ceph: pre-allocate ceph_cap struct for ceph_add_cap()

So that ceph_add_cap() can be used while i_ceph_lock is locked.
This simplifies the code that handle cap import/export.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>

3 files changed, 85 insertions, 79 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 5f6d24ede794..73a42f504357 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -221,8 +221,8 @@ int ceph_unreserve_caps(struct ceph_mds_client *mdsc,
         return 0;
 }
 
-static struct ceph_cap *get_cap(struct ceph_mds_client *mdsc,
-                                struct ceph_cap_reservation *ctx)
+struct ceph_cap *ceph_get_cap(struct ceph_mds_client *mdsc,
+                              struct ceph_cap_reservation *ctx)
 {
         struct ceph_cap *cap = NULL;
 
@@ -508,15 +508,14 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
  * it is < 0.  (This is so we can atomically add the cap and add an
  * open file reference to it.)
  */
-int ceph_add_cap(struct inode *inode,
-                 struct ceph_mds_session *session, u64 cap_id,
-                 int fmode, unsigned issued, unsigned wanted,
-                 unsigned seq, unsigned mseq, u64 realmino, int flags,
-                 struct ceph_cap_reservation *caps_reservation)
+void ceph_add_cap(struct inode *inode,
+                  struct ceph_mds_session *session, u64 cap_id,
+                  int fmode, unsigned issued, unsigned wanted,
+                  unsigned seq, unsigned mseq, u64 realmino, int flags,
+                  struct ceph_cap **new_cap)
 {
         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
         struct ceph_inode_info *ci = ceph_inode(inode);
-        struct ceph_cap *new_cap = NULL;
         struct ceph_cap *cap;
         int mds = session->s_mds;
         int actual_wanted;
@@ -531,20 +530,10 @@ int ceph_add_cap(struct inode *inode,
         if (fmode >= 0)
                 wanted |= ceph_caps_for_mode(fmode);
 
-retry:
-        spin_lock(&ci->i_ceph_lock);
         cap = __get_cap_for_mds(ci, mds);
         if (!cap) {
-                if (new_cap) {
-                        cap = new_cap;
-                        new_cap = NULL;
-                } else {
-                        spin_unlock(&ci->i_ceph_lock);
-                        new_cap = get_cap(mdsc, caps_reservation);
-                        if (new_cap == NULL)
-                                return -ENOMEM;
-                        goto retry;
-                }
+                cap = *new_cap;
+                *new_cap = NULL;
 
                 cap->issued = 0;
                 cap->implemented = 0;
@@ -562,9 +551,6 @@ retry:
                 session->s_nr_caps++;
                 spin_unlock(&session->s_cap_lock);
         } else {
-                if (new_cap)
-                        ceph_put_cap(mdsc, new_cap);
-
                 /*
                  * auth mds of the inode changed. we received the cap export
                  * message, but still haven't received the cap import message.
@@ -626,7 +612,6 @@ retry:
                         ci->i_auth_cap = cap;
                         cap->mds_wanted = wanted;
                 }
-                ci->i_cap_exporting_issued = 0;
         } else {
                 WARN_ON(ci->i_auth_cap == cap);
         }
@@ -648,9 +633,6 @@ retry:
 
         if (fmode >= 0)
                 __ceph_get_fmode(ci, fmode);
-        spin_unlock(&ci->i_ceph_lock);
-        wake_up_all(&ci->i_cap_wq);
-        return 0;
 }
 
 /*
@@ -685,7 +667,7 @@ static int __cap_is_valid(struct ceph_cap *cap)
  */
 int __ceph_caps_issued(struct ceph_inode_info *ci, int *implemented)
 {
-        int have = ci->i_snap_caps | ci->i_cap_exporting_issued;
+        int have = ci->i_snap_caps;
         struct ceph_cap *cap;
         struct rb_node *p;
 
