Re: [PATCH 1/3 v2] journal: use consts instead of 1024 and add helper for journal with 1k blocksize

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Jul 09, 2014 at 08:54:35AM +0400, Azat Khuzhin wrote:
> On Tue, Jul 08, 2014 at 10:46:56PM -0600, Andreas Dilger wrote:
> > The patch looks good, and you can add:
> > 
> > Reviewed-by: Andreas Dilger <adilger@dilger.ca>
> > 
> > One thing that could probably be fixed if this patch is refreshed,
> > or in a precursor patch is to rename SUPERBLOCK_SIZE to be
> > EXT2_SUPERBLOCK_SIZE since this avoids potential name clashes. 
> 
> I don't have any objections, but this change could break the
> header-compatibily, no? (Since lib/ext2fs/ext2fs.h is public available).

Perhaps something like this?

#define EXT2_SUPERBLOCK_SIZE	1024
#define SUPERBLOCK_SIZE		EXT2_SUPERBLOCK_SIZE

...and we can deprecate the old cpp symbol the next major release?

If anybody prepends EXT2_ to that symbol, please be sure to rename
SUPERBLOCK_OFFSET too.

> Cheers, Azat.
> 
> > 
> > Cheers, Andreas
> > 
> > > On Jul 8, 2014, at 21:56, Azat Khuzhin <a3at.mail@gmail.com> wrote:
> > > 
> > > Use EXT2_MIN_BLOCK_SIZE/JFS_MIN_JOURNAL_BLOCKS 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>
> > > ---
> > > v2: mixxed htonl() (thanks to Andreas Dilger)
> > > 
> > > 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 a7b1150..5780be0 100644
> > > --- a/e2fsck/journal.c
> > > +++ b/e2fsck/journal.c
> > > @@ -443,8 +443,7 @@ 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;
> > > @@ -455,7 +454,7 @@ 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 + EXT2_MIN_BLOCK_SIZE,

I ... think this 1024 looks more like an offset; did you mean SUPERBLOCK_OFFSET
here?

--D

> > >               sizeof(jsuper));
> > >        brelse(bh);
> > > #ifdef WORDS_BIGENDIAN
> > > diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
> > > index 599c972..a759741 100644
> > > --- a/lib/ext2fs/ext2fs.h
> > > +++ b/lib/ext2fs/ext2fs.h
> > > @@ -1498,6 +1498,7 @@ 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 884d9c0..0ad674d 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;
> > > @@ -430,6 +427,13 @@ 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
> > >  */
> > > @@ -437,7 +441,7 @@ 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;
> > > @@ -450,10 +454,9 @@ 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;
> > > 
> > > @@ -479,7 +482,8 @@ 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;
> > > @@ -632,7 +636,7 @@ 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 d95cc3d..0e7caf2 100644
> > > --- a/misc/tune2fs.c
> > > +++ b/misc/tune2fs.c
> > > @@ -187,7 +187,7 @@ 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;
> > > @@ -230,7 +230,7 @@ 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;
> > > @@ -261,7 +261,7 @@ 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;
> > > -- 
> > > 2.0.0
> > > 
> 
> -- 
> Respectfully
> Azat Khuzhin
> --
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