On Thu, 21 Feb 2013, Lukáš Czerner wrote: > Date: Thu, 21 Feb 2013 13:50:03 +0100 (CET) > From: Lukáš Czerner <lczerner@xxxxxxxxxx> > To: Lukáš Czerner <lczerner@xxxxxxxxxx> > Cc: Zheng Liu <gnehzuil.liu@xxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx, > Theodore Ts'o <tytso@xxxxxxx> > Subject: Re: [PATCH] ext4: fix overhead calculation in bigalloc filesystem > (Re: ... ) > > On Thu, 21 Feb 2013, Lukáš Czerner wrote: > > ..snip... > > > > > Hi Zheng, > > > > thanks for the review. I know about the other issues and I'm trying > > to resolve those as well. Right now I have a patch which includes > > the changes ext4_calculate_overhead() you've described below and more, > > but even with this I still see some problems remaining. > > > > Hopefully will send another patch soon. > > > > Thanks! > > -Lukas > > > > > > > > Subject: [PATCH] ext4: fix overhead calculation in bigalloc filesystem > > > > > > From: Zheng Liu <wenqing.lz@xxxxxxxxxx> > > > > > > ext4_calculate_overhead() should compute the overhead and stash it in > > > sbi->s_overhead. But we miss use EXT4_B2C() to calculate the number of > > > clusters before first_data_block and the number of journal blocks. This > > > commit use EXT4_NUM_B2C() instead of EXT4_B2C() to calculate the > > > overhead. > > > > > > Signed-off-by: Zheng Liu <wenqing.lz@xxxxxxxxxx> > > > Cc: "Theodore Ts'o" <tytso@xxxxxxx> > > > --- > > > fs/ext4/super.c | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > > > index 3d4fb81..6165558 100644 > > > --- a/fs/ext4/super.c > > > +++ b/fs/ext4/super.c > > > @@ -3219,7 +3219,7 @@ int ext4_calculate_overhead(struct super_block *sb) > > > /* > > > * All of the blocks before first_data_block are overhead > > > */ > > > - overhead = EXT4_B2C(sbi, le32_to_cpu(es->s_first_data_block)); > > > + overhead = EXT4_NUM_B2C(sbi, le32_to_cpu(es->s_first_data_block)); > > ...except this. I do not think this is right because we do not skip > the first cluster right ? We're still using it, but we can never use > the block before es->s_first_data_block. Please correct me if I am > wrong. moreover we do not allow bigalloc file system with block size < 4k. > > > > > > > > /* > > > * Add the overhead found in each block group > > > @@ -3235,7 +3235,7 @@ int ext4_calculate_overhead(struct super_block *sb) > > > } > > > /* Add the journal blocks as well */ > > > if (sbi->s_journal) > > > - overhead += EXT4_B2C(sbi, sbi->s_journal->j_maxlen); > > > + overhead += EXT4_NUM_B2C(sbi, sbi->s_journal->j_maxlen); > > This I already have in my patch I'm testing right now. And as I said > there are other places where we misuse EXT4_B2C(). > > -Lukas > > > > > > > sbi->s_overhead = overhead; > > > smp_wmb(); > > > > > >
