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Subject[PATCH 07/10] afs: Use ITER_MAPPING for writing
From
Date
Use a single ITER_MAPPING 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>
---

fs/afs/file.c | 4 --
fs/afs/fsclient.c | 40 +++++-------------
fs/afs/internal.h | 15 ++-----
fs/afs/rxrpc.c | 99 +++++++-------------------------------------
fs/afs/write.c | 84 +++++++++++++++++++++----------------
include/trace/events/afs.h | 51 ++++++++---------------
6 files changed, 100 insertions(+), 193 deletions(-)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 6d55dabccd79..7d65efe69929 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -195,11 +195,9 @@ static void afs_readpages_page_done(const struct iov_iter *iter,
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
struct afs_read *req = container_of(iter, struct afs_read, iter);

- SetPageUptodate(page);
-
if (0 && afs_vnode_cache(vnode))
SetPageFsCache(page);
- unlock_page(page);
+ page_endio(page, false, 0);
put_page(page);
req->done_pages++;
}
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index eb60c570dca2..4c6997d91552 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -1230,10 +1230,7 @@ static const struct afs_call_type afs_RXFSStoreData64 = {
/*
* store a set of pages to a very large file
*/
-static int afs_fs_store_data64(struct afs_fs_cursor *fc,
- struct address_space *mapping,
- pgoff_t first, pgoff_t last,
- unsigned offset, unsigned to,
+static int afs_fs_store_data64(struct afs_fs_cursor *fc, struct iov_iter *iter,
loff_t size, loff_t pos, loff_t i_size)
{
struct afs_vnode *vnode = fc->vnode;
@@ -1251,13 +1248,10 @@ static int afs_fs_store_data64(struct afs_fs_cursor *fc,
return -ENOMEM;

call->key = fc->key;
- call->mapping = mapping;
+ call->write_iter = iter;
+ call->write_first = pos >> PAGE_SHIFT;
+ call->write_last = (pos + size - 1) >> PAGE_SHIFT;
call->reply[0] = vnode;
- call->first = first;
- call->last = last;
- call->first_offset = offset;
- call->last_to = to;
- call->send_pages = true;
call->expected_version = vnode->status.data_version + 1;

/* marshall the parameters */
@@ -1286,26 +1280,20 @@ static int afs_fs_store_data64(struct afs_fs_cursor *fc,
}

/*
- * store a set of pages
+ * Write data to a file on the server.
*/
-int afs_fs_store_data(struct afs_fs_cursor *fc, struct address_space *mapping,
- pgoff_t first, pgoff_t last,
- unsigned offset, unsigned to)
+int afs_fs_store_data(struct afs_fs_cursor *fc, struct iov_iter *iter, loff_t pos)
{
struct afs_vnode *vnode = fc->vnode;
struct afs_call *call;
struct afs_net *net = afs_v2net(vnode);
- loff_t size, pos, i_size;
+ loff_t size, i_size;
__be32 *bp;

_enter(",%x,{%x:%u},,",
key_serial(fc->key), vnode->fid.vid, vnode->fid.vnode);

- size = (loff_t)to - (loff_t)offset;
- if (first != last)
- size += (loff_t)(last - first) << PAGE_SHIFT;
- pos = (loff_t)first << PAGE_SHIFT;
- pos += offset;
+ size = iov_iter_count(iter);

i_size = i_size_read(&vnode->vfs_inode);
if (pos + size > i_size)
@@ -1316,8 +1304,7 @@ int afs_fs_store_data(struct afs_fs_cursor *fc, struct address_space *mapping,
(unsigned long long) i_size);

if (pos >> 32 || i_size >> 32 || size >> 32 || (pos + size) >> 32)
- return afs_fs_store_data64(fc, mapping, first, last, offset, to,
- size, pos, i_size);
+ return afs_fs_store_data64(fc, iter, size, pos, i_size);

call = afs_alloc_flat_call(net, &afs_RXFSStoreData,
(4 + 6 + 3) * 4,
@@ -1326,13 +1313,10 @@ int afs_fs_store_data(struct afs_fs_cursor *fc, struct address_space *mapping,
return -ENOMEM;

call->key = fc->key;
- call->mapping = mapping;
+ call->write_iter = iter;
+ call->write_first = pos >> PAGE_SHIFT;
+ call->write_last = (pos + size - 1) >> PAGE_SHIFT;
call->reply[0] = vnode;
- call->first = first;
- call->last = last;
- call->first_offset = offset;
- call->last_to = to;
- call->send_pages = true;
call->expected_version = vnode->status.data_version + 1;

