[PATCH 0/4 v3] e2fsprogs journal fixes (UUID and 1k block size issue)

[PATCH 0/4 v3] e2fsprogs journal fixes (UUID and 1k block size issue)

[Azat Khuzhin]

Hi all,

Here is patchset with some fixes for journal code in e2fsprogs.
I've removed first patch from previous version "lib: add EXT2_ prefix for
SUPERBLOCK_{OFFSET,SIZE}", and rebase other patches on top of the maint branch.

I've tested it using "make check" and commands from commits.
I do want to add tests for this cases, but they requires some extra
capabilities (CAP_SYS_ADMIN for mount(2)), while right now tests don't have
such cases, if somebody have proposal how to do this tests without extra
mount(2) I will be happy to hear (for more info about possible test cases see
"tune2fs: update journal super block when changing UUID for fs." and "tune2fs:
update journal users while updating fs UUID (with external journal)")

Thanks.
Azat.

Azat Khuzhin (4):
  journal: use consts instead of 1024 and add helper for journal with 1k
    blocksize
  tune2fs: remove_journal_device(): use the correct block to find jsb
  tune2fs: update journal super block when changing UUID for fs.
  tune2fs: update journal users while updating fs UUID (with external
    journal)

 e2fsck/journal.c        |   5 +-
 lib/ext2fs/ext2fs.h     |   3 +
 lib/ext2fs/kernel-jbd.h |   6 +-
 lib/ext2fs/mkjournal.c  |  28 ++++----
 misc/tune2fs.c          | 166 +++++++++++++++++++++++++++++++++++++++++-------
 misc/uuidd.c            |   3 +-
 6 files changed, 171 insertions(+), 40 deletions(-)

-- 
2.0.1

[PATCH 1/4 v3] journal: use consts instead of 1024 and add helper for journal with 1k blocksize

[Azat Khuzhin]

Use
EXT2_MIN_BLOCK_SIZE/JFS_MIN_JOURNAL_BLOCKS/SUPERBLOCK_SIZE/SUPERBLOCK_OFFSET
instead of hardcoded 1024 when it is okay, and also add a helper
ext2fs_journal_sb_start() that will return start of journal sb with
special case for fs with 1k block size.

Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 e2fsck/journal.c       |  5 ++---
 lib/ext2fs/ext2fs.h    |  1 +
 lib/ext2fs/mkjournal.c | 28 ++++++++++++++++------------
 misc/tune2fs.c         |  6 +++---
 4 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/e2fsck/journal.c b/e2fsck/journal.c
index 9be52cd..3b40e00 100644
--- a/e2fsck/journal.c
+++ b/e2fsck/journal.c
@@ -393,8 +393,7 @@ static errcode_t e2fsck_get_journal(e2fsck_t ctx, journal_t **ret_journal)
 	if (ext_journal) {
 		blk64_t maxlen;
 
-		if (ctx->fs->blocksize == 1024)
-			start = 1;
+		start = ext2fs_journal_sb_start(ctx->fs->blocksize) - 1;
 		bh = getblk(dev_journal, start, ctx->fs->blocksize);
 		if (!bh) {
 			retval = EXT2_ET_NO_MEMORY;
@@ -405,7 +404,7 @@ static errcode_t e2fsck_get_journal(e2fsck_t ctx, journal_t **ret_journal)
 			brelse(bh);
 			goto errout;
 		}
-		memcpy(&jsuper, start ? bh->b_data :  bh->b_data + 1024,
+		memcpy(&jsuper, start ? bh->b_data :  bh->b_data + SUPERBLOCK_OFFSET,
 		       sizeof(jsuper));
 		brelse(bh);
 #ifdef WORDS_BIGENDIAN
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 33b2519..ab57534 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1377,6 +1377,7 @@ extern errcode_t ext2fs_add_journal_inode(ext2_filsys fs, blk_t num_blocks,
 extern errcode_t ext2fs_add_journal_inode2(ext2_filsys fs, blk_t num_blocks,
 					   blk64_t goal, int flags);
 extern int ext2fs_default_journal_size(__u64 num_blocks);
+extern int ext2fs_journal_sb_start(int blocksize);
 
