ return retval;
+}
+
+static int setup_tdb(const char *name)
+{
+ char *tdb_dir, tdb_file[PATH_MAX];
+#if 0 /* FIXME!! */
+ /*
+ * Configuration via a conf file would be
+ * nice
+ */
+ profile_get_string(profile, "scratch_files",
+ "directory", 0, 0,
+ &tdb_dir);
+#endif
+ tdb_dir = getenv("TUNE2FS_SCRATCH_DIR");
+ if (!tdb_dir) {
+ com_err(__FUNCTION__, 0,
+ _("TUNE2FS_SCRATCH_DIR not configured\n"));
+ printf(_("Using /var/lib/e2fsprogs\n"));
+ tdb_dir="/var/lib/e2fsprogs";
+
+ }
+ if (access(tdb_dir, W_OK)) {
+ fprintf(stderr,
+ _("Cannot create file under %s\n"),
+ tdb_dir);
+ return EXT2_ET_INVALID_ARGUMENT;
+
+ }
+
+ sprintf(tdb_file, "%s/tune2fs-XXXXXX", tdb_dir);
+
+ if (!access(tdb_file, F_OK)) {
+ fprintf(stderr,
+ _("File exist %s\n"), tdb_file);
+ return EXT2_ET_INVALID_ARGUMENT;
+ }
+
+ set_undo_io_backup_file(tdb_file);
+ printf(_("To undo the tune2fs operations please run "
+ "the command\nundoe2fs %s %s\n\n"),
+ tdb_file, name);
+
+ return 0;
+}

int main (int argc, char ** argv)
{
@@ -768,7 +1253,19 @@ int main (int argc, char ** argv)
io_ptr = test_io_manager;
test_io_backing_manager = unix_io_manager;
#else
- io_ptr = unix_io_manager;
+ if (I_flag) {
+ /*
+ * If inode resize is requested use the
+ * Undo I/O manager
+ */
+ io_ptr = undo_io_manager;
+ set_undo_io_backing_manager(unix_io_manager);
+ retval = setup_tdb(device_name);
+ if (retval)
+ exit(1);
+ } else {
+ io_ptr = unix_io_manager;
+ }
#endif
retval = ext2fs_open2(device_name, io_options, open_flag,
0, 0, io_ptr, &fs);
@@ -919,6 +1416,28 @@ int main (int argc, char ** argv)
}
ext2fs_mark_super_dirty(fs);
}
+ if (I_flag) {
+ if (mount_flags & EXT2_MF_MOUNTED) {
+ fputs(_("The Inode size may only be "
+ "changed when the filesystem is "
+ "unmounted.\n"), stderr);
+ exit(1);
+ }
+ /*
+ * We want to update group descriptor also
+ * with the new free inode count
+ */
+ fs->flags &= ~EXT2_FLAG_SUPER_ONLY;
+ if (resize_inode(fs, new_inode_size)) {
+
+ fputs(_("Error in resizing the Inode.\n"
+ "Run undoe2fs to undo the "
+ "file system changes. \n"), stderr);
+ } else {
+ printf (_("Setting Inode size %d\n"),
+ new_inode_size);
+ }
+ }

if (l_flag)
list_super (sb);
--
1.5.3.rc2.22.g69a9b-dirty

2007-08-01 06:02:55

by Andreas Dilger

[permalink] [raw]
Subject: Re: [PATCH 2/4] e2fsprogs: Add undoe2fs

On Aug 01, 2007 07:34 +0530, Aneesh Kumar K.V wrote:
> undoe2fs can be used to replay the transaction saved
> in the transaction file using undo I/O Manager

This should save the mtime of the superblock, and only do the undo
step if the filesystem hasn't changed. Otherwise it could seriously
corrupt the filesystem.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

2007-08-01 06:05:04

by Andreas Dilger

[permalink] [raw]
Subject: Re: [PATCH 3/4] e2fsprogs: Make mke2fs use undo I/O manager.

On Aug 01, 2007 07:34 +0530, Aneesh Kumar K.V wrote:
> When running mke2fs, if a file system is detected
> on the device, we use Undo I/O manager as the io manager.
> This helps in reverting the changes made to the filesystem
> in case we wrongly selected the device.
>
> The environment variable MKE2FS_SCRATCH_DIR
> is used to indicate the directory within which the tdb
> file need to be created. The file will be named mke2fs-XXXXXX

It might be more useful to have "mke2fs-{dev}-{timestamp}" as
the filename, so that it is clear where the image came from.


Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

2007-08-01 06:18:22

by Aneesh Kumar K.V

[permalink] [raw]
Subject: Re: [PATCH 2/4] e2fsprogs: Add undoe2fs



Andreas Dilger wrote:
> On Aug 01, 2007 07:34 +0530, Aneesh Kumar K.V wrote:
>> undoe2fs can be used to replay the transaction saved
>> in the transaction file using undo I/O Manager
>
> This should save the mtime of the superblock, and only do the undo
> step if the filesystem hasn't changed. Otherwise it could seriously
> corrupt the filesystem.


I am not sure i understand this. The Undo I/O manager tracks all the write
happening to the file system and copy the original content of the blocks to
the tdb file. Undoe2fs simply copies these blocks back to the file system. So
That way if you look at undoe2fs it doesn't have any knowledge of the file
system at all.

Can you let me know a use case where this will fail.

-aneesh

2007-08-01 06:32:33

by Kalpak Shah

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Subject: Re: [PATCH 2/4] e2fsprogs: Add undoe2fs

On Wed, 2007-08-01 at 11:46 +0530, Aneesh Kumar K.V wrote:
>
> Andreas Dilger wrote:
> > On Aug 01, 2007 07:34 +0530, Aneesh Kumar K.V wrote:
> >> undoe2fs can be used to replay the transaction saved
> >> in the transaction file using undo I/O Manager
> >
> > This should save the mtime of the superblock, and only do the undo
> > step if the filesystem hasn't changed. Otherwise it could seriously
> > corrupt the filesystem.
>
>
> I am not sure i understand this. The Undo I/O manager tracks all the write
> happening to the file system and copy the original content of the blocks to
> the tdb file. Undoe2fs simply copies these blocks back to the file system. So
> That way if you look at undoe2fs it doesn't have any knowledge of the file
> system at all.
>
> Can you let me know a use case where this will fail.

undoe2fs made a copy of all the changes to the filesystem. After that
the filesystem was mounted and used thereby rendering the checkpoint
invalid. If this checkpoint was replayed it could seriously corrupt the
filesystem. Hence as Andreas suggests the mtime of the filesystem should
be checked and only then the transaction should be replayed.

Infact mounting the filesystem when the replay is in progress would also
corrupt the filesystem.

Is should the checkpoint be deleted if e2fsck was aborted?

Thanks,
Kalpak.

2007-08-01 07:10:35

by Andreas Dilger

[permalink] [raw]
Subject: Re: [PATCH 2/4] e2fsprogs: Add undoe2fs

On Aug 01, 2007 11:46 +0530, Aneesh Kumar K.V wrote:
> Andreas Dilger wrote:
> >On Aug 01, 2007 07:34 +0530, Aneesh Kumar K.V wrote:
> >>undoe2fs can be used to replay the transaction saved
> >>in the transaction file using undo I/O Manager
> >
> >This should save the mtime of the superblock, and only do the undo
> >step if the filesystem hasn't changed. Otherwise it could seriously
> >corrupt the filesystem.
>
> I am not sure i understand this. The Undo I/O manager tracks all the write
> happening to the file system and copy the original content of the blocks to
> the tdb file. Undoe2fs simply copies these blocks back to the file system.
>
> That way if you look at undoe2fs it doesn't have any knowledge of the file
> system at all.
>
> Can you let me know a use case where this will fail.

- modify filesystem with undo manager (e.g. inode resize)
- mount filesystem, make changes, unmount
- run undoe2fs to overwrite filesystem, corrupting it

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

2007-08-01 07:14:50

by Andreas Dilger

[permalink] [raw]
Subject: Re: [PATCH 3/4] e2fsprogs: Make mke2fs use undo I/O manager.

On Aug 01, 2007 11:44 +0530, Aneesh Kumar K.V wrote:
> Andreas Dilger wrote:
> >On Aug 01, 2007 07:34 +0530, Aneesh Kumar K.V wrote:
> >>When running mke2fs, if a file system is detected
> >>on the device, we use Undo I/O manager as the io manager.
> >>This helps in reverting the changes made to the filesystem
> >>in case we wrongly selected the device.
> >>
> >>The environment variable MKE2FS_SCRATCH_DIR
> >>is used to indicate the directory within which the tdb
> >>file need to be created. The file will be named mke2fs-XXXXXX
> >
> >It might be more useful to have "mke2fs-{dev}-{timestamp}" as
> >the filename, so that it is clear where the image came from.
> >
>
> I added it as a FIXME!! in the code. So i was intending to do it.
>
> + /* FIXME!! Should we generate Unique file name ?? */
> + sprintf(tdb_file, "%s/mke2fs-XXXXXX", tdb_dir);

I don't think the "uniqueness" is as important as the fact that
having the dev and timestamp makes it easier to know which undo
file is related to a particular filesystem. In that regard, the
undo file should also contain the filesystem UUID in addition to
the mtime to ensure it is being replayed on the same filesystem.


Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

2007-08-01 07:14:50

by Aneesh Kumar K.V

[permalink] [raw]
Subject: Re: [PATCH 3/4] e2fsprogs: Make mke2fs use undo I/O manager.



Andreas Dilger wrote:
> On Aug 01, 2007 07:34 +0530, Aneesh Kumar K.V wrote:
>> When running mke2fs, if a file system is detected
>> on the device, we use Undo I/O manager as the io manager.
>> This helps in reverting the changes made to the filesystem
>> in case we wrongly selected the device.
>>
>> The environment variable MKE2FS_SCRATCH_DIR
>> is used to indicate the directory within which the tdb
>> file need to be created. The file will be named mke2fs-XXXXXX
>
> It might be more useful to have "mke2fs-{dev}-{timestamp}" as
> the filename, so that it is clear where the image came from.
>

I added it as a FIXME!! in the code. So i was intending to do it.

+ /* FIXME!! Should we generate Unique file name ?? */
+ sprintf(tdb_file, "%s/mke2fs-XXXXXX", tdb_dir);



I will add it in my next patch set.

-aneesh

2007-08-01 07:55:34

by Aneesh Kumar K.V

[permalink] [raw]
Subject: Re: [PATCH 2/4] e2fsprogs: Add undoe2fs



Andreas Dilger wrote:
> On Aug 01, 2007 11:46 +0530, Aneesh Kumar K.V wrote:
>> Andreas Dilger wrote:
>>> On Aug 01, 2007 07:34 +0530, Aneesh Kumar K.V wrote:
>>>> undoe2fs can be used to replay the transaction saved
>>>> in the transaction file using undo I/O Manager
>>> This should save the mtime of the superblock, and only do the undo
>>> step if the filesystem hasn't changed. Otherwise it could seriously
>>> corrupt the filesystem.
>> I am not sure i understand this. The Undo I/O manager tracks all the write
>> happening to the file system and copy the original content of the blocks to
>> the tdb file. Undoe2fs simply copies these blocks back to the file system.
>>
>> That way if you look at undoe2fs it doesn't have any knowledge of the file
>> system at all.
>>
>> Can you let me know a use case where this will fail.
>
> - modify filesystem with undo manager (e.g. inode resize)
> - mount filesystem, make changes, unmount
> - run undoe2fs to overwrite filesystem, corrupting it
>


But that won't corrupt it. It will bring the file system back to
the state before inode resize. I understand that we may want to have

a) Don't replay if file system is mounted
b) Don't replay if UUID doesn't match


But i guess we should allow a replay if file system got changed afterwards.
Ofcourse the changes will no longer be available after the replay.

-aneesh

2007-08-01 08:28:01

by Andreas Dilger

[permalink] [raw]
Subject: Re: [PATCH 2/4] e2fsprogs: Add undoe2fs

On Aug 01, 2007 13:22 +0530, Aneesh Kumar K.V wrote:
> >>Can you let me know a use case where this will fail.
> >
> >- modify filesystem with undo manager (e.g. inode resize)
> >- mount filesystem, make changes, unmount
> >- run undoe2fs to overwrite filesystem, corrupting it
>
> But that won't corrupt it. It will bring the file system back to
> the state before inode resize.

No, that isn't correct. The changes done to the filesystem while
mounted will not be recorded in the undo file. If the undo file
can be replayed over the modified filesystem then only the blocks
in the undo file will be restored, but none of the other blocks
that were modified while the filesystem was mounted.

> I understand that we may want to have
>
> a) Don't replay if file system is mounted
> b) Don't replay if UUID doesn't match
>
> But i guess we should allow a replay if file system got changed afterwards.
> Ofcourse the changes will no longer be available after the replay.

No this shouldn't be allowed, except in "--force" mode (which would be
needed after mke2fs because the UUID and s_mtime would change). For
cases like e2fsck the undo might be helpful.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.