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Date: Wed, 01 Apr 2015 19:35:58 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: tytso@....edu, darrick.wong@...cle.com
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 18/35] tune2fs: optionally create undo file
Provide the user with an option to create an undo file so that they
can roll back a failed tuning operation. Previously, one would be
created for inode resize if a bunch of (undocumented) conditions were
met.
v2: Enable re-opening of undo files.
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
misc/tune2fs.8.in | 14 ++++++++++++++
misc/tune2fs.c | 30 ++++++++++++++++++++++++++----
2 files changed, 40 insertions(+), 4 deletions(-)
diff --git a/misc/tune2fs.8.in b/misc/tune2fs.8.in
index 9d1df82..4373fc4 100644
--- a/misc/tune2fs.8.in
+++ b/misc/tune2fs.8.in
@@ -88,6 +88,10 @@ tune2fs \- adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems
.B \-U
.I UUID
]
+[
+.B \-z
+.I undo_file
+]
device
.SH DESCRIPTION
.BI tune2fs
@@ -687,6 +691,16 @@ or
.IR /dev/urandom ,
.B tune2fs
will automatically use a time-based UUID instead of a randomly-generated UUID.
+.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
+tune2fs-\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 BUGS
We haven't found any bugs yet. That doesn't mean there aren't any...
.SH AUTHOR
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 550932d..ddaad59 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -99,6 +99,7 @@ static int usrquota, grpquota;
static int rewrite_checksums;
static int feature_64bit;
static int fsck_requested;
+static char *undo_file;
int journal_size, journal_flags;
char *journal_device;
@@ -136,7 +137,8 @@ static void usage(void)
"\t[-Q quota_options]\n"
#endif
"\t[-E extended-option[,...]] [-T last_check_time] "
- "[-U UUID]\n\t[ -I new_inode_size ] device\n"), program_name);
+ "[-U UUID]\n\t[-I new_inode_size] [-z undo_file] device\n"),
+ program_name);
exit(1);
}
@@ -465,6 +467,8 @@ static void convert_64bit(ext2_filsys fs, int direction)
fprintf(stderr, _("Please run `resize2fs %s %s"),
direction > 0 ? "-b" : "-s", fs->device_name);
+ if (undo_file)
+ fprintf(stderr, _(" -z \"%s\""), undo_file);
if (direction > 0)
fprintf(stderr, _("' to enable 64-bit mode.\n"));
else
@@ -1563,7 +1567,7 @@ static void parse_tune2fs_options(int argc, char **argv)
char *tmp;
struct group *gr;
struct passwd *pw;
- char optstring[100] = "c:e:fg:i:jlm:o:r:s:u:C:E:I:J:L:M:O:T:U:";
+ char optstring[100] = "c:e:fg:i:jlm:o:r:s:u:C:E:I:J:L:M:O:T:U:z:";
#ifdef CONFIG_QUOTA
strcat(optstring, "Q:");
@@ -1797,6 +1801,9 @@ static void parse_tune2fs_options(int argc, char **argv)
open_flag = EXT2_FLAG_RW;
I_flag = 1;
break;
+ case 'z':
+ undo_file = optarg;
+ break;
default:
usage();
}
@@ -2517,6 +2524,17 @@ static int tune2fs_setup_tdb(const char *name, io_manager *io_ptr)
char *tdb_file;
char *dev_name, *tmp_name;
+ /* (re)open a specific undo file */
+ if (undo_file && undo_file[0] != 0) {
+ set_undo_io_backing_manager(*io_ptr);
+ *io_ptr = undo_io_manager;
+ set_undo_io_backup_file(undo_file);
+ printf(_("To undo the tune2fs operation please run "
+ "the command\n e2undo %s %s\n\n"),
+ undo_file, name);
+ return retval;
+ }
+
#if 0 /* FIXME!! */
/*
* Configuration via a conf file would be
@@ -2712,7 +2730,7 @@ retry_open:
}
fs->default_bitmap_type = EXT2FS_BMAP64_RBTREE;
- if (I_flag && !io_ptr_orig) {
+ if (I_flag) {
/*
* Check the inode size is right so we can issue an
* error message and bail before setting up the tdb
@@ -2736,11 +2754,15 @@ retry_open:
rc = 1;
goto closefs;
}
-
/*
* If inode resize is requested use the
* Undo I/O manager
*/
+ undo_file = "";
+ }
+
+ /* Set up an undo file */
+ if (undo_file && io_ptr_orig == NULL) {
io_ptr_orig = io_ptr;
retval = tune2fs_setup_tdb(device_name, &io_ptr);
if (retval) {
--
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