On Sun, Sep 04, 2011 at 12:28:24PM -0600, Andreas Dilger wrote:
> On 2011-08-31, at 6:36 PM, "Darrick J. Wong" <djwong@xxxxxxxxxx> wrote:
> > Write out checksummed inodes even when writing out a zeroed table.
> >
> > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> > ---
> > misc/mke2fs.c | 37 ++++++++++++++++++++++++++++++-------
> > 1 files changed, 30 insertions(+), 7 deletions(-)
> >
> >
> > diff --git a/misc/mke2fs.c b/misc/mke2fs.c
> > index 2d57d09..bbc0533 100644
> > --- a/misc/mke2fs.c
> > +++ b/misc/mke2fs.c
> > @@ -309,6 +309,8 @@ static void write_inode_tables(ext2_filsys fs, int lazy_flag, int itable_zeroed)
> > dgrp_t i;
> > int num;
> > struct ext2fs_numeric_progress_struct progress;
> > + ext2_ino_t ino;
> > + struct ext2_inode_large inode;
> >
> > ext2fs_numeric_progress_init(fs, &progress,
> > _("Writing inode tables: "),
> > @@ -330,12 +332,32 @@ static void write_inode_tables(ext2_filsys fs, int lazy_flag, int itable_zeroed)
> > ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_ZEROED);
> > ext2fs_group_desc_csum_set(fs, i);
> > }
> > - retval = ext2fs_zero_blocks2(fs, blk, num, &blk, &num);
> > - if (retval) {
> > - fprintf(stderr, _("\nCould not write %d "
> > - "blocks in inode table starting at %llu: %s\n"),
> > - num, blk, error_message(retval));
> > - exit(1);
> > + if (fs->super->s_creator_os == EXT2_OS_LINUX &&
> > + fs->super->s_feature_ro_compat &
> > + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) {
>
> Somehow it doesn't look like this is skipping the zeroing of the inode table
> blocks if lazy itable zeroing is set.
>
> Any measurements on how much this slows down inode table writing (which is
> already the slowest part of mke2fs)?
Quite a lot, actually. Trouble is, if you're going to write zeroes to the
inode table (without using uninit) then I think you need the checksums to
match. Maybe the solution is to modify the kernel/e2fsck to ignore the
checksum if the inode bitmap says the inode isn't in use?
A better solution is to zero the buffer, stuff in all the checksums in the
correct places, and then write the block out.
> > + bzero(&inode, sizeof(inode));
> > + for (ino = fs->super->s_inodes_per_group * i;
> > + ino < fs->super->s_inodes_per_group * (i + 1);
> > + ino++) {
>
> Why recompute "ino" each time through this loop? It should be enough to
> simply initialize it at 1 and then increment it for each inode written.
Agreed.
--D
> > + if (!ino)
> > + continue;
> > + retval = ext2fs_write_inode(fs, ino, &inode);
> > + if (retval) {
> > + com_err("inode_init", retval,
> > + "while writing inode %d\n",
> > + ino);
> > + exit(1);
> > + }
> > + }
> > + } else {
> > + retval = ext2fs_zero_blocks2(fs, blk, num, &blk, &num);
> > + if (retval) {
> > + fprintf(stderr, _("\nCould not write %d "
> > + "blocks in inode table starting "
> > + "at %llu: %s\n"),
> > + num, blk, error_message(retval));
> > + exit(1);
> > + }
> > }
> > if (sync_kludge) {
> > if (sync_kludge == 1)
> > @@ -829,7 +851,8 @@ static __u32 ok_features[3] = {
> > EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE|
> > EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER|
> > EXT4_FEATURE_RO_COMPAT_GDT_CSUM|
> > - EXT4_FEATURE_RO_COMPAT_BIGALLOC
> > + EXT4_FEATURE_RO_COMPAT_BIGALLOC|
> > + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM
> > };
> >
> >
> >
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