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Date: Sat, 20 Dec 2014 13:18:50 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: tytso@....edu, darrick.wong@...cle.com
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 18/31] resize2fs: optionally create undo file
Provide the user with an option to create an undo file so that they
can roll back a failed resize operation.
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
resize/main.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++--
resize/resize2fs.8.in | 14 +++++++
2 files changed, 108 insertions(+), 3 deletions(-)
diff --git a/resize/main.c b/resize/main.c
index c25de61..ea9a91b 100644
--- a/resize/main.c
+++ b/resize/main.c
@@ -29,6 +29,7 @@ extern int optind;
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
+#include <libgen.h>
#include "e2p/e2p.h"
@@ -42,7 +43,8 @@ static char *device_name, *io_options;
static void usage (char *prog)
{
fprintf (stderr, _("Usage: %s [-d debug_flags] [-f] [-F] [-M] [-P] "
- "[-p] device [-b|-s|new_size]\n\n"), prog);
+ "[-p] device [-b|-s|new_size] [-z undo_file]\n\n"),
+ prog);
exit (1);
}
@@ -162,6 +164,86 @@ static void bigalloc_check(ext2_filsys fs, int force)
}
}
+static int resize2fs_setup_tdb(const char *device_name, char *undo_file,
+ io_manager *io_ptr)
+{
+ errcode_t retval = ENOMEM;
+ char *tdb_dir = NULL, *tdb_file = NULL;
+ char *dev_name, *tmp_name;
+ int free_tdb_dir = 0;
+
+ if (undo_file && undo_file[0] != 0) {
+ if ((unlink(undo_file) < 0) && (errno != ENOENT)) {
+ retval = errno;
+ goto err;
+ }
+
+ set_undo_io_backing_manager(*io_ptr);
+ *io_ptr = undo_io_manager;
+ retval = set_undo_io_backup_file(undo_file);
+ if (retval)
+ goto err;
+ printf(_("Overwriting existing filesystem; this can be undone "
+ "using the command:\n"
+ " e2undo %s %s\n\n"),
+ undo_file, device_name);
+ return 0;
+ }
+
+ /*
+ * Configuration via a conf file would be
+ * nice
+ */
+ tdb_dir = getenv("E2FSPROGS_UNDO_DIR");
+
+ if (tdb_dir == NULL || !strcmp(tdb_dir, "none") || (tdb_dir[0] == 0) ||
+ access(tdb_dir, W_OK)) {
+ if (free_tdb_dir)
+ free(tdb_dir);
+ return 0;
+ }
+
+ tmp_name = strdup(device_name);
+ if (!tmp_name)
+ goto errout;
+ dev_name = basename(tmp_name);
+ tdb_file = malloc(strlen(tdb_dir) + 8 + strlen(dev_name) + 7 + 1);
+ if (!tdb_file) {
+ free(tmp_name);
+ goto errout;
+ }
+ sprintf(tdb_file, "%s/resize2fs-%s.e2undo", tdb_dir, dev_name);
+ free(tmp_name);
+
+ if ((unlink(tdb_file) < 0) && (errno != ENOENT)) {
+ retval = errno;
+ goto errout;
+ }
+
+ set_undo_io_backing_manager(*io_ptr);
+ *io_ptr = undo_io_manager;
+ retval = set_undo_io_backup_file(tdb_file);
+ if (retval)
+ goto errout;
+ printf(_("Overwriting existing filesystem; this can be undone "
+ "using the command:\n"
+ " e2undo %s %s\n\n"), tdb_file, device_name);
+
+ if (free_tdb_dir)
+ free(tdb_dir);
+ free(tdb_file);
+ return 0;
+
+errout:
+ if (free_tdb_dir)
+ free(tdb_dir);
+ free(tdb_file);
+err:
+ com_err(program_name, retval, "%s",
+ _("while trying to setup undo file\n"));
+ return retval;
+}
+
int main (int argc, char ** argv)
{
errcode_t retval;
@@ -186,7 +268,7 @@ int main (int argc, char ** argv)
unsigned int blocksize;
long sysval;
int len, mount_flags;
- char *mtpt;
+ char *mtpt, *undo_file = NULL;
#ifdef ENABLE_NLS
setlocale(LC_MESSAGES, "");
@@ -203,7 +285,7 @@ int main (int argc, char ** argv)
if (argc && *argv)
program_name = *argv;
- while ((c = getopt(argc, argv, "d:fFhMPpS:bs")) != EOF) {
+ while ((c = getopt(argc, argv, "d:fFhMPpS:bsz:")) != EOF) {
switch (c) {
case 'h':
usage(program_name);
@@ -235,6 +317,9 @@ int main (int argc, char ** argv)
case 's':
flags |= RESIZE_DISABLE_64BIT;
break;
+ case 'z':
+ undo_file = optarg;
+ break;
default:
usage(program_name);
}
@@ -319,6 +404,12 @@ int main (int argc, char ** argv)
io_flags |= EXT2_FLAG_64BITS;
+ if (undo_file) {
+ retval = resize2fs_setup_tdb(device_name, undo_file, &io_ptr);
+ if (retval)
+ exit(1);
+ }
+
retval = ext2fs_open2(device_name, io_options, io_flags,
0, 0, io_ptr, &fs);
if (retval) {
diff --git a/resize/resize2fs.8.in b/resize/resize2fs.8.in
index 0129bfc..d2738e9 100644
--- a/resize/resize2fs.8.in
+++ b/resize/resize2fs.8.in
@@ -18,6 +18,10 @@ resize2fs \- ext2/ext3/ext4 file system resizer
.B \-S
.I RAID-stride
]
+[
+.B \-z
+.I undo_file
+]
.I device
[
.I size
@@ -149,6 +153,16 @@ The
program will heuristically determine the RAID stride that was specified
when the filesystem was created. This option allows the user to
explicitly specify a RAID stride setting to be used by resize2fs instead.
+.TP
+.BI \-z " undo_file"
+Before overwriting a file system block, write the old contents of the block to
+an undo file. This undo file can be used with e2undo(8) to restore the old
+contents of the file system should something go wrong. If the empty string is
+passed as the undo_file argument, the undo file will be written to a file named
+resize2fs-\fIdevice\fR.e2undo in the directory specified via the
+\fIE2FSPROGS_UNDO_DIR\fR environment variable.
+
+WARNING: The undo file cannot be used to recover from a power or system crash.
.SH KNOWN BUGS
The minimum size of the filesystem as estimated by resize2fs may be
incorrect, especially for filesystems with 1k and 2k blocksizes.
--
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