On Mon, Jun 02, 2008 at 12:14:33PM +0530, Aneesh Kumar K.V wrote:
> On Sun, Jun 01, 2008 at 04:35:55PM -0700, Mingming Cao wrote:
> > ext4: delalloc ENOSPC handling core
> >
> > From: Mingming cao <cmm@xxxxxxxxxx>
> >
> > Core part of delaloc ENOSPC (block reservation.)
> > data/meta blocks are reserved on write_begin(), and per-inode reserved counters
> > are updated after block allocation.
> >
> > Signed-off-by: Mingming cao <cmm@xxxxxxxxxx>
> >
> > ---
> > fs/ext4/inode.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 66 insertions(+), 3 deletions(-)
> >
> > Index: linux-2.6.26-rc4/fs/ext4/inode.c
> > ===================================================================
> > --- linux-2.6.26-rc4.orig/fs/ext4/inode.c 2008-06-01 14:26:13.000000000 -0700
> > +++ linux-2.6.26-rc4/fs/ext4/inode.c 2008-06-01 15:04:06.000000000 -0700
> > @@ -38,6 +38,7 @@
> > #include "ext4_jbd2.h"
> > #include "xattr.h"
> > #include "acl.h"
> > +#include "ext4_extents.h"
> >
> > static void ext4_invalidatepage(struct page *page, unsigned long offset);
> >
> > @@ -1410,6 +1411,61 @@ static int ext4_journalled_write_end(str
> > return ret ? ret : copied;
> > }
> >
> > +static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
> > +{
> > + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> > + unsigned long md_needed, mdblocks, total = 0;
> > +
> > + /*
> > + * calculate the amount of metadata blocks to reserve
>
> recalculate the amount of metadata blocks to reserve.
>
>
>
>
> > + * in order to allocate nrblocks
> > + * worse case is one extent per block
> > + */
> > + total = EXT4_I(inode)->i_reserved_data_blocks + nrblocks;
> > + mdblocks = ext4_ext_calc_metadata_amount(inode, total);
> > + BUG_ON(mdblocks < EXT4_I(inode)->i_reserved_meta_blocks);
> > +
> > + md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
> > + total = md_needed + nrblocks;
> > +
> > + if (ext4_has_free_blocks(sbi, total) < total)
> > + return -ENOSPC;
> > +
> > + /* reduce fs free blocks counter */
> > + percpu_counter_sub(&sbi->s_freeblocks_counter, total);
> > +
> > + EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
> > + EXT4_I(inode)->i_reserved_meta_blocks += md_needed;
>
> Better written as
> EXT4_I(inode)->i_reserved_meta_blocks += mdblocks;
>
>
EXT4_I(inode)->i_reserved_meta_blocks = mdblocks;
-aneesh
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