ceph: simplify arguments and return semantics of try_get_cap_refs

The return of this function is rather complex. It can return 0 or 1,
and in the case of a 1 return, the "err" pointer will be filled out.
This necessitates a lot of copying of values.

We can achieve the same effect by just returning 0, 1 or a negative
error code, and drop the "err" argument from this function.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 90090a56899ee40b5db7d822cd3b262aa17cc994..9e0b464d374faf688e06ea22b418d176f4315e95 100644 (file)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2525,9 +2525,14 @@ static void __take_cap_refs(struct ceph_inode_info *ci, int got,
  * to (when applicable), and check against max_size here as well.
  * Note that caller is responsible for ensuring max_size increases are
  * requested from the MDS.
+ *
+ * Returns 0 if caps were not able to be acquired (yet), a 1 if they were,
+ * or a negative error code.
+ *
+ * FIXME: how does a 0 return differ from -EAGAIN?
  */
 static int try_get_cap_refs(struct ceph_inode_info *ci, int need, int want,
-                           loff_t endoff, bool nonblock, int *got, int *err)
+                           loff_t endoff, bool nonblock, int *got)
 {
        struct inode *inode = &ci->vfs_inode;
        struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
@@ -2547,8 +2552,7 @@ again:
        if ((file_wanted & need) != need) {
                dout("try_get_cap_refs need %s file_wanted %s, EBADF\n",
                     ceph_cap_string(need), ceph_cap_string(file_wanted));
-               *err = -EBADF;
-               ret = 1;
+               ret = -EBADF;
                goto out_unlock;
        }
 
@@ -2569,10 +2573,8 @@ again:
                if (endoff >= 0 && endoff > (loff_t)ci->i_max_size) {
                        dout("get_cap_refs %p endoff %llu > maxsize %llu\n",
                             inode, endoff, ci->i_max_size);
-                       if (endoff > ci->i_requested_max_size) {
-                               *err = -EAGAIN;
-                               ret = 1;
-                       }
+                       if (endoff > ci->i_requested_max_size)
+                               ret = -EAGAIN;
                        goto out_unlock;
                }
                /*
@@ -2607,8 +2609,7 @@ again:
                                         * task isn't in TASK_RUNNING state
                                         */
                                        if (nonblock) {
-                                               *err = -EAGAIN;
-                                               ret = 1;
+                                               ret = -EAGAIN;
                                                goto out_unlock;
                                        }
 
@@ -2637,8 +2638,7 @@ again:
                if (session_readonly) {
                        dout("get_cap_refs %p needed %s but mds%d readonly\n",
                             inode, ceph_cap_string(need), ci->i_auth_cap->mds);
-                       *err = -EROFS;
-                       ret = 1;
+                       ret = -EROFS;
                        goto out_unlock;
                }
 
@@ -2647,16 +2647,14 @@ again:
                        if (READ_ONCE(mdsc->fsc->mount_state) ==
                            CEPH_MOUNT_SHUTDOWN) {
                                dout("get_cap_refs %p forced umount\n", inode);
-                               *err = -EIO;
-                               ret = 1;
+                               ret = -EIO;
                                goto out_unlock;
                        }
                        mds_wanted = __ceph_caps_mds_wanted(ci, false);
                        if (need & ~(mds_wanted & need)) {
                                dout("get_cap_refs %p caps were dropped"
                                     " (session killed?)\n", inode);
-                               *err = -ESTALE;
-                               ret = 1;
+                               ret = -ESTALE;
                                goto out_unlock;
                        }
                        if (!(file_wanted & ~mds_wanted))
@@ -2707,7 +2705,7 @@ static void check_max_size(struct inode *inode, loff_t endoff)
 int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want,
                      bool nonblock, int *got)
 {
-       int ret, err = 0;
+       int ret;
 
        BUG_ON(need & ~CEPH_CAP_FILE_RD);
        BUG_ON(want & ~(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO|CEPH_CAP_FILE_SHARED));
@@ -2715,15 +2713,8 @@ int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want,
        if (ret < 0)
                return ret;
 
-       ret = try_get_cap_refs(ci, need, want, 0, nonblock, got, &err);
-       if (ret) {
-               if (err == -EAGAIN) {
-                       ret = 0;
-               } else if (err < 0) {
-                       ret = err;
-               }
-       }
-       return ret;
+       ret = try_get_cap_refs(ci, need, want, 0, nonblock, got);
+       return ret == -EAGAIN ? 0 : ret;
 }
 
 /*
@@ -2734,7 +2725,7 @@ int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want,
 int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
                  loff_t endoff, int *got, struct page **pinned_page)
 {
-       int _got, ret, err = 0;
+       int _got, ret;
 
        ret = ceph_pool_perm_check(ci, need);
        if (ret < 0)
@@ -2744,21 +2735,19 @@ int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
                if (endoff > 0)
                        check_max_size(&ci->vfs_inode, endoff);
 
-               err = 0;
                _got = 0;
                ret = try_get_cap_refs(ci, need, want, endoff,
-                                      false, &_got, &err);
-               if (ret) {
-                       if (err == -EAGAIN)
-                               continue;
-                       if (err < 0)
-                               ret = err;
-               } else {
+                                      false, &_got);
+               if (ret == -EAGAIN) {
+                       continue;
+               } else if (!ret) {
+                       int err;
+
                        DEFINE_WAIT_FUNC(wait, woken_wake_function);
                        add_wait_queue(&ci->i_cap_wq, &wait);
 
-                       while (!try_get_cap_refs(ci, need, want, endoff,
-                                                true, &_got, &err)) {
+                       while (!(err = try_get_cap_refs(ci, need, want, endoff,
+                                                       true, &_got))) {
                                if (signal_pending(current)) {
                                        ret = -ERESTARTSYS;
                                        break;
@@ -2767,19 +2756,14 @@ int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
                        }
 
                        remove_wait_queue(&ci->i_cap_wq, &wait);
-
                        if (err == -EAGAIN)
                                continue;
-                       if (err < 0)
-                               ret = err;
                }
-               if (ret < 0) {
-                       if (err == -ESTALE) {
-                               /* session was killed, try renew caps */
-                               ret = ceph_renew_caps(&ci->vfs_inode);
-                               if (ret == 0)
-                                       continue;
-                       }
+               if (ret == -ESTALE) {
+                       /* session was killed, try renew caps */
+                       ret = ceph_renew_caps(&ci->vfs_inode);
+                       if (ret == 0)
+                               continue;
                        return ret;
                }