CIFS: Adjust MTU credits before reopening a file

Currently we adjust MTU credits before sending an IO request
and after reopening a file. This approach doesn't allow the
reopen routine to use existing credits that are not needed
for IO. Reorder credit adjustment and reopening a file to
use credits available to the client more efficiently. Also
unwrap complex if statement into few pieces to improve
readability.

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

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 84ce388..f293e05 100644 (file)
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -457,6 +457,10 @@ struct smb_version_operations {
        /* get mtu credits */
        int (*wait_mtu_credits)(struct TCP_Server_Info *, unsigned int,
                                unsigned int *, struct cifs_credits *);
+       /* adjust previously taken mtu credits to request size */
+       int (*adjust_credits)(struct TCP_Server_Info *server,
+                             struct cifs_credits *credits,
+                             const unsigned int payload_size);
        /* check if we need to issue closedir */
        bool (*dir_needs_close)(struct cifsFileInfo *);
        long (*fallocate)(struct file *, struct cifs_tcon *, int, loff_t,
@@ -763,6 +767,14 @@ set_credits(struct TCP_Server_Info *server, const int val)
        server->ops->set_credits(server, val);
 }
 
+static inline int
+adjust_credits(struct TCP_Server_Info *server, struct cifs_credits *credits,
+              const unsigned int payload_size)
+{
+       return server->ops->adjust_credits ?
+               server->ops->adjust_credits(server, credits, payload_size) : 0;
+}
+
 static inline __le64
 get_next_mid64(struct TCP_Server_Info *server)
 {

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 61b4dc7..67b361a 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2076,11 +2076,11 @@ wdata_prepare_pages(struct cifs_writedata *wdata, unsigned int found_pages,
 }
 
 static int
-wdata_send_pages(struct cifs_writedata *wdata, unsigned int nr_pages,
-                struct address_space *mapping, struct writeback_control *wbc)
+wdata_send_pages(struct TCP_Server_Info *server, struct cifs_writedata *wdata,
+                unsigned int nr_pages, struct address_space *mapping,
+                struct writeback_control *wbc)
 {
        int rc = 0;
-       struct TCP_Server_Info *server;
        unsigned int i;
 
        wdata->sync_mode = wbc->sync_mode;
@@ -2092,6 +2092,10 @@ wdata_send_pages(struct cifs_writedata *wdata, unsigned int nr_pages,
                        (loff_t)PAGE_SIZE);
        wdata->bytes = ((nr_pages - 1) * PAGE_SIZE) + wdata->tailsz;
 
+       rc = adjust_credits(server, &wdata->credits, wdata->bytes);
+       if (rc)
+               goto send_pages_out;
+
        if (wdata->cfile != NULL)
                cifsFileInfo_put(wdata->cfile);
        wdata->cfile = find_writable_file(CIFS_I(mapping->host), false);
@@ -2100,10 +2104,10 @@ wdata_send_pages(struct cifs_writedata *wdata, unsigned int nr_pages,
                rc = -EBADF;
        } else {
                wdata->pid = wdata->cfile->pid;
-               server = tlink_tcon(wdata->cfile->tlink)->ses->server;
                rc = server->ops->async_writev(wdata, cifs_writedata_release);
        }
 
+send_pages_out:
        for (i = 0; i < nr_pages; ++i)
                unlock_page(wdata->pages[i]);
 
@@ -2184,7 +2188,7 @@ retry:
 
                wdata->credits = credits_on_stack;
 
-               rc = wdata_send_pages(wdata, nr_pages, mapping, wbc);
+               rc = wdata_send_pages(server, wdata, nr_pages, mapping, wbc);
 
                /* send failure -- clean up the mess */
                if (rc != 0) {
@@ -2743,10 +2747,17 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
                wdata->ctx = ctx;
                kref_get(&ctx->refcount);
 
-               if (!wdata->cfile->invalidHandle ||
-                   !(rc = cifs_reopen_file(wdata->cfile, false)))
-                       rc = server->ops->async_writev(wdata,
+               rc = adjust_credits(server, &wdata->credits, wdata->bytes);
+
+               if (!rc) {
+                       if (wdata->cfile->invalidHandle)
+                               rc = cifs_reopen_file(wdata->cfile, false);
+
+                       if (!rc)
+                               rc = server->ops->async_writev(wdata,
                                        cifs_uncached_writedata_release);
+               }
+
                if (rc) {
                        add_credits_and_wake_if(server, &wdata->credits, 0);
                        kref_put(&wdata->refcount,
@@ -3423,9 +3434,16 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
                rdata->ctx = ctx;
                kref_get(&ctx->refcount);
 
-               if (!rdata->cfile->invalidHandle ||
-                   !(rc = cifs_reopen_file(rdata->cfile, true)))
-                       rc = server->ops->async_readv(rdata);
+               rc = adjust_credits(server, &rdata->credits, rdata->bytes);
+
+               if (!rc) {
+                       if (rdata->cfile->invalidHandle)
+                               rc = cifs_reopen_file(rdata->cfile, true);
+
+                       if (!rc)
+                               rc = server->ops->async_readv(rdata);
+               }
+
                if (rc) {
                        add_credits_and_wake_if(server, &rdata->credits, 0);
                        kref_put(&rdata->refcount,
@@ -4163,9 +4181,16 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                        rdata->pages[rdata->nr_pages++] = page;
                }
 
