在 2008-08-13三的 15:49 +0530，Aneesh Kumar K.V写道：
> On Tue, Aug 12, 2008 at 09:25:54AM -0700, Mingming Cao wrote:
> > +int ext4_meta_trans_blocks(struct inode* inode, int nrblocks, int idxblocks)
> > +{
> > + int groups, gdpblocks;
> > + int ret = 0;
> > +
> > + groups = nrblocks + idxblocks;
> > + gdpblocks = groups;
> > + if (groups > EXT4_SB(inode->i_sb)->s_groups_count)
> > + groups = EXT4_SB(inode->i_sb)->s_groups_count;
> > + if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
> > + gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
>
>
> I guess we should pass chunk to ext4_meta_trans_blocks also.
> if (chunk) we should update only one group descriptor and one
> bitmap block ie,
> if(chunk)
> groups = 1 + idxblocks;
>
>
Agree. will update the patch to do that
Mingming
>
> > +
> > + /* bitmaps and block group descriptor blocks */
> > + ret += groups + gdpblocks;
> > +
> > + ret += idxblocks;
> > +
> > + /* journalled mode, include buffer to modify data blocks */
> > + if (ext4_should_journal_data(inode))
> > + ret += nrblocks;
> > +
> > + /* Blocks for super block, inode, quota and xattr blocks */
> > + ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
> > +
> > + return ret;
> > +}
> > +
> ....
> ...
>
> > +static int ext4_writeblocks_trans_credits_old(struct inode *inode, int nrblocks,
> > + int chunk)
> > {
> > - int bpp = ext4_journal_blocks_per_page(inode);
> > - int indirects = (EXT4_NDIR_BLOCKS % bpp) ? 5 : 3;
> > + int indirects;
> > int ret;
> >
> > - if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
> > - return ext4_ext_writepage_trans_blocks(inode, bpp);
> > -
> > - if (ext4_should_journal_data(inode))
> > - ret = 3 * (bpp + indirects) + 2;
> > - else
> > - ret = 2 * (bpp + indirects) + 2;
> > + /*
> > + * How many index blocks need to touch to modify nrblocks?
> > + * The "Chunk" flag indicating whether the nrblocks is
> > + * physically contigous on disk
> > + *
> > + * For Direct IO and fallocate, they calls get_block to allocate
> > + * one single extent at a time, so they could set the "Chunk" flag
> > + */
> > + indirects = ext4_indirect_trans_blocks(inode, nrblocks, chunk);
> >
> > -#ifdef CONFIG_QUOTA
> > - /* We know that structure was already allocated during DQUOT_INIT so
> > - * we will be updating only the data blocks + inodes */
> > - ret += 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
> > -#endif
> > + /* Account for block group bitmaps and block groups
> > + * descriptors.Worse case, the nrblocks+indirects blocks spread
> > + * over different block groups
> > + */
> > + ret = ext4_meta_trans_blocks(inode, nrblocks, indirects);
> >
> > return ret;
> > }
>
> -aneesh
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