 /* openfs.c */
 extern errcode_t ext2fs_open(const char *name, int flags, int superblock,
diff --git a/lib/ext2fs/mkjournal.c b/lib/ext2fs/mkjournal.c
index e8316a7..96b6d36 100644
--- a/lib/ext2fs/mkjournal.c
+++ b/lib/ext2fs/mkjournal.c
@@ -49,7 +49,7 @@ errcode_t ext2fs_create_journal_superblock(ext2_filsys fs,
 	errcode_t		retval;
 	journal_superblock_t	*jsb;
 
-	if (num_blocks < 1024)
+	if (num_blocks < JFS_MIN_JOURNAL_BLOCKS)
 		return EXT2_ET_JOURNAL_TOO_SMALL;
 
 	if ((retval = ext2fs_get_mem(fs->blocksize, &jsb)))
@@ -75,10 +75,7 @@ errcode_t ext2fs_create_journal_superblock(ext2_filsys fs,
 	if (fs->super->s_feature_incompat &
 	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 		jsb->s_nr_users = 0;
-		if (fs->blocksize == 1024)
-			jsb->s_first = htonl(3);
-		else
-			jsb->s_first = htonl(2);
+		jsb->s_first = htonl(ext2fs_journal_sb_start(fs->blocksize) + 1);
 	}
 
 	*ret_jsb = (char *) jsb;
@@ -428,6 +425,13 @@ int ext2fs_default_journal_size(__u64 num_blocks)
 	return 32768;
 }
 
+int ext2fs_journal_sb_start(int blocksize)
+{
+	if (blocksize == EXT2_MIN_BLOCK_SIZE)
+		return 2;
+	return 1;
+}
+
 /*
  * This function adds a journal device to a filesystem
  */
@@ -435,7 +439,7 @@ errcode_t ext2fs_add_journal_device(ext2_filsys fs, ext2_filsys journal_dev)
 {
 	struct stat	st;
 	errcode_t	retval;
-	char		buf[1024];
+	char		buf[SUPERBLOCK_SIZE];
 	journal_superblock_t	*jsb;
 	int		start;
 	__u32		i, nr_users;
@@ -448,10 +452,9 @@ errcode_t ext2fs_add_journal_device(ext2_filsys fs, ext2_filsys journal_dev)
 		return EXT2_ET_JOURNAL_NOT_BLOCK; /* Must be a block device */
 
 	/* Get the journal superblock */
-	start = 1;
-	if (journal_dev->blocksize == 1024)
-		start++;
-	if ((retval = io_channel_read_blk64(journal_dev->io, start, -1024,
+	start = ext2fs_journal_sb_start(journal_dev->blocksize);
+	if ((retval = io_channel_read_blk64(journal_dev->io, start,
+					    -SUPERBLOCK_SIZE,
 					    buf)))
 		return retval;
 
@@ -477,7 +480,8 @@ errcode_t ext2fs_add_journal_device(ext2_filsys fs, ext2_filsys journal_dev)
 	}
 
 	/* Writeback the journal superblock */
-	if ((retval = io_channel_write_blk64(journal_dev->io, start, -1024, buf)))
+	if ((retval = io_channel_write_blk64(journal_dev->io, start,
+					    -SUPERBLOCK_SIZE, buf)))
 		return retval;
 
 	fs->super->s_journal_inum = 0;
@@ -630,7 +634,7 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
-	retval = ext2fs_add_journal_inode(fs, 1024, 0);
+	retval = ext2fs_add_journal_inode(fs, JFS_MIN_JOURNAL_BLOCKS, 0);
 	if (retval) {
 		com_err(argv[0], retval, "while adding journal to %s",
 			device_name);
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index ad0b05f..ff50f37 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -182,7 +182,7 @@ static int remove_journal_device(ext2_filsys fs)
 {
 	char		*journal_path;
 	ext2_filsys	jfs;
-	char		buf[1024];
+	char		buf[SUPERBLOCK_SIZE];
 	journal_superblock_t	*jsb;
 	int		i, nr_users;
 	errcode_t	retval;
@@ -225,7 +225,7 @@ static int remove_journal_device(ext2_filsys fs)
 	}
 
