ceph: use pagelist to present MDS request data

Current code uses page array to present MDS request data. Pages in the
array are allocated/freed by caller of ceph_mdsc_do_request(). If request
is interrupted, the pages can be freed while they are still being used by
the request message.

The fix is use pagelist to present MDS request data. Pagelist is
reference counted.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

1 files changed, 18 insertions, 31 deletions

diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index 19da502..678b0d2 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -1,4 +1,5 @@
 #include <linux/ceph/ceph_debug.h>
+#include <linux/ceph/pagelist.h>
 
 #include "super.h"
 #include "mds_client.h"
@@ -850,35 +851,25 @@ static int ceph_sync_setxattr(struct dentry *dentry, const char *name,
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_mds_request *req;
 	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_pagelist *pagelist = NULL;
 	int err;
-	int i, nr_pages;
-	struct page **pages = NULL;
-	void *kaddr;
-
-	/* copy value into some pages */
-	nr_pages = calc_pages_for(0, size);
-	if (nr_pages) {
-		pages = kmalloc(sizeof(pages[0])*nr_pages, GFP_NOFS);
-		if (!pages)
+
+	if (value) {
+		/* copy value into pagelist */
+		pagelist = kmalloc(sizeof(*pagelist), GFP_NOFS);
+		if (!pagelist)
 			return -ENOMEM;
-		err = -ENOMEM;
-		for (i = 0; i < nr_pages; i++) {
-			pages[i] = __page_cache_alloc(GFP_NOFS);
-			if (!pages[i]) {
-				nr_pages = i;
-				goto out;
-			}
-			kaddr = kmap(pages[i]);
-			memcpy(kaddr, value + i*PAGE_CACHE_SIZE,
-			       min(PAGE_CACHE_SIZE, size-i*PAGE_CACHE_SIZE));
-		}
+
+		ceph_pagelist_init(pagelist);
+		err = ceph_pagelist_append(pagelist, value, size);
+		if (err)
+			goto out;
+	} else {
+		flags |= CEPH_XATTR_REMOVE;
 	}
 
 	dout("setxattr value=%.*s\n", (int)size, value);
 
-	if (!value)
-		flags |= CEPH_XATTR_REMOVE;
-
 	/* do request */
 	req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETXATTR,
 				       USE_AUTH_MDS);
@@ -893,9 +884,8 @@ static int ceph_sync_setxattr(struct dentry *dentry, const char *name,
 	req->r_args.setxattr.flags = cpu_to_le32(flags);
 	req->r_path2 = kstrdup(name, GFP_NOFS);
 
-	req->r_pages = pages;
-	req->r_num_pages = nr_pages;
-	req->r_data_len = size;
+	req->r_pagelist = pagelist;
+	pagelist = NULL;
 
 	dout("xattr.ver (before): %lld\n", ci->i_xattrs.version);
 	err = ceph_mdsc_do_request(mdsc, NULL, req);
@@ -903,11 +893,8 @@ static int ceph_sync_setxattr(struct dentry *dentry, const char *name,
 	dout("xattr.ver (after): %lld\n", ci->i_xattrs.version);
 
 out:
-	if (pages) {
-		for (i = 0; i < nr_pages; i++)
-			__free_page(pages[i]);
-		kfree(pages);
-	}
+	if (pagelist)
+		ceph_pagelist_release(pagelist);
 	return err;
 }