On Sun, 28 Nov 2010 11:12:48 +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 | 31 +++++++++++++++++++++++++++++--
> 1 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 9c37897..bbb5294 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -568,6 +568,33 @@ 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;
> +
> + 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 */
^^^^^^^^^^^
Nit: while much of the existing cifs code doesn't, it's best to
follow kernel coding style when you're adding code. The above
comment doesn't do this however. You may want to have a look at
Documentation/CodingStyle in the kernel sources.
> + read = cifs_user_read(iocb->ki_filp, iov->iov_base,
> + iov->iov_len, &pos);
> + 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 +717,7 @@ 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 +754,7 @@ 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,
Looks reasonable:
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
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