On Tue, 27 Nov 2012 10:50:28 +0400
Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
> If we have a read oplock and set a read lock in it, we can't write to the
> locked area - so, filemap_fdatawrite may fail with a no information for a
> userspace application even if we request a write to non-locked area. Fix
> this by replacing it with filemap_write_and_wait call and sending non-page
> write in a error case.
>
> While this may end up with two write requests to the server, we can be sure
> that our data will be the same at the server and the page cache - the next read
> on this file gets the valid data.
>
> Signed-off-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
> ---
> fs/cifs/file.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index f8fe1bd..89efd85 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2511,14 +2511,12 @@ cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
> */
> if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead) {
> ssize_t written;
> - int rc;
>
> written = generic_file_aio_write(iocb, iov, nr_segs, pos);
> - rc = filemap_fdatawrite(inode->i_mapping);
> - if (rc)
> - return (ssize_t)rc;
> -
> - return written;
> + /* try page write at first */
> + if (!filemap_write_and_wait(inode->i_mapping))
> + return written;
> + /* page write failed - try from pos to pos+len-1 */
> }
> #endif
>
Bleh -- nasty. I guess this will work though...
Wonder if there's some way to populate the cache and then just mark the
pages clean without sending out writes? That would be a better solution
IMO, but I guess we can live with this for now...
Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
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