/* marshall the parameters */
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 8e248051afde..b12566b640f6 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -96,14 +96,15 @@ struct afs_call {
struct address_space *mapping; /* Pages being written from */
struct iov_iter iter; /* Buffer iterator */
struct iov_iter *_iter; /* Iterator currently in use */
+ struct iov_iter *write_iter; /* Iterator defining write to be made */
union { /* Convenience for ->iter */
struct kvec kvec[1];
struct bio_vec bvec[1];
};
void *buffer; /* reply receive buffer */
void *reply[4]; /* Where to put the reply */
- pgoff_t first; /* first page in mapping to deal with */
- pgoff_t last; /* last page in mapping to deal with */
+ pgoff_t write_first; /* First page of write */
+ pgoff_t write_last; /* Last page of write */
atomic_t usage;
enum afs_call_state state;
spinlock_t state_lock;
@@ -111,15 +112,10 @@ struct afs_call {
u32 abort_code; /* Remote abort ID or 0 */
unsigned request_size; /* size of request data */
unsigned reply_max; /* maximum size of reply */
- unsigned first_offset; /* offset into mapping[first] */
unsigned int cb_break; /* cb_break + cb_s_break before the call */
- union {
- unsigned last_to; /* amount of mapping[last] */
- unsigned count2; /* count used in unmarshalling */
- };
+ unsigned count2; /* count used in unmarshalling */
unsigned char unmarshall; /* unmarshalling phase */
bool incoming; /* T if incoming call */
- bool send_pages; /* T if data from mapping should be sent */
bool need_attention; /* T if RxRPC poked us */
bool async; /* T if asynchronous */
bool ret_reply0; /* T if should return reply[0] on success */
@@ -798,8 +794,7 @@ extern int afs_fs_symlink(struct afs_fs_cursor *, const char *, const char *, u6
struct afs_fid *, struct afs_file_status *);
extern int afs_fs_rename(struct afs_fs_cursor *, const char *,
struct afs_vnode *, const char *, u64, u64);
-extern int afs_fs_store_data(struct afs_fs_cursor *, struct address_space *,
- pgoff_t, pgoff_t, unsigned, unsigned);
+extern int afs_fs_store_data(struct afs_fs_cursor *, struct iov_iter *, loff_t);
extern int afs_fs_setattr(struct afs_fs_cursor *, struct iattr *);
extern int afs_fs_get_volume_status(struct afs_fs_cursor *, struct afs_volume_status *);
extern int afs_fs_set_lock(struct afs_fs_cursor *, afs_lock_type_t);
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 09479677f11f..fa22739cbf4f 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -258,39 +258,6 @@ void afs_flat_call_destructor(struct afs_call *call)
call->buffer = NULL;
}

