Re: [PATCH v2 2/3] afs: Fix afs_write_end() to handle short writes
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-06-21 14:37:38
Also in:
linux-fsdevel
On Thu, Jun 17, 2021 at 09:24:16AM +0100, David Howells wrote:
Fix afs_write_end() to correctly handle a short copy into the intended
write region of the page. Two things are necessary:
(1) If the page is not up to date, then we should just return 0
(ie. indicating a zero-length copy). The loop in
generic_perform_write() will go around again, possibly breaking up the
iterator into discrete chunks.
This is analogous to commit b9de313cf05fe08fa59efaf19756ec5283af672a
for ceph.
(2) The page should not have been set uptodate if it wasn't completely set
up by netfs_write_begin() (this will be fixed in the next patch), so
we need to set uptodate here in such a case.
Also remove the assertion that was checking that the page was set uptodate
since it's now set uptodate if it wasn't already a few lines above. The
assertion was from when uptodate was set elsewhere.Thanks for adding that explanation.
quoted hunk ↗ jump to hunk
+++ b/fs/afs/write.c@@ -119,6 +119,16 @@ int afs_write_end(struct file *file, struct address_space *mapping, _enter("{%llx:%llu},{%lx}", vnode->fid.vid, vnode->fid.vnode, page->index); + len = min_t(size_t, len, thp_size(page) - from);
This line isn't necessary yet, right?
quoted hunk ↗ jump to hunk
+ if (!PageUptodate(page)) { + if (copied < len) { + copied = 0; + goto out; + } + + SetPageUptodate(page); + } + if (copied == 0) goto out;@@ -133,8 +143,6 @@ int afs_write_end(struct file *file, struct address_space *mapping, write_sequnlock(&vnode->cb_lock); } - ASSERT(PageUptodate(page)); - if (PagePrivate(page)) { priv = page_private(page); f = afs_page_dirty_from(page, priv);
The rest of this looks good.