 	/* Get the journal superblock */
-	if ((retval = io_channel_read_blk64(jfs->io, 1, -1024, buf))) {
+	if ((retval = io_channel_read_blk64(jfs->io, 1, -SUPERBLOCK_SIZE, buf))) {
 		com_err(program_name, retval, "%s",
 			_("while reading journal superblock"));
 		goto no_valid_journal;
@@ -256,7 +256,7 @@ static int remove_journal_device(ext2_filsys fs)
 	jsb->s_nr_users = htonl(nr_users);
 
 	/* Write back the journal superblock */
-	if ((retval = io_channel_write_blk64(jfs->io, 1, -1024, buf))) {
+	if ((retval = io_channel_write_blk64(jfs->io, 1, -SUPERBLOCK_SIZE, buf))) {
 		com_err(program_name, retval,
 			"while writing journal superblock.");
 		goto no_valid_journal;
-- 
2.0.1

[PATCH 2/4 v3] tune2fs: remove_journal_device(): use the correct block to find jsb

[Azat Khuzhin]

Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 misc/tune2fs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index ff50f37..1df655a 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -188,6 +188,7 @@ static int remove_journal_device(ext2_filsys fs)
 	errcode_t	retval;
 	int		commit_remove_journal = 0;
 	io_manager	io_ptr;
+	int start;
 
 	if (f_flag)
 		commit_remove_journal = 1; /* force removal even if error */
@@ -224,8 +225,10 @@ static int remove_journal_device(ext2_filsys fs)
 		goto no_valid_journal;
 	}
 
+	start = ext2fs_journal_sb_start(fs->blocksize);
 	/* Get the journal superblock */
-	if ((retval = io_channel_read_blk64(jfs->io, 1, -SUPERBLOCK_SIZE, buf))) {
+	if ((retval = io_channel_read_blk64(jfs->io, start,
+	    -SUPERBLOCK_SIZE, buf))) {
 		com_err(program_name, retval, "%s",
 			_("while reading journal superblock"));
 		goto no_valid_journal;
@@ -256,7 +259,8 @@ static int remove_journal_device(ext2_filsys fs)
 	jsb->s_nr_users = htonl(nr_users);
 
 	/* Write back the journal superblock */
-	if ((retval = io_channel_write_blk64(jfs->io, 1, -SUPERBLOCK_SIZE, buf))) {
+	if ((retval = io_channel_write_blk64(jfs->io, start,
+	    -SUPERBLOCK_SIZE, buf))) {
 		com_err(program_name, retval,
 			"while writing journal superblock.");
 		goto no_valid_journal;
-- 
2.0.1

[PATCH 3/4 v3] tune2fs: update journal super block when changing UUID for fs.

[Azat Khuzhin]

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@gmail.com>
Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.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

[PATCH 4/4 v3] tune2fs: update journal users while updating fs UUID (with external journal)

[Azat Khuzhin]

When we have fs with external journal device, and updating it's UUID, we
should update UUID in users list for that external journal device.

