ceph: try getting buffer capability for readahead/fadvise
For readahead/fadvise cases, caller of ceph_readpages does not
hold buffer capability. Pages can be added to page cache while
there is no buffer capability. This can cause data integrity
issue.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index ef3ebd7..dbb5f7d 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -315,7 +315,32 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
struct page **pages;
pgoff_t next_index;
int nr_pages = 0;
- int ret;
+ int got = 0;
+ int ret = 0;
+
+ if (!current->journal_info) {
+ /* caller of readpages does not hold buffer and read caps
+ * (fadvise, madvise and readahead cases) */
+ int want = CEPH_CAP_FILE_CACHE;
+ ret = ceph_try_get_caps(ci, CEPH_CAP_FILE_RD, want, &got);
+ if (ret < 0) {
+ dout("start_read %p, error getting cap\n", inode);
+ } else if (!(got & want)) {
+ dout("start_read %p, no cache cap\n", inode);
+ ret = 0;
+ }
+ if (ret <= 0) {
+ if (got)
+ ceph_put_cap_refs(ci, got);
+ while (!list_empty(page_list)) {
+ page = list_entry(page_list->prev,
+ struct page, lru);
+ list_del(&page->lru);
+ put_page(page);
+ }
+ return ret;
+ }
+ }
off = (u64) page_offset(page);
@@ -338,15 +363,18 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
CEPH_OSD_FLAG_READ, NULL,
ci->i_truncate_seq, ci->i_truncate_size,
false);
- if (IS_ERR(req))
- return PTR_ERR(req);
+ if (IS_ERR(req)) {
+ ret = PTR_ERR(req);
+ goto out;
+ }
/* build page vector */
nr_pages = calc_pages_for(0, len);
pages = kmalloc(sizeof(*pages) * nr_pages, GFP_KERNEL);
- ret = -ENOMEM;
- if (!pages)
- goto out;
+ if (!pages) {
+ ret = -ENOMEM;
+ goto out_put;
+ }
for (i = 0; i < nr_pages; ++i) {
page = list_entry(page_list->prev, struct page, lru);
BUG_ON(PageLocked(page));
@@ -378,6 +406,12 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
if (ret < 0)
goto out_pages;
ceph_osdc_put_request(req);
+
+ /* After adding locked pages to page cache, the inode holds cache cap.
+ * So we can drop our cap refs. */
+ if (got)
+ ceph_put_cap_refs(ci, got);
+
return nr_pages;
out_pages:
@@ -386,8 +420,11 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
unlock_page(pages[i]);
}
ceph_put_page_vector(pages, nr_pages, false);
-out:
+out_put:
ceph_osdc_put_request(req);
+out:
+ if (got)
+ ceph_put_cap_refs(ci, got);
return ret;
}
@@ -424,7 +461,6 @@ static int ceph_readpages(struct file *file, struct address_space *mapping,
rc = start_read(inode, page_list, max);
if (rc < 0)
goto out;
- BUG_ON(rc == 0);
}
out:
ceph_fscache_readpages_cancel(inode, page_list);
@@ -1371,9 +1407,11 @@ static int ceph_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
inode, off, (size_t)PAGE_SIZE, ceph_cap_string(got));
if ((got & (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO)) ||
- ci->i_inline_version == CEPH_INLINE_NONE)
+ ci->i_inline_version == CEPH_INLINE_NONE) {
+ current->journal_info = vma->vm_file;
ret = filemap_fault(vma, vmf);
- else
+ current->journal_info = NULL;
+ } else
ret = -EAGAIN;
dout("filemap_fault %p %llu~%zd dropping cap refs on %s ret %d\n",