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Date: Wed, 21 Oct 2009 15:48:01 -0700
From: Mingming <cmm@...ibm.com>
To: Curt Wohlgemuth <curtw@...gle.com>
Cc: tytso@....edu, ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 2/4 v2] avoid perform unwritten convertion for direct
IO over non fallocated space
On Tue, 2009-10-20 at 08:03 -0700, Curt Wohlgemuth wrote:
> Hi Mingming:
>
> On Thu, Oct 8, 2009 at 6:13 PM, Mingming <cmm@...ibm.com> wrote:
> > ext4: avoid perform unwritten convertion for direct IO over non fallocated space
> >
> > When direct IO complete, without this patch, it always check and convert
> > the range covered by the completed IO to be written. This is unnecessary
> > if the range doesn't has any preallocated area or holes. This patch add
> > a state flag to alart direct IO code to only run the convertion when
> > there is unwritten extents being covered in this IO.
> >
> > Signed-off-by: Mingming Cao <cmm@...ibm.com>
> > ---
> > fs/ext4/ext4.h | 1 +
> > fs/ext4/extents.c | 22 +++++++++++++++++-----
> > fs/ext4/inode.c | 4 +++-
> > 3 files changed, 21 insertions(+), 6 deletions(-)
> >
> > Index: linux-2.6.31-rc4/fs/ext4/ext4.h
> > ===================================================================
> > --- linux-2.6.31-rc4.orig/fs/ext4/ext4.h
> > +++ linux-2.6.31-rc4/fs/ext4/ext4.h
> > @@ -299,6 +299,7 @@ static inline __u32 ext4_mask_flags(umod
> > #define EXT4_STATE_XATTR 0x00000004 /* has in-inode xattrs */
> > #define EXT4_STATE_NO_EXPAND 0x00000008 /* No space for expansion */
> > #define EXT4_STATE_DA_ALLOC_CLOSE 0x00000010 /* Alloc DA blks on close */
> > +#define EXT4_STATE_DIO_UNWRITTEN 0x00000020 /* need convert on dio done*/
>
> You'll need to change this value, since EXT4_STATE_EXT_MIGRATE has
> already been assigned 0x20.
>
> Thanks,
> Curt
>
thanks, The patch was originally made on a older kernel, the following
patch is rebased on the new kernel
> >
> > /* Used to pass group descriptor data when online resize is done */
> > struct ext4_new_group_input {
> > Index: linux-2.6.31-rc4/fs/ext4/extents.c
> > ===================================================================
> > --- linux-2.6.31-rc4.orig/fs/ext4/extents.c
> > +++ linux-2.6.31-rc4/fs/ext4/extents.c
> > @@ -3029,12 +3029,18 @@ ext4_ext_handle_uninitialized_extents(ha
> > ret = ext4_split_unwritten_extents(handle,
> > inode, path, iblock,
> > max_blocks, flags);
> > - /* flag the io_end struct that we need convert when IO done */
> > + /*
> > + * Flag the inode(non aio case) or end_io struct (aio case)
> > + * that this IO needs to convertion to written when IO is
> > + * completed
> > + */
> > if (io)
> > io->flag = DIO_AIO_UNWRITTEN;
> > + else
> > + EXT4_I(inode)->i_state |= EXT4_STATE_DIO_UNWRITTEN;
> > goto out;
> > }
> > - /* DIO end_io complete, convert the filled extent to written */
> > + /* async DIO end_io complete, convert the filled extent to written */
> > if (flags == EXT4_GET_BLOCKS_DIO_CONVERT_EXT) {
> > ret = ext4_convert_unwritten_extents_dio(handle, inode,
> > path);
> > @@ -3276,10 +3282,16 @@ int ext4_ext_get_blocks(handle_t *handle
> > * To avoid unecessary convertion for every aio dio rewrite
> > * to the mid of file, here we flag the IO that is really
> > * need the convertion.
> > - *
> > + * For non asycn direct IO case, flag the inode state
> > + * that we need to perform convertion when IO is done.
> > */
> > - if (io && flags == EXT4_GET_BLOCKS_DIO_CREATE_EXT)
> > - io->flag = DIO_AIO_UNWRITTEN;
> > + if (flags == EXT4_GET_BLOCKS_DIO_CREATE_EXT) {
> > + if (io)
> > + io->flag = DIO_AIO_UNWRITTEN;
> > + else
> > + EXT4_I(inode)->i_state |=
> > + EXT4_STATE_DIO_UNWRITTEN;;
> > + }
> > }
> > err = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
> > if (err) {
> > Index: linux-2.6.31-rc4/fs/ext4/inode.c
> > ===================================================================
> > --- linux-2.6.31-rc4.orig/fs/ext4/inode.c
> > +++ linux-2.6.31-rc4/fs/ext4/inode.c
> > @@ -3693,7 +3693,8 @@ static ssize_t ext4_ext_direct_IO(int rw
> > if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
> > ext4_free_io_end(iocb->private);
> > iocb->private = NULL;
> > - } else if (ret > 0){
> > + } else if (ret > 0 && EXT4_I(inode)->i_state &
> > + EXT4_STATE_DIO_UNWRITTEN){
> > int err;
> > /*
> > * for non AIO case, since the IO is already
> > @@ -3703,6 +3704,7 @@ static ssize_t ext4_ext_direct_IO(int rw
> > offset, ret);
> > if (err < 0)
> > ret = err;
> > + EXT4_I(inode)->i_state &= ~EXT4_STATE_DIO_UNWRITTEN;
> > }
> > return ret;
> > }
> >
> >
> >
> --
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a
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