Before:
$ tune2fs -U clear /tmp/dev
tune2fs 1.42.10 (18-May-2014)
$ dumpe2fs /tmp/dev | fgrep UUID
dumpe2fs 1.42.10 (18-May-2014)
Filesystem UUID:          <none>
Journal UUID:             da1f2ed0-60f6-aaaa-92fd-738701418523
$ dumpe2fs /tmp/journal | fgrep users -A10
dumpe2fs 1.42.10 (18-May-2014)
Journal number of users:  2
Journal users:            0707762d-638e-4bc6-944e-ae8ee7a3359e
                          0ad849df-1041-4f0a-b1c1-2f949d6a1e37

After:
$ sudo tune2fs -U clear /tmp/dev
tune2fs 1.43-WIP (18-May-2014)
$ dumpe2fs /tmp/dev | fgrep UUID
dumpe2fs 1.42.10 (18-May-2014)
Filesystem UUID:          <none>
Journal UUID:             da1f2ed0-60f6-aaaa-92fd-738701418523
$ dumpe2fs /tmp/journal | fgrep users -A10
dumpe2fs 1.42.10 (18-May-2014)
Journal number of users:  2
Journal users:            0707762d-638e-4bc6-944e-ae8ee7a3359e
                          00000000-0000-0000-0000-000000000000

Also add some consts to avoid *magic numbers*:
- UUID_STR_SIZE
- UUID_SIZE
- JFS_USERS_MAX
- JFS_USERS_SIZE

Proposed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
---
 lib/ext2fs/ext2fs.h     |  2 ++
 lib/ext2fs/kernel-jbd.h |  6 +++-
 misc/tune2fs.c          | 90 +++++++++++++++++++++++++++++++++++++++++++++----
 misc/uuidd.c            |  3 +-
 4 files changed, 93 insertions(+), 8 deletions(-)

diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index ab57534..d3a34d5 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -39,6 +39,8 @@ extern "C" {
 #define SUPERBLOCK_OFFSET	1024
 #define SUPERBLOCK_SIZE		1024
 
+#define UUID_STR_SIZE 37
+
 /*
  * The last ext2fs revision level that this version of the library is
  * able to support.
diff --git a/lib/ext2fs/kernel-jbd.h b/lib/ext2fs/kernel-jbd.h
index 059bf8f..2baae73 100644
--- a/lib/ext2fs/kernel-jbd.h
+++ b/lib/ext2fs/kernel-jbd.h
@@ -164,6 +164,9 @@ typedef struct journal_revoke_header_s
 #define JFS_FLAG_LAST_TAG	8	/* last tag in this descriptor block */
 
 
+#define UUID_SIZE 16
+#define JFS_USERS_MAX 48
+#define JFS_USERS_SIZE (UUID_SIZE * JFS_USERS_MAX)
 /*
  * The journal superblock.  All fields are in big-endian byte order.
  */
@@ -208,7 +211,8 @@ typedef struct journal_superblock_s
 	__u32	s_padding[44];
 
 /* 0x0100 */
-	__u8	s_users[16*48];		/* ids of all fs'es sharing the log */
+	__u8	s_users[JFS_USERS_SIZE];		/* ids of all fs'es sharing the log */
+
 /* 0x0400 */
 } journal_superblock_t;
 
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 74e57ae..0c1feb1 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -207,6 +207,18 @@ static int get_journal_sb(ext2_filsys jfs, char buf[SUPERBLOCK_SIZE])
 	return 0;
 }
 
+static void *
+journal_user(char uuid[UUID_SIZE], char s_users[JFS_USERS_SIZE], int nr_users)
+{
+	int i;
+	for (i = 0; i < nr_users; i++) {
+		if (memcmp(uuid, &s_users[i * UUID_SIZE], UUID_SIZE) == 0)
+			return &s_users[i * UUID_SIZE];
+	}
+
+	return NULL;
+}
+
 /*
  * Remove an external journal from the filesystem
  */
@@ -261,11 +273,8 @@ static int remove_journal_device(ext2_filsys fs)
 	jsb = (journal_superblock_t *) buf;
 	/* Find the filesystem UUID */
 	nr_users = ntohl(jsb->s_nr_users);
-	for (i = 0; i < nr_users; i++) {
-		if (memcmp(fs->super->s_uuid, &jsb->s_users[i * 16], 16) == 0)
-			break;
-	}
-	if (i >= nr_users) {
+
+	if (!journal_user(fs->super->s_uuid, jsb->s_users, nr_users)) {
 		fputs(_("Filesystem's UUID not found on journal device.\n"),
 		      stderr);
 		commit_remove_journal = 1;
@@ -1915,6 +1924,68 @@ static int tune2fs_setup_tdb(const char *name, io_manager *io_ptr)
 	return retval;
 }
 
