On Thu, Jun 02, 2011 at 09:02:33PM -0400, Christoph Hellwig wrote:
> On Thu, Jun 02, 2011 at 08:54:03PM -0400, Vivek Goyal wrote:
> > Just wondering why ext4 and XFS behavior are different and which is a
> > more appropriate behavior. ext4 does not seem to be waiting for all
> > pending AIO/DIO to finish while XFS does.
>
> They're both wrong. Ext4 completely misses support in fsync or sync
> to catch pending unwrittent extent conversions, and thus fails to obey
> the data integrity guarante. XFS is beeing rather stupid about the
> amount of synchronization it requires. The untested patch below
> should help with avoiding the synchronization if you're purely doing
> overwrites:
Yes this patch helps. I have already laid out the file and doing
overwrites.
I throttled aio-stress in one cgroup to 1 byte/sec and edited another
file from other cgroup and did a "sync" and it completed.
Thanks
Vivek
>
>
> Index: xfs/fs/xfs/linux-2.6/xfs_aops.c
> ===================================================================
> --- xfs.orig/fs/xfs/linux-2.6/xfs_aops.c 2011-06-03 09:54:52.964337556 +0900
> +++ xfs/fs/xfs/linux-2.6/xfs_aops.c 2011-06-03 09:57:06.877674259 +0900
> @@ -270,7 +270,7 @@ xfs_finish_ioend_sync(
> * (vs. incore size).
> */
> STATIC xfs_ioend_t *
> -xfs_alloc_ioend(
> +__xfs_alloc_ioend(
> struct inode *inode,
> unsigned int type)
> {
> @@ -290,7 +290,6 @@ xfs_alloc_ioend(
> ioend->io_inode = inode;
> ioend->io_buffer_head = NULL;
> ioend->io_buffer_tail = NULL;
> - atomic_inc(&XFS_I(ioend->io_inode)->i_iocount);
> ioend->io_offset = 0;
> ioend->io_size = 0;
> ioend->io_iocb = NULL;
> @@ -300,6 +299,18 @@ xfs_alloc_ioend(
> return ioend;
> }
>
> +STATIC xfs_ioend_t *
> +xfs_alloc_ioend(
> + struct inode *inode,
> + unsigned int type)
> +{
> + struct xfs_ioend *ioend;
> +
> + ioend = __xfs_alloc_ioend(inode, type);
> + atomic_inc(&XFS_I(ioend->io_inode)->i_iocount);
> + return ioend;
> +}
> +
> STATIC int
> xfs_map_blocks(
> struct inode *inode,
> @@ -1318,6 +1329,7 @@ xfs_end_io_direct_write(
> */
> iocb->private = NULL;
>
> + atomic_inc(&XFS_I(ioend->io_inode)->i_iocount);
> ioend->io_offset = offset;
> ioend->io_size = size;
> if (private && size > 0)
> @@ -1354,7 +1366,7 @@ xfs_vm_direct_IO(
> ssize_t ret;
>
> if (rw & WRITE) {
> - iocb->private = xfs_alloc_ioend(inode, IO_DIRECT);
> + iocb->private = __xfs_alloc_ioend(inode, IO_DIRECT);
>
> ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iov,
> offset, nr_segs,
--
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