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Message-ID: <20150127073922.13308.42287.stgit@birch.djwong.org>
Date: Mon, 26 Jan 2015 23:39:22 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: tytso@....edu, darrick.wong@...cle.com
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 35/54] e2fsck: optionally create an undo file
Provide the user with an option to create an undo file so that they
can roll back a failed repair operation.
v2: Support reopening undo files.
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
e2fsck/e2fsck.8.in | 10 +++++
e2fsck/e2fsck.h | 3 ++
e2fsck/unix.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 107 insertions(+), 2 deletions(-)
diff --git a/e2fsck/e2fsck.8.in b/e2fsck/e2fsck.8.in
index 6e6a2cd..364c7f1 100644
--- a/e2fsck/e2fsck.8.in
+++ b/e2fsck/e2fsck.8.in
@@ -334,6 +334,16 @@ may not be specified at the same time as the
or
.B \-p
options.
+.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
+e2fsck-\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 EXIT CODE
The exit code returned by
.B e2fsck
diff --git a/e2fsck/e2fsck.h b/e2fsck/e2fsck.h
index 15d968e..04f7bac 100644
--- a/e2fsck/e2fsck.h
+++ b/e2fsck/e2fsck.h
@@ -388,6 +388,9 @@ struct e2fsck_struct {
* Inodes to rebuild extent trees
*/
ext2fs_inode_bitmap inodes_to_rebuild;
+
+ /* Undo file */
+ char *undo_file;
};
/* Data structures to evaluate whether an extent tree needs rebuilding. */
diff --git a/e2fsck/unix.c b/e2fsck/unix.c
index b84bffe..d2ef50f 100644
--- a/e2fsck/unix.c
+++ b/e2fsck/unix.c
@@ -45,6 +45,7 @@ extern int optind;
#ifdef HAVE_DIRENT_H
#include <dirent.h>
#endif
+#include <libgen.h>
#include "e2p/e2p.h"
#include "et/com_err.h"
@@ -75,7 +76,7 @@ static void usage(e2fsck_t ctx)
_("Usage: %s [-panyrcdfvtDFV] [-b superblock] [-B blocksize]\n"
"\t\t[-I inode_buffer_blocks] [-P process_inode_size]\n"
"\t\t[-l|-L bad_blocks_file] [-C fd] [-j external_journal]\n"
- "\t\t[-E extended-options] device\n"),
+ "\t\t[-E extended-options] [-z undo_file] device\n"),
ctx->program_name);
fprintf(stderr, "%s", _("\nEmergency help:\n"
@@ -91,6 +92,7 @@ static void usage(e2fsck_t ctx)
" -j external_journal Set location of the external journal\n"
" -l bad_blocks_file Add to badblocks list\n"
" -L bad_blocks_file Set badblocks list\n"
+ " -z undo_file Create an undo file\n"
));
exit(FSCK_USAGE);
@@ -795,7 +797,7 @@ static errcode_t PRS(int argc, char *argv[], e2fsck_t *ret_ctx)
phys_mem_kb = get_memory_size() / 1024;
ctx->readahead_kb = ~0ULL;
- while ((c = getopt (argc, argv, "panyrcC:B:dE:fvtFVM:b:I:j:P:l:L:N:SsDk")) != EOF)
+ while ((c = getopt(argc, argv, "panyrcC:B:dE:fvtFVM:b:I:j:P:l:L:N:SsDkz:")) != EOF)
switch (c) {
case 'C':
ctx->progress = e2fsck_update_progress;
@@ -927,6 +929,9 @@ static errcode_t PRS(int argc, char *argv[], e2fsck_t *ret_ctx)
case 'k':
keep_bad_blocks++;
break;
+ case 'z':
+ ctx->undo_file = optarg;
+ break;
default:
usage(ctx);
}
@@ -1205,6 +1210,87 @@ check_error:
return retval;
}
+static int e2fsck_setup_tdb(e2fsck_t ctx, 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;
+
+ /* (re)open a specific undo file */
+ if (ctx->undo_file && ctx->undo_file[0] != 0) {
+ set_undo_io_backing_manager(*io_ptr);
+ *io_ptr = undo_io_manager;
+ retval = set_undo_io_backup_file(ctx->undo_file);
+ if (retval)
+ goto err;
+ printf(_("Overwriting existing filesystem; this can be undone "
+ "using the command:\n"
+ " e2undo %s %s\n\n"),
+ ctx->undo_file, ctx->filesystem_name);
+ return 0;
+ }
+
+ /*
+ * Configuration via a conf file would be
+ * nice
+ */
+ tdb_dir = getenv("E2FSPROGS_UNDO_DIR");
+ if (!tdb_dir) {
+ profile_get_string(ctx->profile, "defaults",
+ "undo_dir", 0, "/var/lib/e2fsprogs",
+ &tdb_dir);
+ free_tdb_dir = 1;
+ }
+
+ if (!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(ctx->filesystem_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/e2fsck-%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, ctx->filesystem_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(ctx->program_name, retval, "%s",
+ _("while trying to setup undo file\n"));
+ return retval;
+}
+
int main (int argc, char *argv[])
{
errcode_t retval = 0, retval2 = 0, orig_retval = 0;
@@ -1315,6 +1401,12 @@ restart:
} else
flags |= EXT2_FLAG_SOFTSUPP_FEATURES;
+ if (ctx->undo_file) {
+ retval = e2fsck_setup_tdb(ctx, &io_ptr);
+ if (retval)
+ exit(FSCK_ERROR);
+ }
+
ctx->openfs_flags = flags;
retval = try_open_fs(ctx, flags, io_ptr, &fs);
--
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