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Message-ID: <158861255792.340223.1309939976492492377.stgit@warthog.procyon.org.uk>
Date: Mon, 04 May 2020 18:15:57 +0100
From: David Howells <dhowells@...hat.com>
To: Trond Myklebust <trondmy@...merspace.com>,
Anna Schumaker <anna.schumaker@...app.com>,
Steve French <sfrench@...ba.org>,
Jeff Layton <jlayton@...hat.com>
Cc: dhowells@...hat.com, Matthew Wilcox <willy@...radead.org>,
Alexander Viro <viro@...iv.linux.org.uk>,
linux-afs@...ts.infradead.org, linux-nfs@...r.kernel.org,
linux-cifs@...r.kernel.org, ceph-devel@...r.kernel.org,
v9fs-developer@...ts.sourceforge.net,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 56/61] afs: Copy local writes to the cache when writing to
the server
When writing to the server from afs_writepage() or afs_writepages(), copy
the data to the cache object too.
Signed-off-by: David Howells <dhowells@...hat.com>
---
fs/afs/write.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 119 insertions(+), 5 deletions(-)
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 312d8f07533e..38637dc6043c 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -13,6 +13,9 @@
#include <linux/pagevec.h>
#include "internal.h"
+static void afs_write_to_cache(struct afs_vnode *vnode,
+ pgoff_t start, pgoff_t end, loff_t a, loff_t b);
+
/*
* mark a page as having been made dirty and thus needing writeback
*/
@@ -389,6 +392,8 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
count = 1;
if (test_set_page_writeback(primary_page))
BUG();
+ if (TestSetPageFsCache(primary_page))
+ BUG();
/* Find all consecutive lockable dirty pages that have contiguous
* written regions, stopping when we find a page that is not
@@ -437,7 +442,8 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
break;
if (!trylock_page(page))
break;
- if (!PageDirty(page) || PageWriteback(page)) {
+ if (!PageDirty(page) || PageWriteback(page) ||
+ PageFsCache(page)) {
unlock_page(page);
break;
}
@@ -459,6 +465,8 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
BUG();
if (test_set_page_writeback(page))
BUG();
+ if (TestSetPageFsCache(page))
+ BUG();
unlock_page(page);
put_page(page);
}
@@ -489,8 +497,13 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
b = last;
b <<= PAGE_SHIFT;
b += to;
- iov_iter_mapping(&iter, WRITE, mapping, a, b - a);
+ /* Speculatively write to the cache. We have to fix this up later if
+ * the store fails.
+ */
+ afs_write_to_cache(vnode, first, last + 1, a, b);
+
+ iov_iter_mapping(&iter, WRITE, mapping, a, b - a);
ret = afs_store_data(vnode, &iter, a, first, last);
switch (ret) {
case 0:
@@ -543,6 +556,10 @@ int afs_writepage(struct page *page, struct writeback_control *wbc)
_enter("{%lx},", page->index);
+#ifdef CONFIG_AFS_FSCACHE
+ wait_on_page_fscache(page);
+#endif
+
ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
wbc->range_end >> PAGE_SHIFT);
if (ret < 0) {
@@ -570,7 +587,7 @@ static int afs_writepages_region(struct address_space *mapping,
do {
n = find_get_pages_range_tag(mapping, &index, end,
- PAGECACHE_TAG_DIRTY, 1, &page);
+ PAGECACHE_TAG_DIRTY, 1, &page);
if (!n)
break;
@@ -595,10 +612,14 @@ static int afs_writepages_region(struct address_space *mapping,
continue;
}
- if (PageWriteback(page)) {
+ if (PageWriteback(page) || PageFsCache(page)) {
unlock_page(page);
- if (wbc->sync_mode != WB_SYNC_NONE)
+ if (wbc->sync_mode != WB_SYNC_NONE) {
wait_on_page_writeback(page);
+#ifdef CONFIG_AFS_FSCACHE
+ wait_on_page_fscache(page);
+#endif
+ }
put_page(page);
continue;
}
@@ -818,3 +839,96 @@ int afs_launder_page(struct page *page)
ClearPagePrivate(page);
return ret;
}
+
+/*
+ * Clear the PG_fscache flag from a sequence of pages and wake up anyone who's
+ * waiting. The last page is included in the sequence.
+ */
+static void afs_clear_fscache_bits(struct address_space *mapping,
+ pgoff_t start, pgoff_t last)
+{
+ struct page *page;
+
+ XA_STATE(xas, &mapping->i_pages, start);
+
+ rcu_read_lock();
+ xas_for_each(&xas, page, last) {
+ unlock_page_fscache(page);
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * Deal with the completion of writing the data to the cache.
+ */
+static void afs_write_to_cache_done(struct fscache_io_request *_req)
+{
+ struct afs_read *req = container_of(_req, struct afs_read, cache);
+ pgoff_t index = req->cache.pos >> PAGE_SHIFT;
+ pgoff_t last = index + req->cache.nr_pages - 1;
+
+ _enter("%lx,%x,%llx", index, req->cache.nr_pages, req->cache.transferred);
+
+ afs_clear_fscache_bits(req->cache.mapping, index, last);
+
+ if (req->cache.error && req->cache.error != -ENOBUFS) {
+ struct afs_vnode *vnode = req->vnode;
+ struct afs_vnode_cache_aux aux = {
+ .data_version = vnode->status.data_version,
+ };
+ _debug("inval wr %d", req->cache.error);
+ fscache_invalidate(req->cache.cookie, &aux,
+ i_size_read(&vnode->vfs_inode), 0);
+ }
+}
+
+static const struct fscache_io_request_ops afs_write_req_ops = {
+ .get = afs_req_get,
+ .put = afs_req_put,
+};
+
+/*
+ * Save the write to the cache also.
+ */
+static void afs_write_to_cache(struct afs_vnode *vnode,
+ pgoff_t start, pgoff_t end, loff_t a, loff_t b)
+{
+ struct afs_read *req;
+ struct iov_iter iter;
+ unsigned int x;
+
+ struct fscache_extent extent = {
+ .start = start,
+ .block_end = end,
+ .limit = end,
+ };
+
+ _enter("%lx,%lx,%llx,%llx", start, end, a, b);
+
+ x = fscache_shape_extent(afs_vnode_cache(vnode), &extent,
+ i_size_read(&vnode->vfs_inode), true);
+ if (!(x & FSCACHE_WRITE_TO_CACHE))
+ goto abandon;
+
+ req = afs_alloc_read(GFP_KERNEL);
+ if (!req)
+ goto abandon;
+
+ fscache_init_io_request(&req->cache, afs_vnode_cache(vnode),
+ &afs_write_req_ops);
+ req->vnode = vnode;
+ req->cache.pos = round_down(a, extent.dio_block_size);
+ req->cache.len = round_up(b, extent.dio_block_size) - req->cache.pos;
+ req->cache.nr_pages = end - start;
+ req->cache.mapping = vnode->vfs_inode.i_mapping;
+ req->cache.io_done = &afs_write_to_cache_done;
+
+ iov_iter_mapping(&iter, WRITE, req->cache.mapping,
+ req->cache.pos, req->cache.len);
+ fscache_write(&req->cache, &iter);
+ afs_put_read(req);
+ return;
+
+abandon:
+ afs_clear_fscache_bits(vnode->vfs_inode.i_mapping, start, end);
+}
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