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>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index bec48f1bc3cab7d8c29092bb1f7462b6c79096a1..d6279185e2f0bb6caa525f83eb92f7791e5c6ea7 100644 (file)
--- 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);
 
        /*
@@ -3404,18 +3406,9 @@ 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;
                }