ceph: avoid 32-bit page index overflow

A pgoff_t is defined (by default) to have type (unsigned long).  On
architectures such as i686 that's a 32-bit type.  The ceph address
space code was attempting to produce 64 bit offsets by shifting a
page's index by PAGE_CACHE_SHIFT, but the result was not what was
desired because the shift occurred before the result got promoted
to 64 bits.

Fix this by converting all uses of page->index used in this way to
use the page_offset() macro, which ensures the 64-bit result has the
intended value.

This fixes http://tracker.newdream.net/issues/3112

Reported-by:  Mohamed Pakkeer <pakkeer.mohideen@realimage.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 4469b63..22b6e45 100644 (file)
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -205,7 +205,7 @@ static int readpage_nounlock(struct file *filp, struct page *page)
        dout("readpage inode %p file %p page %p index %lu\n",
             inode, filp, page, page->index);
        err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
-                                 page->index << PAGE_CACHE_SHIFT, &len,
+                                 (u64) page_offset(page), &len,
                                  ci->i_truncate_seq, ci->i_truncate_size,
                                  &page, 1, 0);
        if (err == -ENOENT)
@@ -286,7 +286,7 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
        int nr_pages = 0;
        int ret;
 
-       off = page->index << PAGE_CACHE_SHIFT;
+       off = (u64) page_offset(page);
 
        /* count pages */
        next_index = page->index;
@@ -426,7 +426,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
        struct ceph_inode_info *ci;
        struct ceph_fs_client *fsc;
        struct ceph_osd_client *osdc;
-       loff_t page_off = page->index << PAGE_CACHE_SHIFT;
+       loff_t page_off = page_offset(page);
        int len = PAGE_CACHE_SIZE;
        loff_t i_size;
        int err = 0;
@@ -817,8 +817,7 @@ get_more_pages:
                        /* ok */
                        if (locked_pages == 0) {
                                /* prepare async write request */
-                               offset = (unsigned long long)page->index
-                                       << PAGE_CACHE_SHIFT;
+                               offset = (u64) page_offset(page);
                                len = wsize;
                                req = ceph_osdc_new_request(&fsc->client->osdc,
                                            &ci->i_layout,
@@ -1180,7 +1179,7 @@ static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
        struct inode *inode = vma->vm_file->f_dentry->d_inode;
        struct page *page = vmf->page;
        struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
-       loff_t off = page->index << PAGE_CACHE_SHIFT;
+       loff_t off = page_offset(page);
        loff_t size, len;
        int ret;