+int
+fs_update_journal_user(struct ext2_super_block *sb, char old_uuid[UUID_SIZE])
+{
+	int retval, nr_users, start;
+	journal_superblock_t *jsb;
+	ext2_filsys jfs;
+	char *j_uuid, *journal_path;
+	char uuid[UUID_STR_SIZE];
+	char buf[SUPERBLOCK_SIZE];
+
+	if (!(sb->s_feature_compat & EXT3_FEATURE_COMPAT_HAS_JOURNAL) ||
+		uuid_is_null(sb->s_journal_uuid))
+		return 0;
+
+	uuid_unparse(sb->s_journal_uuid, uuid);
+	journal_path = blkid_get_devname(NULL, "UUID", uuid);
+	if (!journal_path)
+		return 0;
+
+	retval = ext2fs_open2(journal_path, io_options,
+			      EXT2_FLAG_JOURNAL_DEV_OK | EXT2_FLAG_RW,
+			      0, 0, unix_io_manager, &jfs);
+	if (retval) {
+		com_err(program_name, retval,
+			_("while trying to open %s"),
+			journal_path);
+		return retval;
+	}
+
+	if ((retval = get_journal_sb(jfs, buf))) {
+		if (retval == EXT2_ET_UNSUPP_FEATURE)
+			fprintf(stderr, _("%s is not a journal device.\n"),
+				journal_path);
+		return retval;
+	}
+
+	jsb = (journal_superblock_t *) buf;
+	/* Find the filesystem UUID */
+	nr_users = ntohl(jsb->s_nr_users);
+
+	if (!(j_uuid = journal_user(old_uuid, jsb->s_users, nr_users))) {
+		fputs(_("Filesystem's UUID not found on journal device.\n"),
+		      stderr);
+		return EXT2_ET_LOAD_EXT_JOURNAL;
+	}
+
+	memcpy(j_uuid, sb->s_uuid, UUID_SIZE);
+
+	start = ext2fs_journal_sb_start(jfs->blocksize);
+	/* Write back the journal superblock */
+	if ((retval = io_channel_write_blk64(jfs->io, start,
+	    -SUPERBLOCK_SIZE, buf))) {
+		com_err(program_name, retval,
+			"while writing journal superblock.");
+		return retval;
+	}
+
+	ext2fs_close(jfs);
+
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	errcode_t retval;
@@ -2203,6 +2274,7 @@ retry_open:
 		int set_csum = 0;
 		dgrp_t i;
 		char buf[SUPERBLOCK_SIZE];
+		char old_uuid[UUID_SIZE];
 
 		if (sb->s_feature_ro_compat &
 		    EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
@@ -2230,6 +2302,8 @@ retry_open:
 			if (i >= fs->group_desc_count)
 				set_csum = 1;
 		}
+
+		memcpy(old_uuid, sb->s_uuid, UUID_SIZE);
 		if ((strcasecmp(new_UUID, "null") == 0) ||
 		    (strcasecmp(new_UUID, "clear") == 0)) {
 			uuid_clear(sb->s_uuid);
@@ -2264,9 +2338,13 @@ retry_open:
 				goto closefs;
 		} else if (rc != EXT2_ET_UNSUPP_FEATURE)
 			goto closefs;
-		else
+		else {
 			rc = 0; /** Reset rc to avoid ext2fs_mmp_stop() */
 
+			if ((rc = fs_update_journal_user(sb, old_uuid)))
+				goto closefs;
+		}
+
 		ext2fs_mark_super_dirty(fs);
 	}
 	if (I_flag) {
diff --git a/misc/uuidd.c b/misc/uuidd.c
index 5a53138..02ca6be 100644
--- a/misc/uuidd.c
+++ b/misc/uuidd.c
@@ -36,6 +36,7 @@ extern int optind;
 #include "uuid/uuid.h"
 #include "uuid/uuidd.h"
 #include "nls-enable.h"
+#include "ext2fs/ext2fs.h"
 
