[PATCH 26/26] netfs, afs: Use writeback retry to deal with alternate keys

David Howells
2024-03-28T16:39:14Z

Use a hook in the new writeback code's retry algorithm to rotate the keys
once all the outstanding subreqs have failed rather than doing it
separately on each subreq.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-afs@lists.infradead.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
fs/afs/file.c | 1 +
fs/afs/internal.h | 1 +
fs/afs/write.c | 175 +++++++++++++++++++--------------------
fs/netfs/write_collect.c | 9 +-
include/linux/netfs.h | 2 +
5 files changed, 96 insertions(+), 92 deletions(-)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 8f983e3ecae7..c3f0c45ae9a9 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -368,6 +368,7 @@ static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
static void afs_free_request(struct netfs_io_request *rreq)
{
key_put(rreq->netfs_priv);
+ afs_put_wb_key(rreq->netfs_priv2);
}

static void afs_update_i_size(struct inode *inode, loff_t new_i_size)
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 887245f9336d..6e1d3c4daf72 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1601,6 +1601,7 @@ extern int afs_check_volume_status(struct afs_volume *, struct afs_operation *);
void afs_prepare_write(struct netfs_io_subrequest *subreq);
void afs_issue_write(struct netfs_io_subrequest *subreq);
void afs_begin_writeback(struct netfs_io_request *wreq);
+void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
extern int afs_writepages(struct address_space *, struct writeback_control *);
extern int afs_fsync(struct file *, loff_t, loff_t, int);
extern vm_fault_t afs_page_mkwrite(struct vm_fault *vmf);
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 6ef7d4cbc008..838db2e94388 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -29,43 +29,39 @@ static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsign

/*
* Find a key to use for the writeback. We cached the keys used to author the
- * writes on the vnode. *_wbk will contain the last writeback key used or NULL
- * and we need to start from there if it's set.
+ * writes on the vnode. wreq->netfs_priv2 will contain the last writeback key
+ * record used or NULL and we need to start from there if it's set.
+ * wreq->netfs_priv will be set to the key itself or NULL.
*/
-static int afs_get_writeback_key(struct afs_vnode *vnode,
- struct afs_wb_key **_wbk)
+static void afs_get_writeback_key(struct netfs_io_request *wreq)
{
- struct afs_wb_key *wbk = NULL;
- struct list_head *p;
- int ret = -ENOKEY, ret2;
+ struct afs_wb_key *wbk, *old = wreq->netfs_priv2;
+ struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
+
+ key_put(wreq->netfs_priv);
+ wreq->netfs_priv = NULL;
+ wreq->netfs_priv2 = NULL;

spin_lock(&vnode->wb_lock);
- if (*_wbk)
- p = (*_wbk)->vnode_link.next;
+ if (old)
+ wbk = list_next_entry(old, vnode_link);
else
- p = vnode->wb_keys.next;
+ wbk = list_first_entry(&vnode->wb_keys, struct afs_wb_key, vnode_link);

- while (p != &vnode->wb_keys) {
- wbk = list_entry(p, struct afs_wb_key, vnode_link);
+ list_for_each_entry_from(wbk, &vnode->wb_keys, vnode_link) {
_debug("wbk %u", key_serial(wbk->key));
- ret2 = key_validate(wbk->key);
- if (ret2 == 0) {
+ if (key_validate(wbk->key) == 0) {
refcount_inc(&wbk->usage);
+ wreq->netfs_priv = key_get(wbk->key);
+ wreq->netfs_priv2 = wbk;
_debug("USE WB KEY %u", key_serial(wbk->key));
break;
}
-
- wbk = NULL;
- if (ret == -ENOKEY)
- ret = ret2;
- p = p->next;
}

spin_unlock(&vnode->wb_lock);
- if (*_wbk)
- afs_put_wb_key(*_wbk);
- *_wbk = wbk;
- return 0;
+
+ afs_put_wb_key(old);
}

static void afs_store_data_success(struct afs_operation *op)
@@ -88,72 +84,83 @@ static const struct afs_operation_ops afs_store_data_operation = {
};

/*
- * write to a file
+ * Prepare a subrequest to write to the server. This sets the max_len
+ * parameter.
*/
-static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos)
+void afs_prepare_write(struct netfs_io_subrequest *subreq)
+{
+ //if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags))
+ // subreq->max_len = 512 * 1024;
+ //else
+ subreq->max_len = 256 * 1024 * 1024;
+}
+
+/*
+ * Issue a subrequest to write to the server.
+ */
+void afs_issue_write(struct netfs_io_subrequest *subreq)
{
+ struct netfs_io_request *wreq = subreq->rreq;
struct afs_operation *op;
- struct afs_wb_key *wbk = NULL;
- loff_t size = iov_iter_count(iter);
+ struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
+ unsigned long long pos = subreq->start + subreq->transferred;
+ size_t len = subreq->len - subreq->transferred;
int ret = -ENOKEY;

- _enter("%s{%llx:%llu.%u},%llx,%llx",
+ _enter("R=%x[%x],%s{%llx:%llu.%u},%llx,%zx",
+ wreq->debug_id, subreq->debug_index,
vnode->volume->name,
vnode->fid.vid,
vnode->fid.vnode,
vnode->fid.unique,
- size, pos);
+ pos, len);

- ret = afs_get_writeback_key(vnode, &wbk);
- if (ret) {
- _leave(" = %d [no keys]", ret);
- return ret;
- }
+#if 0 // Error injection
+ if (subreq->debug_index == 3)
+ return netfs_write_subrequest_terminated(subreq, -ENOANO, false);

