On Sat, 18 Sep 2010 10:32:03 +0400
Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
> Add cifs_sync_read call to provide reading from the cache if we have at least
> Level II oplock and otherwise - reading from the server.
>
> Signed-off-by: Pavel Shilovsky <piastryyy@xxxxxxxxx>
> ---
> fs/cifs/cifsfs.c | 23 +++++++++++++++++++++--
> 1 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index b7431af..ba70048 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -533,6 +533,25 @@ cifs_get_sb(struct file_system_type *fs_type,
> return 0;
> }
>
> +static ssize_t cifs_sync_read(struct file *filp, char __user *buf,
> + size_t len, loff_t *ppos)
> +{
> + ssize_t read;
> + struct cifsInodeInfo *cinode;
> +
> + if (filp && filp->f_path.dentry && filp->f_path.dentry->d_inode)
A NULL filp or one with a negative dentry would be a serious VFS bug.
I'd get rid of the NULL pointer checks above. I don't think they're
necessary.
> + cinode = CIFS_I(filp->f_path.dentry->d_inode);
> + else
> + return -ENOENT;
> +
> + if (cinode->clientCanCacheRead)
> + read = do_sync_read(filp, buf, len, ppos);
> + else
> + read = cifs_user_read(filp, buf, len, ppos);
> +
> + return read;
> +}
> +
> static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
> unsigned long nr_segs, loff_t pos)
> {
> @@ -652,7 +671,7 @@ const struct inode_operations cifs_symlink_inode_ops = {
> };
>
> const struct file_operations cifs_file_ops = {
> - .read = do_sync_read,
> + .read = cifs_sync_read,
> .write = do_sync_write,
> .aio_read = generic_file_aio_read,
> .aio_write = cifs_file_aio_write,
> @@ -689,7 +708,7 @@ const struct file_operations cifs_file_direct_ops = {
> .setlease = cifs_setlease,
> };
> const struct file_operations cifs_file_nobrl_ops = {
> - .read = do_sync_read,
> + .read = cifs_sync_read,
> .write = do_sync_write,
> .aio_read = generic_file_aio_read,
> .aio_write = cifs_file_aio_write,
Looks reasonable, but it would be good to know what sort of performance
impact to expect from this. Have you done any benchmarking pre and post
patch?
--
Jeff Layton <jlayton@xxxxxxxxx>
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