 #ifdef __GNUC__
 #define CODE_ATTR(x) __attribute__(x)
@@ -236,7 +237,7 @@ static void server_loop(const char *socket_path, const char *pidfile_path,
 	uuid_t			uu;
 	mode_t			save_umask;
 	char			reply_buf[1024], *cp;
-	char			op, str[37];
+	char			op, str[UUID_STR_SIZE];
 	int			i, s, ns, len, num;
 	int			fd_pidfile, ret;
 
-- 
2.0.1

Re: [PATCH 0/4 v3] e2fsprogs journal fixes (UUID and 1k block size issue)

[Andreas Dilger]

[-- Attachment #1: Type: text/plain, Size: 469 bytes --]

On Jul 28, 2014, at 1:43 AM, Azat Khuzhin <a3at.mail@gmail.com> wrote:
> Here is patchset with some fixes for journal code in e2fsprogs.
> I've removed first patch from previous version "lib: add EXT2_ prefix for
> SUPERBLOCK_{OFFSET,SIZE}", and rebase other patches on top of the maint branch.

Any reason you removed that first patch?  I thought the only negative
feedback was because you renamed GFS_SUPERBLOCK_SIZE accidentally?

Cheers, Andreas






[-- Attachment #2: Message signed with OpenPGP using GPGMail --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH 0/4 v3] e2fsprogs journal fixes (UUID and 1k block size issue)

[Theodore Ts'o]

On Mon, Jul 28, 2014 at 02:07:44PM -0600, Andreas Dilger wrote:
> On Jul 28, 2014, at 1:43 AM, Azat Khuzhin <a3at.mail@gmail.com> wrote:
> > Here is patchset with some fixes for journal code in e2fsprogs.
> > I've removed first patch from previous version "lib: add EXT2_ prefix for
> > SUPERBLOCK_{OFFSET,SIZE}", and rebase other patches on top of the maint branch.
> 
> Any reason you removed that first patch?  I thought the only negative
> feedback was because you renamed GFS_SUPERBLOCK_SIZE accidentally?

I don't want to make big changes like that until after we've released
1.43.0.

						- Ted

Re: [PATCH 0/4 v3] e2fsprogs journal fixes (UUID and 1k block size issue)

[Theodore Ts'o]

On Mon, Jul 28, 2014 at 11:43:21AM +0400, Azat Khuzhin wrote:
> 
> Azat Khuzhin (4):
>   journal: use consts instead of 1024 and add helper for journal with 1k
>     blocksize
>   tune2fs: remove_journal_device(): use the correct block to find jsb
>   tune2fs: update journal super block when changing UUID for fs.
>   tune2fs: update journal users while updating fs UUID (with external
>     journal)

Thanks for working on this!  I've applied these patches to the maint branch.

       	   	      	     	  - Ted

Re: [PATCH 3/4 v3] tune2fs: update journal super block when changing UUID for fs.

[Eric Sandeen]

On 7/28/14, 2:43 AM, Azat Khuzhin wrote:
> 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@gmail.com>
> Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
> Reviewed-by: Andreas Dilger <adilger@dilger.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);

This is already committed (which is why Coverity whined about it), but:
removing this assignment causes an uninitialized use of "start" later
in this function:

        /* Write back the journal superblock */
        if ((retval = io_channel_write_blk64(jfs->io, start,
            -SUPERBLOCK_SIZE, buf)))

-Eric

Re: [PATCH 3/4 v3] tune2fs: update journal super block when changing UUID for fs.

