| Message ID | 20220518233709.1937634-17-shr@fb.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | io-uring/xfs: support async buffered writes | expand |
> --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -784,6 +784,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) > do { > struct folio *folio; > struct page *page; > + struct address_space *i_mapping = iter->inode->i_mapping; We tend to call these variables just mapping without the i_ prefix. > again: > + if (iter->flags & IOMAP_NOWAIT) { > + status = balance_dirty_pages_ratelimited_async(i_mapping); Which also nicely avoids the overly long line here. > + if (unlikely(status)) > + break; > + } else { > + balance_dirty_pages_ratelimited(i_mapping); > + } Then again directly calling the underlying helper here would be simpler to start with. unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0; ... status = balance_dirty_pages_ratelimited_flags(mapping, bdp_flags); if (status) break;
On 5/19/22 1:32 AM, Christoph Hellwig wrote: >> --- a/fs/iomap/buffered-io.c >> +++ b/fs/iomap/buffered-io.c >> @@ -784,6 +784,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) >> do { >> struct folio *folio; >> struct page *page; >> + struct address_space *i_mapping = iter->inode->i_mapping; > > We tend to call these variables just mapping without the i_ prefix. > Will change the name to mapping. >> again: >> + if (iter->flags & IOMAP_NOWAIT) { >> + status = balance_dirty_pages_ratelimited_async(i_mapping); > > Which also nicely avoids the overly long line here. > >> + if (unlikely(status)) >> + break; >> + } else { >> + balance_dirty_pages_ratelimited(i_mapping); >> + } > > Then again directly calling the underlying helper here would be simpler > to start with. > > unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0; > > ... > > > status = balance_dirty_pages_ratelimited_flags(mapping, > bdp_flags); > if (status) > break; > I introduced the BDP_ASYNC define and used the above code. I also wired it accordingly in balance_dirty_pages().
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index b029e2b10e07..2b85ddfa6ea1 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -784,6 +784,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) do { struct folio *folio; struct page *page; + struct address_space *i_mapping = iter->inode->i_mapping; unsigned long offset; /* Offset into pagecache page */ unsigned long bytes; /* Bytes to write to page */ size_t copied; /* Bytes copied from user */ @@ -792,6 +793,14 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) bytes = min_t(unsigned long, PAGE_SIZE - offset, iov_iter_count(i)); again: + if (iter->flags & IOMAP_NOWAIT) { + status = balance_dirty_pages_ratelimited_async(i_mapping); + if (unlikely(status)) + break; + } else { + balance_dirty_pages_ratelimited(i_mapping); + } + if (bytes > length) bytes = length; @@ -815,7 +824,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) break; page = folio_file_page(folio, pos >> PAGE_SHIFT); - if (mapping_writably_mapped(iter->inode->i_mapping)) + if (mapping_writably_mapped(i_mapping)) flush_dcache_page(page); copied = copy_page_from_iter_atomic(page, offset, bytes, i); @@ -840,8 +849,6 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) pos += status; written += status; length -= status; - - balance_dirty_pages_ratelimited(iter->inode->i_mapping); } while (iov_iter_count(i) && length); return written ? written : status;
This replaces the call to balance_dirty_pages_ratelimited() with the call to balance_dirty_pages_ratelimited_flags. This allows to specify if the write request is async or not. In addition this also moves the above function call to the beginning of the function. If the function call is at the end of the function and the decision is made to throttle writes, then there is no request that io-uring can wait on. By moving it to the beginning of the function, the write request is not issued, but returns -EAGAIN instead. io-uring will punt the request and process it in the io-worker. By moving the function call to the beginning of the function, the write throttling will happen one page later. Signed-off-by: Stefan Roesch <shr@fb.com> --- fs/iomap/buffered-io.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)