Jeff Layton [jlayton@xxxxxxxxxx] wrote:
> When given a range to write with unstable writes, the current code
> always does a COMMIT of the entire file afterward. This is potentially
> expensive on some servers and unnecessary. Instead, just do a COMMIT for
> the offset and count that was written.
>
> Khoa, who reported this bug, stated that this made a big difference in
> performance in their environment, which I believe involves GPFS on the
> server. He didn't pass along any hard numbers so I can't quantify the
> gain, but it stands to reason that clustered filesystems might suffer
> more contention issues when issuing a commit over the whole file.
>
> Reported-by: Khoa Huynh <khoa@xxxxxxxxxx>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/nfs/direct.c | 6 ++++--
> 1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
> index 1940f1a..33f2be7 100644
> --- a/fs/nfs/direct.c
> +++ b/fs/nfs/direct.c
> @@ -77,6 +77,7 @@ struct nfs_direct_req {
> /* completion state */
> atomic_t io_count; /* i/os we're waiting for */
> spinlock_t lock; /* protect completion state */
> + loff_t pos; /* offset into file */
Why not call it "offset"? Should we set this to zero in
nfs_direct_req_alloc (just like count is set to zero there)?
Thanks, Malahal.
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