[Azat Khuzhin]

On Thu, Jul 31, 2014 at 10:16:44AM -0500, Eric Sandeen wrote:
> On 7/28/14, 2:43 AM, Azat Khuzhin wrote:
> > 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@gmail.com>
> > Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
> > Reviewed-by: Andreas Dilger <adilger@dilger.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);
> 
> This is already committed (which is why Coverity whined about it), but:
> removing this assignment causes an uninitialized use of "start" later
> in this function:
> 
>         /* Write back the journal superblock */
>         if ((retval = io_channel_write_blk64(jfs->io, start,
>             -SUPERBLOCK_SIZE, buf)))
> 
> -Eric

Hi Eric,

Thanks for catching this.
Patch in attachment must fix this issue.

I maked with -Wall to catch more bugs like this.
And there is one more note:
expected ‘char *’ but argument is of type ‘__u8 *’
journal_user()
I will send a patch later.


From 903f251e1ebce3d666a8b2af04b812d4f6751056 Mon Sep 17 00:00:00 2001
From: Azat Khuzhin <a3at.mail@gmail.com>
Date: Thu, 31 Jul 2014 19:26:16 +0400
Subject: [PATCH] tune2fs: initialize start block in remove_journal_device()

---
 misc/tune2fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 0c1feb1..044daaf 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -181,7 +181,6 @@ static __u32 clear_ok_features[3] = {
 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 &
@@ -286,6 +285,7 @@ static int remove_journal_device(ext2_filsys fs)
 	jsb->s_nr_users = htonl(nr_users);
 
 	/* Write back the journal superblock */
+	start = ext2fs_journal_sb_start(jfs->blocksize);
 	if ((retval = io_channel_write_blk64(jfs->io, start,
 	    -SUPERBLOCK_SIZE, buf))) {
 		com_err(program_name, retval,
-- 
2.0.1

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[PATCH] tune2fs: fix uninitialized variable in remove_journal_device

[Theodore Ts'o]

This bug was introduced by commit 7dfefaf413bbd ("tune2fs: update
journal super block when changing UUID for fs").

Fixes-Coverity-Bug: 1229243

Reported-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 misc/tune2fs.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 0c1feb1..639809d 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -232,7 +232,6 @@ static int remove_journal_device(ext2_filsys fs)
 	errcode_t	retval;
 	int		commit_remove_journal = 0;
 	io_manager	io_ptr;
-	int start;
 
 	if (f_flag)
 		commit_remove_journal = 1; /* force removal even if error */
@@ -286,8 +285,9 @@ static int remove_journal_device(ext2_filsys fs)
 	jsb->s_nr_users = htonl(nr_users);
 
 	/* Write back the journal superblock */
-	if ((retval = io_channel_write_blk64(jfs->io, start,
-	    -SUPERBLOCK_SIZE, buf))) {
+	if ((retval = io_channel_write_blk64(jfs->io,
+				ext2fs_journal_sb_start(fs->blocksize),
+				-SUPERBLOCK_SIZE, buf))) {
 		com_err(program_name, retval,
 			"while writing journal superblock.");
 		goto no_valid_journal;
-- 
2.0.0

Re: [PATCH] tune2fs: fix uninitialized variable in remove_journal_device

[Andreas Dilger]

On Jul 31, 2014, at 17:53, Theodore Ts'o <tytso@mit.edu> wrote:
> 
> This bug was introduced by commit 7dfefaf413bbd ("tune2fs: update
> journal super block when changing UUID for fs").
> 
> Fixes-Coverity-Bug: 1229243
> 
> Reported-by: Eric Sandeen <sandeen@redhat.com>
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---
> misc/tune2fs.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/misc/tune2fs.c b/misc/tune2fs.c
> index 0c1feb1..639809d 100644
> --- a/misc/tune2fs.c
> +++ b/misc/tune2fs.c
> @@ -232,7 +232,6 @@ static int remove_journal_device(ext2_filsys fs)
>    errcode_t    retval;
>    int        commit_remove_journal = 0;
>    io_manager    io_ptr;
> -    int start;
> 
>    if (f_flag)
>        commit_remove_journal = 1; /* force removal even if error */
> @@ -286,8 +285,9 @@ static int remove_journal_device(ext2_filsys fs)
>    jsb->s_nr_users = htonl(nr_users);
> 
>    /* Write back the journal superblock */
> -    if ((retval = io_channel_write_blk64(jfs->io, start,
> -        -SUPERBLOCK_SIZE, buf))) {
> +    if ((retval = io_channel_write_blk64(jfs->io,
> +                ext2fs_journal_sb_start(fs->blocksize),
> +                -SUPERBLOCK_SIZE, buf))) {