- op = afs_alloc_operation(wbk->key, vnode->volume);
- if (IS_ERR(op)) {
- afs_put_wb_key(wbk);
- return -ENOMEM;
+ if (!test_bit(NETFS_SREQ_RETRYING, &subreq->flags)) {
+ set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+ return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
}
+#endif
+
+ op = afs_alloc_operation(wreq->netfs_priv, vnode->volume);
+ if (IS_ERR(op))
+ return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);

afs_op_set_vnode(op, 0, vnode);
- op->file[0].dv_delta = 1;
+ op->file[0].dv_delta = 1;
op->file[0].modification = true;
- op->store.pos = pos;
- op->store.size = size;
- op->flags |= AFS_OPERATION_UNINTR;
- op->ops = &afs_store_data_operation;
+ op->store.pos = pos;
+ op->store.size = len,
+ op->flags |= AFS_OPERATION_UNINTR;
+ op->ops = &afs_store_data_operation;

-try_next_key:
afs_begin_vnode_operation(op);

- op->store.write_iter = iter;
- op->store.i_size = max(pos + size, vnode->netfs.remote_i_size);
- op->mtime = inode_get_mtime(&vnode->netfs.inode);
+ op->store.write_iter = &subreq->io_iter;
+ op->store.i_size = umax(pos + len, vnode->netfs.remote_i_size);
+ op->mtime = inode_get_mtime(&vnode->netfs.inode);

afs_wait_for_operation(op);
-
- switch (afs_op_error(op)) {
+ ret = afs_put_operation(op);
+ switch (ret) {
case -EACCES:
case -EPERM:
case -ENOKEY:
case -EKEYEXPIRED:
case -EKEYREJECTED:
case -EKEYREVOKED:
- _debug("next");
-
- ret = afs_get_writeback_key(vnode, &wbk);
- if (ret == 0) {
- key_put(op->key);
- op->key = key_get(wbk->key);
- goto try_next_key;
- }
+ /* If there are more keys we can try, use the retry algorithm
+ * to rotate the keys.
+ */
+ if (wreq->netfs_priv2)
+ set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
break;
}

- afs_put_wb_key(wbk);
- _leave(" = %d", afs_op_error(op));
- return afs_put_operation(op);
+ netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, false);
}

/*
@@ -162,44 +169,32 @@ static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t
*/
void afs_begin_writeback(struct netfs_io_request *wreq)
{
+ afs_get_writeback_key(wreq);
wreq->io_streams[0].avail = true;
}

/*
- * Prepare a subrequest to write to the server. This sets the max_len
- * parameter.
- */
-void afs_prepare_write(struct netfs_io_subrequest *subreq)
-{
- //if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags))
- // subreq->max_len = 512 * 1024;
- //else
- subreq->max_len = 256 * 1024 * 1024;
-}
-
-/*
- * Issue a subrequest to write to the server.
+ * Prepare to retry the writes in request. Use this to try rotating the
+ * available writeback keys.
*/
-void afs_issue_write(struct netfs_io_subrequest *subreq)
+void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream)
{
- struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
- ssize_t ret;
-
- _enter("%x[%x],%zx",
- subreq->rreq->debug_id, subreq->debug_index, subreq->io_iter.count);
-
-#if 0 // Error injection
- if (subreq->debug_index == 3)
- return netfs_write_subrequest_terminated(subreq, -ENOANO, false);
+ struct netfs_io_subrequest *subreq =
+ list_first_entry(&stream->subrequests,
+ struct netfs_io_subrequest, rreq_link);

- if (!test_bit(NETFS_SREQ_RETRYING, &subreq->flags)) {
- set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
- return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
+ switch (subreq->error) {
+ case -EACCES:
+ case -EPERM:
+ case -ENOKEY:
+ case -EKEYEXPIRED:
+ case -EKEYREJECTED:
+ case -EKEYREVOKED:
+ afs_get_writeback_key(wreq);
+ if (!wreq->netfs_priv)
+ stream->failed = true;
+ break;
}
-#endif
-
- ret = afs_store_data(vnode, &subreq->io_iter, subreq->start);
- netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, false);
}

/*
diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c
index bea939ab0830..7ff15e2d7270 100644
--- a/fs/netfs/write_collect.c
+++ b/fs/netfs/write_collect.c
@@ -168,6 +168,13 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq,

_enter("R=%x[%x:]", wreq->debug_id, stream->stream_nr);

+ if (list_empty(&stream->subrequests))
+ return;
+
+ if (stream->source == NETFS_UPLOAD_TO_SERVER &&
+ wreq->netfs_ops->retry_request)
+ wreq->netfs_ops->retry_request(wreq, stream);
+
if (unlikely(stream->failed))
return;

@@ -187,8 +194,6 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq,
return;
}

- if (list_empty(&stream->subrequests))
- return;
next = stream->subrequests.next;

do {
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index c2ba364041b0..298552f5122c 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -235,6 +235,7 @@ struct netfs_io_request {
struct iov_iter iter; /* Unencrypted-side iterator */
struct iov_iter io_iter; /* I/O (Encrypted-side) iterator */
void *netfs_priv; /* Private data for the netfs */
+ void *netfs_priv2; /* Private data for the netfs */
struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */
unsigned int direct_bv_count; /* Number of elements in direct_bv[] */
unsigned int debug_id;
@@ -306,6 +307,7 @@ struct netfs_request_ops {
void (*begin_writeback)(struct netfs_io_request *wreq);
void (*prepare_write)(struct netfs_io_subrequest *subreq);
void (*issue_write)(struct netfs_io_subrequest *subreq);
+ void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
void (*invalidate_cache)(struct netfs_io_request *wreq);
};