-#define AFS_BVEC_MAX 8
-
-/*
- * Load the given bvec with the next few pages.
- */
-static void afs_load_bvec(struct afs_call *call, struct msghdr *msg,
- struct bio_vec *bv, pgoff_t first, pgoff_t last,
- unsigned offset)
-{
- struct page *pages[AFS_BVEC_MAX];
- unsigned int nr, n, i, to, bytes = 0;
-
- nr = min_t(pgoff_t, last - first + 1, AFS_BVEC_MAX);
- n = find_get_pages_contig(call->mapping, first, nr, pages);
- ASSERTCMP(n, ==, nr);
-
- msg->msg_flags |= MSG_MORE;
- for (i = 0; i < nr; i++) {
- to = PAGE_SIZE;
- if (first + i >= last) {
- to = call->last_to;
- msg->msg_flags &= ~MSG_MORE;
- }
- bv[i].bv_page = pages[i];
- bv[i].bv_len = to - offset;
- bv[i].bv_offset = offset;
- bytes += to - offset;
- offset = 0;
- }
-
- iov_iter_bvec(&msg->msg_iter, WRITE, bv, nr, bytes);
-}
-
/*
* Advance the AFS call state when the RxRPC call ends the transmit phase.
*/
@@ -303,41 +270,6 @@ static void afs_notify_end_request_tx(struct sock *sock,
afs_set_call_state(call, AFS_CALL_CL_REQUESTING, AFS_CALL_CL_AWAIT_REPLY);
}

-/*
- * attach the data from a bunch of pages on an inode to a call
- */
-static int afs_send_pages(struct afs_call *call, struct msghdr *msg)
-{
- struct bio_vec bv[AFS_BVEC_MAX];
- unsigned int bytes, nr, loop, offset;
- pgoff_t first = call->first, last = call->last;
- int ret;
-
- offset = call->first_offset;
- call->first_offset = 0;
-
- do {
- afs_load_bvec(call, msg, bv, first, last, offset);
- trace_afs_send_pages(call, msg, first, last, offset);
-
- offset = 0;
- bytes = msg->msg_iter.count;
- nr = msg->msg_iter.nr_segs;
-
- ret = rxrpc_kernel_send_data(call->net->socket, call->rxcall, msg,
- bytes, afs_notify_end_request_tx);
- for (loop = 0; loop < nr; loop++)
- put_page(bv[loop].bv_page);
- if (ret < 0)
- break;
-
- first += nr;
- } while (first <= last);
-
- trace_afs_sent_pages(call, call->first, last, first, ret);
- return ret;
-}
-
/*
* initiate a call
*/
@@ -367,19 +299,8 @@ long afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call,
* after the initial fixed part.
*/
tx_total_len = call->request_size;
- if (call->send_pages) {
- if (call->last == call->first) {
- tx_total_len += call->last_to - call->first_offset;
- } else {
- /* It looks mathematically like you should be able to
- * combine the following lines with the ones above, but
- * unsigned arithmetic is fun when it wraps...
- */
- tx_total_len += PAGE_SIZE - call->first_offset;
- tx_total_len += call->last_to;
- tx_total_len += (call->last - call->first - 1) * PAGE_SIZE;
- }
- }
+ if (call->write_iter)
+ tx_total_len += iov_iter_count(call->write_iter);

/* create a call */
rxcall = rxrpc_kernel_begin_call(call->net->socket, srx, call->key,
@@ -406,7 +327,7 @@ long afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call,
iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, call->request_size);
msg.msg_control = NULL;
msg.msg_controllen = 0;
- msg.msg_flags = MSG_WAITALL | (call->send_pages ? MSG_MORE : 0);
+ msg.msg_flags = MSG_WAITALL | (call->write_iter ? MSG_MORE : 0);

ret = rxrpc_kernel_send_data(call->net->socket, rxcall,
&msg, call->request_size,
@@ -414,8 +335,18 @@ long afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call,
if (ret < 0)
goto error_do_abort;

- if (call->send_pages) {
- ret = afs_send_pages(call, &msg);
+ if (call->write_iter) {
+ msg.msg_iter = *call->write_iter;
+ msg.msg_flags &= ~MSG_MORE;
+ trace_afs_send_data(call, &msg);
+
+ ret = rxrpc_kernel_send_data(call->net->socket,
+ call->rxcall, &msg,
+ iov_iter_count(&msg.msg_iter),
+ afs_notify_end_request_tx);
+ *call->write_iter = msg.msg_iter;
+
+ trace_afs_sent_data(call, &msg, ret);
if (ret < 0)
goto error_do_abort;
}
diff --git a/fs/afs/write.c b/fs/afs/write.c
index ad3d706aa9e3..8ce5142f0f08 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -302,22 +302,21 @@ static void afs_redirty_pages(struct writeback_control *wbc,
/*
* write to a file
*/
-static int afs_store_data(struct address_space *mapping,
- pgoff_t first, pgoff_t last,
- unsigned offset, unsigned to)
+static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter,
+ loff_t pos)
{
- struct afs_vnode *vnode = AFS_FS_I(mapping->host);
struct afs_fs_cursor fc;
struct afs_wb_key *wbk = NULL;
struct list_head *p;
+ loff_t count = iov_iter_count(iter);
int ret = -ENOKEY, ret2;

