CIFS: Respect reconnect in MTU credits calculations

Every time after a session reconnect we don't need to account for
credits obtained in previous sessions. Introduce new struct cifs_credits
which contains both credits value and reconnect instance of the
time those credits were taken. Modify a routine that add credits
back to handle the reconnect instance by assuming zero credits
if the reconnect happened after the credits were obtained and
before we decided to add them back due to some errors during sending.

This patch fixes the MTU credits cases. The subsequent patch
will handle non-MTU ones.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 38 insertions, 24 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index da1f05f4ac0c..61b4dc7cfb91 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2143,11 +2143,13 @@ static int cifs_writepages(struct address_space *mapping,
 	server = cifs_sb_master_tcon(cifs_sb)->ses->server;
 retry:
 	while (!done && index <= end) {
-		unsigned int i, nr_pages, found_pages, wsize, credits;
+		unsigned int i, nr_pages, found_pages, wsize;
 		pgoff_t next = 0, tofind, saved_index = index;
+		struct cifs_credits credits_on_stack;
+		struct cifs_credits *credits = &credits_on_stack;
 
 		rc = server->ops->wait_mtu_credits(server, cifs_sb->wsize,
-						   &wsize, &credits);
+						   &wsize, credits);
 		if (rc != 0) {
 			done = true;
 			break;
@@ -2180,13 +2182,13 @@ retry:
 			continue;
 		}
 
-		wdata->credits = credits;
+		wdata->credits = credits_on_stack;
 
 		rc = wdata_send_pages(wdata, nr_pages, mapping, wbc);
 
 		/* send failure -- clean up the mess */
 		if (rc != 0) {
-			add_credits_and_wake_if(server, wdata->credits, 0);
+			add_credits_and_wake_if(server, &wdata->credits, 0);
 			for (i = 0; i < nr_pages; ++i) {
 				if (is_retryable_error(rc))
 					redirty_page_for_writepage(wbc,
@@ -2567,7 +2569,8 @@ static int
 cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
 	struct cifs_aio_ctx *ctx)
 {
-	unsigned int wsize, credits;
+	unsigned int wsize;
+	struct cifs_credits credits;
 	int rc;
 	struct TCP_Server_Info *server =
 		tlink_tcon(wdata->cfile->tlink)->ses->server;
@@ -2577,18 +2580,19 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
 	 * Note: we are attempting to resend the whole wdata not in segments
 	 */
 	do {
-		rc = server->ops->wait_mtu_credits(
-			server, wdata->bytes, &wsize, &credits);
+		rc = server->ops->wait_mtu_credits(server, wdata->bytes, &wsize,
+						   &credits);
 
 		if (rc)
 			goto out;
 
 		if (wsize < wdata->bytes) {
-			add_credits_and_wake_if(server, credits, 0);
+			add_credits_and_wake_if(server, &credits, 0);
 			msleep(1000);
 		}
 	} while (wsize < wdata->bytes);
 
+	wdata->credits = credits;
 	rc = -EAGAIN;
 	while (rc == -EAGAIN) {
 		rc = 0;
@@ -2604,7 +2608,7 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
 		return 0;
 	}
 
-	add_credits_and_wake_if(server, wdata->credits, 0);
+	add_credits_and_wake_if(server, &wdata->credits, 0);
 out:
 	kref_put(&wdata->refcount, cifs_uncached_writedata_release);
 
@@ -2627,6 +2631,7 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 	struct TCP_Server_Info *server;
 	struct page **pagevec;
 	size_t start;
+	unsigned int xid;
 
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
 		pid = open_file->pid;
@@ -2634,12 +2639,15 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 		pid = current->tgid;
 
 	server = tlink_tcon(open_file->tlink)->ses->server;
+	xid = get_xid();
 
 	do {
-		unsigned int wsize, credits;
+		unsigned int wsize;
+		struct cifs_credits credits_on_stack;
+		struct cifs_credits *credits = &credits_on_stack;
 
 		rc = server->ops->wait_mtu_credits(server, cifs_sb->wsize,
-						   &wsize, &credits);
+						   &wsize, credits);
 		if (rc)
 			break;
 
@@ -2731,7 +2739,7 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 		wdata->pid = pid;
 		wdata->bytes = cur_len;
 		wdata->pagesz = PAGE_SIZE;
-		wdata->credits = credits;
+		wdata->credits = credits_on_stack;
 		wdata->ctx = ctx;
 		kref_get(&ctx->refcount);
 