Better to also remove assignment in conditional check. 

Cheers, Andreas

>        com_err(program_name, retval,
>            "while writing journal superblock.");
>        goto no_valid_journal;
> -- 
> 2.0.0
> 
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> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 3/4 v3] tune2fs: update journal super block when changing UUID for fs.

[Andreas Dilger]

I already fixed that in my recent patch:

http://marc.info/?l=linux-ext4&m=140667665421773&w=2

Cheers, Andreas

> On Jul 31, 2014, at 17:45, Azat Khuzhin <a3at.mail@gmail.com> wrote:
> 
>> On Thu, Jul 31, 2014 at 10:16:44AM -0500, Eric Sandeen wrote:
>>> On 7/28/14, 2:43 AM, Azat Khuzhin wrote:
>>> 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@gmail.com>
>>> Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
>>> Reviewed-by: Andreas Dilger <adilger@dilger.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);
>> 
>> This is already committed (which is why Coverity whined about it), but:
>> removing this assignment causes an uninitialized use of "start" later
>> in this function:
>> 
>>        /* Write back the journal superblock */
>>        if ((retval = io_channel_write_blk64(jfs->io, start,
>>            -SUPERBLOCK_SIZE, buf)))
>> 
>> -Eric
> 
> Hi Eric,
> 
> Thanks for catching this.
> Patch in attachment must fix this issue.
> 
> I maked with -Wall to catch more bugs like this.
> And there is one more note:
> expected ‘char *’ but argument is of type ‘__u8 *’
> journal_user()
> I will send a patch later.
> 
> 
> From 903f251e1ebce3d666a8b2af04b812d4f6751056 Mon Sep 17 00:00:00 2001
> From: Azat Khuzhin <a3at.mail@gmail.com>
> Date: Thu, 31 Jul 2014 19:26:16 +0400
> Subject: [PATCH] tune2fs: initialize start block in remove_journal_device()
> 
> ---
> misc/tune2fs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/misc/tune2fs.c b/misc/tune2fs.c
> index 0c1feb1..044daaf 100644
> --- a/misc/tune2fs.c
> +++ b/misc/tune2fs.c
> @@ -181,7 +181,6 @@ static __u32 clear_ok_features[3] = {
> 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 &
> @@ -286,6 +285,7 @@ static int remove_journal_device(ext2_filsys fs)
>    jsb->s_nr_users = htonl(nr_users);
> 
>    /* Write back the journal superblock */
> +    start = ext2fs_journal_sb_start(jfs->blocksize);
>    if ((retval = io_channel_write_blk64(jfs->io, start,
>        -SUPERBLOCK_SIZE, buf))) {
>        com_err(program_name, retval,
> -- 
> 2.0.1
> 
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Re: [PATCH] tune2fs: fix uninitialized variable in remove_journal_device

[Theodore Ts'o]

On Fri, Aug 01, 2014 at 08:38:30AM +0200, Andreas Dilger wrote:
> >    /* Write back the journal superblock */
> > -    if ((retval = io_channel_write_blk64(jfs->io, start,
> > -        -SUPERBLOCK_SIZE, buf))) {
> > +    if ((retval = io_channel_write_blk64(jfs->io,
> > +                ext2fs_journal_sb_start(fs->blocksize),
> > +                -SUPERBLOCK_SIZE, buf))) {
> 
> Better to also remove assignment in conditional check. 

Good point, done.

						- Ted