-               if (!rdata->cfile->invalidHandle ||
-                   !(rc = cifs_reopen_file(rdata->cfile, true)))
-                       rc = server->ops->async_readv(rdata);
+               rc = adjust_credits(server, &rdata->credits, rdata->bytes);
+
+               if (!rc) {
+                       if (rdata->cfile->invalidHandle)
+                               rc = cifs_reopen_file(rdata->cfile, true);
+
+                       if (!rc)
+                               rc = server->ops->async_readv(rdata);
+               }
+
                if (rc) {
                        add_credits_and_wake_if(server, &rdata->credits, 0);
                        for (i = 0; i < rdata->nr_pages; i++) {

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 6f1a5f5..085e914 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -222,6 +222,38 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
        return rc;
 }
 
+static int
+smb2_adjust_credits(struct TCP_Server_Info *server,
+                   struct cifs_credits *credits,
+                   const unsigned int payload_size)
+{
+       int new_val = DIV_ROUND_UP(payload_size, SMB2_MAX_BUFFER_SIZE);
+
+       if (!credits->value || credits->value == new_val)
+               return 0;
+
+       if (credits->value < new_val) {
+               WARN_ONCE(1, "request has less credits (%d) than required (%d)",
+                         credits->value, new_val);
+               return -ENOTSUPP;
+       }
+
+       spin_lock(&server->req_lock);
+
+       if (server->reconnect_instance != credits->instance) {
+               spin_unlock(&server->req_lock);
+               cifs_dbg(VFS, "trying to return %d credits to old session\n",
+                        credits->value - new_val);
+               return -EAGAIN;
+       }
+
+       server->credits += credits->value - new_val;
+       spin_unlock(&server->req_lock);
+       wake_up(&server->request_q);
+       credits->value = new_val;
+       return 0;
+}
+
 static __u64
 smb2_get_next_mid(struct TCP_Server_Info *server)
 {
@@ -3678,6 +3710,7 @@ struct smb_version_operations smb21_operations = {
        .get_credits_field = smb2_get_credits_field,
        .get_credits = smb2_get_credits,
        .wait_mtu_credits = smb2_wait_mtu_credits,
+       .adjust_credits = smb2_adjust_credits,
        .get_next_mid = smb2_get_next_mid,
        .revert_current_mid = smb2_revert_current_mid,
        .read_data_offset = smb2_read_data_offset,
@@ -3775,6 +3808,7 @@ struct smb_version_operations smb30_operations = {
        .get_credits_field = smb2_get_credits_field,
        .get_credits = smb2_get_credits,
        .wait_mtu_credits = smb2_wait_mtu_credits,
+       .adjust_credits = smb2_adjust_credits,
        .get_next_mid = smb2_get_next_mid,
        .revert_current_mid = smb2_revert_current_mid,
        .read_data_offset = smb2_read_data_offset,
@@ -3881,6 +3915,7 @@ struct smb_version_operations smb311_operations = {
        .get_credits_field = smb2_get_credits_field,
        .get_credits = smb2_get_credits,
        .wait_mtu_credits = smb2_wait_mtu_credits,
+       .adjust_credits = smb2_adjust_credits,
        .get_next_mid = smb2_get_next_mid,
        .revert_current_mid = smb2_revert_current_mid,
        .read_data_offset = smb2_read_data_offset,

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 7105312..7d1e069 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3322,21 +3322,11 @@ smb2_async_readv(struct cifs_readdata *rdata)
                                                SMB2_MAX_BUFFER_SIZE));
                shdr->CreditRequest =
                        cpu_to_le16(le16_to_cpu(shdr->CreditCharge) + 1);
-               spin_lock(&server->req_lock);
-               if (server->reconnect_instance == rdata->credits.instance)
-                       server->credits += rdata->credits.value -
-                                               le16_to_cpu(shdr->CreditCharge);
-               else {
-                       spin_unlock(&server->req_lock);
-                       cifs_dbg(VFS, "trying to return %u credits to old session\n",
-                                rdata->credits.value
-                                - le16_to_cpu(shdr->CreditCharge));
-                       rc = -EAGAIN;
+
+               rc = adjust_credits(server, &rdata->credits, rdata->bytes);
+               if (rc)
                        goto async_readv_out;
-               }
-               spin_unlock(&server->req_lock);
-               wake_up(&server->request_q);
-               rdata->credits.value = le16_to_cpu(shdr->CreditCharge);
+
                flags |= CIFS_HAS_CREDITS;
        }
 
@@ -3626,21 +3616,11 @@ smb2_async_writev(struct cifs_writedata *wdata,
                                                    SMB2_MAX_BUFFER_SIZE));
                shdr->CreditRequest =
                        cpu_to_le16(le16_to_cpu(shdr->CreditCharge) + 1);
-               spin_lock(&server->req_lock);
-               if (server->reconnect_instance == wdata->credits.instance)
-                       server->credits += wdata->credits.value -
-                                               le16_to_cpu(shdr->CreditCharge);
-               else {
-                       spin_unlock(&server->req_lock);
-                       cifs_dbg(VFS, "trying to return %d credits to old session\n",
-                                wdata->credits.value
-                                - le16_to_cpu(shdr->CreditCharge));
-                       rc = -EAGAIN;
+
+               rc = adjust_credits(server, &wdata->credits, wdata->bytes);
+               if (rc)
                        goto async_writev_out;
-               }
-               spin_unlock(&server->req_lock);
-               wake_up(&server->request_q);
-               wdata->credits.value = le16_to_cpu(shdr->CreditCharge);
+
                flags |= CIFS_HAS_CREDITS;
        }