@@ -2740,7 +2748,7 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 			rc = server->ops->async_writev(wdata,
 					cifs_uncached_writedata_release);
 		if (rc) {
-			add_credits_and_wake_if(server, wdata->credits, 0);
+			add_credits_and_wake_if(server, &wdata->credits, 0);
 			kref_put(&wdata->refcount,
 				 cifs_uncached_writedata_release);
 			if (rc == -EAGAIN) {
@@ -2756,6 +2764,7 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 		len -= cur_len;
 	} while (len > 0);
 
+	free_xid(xid);
 	return rc;
 }
 
@@ -3260,7 +3269,8 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
 			struct list_head *rdata_list,
 			struct cifs_aio_ctx *ctx)
 {
-	unsigned int rsize, credits;
+	unsigned int rsize;
+	struct cifs_credits credits;
 	int rc;
 	struct TCP_Server_Info *server =
 		tlink_tcon(rdata->cfile->tlink)->ses->server;
@@ -3277,11 +3287,12 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
 			goto out;
 
 		if (rsize < rdata->bytes) {
-			add_credits_and_wake_if(server, credits, 0);
+			add_credits_and_wake_if(server, &credits, 0);
 			msleep(1000);
 		}
 	} while (rsize < rdata->bytes);
 
+	rdata->credits = credits;
 	rc = -EAGAIN;
 	while (rc == -EAGAIN) {
 		rc = 0;
@@ -3297,7 +3308,7 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
 		return 0;
 	}
 
-	add_credits_and_wake_if(server, rdata->credits, 0);
+	add_credits_and_wake_if(server, &rdata->credits, 0);
 out:
 	kref_put(&rdata->refcount,
 		cifs_uncached_readdata_release);
@@ -3311,7 +3322,9 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 		     struct cifs_aio_ctx *ctx)
 {
 	struct cifs_readdata *rdata;
-	unsigned int npages, rsize, credits;
+	unsigned int npages, rsize;
+	struct cifs_credits credits_on_stack;
+	struct cifs_credits *credits = &credits_on_stack;
 	size_t cur_len;
 	int rc;
 	pid_t pid;
@@ -3332,7 +3345,7 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 
 	do {
 		rc = server->ops->wait_mtu_credits(server, cifs_sb->rsize,
-						   &rsize, &credits);
+						   &rsize, credits);
 		if (rc)
 			break;
 
@@ -3406,7 +3419,7 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 		rdata->pagesz = PAGE_SIZE;
 		rdata->read_into_pages = cifs_uncached_read_into_pages;
 		rdata->copy_into_pages = cifs_uncached_copy_into_pages;
-		rdata->credits = credits;
+		rdata->credits = credits_on_stack;
 		rdata->ctx = ctx;
 		kref_get(&ctx->refcount);
 
@@ -3414,7 +3427,7 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 		    !(rc = cifs_reopen_file(rdata->cfile, true)))
 			rc = server->ops->async_readv(rdata);
 		if (rc) {
-			add_credits_and_wake_if(server, rdata->credits, 0);
+			add_credits_and_wake_if(server, &rdata->credits, 0);
 			kref_put(&rdata->refcount,
 				cifs_uncached_readdata_release);
 			if (rc == -EAGAIN) {
@@ -4093,10 +4106,11 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
 		loff_t offset;
 		struct page *page, *tpage;
 		struct cifs_readdata *rdata;
-		unsigned credits;
+		struct cifs_credits credits_on_stack;
+		struct cifs_credits *credits = &credits_on_stack;
 
 		rc = server->ops->wait_mtu_credits(server, cifs_sb->rsize,
-						   &rsize, &credits);
+						   &rsize, credits);
 		if (rc)
 			break;
 
@@ -4142,7 +4156,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
 		rdata->tailsz = PAGE_SIZE;
 		rdata->read_into_pages = cifs_readpages_read_into_pages;
 		rdata->copy_into_pages = cifs_readpages_copy_into_pages;
-		rdata->credits = credits;
+		rdata->credits = credits_on_stack;
 
 		list_for_each_entry_safe(page, tpage, &tmplist, lru) {
 			list_del(&page->lru);
@@ -4153,7 +4167,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
 		    !(rc = cifs_reopen_file(rdata->cfile, true)))
 			rc = server->ops->async_readv(rdata);
 		if (rc) {
-			add_credits_and_wake_if(server, rdata->credits, 0);
+			add_credits_and_wake_if(server, &rdata->credits, 0);
 			for (i = 0; i < rdata->nr_pages; i++) {
 				page = rdata->pages[i];
 				lru_cache_add_file(page);