CIFS: Fix rsize usage in readpages

If a server changes maximum buffer size for read (rsize) requests
on reconnect we can fail on repeating with a big size buffer on
-EAGAIN error in readpages. Fix this by checking rsize all the
time before repeating requests.

Reviewed-by: Shirish Pargaonkar <spargaonkar@suse.com>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 26 insertions, 15 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index bec48f1bc3ca..d6279185e2f0 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3349,6 +3349,8 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
         unsigned int expected_index;
         int rc;
 
+        INIT_LIST_HEAD(tmplist);
+
         page = list_entry(page_list->prev, struct page, lru);
 
         /*
@@ -3404,19 +3406,10 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
         struct list_head tmplist;
         struct cifsFileInfo *open_file = file->private_data;
         struct cifs_sb_info *cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
-        unsigned int rsize = cifs_sb->rsize;
+        struct TCP_Server_Info *server;
         pid_t pid;
 
         /*
-         * Give up immediately if rsize is too small to read an entire page.
-         * The VFS will fall back to readpage. We should never reach this
-         * point however since we set ra_pages to 0 when the rsize is smaller
-         * than a cache page.
-         */
-        if (unlikely(rsize < PAGE_CACHE_SIZE))
-                return 0;
-
-        /*
          * Reads as many pages as possible from fscache. Returns -ENOBUFS
          * immediately if the cookie is negative
          *
@@ -3434,7 +3427,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                 pid = current->tgid;
 
         rc = 0;
-        INIT_LIST_HEAD(&tmplist);
+        server = tlink_tcon(open_file->tlink)->ses->server;
 
         cifs_dbg(FYI, "%s: file=%p mapping=%p num_pages=%u\n",
                  __func__, file, mapping, num_pages);
@@ -3456,8 +3449,17 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                 struct page *page, *tpage;
                 struct cifs_readdata *rdata;
 
-                rc = readpages_get_pages(mapping, page_list, rsize, &tmplist,
-                                         &nr_pages, &offset, &bytes);
+                /*
+                 * Give up immediately if rsize is too small to read an entire
+                 * page. The VFS will fall back to readpage. We should never
+                 * reach this point however since we set ra_pages to 0 when the
+                 * rsize is smaller than a cache page.
+                 */
+                if (unlikely(cifs_sb->rsize < PAGE_CACHE_SIZE))
+                        return 0;
+
+                rc = readpages_get_pages(mapping, page_list, cifs_sb->rsize,
+                                         &tmplist, &nr_pages, &offset, &bytes);
                 if (rc)
                         break;
 
@@ -3487,15 +3489,24 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                         rdata->pages[rdata->nr_pages++] = page;
                 }
 
-                rc = cifs_retry_async_readv(rdata);
-                if (rc != 0) {
+                if (!rdata->cfile->invalidHandle ||
+                    !cifs_reopen_file(rdata->cfile, true))
+                        rc = server->ops->async_readv(rdata);
+                if (rc) {
                         for (i = 0; i < rdata->nr_pages; i++) {
                                 page = rdata->pages[i];
                                 lru_cache_add_file(page);
                                 unlock_page(page);
                                 page_cache_release(page);
+                                if (rc == -EAGAIN)
+                                        list_add_tail(&page->lru, &tmplist);
                         }
                         kref_put(&rdata->refcount, cifs_readdata_release);
+                        if (rc == -EAGAIN) {
+                                /* Re-add pages to the page_list and retry */
+                                list_splice(&tmplist, page_list);
+                                continue;
+                        }
                         break;
                 }