On Tue, 26 Oct 2010 17:03:49 +0400
Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
> Modify cifs_file_aio_write and cifs_write_end to let the client works with
> strict cache mode.
>
Not very descriptive of the logic here. Care to explain why you changed
things the way you did?
> Signed-off-by: Pavel Shilovsky <piastryyy@xxxxxxxxx>
> ---
> fs/cifs/cifsfs.c | 35 ++++++++++++++++++++++++++++++-----
> fs/cifs/file.c | 23 ++++++++++++++++++++++-
> 2 files changed, 52 insertions(+), 6 deletions(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 21e0f47..85042e4 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -603,12 +603,37 @@ static ssize_t cifs_file_aio_read(struct kiocb
> *iocb, const struct iovec *iov,
> static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
> unsigned long nr_segs, loff_t pos)
> {
> - struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
> - ssize_t written;
> + struct inode *inode;
> + struct cifs_sb_info *cifs_sb;
> + ssize_t written, cache_written;
> + loff_t saved_pos;
> +
> + inode = iocb->ki_filp->f_path.dentry->d_inode;
> +
> + if (CIFS_I(inode)->clientCanCacheAll)
> + return generic_file_aio_write(iocb, iov, nr_segs, pos);
> +
> + cifs_sb = CIFS_SB(iocb->ki_filp->f_path.dentry->d_sb);
> +
> + if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) == 0) {
> + written = generic_file_aio_write(iocb, iov, nr_segs, pos);
> + filemap_write_and_wait(inode->i_mapping);
> + return written;
> + }
That doesn't look right. CIFS_MOUNT_STRICT_IO is false. You're
doing a "normal" aio write (fine), and then calling
filemap_write_and_wait to sync it out? Why isn't
filemap_fdatawrite sufficient in the non-strict case?
Also, filemap_write_and_wait can return an error and you're
ignoring it here.
> +
> + saved_pos = pos;
> + written = cifs_user_write(iocb->ki_filp, iov->iov_base,
> + iov->iov_len, &pos);
> +
> + if (written > 0) {
> + cache_written = generic_file_aio_write(iocb, iov,
> + nr_segs, saved_pos);
> + if (cache_written != written)
> + cERROR(1, "Cache written and server written data "
> + "lengths are different");
> + } else
> + iocb->ki_pos = pos;
>
^^^^^
What exactly is this doing? It looks like you're writing the
same data to the server twice?
> - written = generic_file_aio_write(iocb, iov, nr_segs, pos);
> - if (!CIFS_I(inode)->clientCanCacheAll)
> - filemap_fdatawrite(inode->i_mapping);
> return written;
> }
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 02a045e..a4d4b3a 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -1578,11 +1578,31 @@ static int cifs_write_end(struct file *file,
> struct address_space *mapping,
> struct page *page, void *fsdata)
> {
> int rc;
> - struct inode *inode = mapping->host;
> + struct inode *inode;
> + struct cifs_sb_info *cifs_sb;
> +
> + inode = mapping->host;
> + cifs_sb = CIFS_SB(inode->i_sb);
>
> cFYI(1, "write_end for page %p from pos %lld with %d bytes",
> page, pos, copied);
>
> + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) {
> + rc = copied;
> + pos += copied;
> +
> + if (CIFS_I(inode)->clientCanCacheAll) {
> + SetPageUptodate(page);
> + set_page_dirty(page);
> + }
> +
> + /* if we don't have an exclusive oplock the page data was
> + previously written to the server in cifs_file_aio_write,
> + so we don't need to do it again - goto exit */
> +
> + goto exit;
> + }
> +
Oof. So you're only conditionally setting the uptodate and dirty bits
on the pages after dirtying them? What exactly is going to flush these
out to the server?
> if (PageChecked(page)) {
> if (copied == len)
> SetPageUptodate(page);
> @@ -1614,6 +1634,7 @@ static int cifs_write_end(struct file *file,
> struct address_space *mapping,
> set_page_dirty(page);
> }
>
> +exit:
> if (rc > 0) {
> spin_lock(&inode->i_lock);
> if (pos > inode->i_size)
I'm afraid this whole patch doesn't make much sense to me. Perhaps you
should start by explaining how you expect things to work when strict
caching is enabled.
--
Jeff Layton <jlayton@xxxxxxxxxx>
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