On Tue, 30 Nov 2010 10:54:30 +0300
Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
> Add cifs_file_aio_read where we read from the cache if we have at least
> Level II oplock - otherwise read from the server.
>
> Signed-off-by: Pavel Shilovsky <piastryyy@xxxxxxxxx>
> ---
> fs/cifs/cifsfs.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
> 1 files changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 9c37897..370acdc 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -568,6 +568,46 @@ cifs_do_mount(struct file_system_type *fs_type,
> return dget(sb->s_root);
> }
>
> +static ssize_t cifs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
> + unsigned long nr_segs, loff_t pos)
> +{
> + struct inode *inode;
> + struct cifs_sb_info *cifs_sb;
> + ssize_t read = 0, retval;
> + unsigned long i;
> +
> + inode = iocb->ki_filp->f_path.dentry->d_inode;
> + cifs_sb = CIFS_SB(iocb->ki_filp->f_path.dentry->d_sb);
> +
> + if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) == 0 ||
> + CIFS_I(inode)->clientCanCacheRead)
> + return generic_file_aio_read(iocb, iov, nr_segs, pos);
> +
> + /*
> + * In strict cache mode we need to read from the server all the time
> + * if we don't have level II oplock because the server can delay mtime
> + * change - so we can't make a decision about inode invalidating.
> + * And we can also fail with pagereading if there are mandatory locks
> + * on pages affected by this read but not on the region from pos to
> + * pos+len-1.
> + */
> +
> + for (i = 0; i < nr_segs; i++) {
> + retval = cifs_user_read(iocb->ki_filp, iov[i].iov_base,
> + iov[i].iov_len, &pos);
> + if (retval < 0) {
> + read = read ? read : retval;
> + break;
> + }
> +
> + read += retval;
> + }
> +
Hmmm...that looks a little ugly. There is no batching here, so if the
application sends you an array of very small iovecs, then that becomes
a set of very small reads on the wire. I don't think that's what you
want.
> + iocb->ki_pos = pos;
> +
> + return read;
> +}
> +
> static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
> unsigned long nr_segs, loff_t pos)
> {
> @@ -690,7 +730,7 @@ const struct inode_operations cifs_symlink_inode_ops = {
> const struct file_operations cifs_file_ops = {
> .read = do_sync_read,
> .write = do_sync_write,
> - .aio_read = generic_file_aio_read,
> + .aio_read = cifs_file_aio_read,
> .aio_write = cifs_file_aio_write,
> .open = cifs_open,
> .release = cifs_close,
> @@ -727,7 +767,7 @@ const struct file_operations cifs_file_direct_ops = {
> const struct file_operations cifs_file_nobrl_ops = {
> .read = do_sync_read,
> .write = do_sync_write,
> - .aio_read = generic_file_aio_read,
> + .aio_read = cifs_file_aio_read,
> .aio_write = cifs_file_aio_write,
> .open = cifs_open,
> .release = cifs_close,
--
Jeff Layton <jlayton@xxxxxxxxx>
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