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Date: Wed, 1 Aug 2007 21:04:10 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH 3/4] e2fsprogs: Make mke2fs use undo I/O manager.
From: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
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 <aneesh.kumar@...ux.vnet.ibm.com>
---
misc/mke2fs.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 108 insertions(+), 1 deletions(-)
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 0c6d4f3..3ff4b90 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -44,6 +44,7 @@ extern int optind;
#endif
#include <sys/ioctl.h>
#include <sys/types.h>
+#include <libgen.h>
#include "ext2fs/ext2_fs.h"
#include "et/com_err.h"
@@ -1521,6 +1522,102 @@ static void PRS(int argc, char *argv[])
fs_param.s_blocks_count);
}
+static int filesystem_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)
+{
+ errcode_t retval = 0;
+ char *tdb_dir, tdb_file[PATH_MAX];
+ char *device_name, *tmp_name;
+
+#if 0 /* FIXME!! */
+ /*
+ * Configuration via a conf file would be
+ * nice
+ */
+ profile_get_string(profile, "scratch_files",
+ "directory", 0, 0,
+ &tdb_dir);
+#endif
+ tmp_name = strdup(name);
+ device_name = basename(tmp_name);
+
+ 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);
+ retval = EXT2_ET_INVALID_ARGUMENT;
+ goto err_out;
+
+ }
+
+ sprintf(tdb_file, "%s/mke2fs-%s", tdb_dir, device_name);
+
+ if (!access(tdb_file, F_OK)) {
+ fprintf(stderr,
+ _("File exist %s\n"), tdb_file);
+ retval = EXT2_ET_INVALID_ARGUMENT;
+ goto err_out;
+ }
+
+ 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);
+err_out:
+ free(tmp_name);
+ return retval;
+}
+
int main (int argc, char *argv[])
{
errcode_t retval = 0;
@@ -1543,7 +1640,17 @@ 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 (filesystem_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
-
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