afs: Use ITER_XARRAY for writing
Use a single ITER_XARRAY iterator to describe the portion of a file to be
transmitted to the server rather than generating a series of small
ITER_BVEC iterators on the fly. This will make it easier to implement AIO
in afs.
In theory we could maybe use one giant ITER_BVEC, but that means
potentially allocating a huge array of bio_vec structs (max 256 per page)
when in fact the pagecache already has a structure listing all the relevant
pages (radix_tree/xarray) that can be walked over.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/153685395197.14766.16289516750731233933.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/158861251312.340223.17924900795425422532.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/159465828607.1377938.6903132788463419368.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/160588535018.3465195.14509994354240338307.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161118152415.1232039.6452879415814850025.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161161048194.2537118.13763612220937637316.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161340411602.1303470.4661108879482218408.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/161539555629.286939.5241869986617154517.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653811456.2770958.7017388543246759245.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789095005.6155.6789055030327407928.stgit@warthog.procyon.org.uk/ # v6
diff --git a/fs/afs/write.c b/fs/afs/write.c
index cb24f84..6e41b98 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -325,36 +325,27 @@ static void afs_redirty_pages(struct writeback_control *wbc,
/*
* completion of write to server
*/
-static void afs_pages_written_back(struct afs_vnode *vnode,
- pgoff_t first, pgoff_t last)
+static void afs_pages_written_back(struct afs_vnode *vnode, pgoff_t start, pgoff_t last)
{
- struct pagevec pv;
- unsigned count, loop;
+ struct address_space *mapping = vnode->vfs_inode.i_mapping;
+ struct page *page;
+
+ XA_STATE(xas, &mapping->i_pages, start);
_enter("{%llx:%llu},{%lx-%lx}",
- vnode->fid.vid, vnode->fid.vnode, first, last);
+ vnode->fid.vid, vnode->fid.vnode, start, last);
- pagevec_init(&pv);
+ rcu_read_lock();
- do {
- _debug("done %lx-%lx", first, last);
+ xas_for_each(&xas, page, last) {
+ ASSERT(PageWriteback(page));
- count = last - first + 1;
- if (count > PAGEVEC_SIZE)
- count = PAGEVEC_SIZE;
- pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
- first, count, pv.pages);
- ASSERTCMP(pv.nr, ==, count);
+ detach_page_private(page);
+ trace_afs_page_dirty(vnode, tracepoint_string("clear"), page);
+ page_endio(page, true, 0);
+ }
- for (loop = 0; loop < count; loop++) {
- detach_page_private(pv.pages[loop]);
- trace_afs_page_dirty(vnode, tracepoint_string("clear"),
- pv.pages[loop]);
- end_page_writeback(pv.pages[loop]);
- }
- first += count;
- __pagevec_release(&pv);
- } while (first <= last);
+ rcu_read_unlock();
afs_prune_wb_keys(vnode);
_leave("");
@@ -411,9 +402,7 @@ static void afs_store_data_success(struct afs_operation *op)
if (!op->store.laundering)
afs_pages_written_back(vnode, op->store.first, op->store.last);
afs_stat_v(vnode, n_stores);
- atomic_long_add((op->store.last * PAGE_SIZE + op->store.last_to) -
- (op->store.first * PAGE_SIZE + op->store.first_offset),
- &afs_v2net(vnode)->n_store_bytes);
+ atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
}
}
@@ -426,21 +415,21 @@ static const struct afs_operation_ops afs_store_data_operation = {
/*
* write to a file
*/
-static int afs_store_data(struct address_space *mapping,
- pgoff_t first, pgoff_t last,
- unsigned offset, unsigned to, bool laundering)
+static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter,
+ loff_t pos, pgoff_t first, pgoff_t last,
+ bool laundering)
{
- struct afs_vnode *vnode = AFS_FS_I(mapping->host);
struct afs_operation *op;
struct afs_wb_key *wbk = NULL;
- int ret;
+ loff_t size = iov_iter_count(iter), i_size;
+ int ret = -ENOKEY;
- _enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
+ _enter("%s{%llx:%llu.%u},%llx,%llx",
vnode->volume->name,
vnode->fid.vid,
vnode->fid.vnode,
vnode->fid.unique,
- first, last, offset, to);
+ size, pos);
ret = afs_get_writeback_key(vnode, &wbk);
if (ret) {
@@ -454,13 +443,16 @@ static int afs_store_data(struct address_space *mapping,
return -ENOMEM;
}
+ i_size = i_size_read(&vnode->vfs_inode);
+
afs_op_set_vnode(op, 0, vnode);
op->file[0].dv_delta = 1;
- op->store.mapping = mapping;
+ op->store.write_iter = iter;
+ op->store.pos = pos;
op->store.first = first;
op->store.last = last;
- op->store.first_offset = offset;
- op->store.last_to = to;
+ op->store.size = size;
+ op->store.i_size = max(pos + size, i_size);
op->store.laundering = laundering;
op->mtime = vnode->vfs_inode.i_mtime;
op->flags |= AFS_OPERATION_UNINTR;
@@ -503,11 +495,12 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
pgoff_t final_page)
{
struct afs_vnode *vnode = AFS_FS_I(mapping->host);
+ struct iov_iter iter;
struct page *pages[8], *page;
unsigned long count, priv;
unsigned n, offset, to, f, t;
pgoff_t start, first, last;
- loff_t i_size, end;
+ loff_t i_size, pos, end;
int loop, ret;
_enter(",%lx", primary_page->index);
@@ -604,15 +597,28 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
first = primary_page->index;
last = first + count - 1;
-
- end = (loff_t)last * PAGE_SIZE + to;
- i_size = i_size_read(&vnode->vfs_inode);
-
_debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
- if (end > i_size)
- to = i_size & ~PAGE_MASK;
- ret = afs_store_data(mapping, first, last, offset, to, false);
+ pos = first;
+ pos <<= PAGE_SHIFT;
+ pos += offset;
+ end = last;
+ end <<= PAGE_SHIFT;
+ end += to;
+
+ /* Trim the actual write down to the EOF */
+ i_size = i_size_read(&vnode->vfs_inode);
+ if (end > i_size)
+ end = i_size;
+
+ if (pos < i_size) {
+ iov_iter_xarray(&iter, WRITE, &mapping->i_pages, pos, end - pos);
+ ret = afs_store_data(vnode, &iter, pos, first, last, false);
+ } else {
+ /* The dirty region was entirely beyond the EOF. */
+ ret = 0;
+ }
+
switch (ret) {
case 0:
ret = count;
@@ -912,6 +918,8 @@ int afs_launder_page(struct page *page)
{
struct address_space *mapping = page->mapping;
struct afs_vnode *vnode = AFS_FS_I(mapping->host);
+ struct iov_iter iter;
+ struct bio_vec bv[1];
unsigned long priv;
unsigned int f, t;
int ret = 0;
@@ -927,8 +935,14 @@ int afs_launder_page(struct page *page)
t = afs_page_dirty_to(page, priv);
}
+ bv[0].bv_page = page;
+ bv[0].bv_offset = f;
+ bv[0].bv_len = t - f;
+ iov_iter_bvec(&iter, WRITE, bv, 1, bv[0].bv_len);
+
trace_afs_page_dirty(vnode, tracepoint_string("launder"), page);
- ret = afs_store_data(mapping, page->index, page->index, t, f, true);
+ ret = afs_store_data(vnode, &iter, (loff_t)page->index << PAGE_SHIFT,
+ page->index, page->index, true);
}
detach_page_private(page);