ceph: add non-blocking parameter to ceph_try_get_caps()

ceph_try_get_caps currently calls try_get_cap_refs with the nonblock
parameter always set to 'true'.  This change adds a new parameter that
allows to set it's value.  This will be useful for a follow-up patch that
will need to get two sets of capabilities for two different inodes without
risking a deadlock.
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/addr.c

@@ -322,7 +322,7 @@ static int start_read(struct inode *inode, struct ceph_rw_context *rw_ctx,
 		/* 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);
+		ret = ceph_try_get_caps(ci, CEPH_CAP_FILE_RD, want, true, &got);
 		if (ret < 0) {
 			dout("start_read %p, error getting cap\n", inode);
 		} else if (!(got & want)) {

fs/ceph/caps.c

@@ -2673,17 +2673,18 @@ static void check_max_size(struct inode *inode, loff_t endoff)
 		ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
 }
 
-int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want, int *got)
+int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want,
+		      bool nonblock, int *got)
 {
 	int ret, err = 0;
 
 	BUG_ON(need & ~CEPH_CAP_FILE_RD);
-	BUG_ON(want & ~(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO));
+	BUG_ON(want & ~(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO|CEPH_CAP_FILE_SHARED));
 	ret = ceph_pool_perm_check(ci, need);
 	if (ret < 0)
 		return ret;
 
-	ret = try_get_cap_refs(ci, need, want, 0, true, got, &err);
+	ret = try_get_cap_refs(ci, need, want, 0, nonblock, got, &err);
 	if (ret) {
 		if (err == -EAGAIN) {
 			ret = 0;

fs/ceph/super.h

@@ -1008,7 +1008,7 @@ extern int ceph_encode_dentry_release(void **p, struct dentry *dn,
 extern int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
 			 loff_t endoff, int *got, struct page **pinned_page);
 extern int ceph_try_get_caps(struct ceph_inode_info *ci,
-			     int need, int want, int *got);
+			     int need, int want, bool nonblock, int *got);
 
 /* for counting open files by mode */
 extern void __ceph_get_fmode(struct ceph_inode_info *ci, int mode);