ceph: fetch inline data when getting Fcr cap refs

we can't use getattr to fetch inline data after getting Fcr caps,
because it can cause deadlock. The solution is try bringing inline
data to page cache when not holding any cap, and hope the inline
data page is still there after getting the Fcr caps. If the page
is still there, pin it in page cache for later IO.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 4a3f55f27ab4..5d2b88e3ff0b 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1207,6 +1207,7 @@ static int ceph_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
         struct inode *inode = file_inode(vma->vm_file);
         struct ceph_inode_info *ci = ceph_inode(inode);
         struct ceph_file_info *fi = vma->vm_file->private_data;
+        struct page *pinned_page = NULL;
         loff_t off = vmf->pgoff << PAGE_CACHE_SHIFT;
         int want, got, ret;
 
@@ -1218,7 +1219,8 @@ static int ceph_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
                 want = CEPH_CAP_FILE_CACHE;
         while (1) {
                 got = 0;
-                ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, &got, -1);
+                ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, -1,
+                                    &got, &pinned_page);
                 if (ret == 0)
                         break;
                 if (ret != -ERESTARTSYS) {
@@ -1233,6 +1235,8 @@ static int ceph_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 
         dout("filemap_fault %p %llu~%zd dropping cap refs on %s ret %d\n",
              inode, off, (size_t)PAGE_CACHE_SIZE, ceph_cap_string(got), ret);
+        if (pinned_page)
+                page_cache_release(pinned_page);
         ceph_put_cap_refs(ci, got);
 
         return ret;
@@ -1266,7 +1270,8 @@ static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
                 want = CEPH_CAP_FILE_BUFFER;
         while (1) {
                 got = 0;
-                ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, &got, off + len);
+                ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, off + len,
+                                    &got, NULL);
                 if (ret == 0)
                         break;
                 if (ret != -ERESTARTSYS) {