- _enter("%s{%x:%u.%u},%lx,%lx,%x,%x",
+ _enter("%s{%x:%u.%u},%llx,%llx",
vnode->volume->name,
vnode->fid.vid,
vnode->fid.vnode,
vnode->fid.unique,
- first, last, offset, to);
+ count, pos);

spin_lock(&vnode->wb_lock);
p = vnode->wb_keys.next;
@@ -350,7 +349,7 @@ static int afs_store_data(struct address_space *mapping,
if (afs_begin_vnode_operation(&fc, vnode, wbk->key)) {
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(vnode);
- afs_fs_store_data(&fc, mapping, first, last, offset, to);
+ afs_fs_store_data(&fc, iter, pos);
}

afs_check_for_remote_deletion(&fc, fc.vnode);
@@ -361,9 +360,7 @@ static int afs_store_data(struct address_space *mapping,
switch (ret) {
case 0:
afs_stat_v(vnode, n_stores);
- atomic_long_add((last * PAGE_SIZE + to) -
- (first * PAGE_SIZE + offset),
- &afs_v2net(vnode)->n_store_bytes);
+ atomic_long_add(count, &afs_v2net(vnode)->n_store_bytes);
break;
case -EACCES:
case -EPERM:
@@ -393,10 +390,12 @@ 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 a, b;
int loop, ret;

_enter(",%lx", primary_page->index);
@@ -496,10 +495,17 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,

first = primary_page->index;
last = first + count - 1;
-
_debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);

- ret = afs_store_data(mapping, first, last, offset, to);
+ a = first;
+ a <<= PAGE_SHIFT;
+ a += offset;
+ b = last;
+ b <<= PAGE_SHIFT;
+ b += to;
+ iov_iter_mapping(&iter, WRITE, mapping, a, b - a);
+
+ ret = afs_store_data(vnode, &iter, a);
switch (ret) {
case 0:
ret = count;
@@ -668,36 +674,35 @@ int afs_writepages(struct address_space *mapping,
*/
void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
{
- struct pagevec pv;
+ struct radix_tree_iter iter;
+ struct address_space *mapping = vnode->vfs_inode.i_mapping;
unsigned long priv;
- unsigned count, loop;
- pgoff_t first = call->first, last = call->last;
+ pgoff_t cursor = call->write_first, last = call->write_last;
+ void __rcu **slot;

_enter("{%x:%u},{%lx-%lx}",
- vnode->fid.vid, vnode->fid.vnode, first, last);
+ vnode->fid.vid, vnode->fid.vnode, cursor, last);

- pagevec_init(&pv);
+ rcu_read_lock();

- do {
- _debug("done %lx-%lx", first, last);
+ radix_tree_for_each_contig(slot, &mapping->i_pages, &iter, cursor) {
+ struct page *page = radix_tree_deref_slot(slot);

- 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);
+ ASSERT(page);
+ ASSERT(PageWriteback(page));

