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Date: Mon, 28 Jul 2014 11:43:24 +0400
From: Azat Khuzhin <a3at.mail@...il.com>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, darrick.wong@...cle.com, adilger@...ger.ca,
Azat Khuzhin <a3at.mail@...il.com>
Subject: [PATCH 3/4 v3] tune2fs: update journal super block when changing UUID for fs.
Using -U option you can change the UUID for fs, however it will not work
for journal device, since it have a copy of this UUID inside jsb (i.e.
journal super block). So copy UUID on change into that block.
Here is the initial thread:
http://comments.gmane.org/gmane.comp.file-systems.ext4/44532
You can reproduce this by executing following commands:
$ fallocate -l100M /tmp/dev
$ fallocate -l100M /tmp/journal
$ sudo /sbin/losetup /dev/loop1 /tmp/dev
$ sudo /sbin/losetup /dev/loop0 /tmp/journal
$ mke2fs -O journal_dev /tmp/journal
$ tune2fs -U da1f2ed0-60f6-aaaa-92fd-738701418523 /tmp/journal
$ sudo mke2fs -t ext4 -J device=/dev/loop0 /dev/loop1
$ dumpe2fs -h /tmp/dev | fgrep UUID
dumpe2fs 1.43-WIP (18-May-2014)
Filesystem UUID: 8a776be9-12eb-411f-8e88-b873575ecfb6
Journal UUID: e3d02151-e776-4865-af25-aecb7291e8e5
$ sudo e2fsck /dev/vdc
e2fsck 1.43-WIP (18-May-2014)
External journal does not support this filesystem
/dev/loop1: ********** WARNING: Filesystem still has errors **********
Reported-by: Chin Tzung Cheng <chintzung@...il.com>
Signed-off-by: Azat Khuzhin <a3at.mail@...il.com>
Reviewed-by: Andreas Dilger <adilger@...ger.ca>
---
misc/tune2fs.c | 74 ++++++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 56 insertions(+), 18 deletions(-)
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 1df655a..74e57ae 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -175,6 +175,38 @@ static __u32 clear_ok_features[3] = {
EXT4_FEATURE_RO_COMPAT_GDT_CSUM
};
+/**
+ * Try to get journal super block if any
+ */
+static int get_journal_sb(ext2_filsys jfs, char buf[SUPERBLOCK_SIZE])
+{
+ int retval;
+ int start;
+ journal_superblock_t *jsb;
+
+ if (!(jfs->super->s_feature_incompat &
+ EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
+ return EXT2_ET_UNSUPP_FEATURE;
+ }
+
+ /* Get the journal superblock */
+ if ((retval = io_channel_read_blk64(jfs->io,
+ ext2fs_journal_sb_start(jfs->blocksize), -SUPERBLOCK_SIZE, buf))) {
+ com_err(program_name, retval, "%s",
+ _("while reading journal superblock"));
+ return retval;
+ }
+
+ jsb = (journal_superblock_t *) buf;
+ if ((jsb->s_header.h_magic != (unsigned)ntohl(JFS_MAGIC_NUMBER)) ||
+ (jsb->s_header.h_blocktype != (unsigned)ntohl(JFS_SUPERBLOCK_V2))) {
+ fputs(_("Journal superblock not found!\n"), stderr);
+ return EXT2_ET_BAD_MAGIC;
+ }
+
+ return 0;
+}
+
/*
* Remove an external journal from the filesystem
*/
@@ -218,29 +250,15 @@ static int remove_journal_device(ext2_filsys fs)
_("while trying to open external journal"));
goto no_valid_journal;
}
- if (!(jfs->super->s_feature_incompat &
- EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
- fprintf(stderr, _("%s is not a journal device.\n"),
- journal_path);
- goto no_valid_journal;
- }
- start = ext2fs_journal_sb_start(fs->blocksize);
- /* Get the journal superblock */
- if ((retval = io_channel_read_blk64(jfs->io, start,
- -SUPERBLOCK_SIZE, buf))) {
- com_err(program_name, retval, "%s",
- _("while reading journal superblock"));
+ if ((retval = get_journal_sb(jfs, buf))) {
+ if (retval == EXT2_ET_UNSUPP_FEATURE)
+ fprintf(stderr, _("%s is not a journal device.\n"),
+ journal_path);
goto no_valid_journal;
}
jsb = (journal_superblock_t *) buf;
- if ((jsb->s_header.h_magic != (unsigned)ntohl(JFS_MAGIC_NUMBER)) ||
- (jsb->s_header.h_blocktype != (unsigned)ntohl(JFS_SUPERBLOCK_V2))) {
- fputs(_("Journal superblock not found!\n"), stderr);
- goto no_valid_journal;
- }
-
/* Find the filesystem UUID */
nr_users = ntohl(jsb->s_nr_users);
for (i = 0; i < nr_users; i++) {
@@ -2184,6 +2202,7 @@ retry_open:
if (U_flag) {
int set_csum = 0;
dgrp_t i;
+ char buf[SUPERBLOCK_SIZE];
if (sb->s_feature_ro_compat &
EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
@@ -2229,6 +2248,25 @@ retry_open:
ext2fs_group_desc_csum_set(fs, i);
fs->flags &= ~EXT2_FLAG_SUPER_ONLY;
}
+
+ /* If this is a journal dev, we need to copy UUID into jsb */
+ if (!(rc = get_journal_sb(fs, buf))) {
+ journal_superblock_t *jsb;
+
+ jsb = (journal_superblock_t *) buf;
+ fputs(_("Need to update journal superblock.\n"), stdout);
+ memcpy(jsb->s_uuid, sb->s_uuid, sizeof(sb->s_uuid));
+
+ /* Writeback the journal superblock */
+ if ((rc = io_channel_write_blk64(fs->io,
+ ext2fs_journal_sb_start(fs->blocksize),
+ -SUPERBLOCK_SIZE, buf)))
+ goto closefs;
+ } else if (rc != EXT2_ET_UNSUPP_FEATURE)
+ goto closefs;
+ else
+ rc = 0; /** Reset rc to avoid ext2fs_mmp_stop() */
+
ext2fs_mark_super_dirty(fs);
}
if (I_flag) {
--
2.0.1
--
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