Hi Christoph-
On Nov 14, 2013, at 11:50 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
> We'll need the i_mutex to prevent i_dio_count from incrementing while
> truncate is waiting for it to reach zero, and protects against having
> the pagecache repopulated after we flushed it.
How was the performance impact of this change measured?
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/nfs/direct.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
> index c32db2a..6cc7fe1 100644
> --- a/fs/nfs/direct.c
> +++ b/fs/nfs/direct.c
> @@ -500,16 +500,17 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
> if (!count)
> goto out;
>
> + mutex_lock(&inode->i_mutex);
> result = nfs_sync_mapping(mapping);
> if (result)
> - goto out;
> + goto out_unlock;
>
> task_io_account_read(count);
>
> result = -ENOMEM;
> dreq = nfs_direct_req_alloc();
> if (dreq == NULL)
> - goto out;
> + goto out_unlock;
>
> dreq->inode = inode;
> dreq->bytes_left = iov_length(iov, nr_segs);
> @@ -525,13 +526,22 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
>
> NFS_I(inode)->read_io += iov_length(iov, nr_segs);
> result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio);
> +
> + mutex_unlock(&inode->i_mutex);
> +
> if (!result) {
> result = nfs_direct_wait(dreq);
> if (result > 0)
> iocb->ki_pos = pos + result;
> }
> +
> + nfs_direct_req_release(dreq);
> + return result;
> +
> out_release:
> nfs_direct_req_release(dreq);
> +out_unlock:
> + mutex_unlock(&inode->i_mutex);
> out:
> return result;
> }
> --
> 1.7.10.4
>
>
> --
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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