- for (loop = 0; loop < count; loop++) {
- priv = page_private(pv.pages[loop]);
- trace_afs_page_dirty(vnode, tracepoint_string("clear"),
- pv.pages[loop]->index, priv);
- set_page_private(pv.pages[loop], 0);
- end_page_writeback(pv.pages[loop]);
- }
- first += count;
- __pagevec_release(&pv);
- } while (first <= last);
+ priv = page_private(page);
+ trace_afs_page_dirty(vnode, tracepoint_string("clear"),
+ page->index, priv);
+ set_page_private(page, 0);
+ page_endio(page, true, 0);
+
+ if (cursor >= last)
+ break;
+ cursor++;
+ }
+
+ rcu_read_unlock();

afs_prune_wb_keys(vnode);
_leave("");
@@ -829,6 +834,8 @@ 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;
@@ -844,9 +851,14 @@ int afs_launder_page(struct page *page)
t = priv >> AFS_PRIV_SHIFT;
}

+ 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->index, priv);
- ret = afs_store_data(mapping, page->index, page->index, t, f);
+ ret = afs_store_data(vnode, &iter, (loff_t)page->index << PAGE_SHIFT);
}

trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h
index 5e0f8dcede26..9c44245987b3 100644
--- a/include/trace/events/afs.h
+++ b/include/trace/events/afs.h
@@ -392,65 +392,52 @@ TRACE_EVENT(afs_call_done,
__entry->rx_call)
);

-TRACE_EVENT(afs_send_pages,
- TP_PROTO(struct afs_call *call, struct msghdr *msg,
- pgoff_t first, pgoff_t last, unsigned int offset),
+TRACE_EVENT(afs_send_data,
+ TP_PROTO(struct afs_call *call, struct msghdr *msg),

- TP_ARGS(call, msg, first, last, offset),
+ TP_ARGS(call, msg),

TP_STRUCT__entry(
__field(unsigned int, call )
- __field(pgoff_t, first )
- __field(pgoff_t, last )
- __field(unsigned int, nr )
- __field(unsigned int, bytes )
- __field(unsigned int, offset )
__field(unsigned int, flags )
+ __field(loff_t, offset )
+ __field(loff_t, count )
),

TP_fast_assign(
__entry->call = call->debug_id;
- __entry->first = first;
- __entry->last = last;
- __entry->nr = msg->msg_iter.nr_segs;
- __entry->bytes = msg->msg_iter.count;
- __entry->offset = offset;
__entry->flags = msg->msg_flags;
+ __entry->offset = msg->msg_iter.iov_offset;
+ __entry->count = iov_iter_count(&msg->msg_iter);
),

- TP_printk(" c=%08x %lx-%lx-%lx b=%x o=%x f=%x",
- __entry->call,
- __entry->first, __entry->first + __entry->nr - 1, __entry->last,
- __entry->bytes, __entry->offset,
+ TP_printk(" c=%08x o=%llx c=%llx f=%x",
+ __entry->call, __entry->offset, __entry->count,
__entry->flags)
);

-TRACE_EVENT(afs_sent_pages,
- TP_PROTO(struct afs_call *call, pgoff_t first, pgoff_t last,
- pgoff_t cursor, int ret),
+TRACE_EVENT(afs_sent_data,
+ TP_PROTO(struct afs_call *call, struct msghdr *msg, int ret),

- TP_ARGS(call, first, last, cursor, ret),
+ TP_ARGS(call, msg, ret),

TP_STRUCT__entry(
__field(unsigned int, call )
- __field(pgoff_t, first )
- __field(pgoff_t, last )
- __field(pgoff_t, cursor )
__field(int, ret )
+ __field(loff_t, offset )
+ __field(loff_t, count )
),

TP_fast_assign(
__entry->call = call->debug_id;
- __entry->first = first;
- __entry->last = last;
- __entry->cursor = cursor;
__entry->ret = ret;
+ __entry->offset = msg->msg_iter.iov_offset;
+ __entry->count = iov_iter_count(&msg->msg_iter);
),

- TP_printk(" c=%08x %lx-%lx c=%lx r=%d",
- __entry->call,
- __entry->first, __entry->last,
- __entry->cursor, __entry->ret)
+ TP_printk(" c=%08x o=%llx c=%llx r=%d",
+ __entry->call, __entry->offset, __entry->count,
+ __entry->ret)
);

TRACE_EVENT(afs_dir_check_failed,
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