@@ -900,7 +882,7 @@ int __ceph_caps_mds_wanted(struct ceph_inode_info *ci)
  */
 static int __ceph_is_any_caps(struct ceph_inode_info *ci)
 {
-        return !RB_EMPTY_ROOT(&ci->i_caps) || ci->i_cap_exporting_issued;
+        return !RB_EMPTY_ROOT(&ci->i_caps);
 }
 
 int ceph_is_any_caps(struct inode *inode)
@@ -2796,7 +2778,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 {
         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
         struct ceph_mds_session *tsession = NULL;
-        struct ceph_cap *cap, *tcap;
+        struct ceph_cap *cap, *tcap, *new_cap = NULL;
         struct ceph_inode_info *ci = ceph_inode(inode);
         u64 t_cap_id;
         unsigned mseq = le32_to_cpu(ex->migrate_seq);
@@ -2858,15 +2840,14 @@ retry:
                 }
                 __ceph_remove_cap(cap, false);
                 goto out_unlock;
-        }
-
-        if (tsession) {
-                int flag = (cap == ci->i_auth_cap) ? CEPH_CAP_FLAG_AUTH : 0;
-                spin_unlock(&ci->i_ceph_lock);
+        } else if (tsession) {
                 /* add placeholder for the export tagert */
+                int flag = (cap == ci->i_auth_cap) ? CEPH_CAP_FLAG_AUTH : 0;
                 ceph_add_cap(inode, tsession, t_cap_id, -1, issued, 0,
-                             t_seq - 1, t_mseq, (u64)-1, flag, NULL);
-                goto retry;
+                             t_seq - 1, t_mseq, (u64)-1, flag, &new_cap);
+
+                __ceph_remove_cap(cap, false);
+                goto out_unlock;
         }
 
         spin_unlock(&ci->i_ceph_lock);
@@ -2885,6 +2866,7 @@ retry:
                                           SINGLE_DEPTH_NESTING);
                 }
                 ceph_add_cap_releases(mdsc, tsession);
+                new_cap = ceph_get_cap(mdsc, NULL);
         } else {
                 WARN_ON(1);
                 tsession = NULL;
@@ -2899,6 +2881,8 @@ out_unlock:
                 mutex_unlock(&tsession->s_mutex);
                 ceph_put_mds_session(tsession);
         }
+        if (new_cap)
+                ceph_put_cap(mdsc, new_cap);
 }
 
 /*
@@ -2914,7 +2898,7 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
                               void *snaptrace, int snaptrace_len)
 {
         struct ceph_inode_info *ci = ceph_inode(inode);
-        struct ceph_cap *cap;
+        struct ceph_cap *cap, *new_cap = NULL;
         int mds = session->s_mds;
         unsigned issued = le32_to_cpu(im->caps);
         unsigned wanted = le32_to_cpu(im->wanted);
@@ -2936,7 +2920,20 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
         dout("handle_cap_import inode %p ci %p mds%d mseq %d peer %d\n",
              inode, ci, mds, mseq, peer);
 
+retry:
         spin_lock(&ci->i_ceph_lock);
+        cap = __get_cap_for_mds(ci, mds);
+        if (!cap) {
+                if (!new_cap) {
+                        spin_unlock(&ci->i_ceph_lock);
+                        new_cap = ceph_get_cap(mdsc, NULL);
+                        goto retry;
+                }
+        }
+
+        ceph_add_cap(inode, session, cap_id, -1, issued, wanted, seq, mseq,
+                     realmino, CEPH_CAP_FLAG_AUTH, &new_cap);
+
         cap = peer >= 0 ? __get_cap_for_mds(ci, peer) : NULL;
         if (cap && cap->cap_id == p_cap_id) {
                 dout(" remove export cap %p mds%d flags %d\n",
@@ -2951,7 +2948,6 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
                                cap->mseq, mds, le32_to_cpu(ph->seq),
                                le32_to_cpu(ph->mseq));
                 }
-                ci->i_cap_exporting_issued = cap->issued;
                 __ceph_remove_cap(cap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
         }
 
@@ -2960,16 +2956,17 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
         ci->i_requested_max_size = 0;
         spin_unlock(&ci->i_ceph_lock);
 
+        wake_up_all(&ci->i_cap_wq);
+
         down_write(&mdsc->snap_rwsem);
         ceph_update_snap_trace(mdsc, snaptrace, snaptrace+snaptrace_len,
                                false);
         downgrade_write(&mdsc->snap_rwsem);
-        ceph_add_cap(inode, session, cap_id, -1,
-                     issued, wanted, seq, mseq, realmino, CEPH_CAP_FLAG_AUTH,
-                     NULL /* no caps context */);
         kick_flushing_inode_caps(mdsc, session, inode);
         up_read(&mdsc->snap_rwsem);
 
+        if (new_cap)
+                ceph_put_cap(mdsc, new_cap);
 }
 
 /*
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index f9e7399877d6..8ad50a30808e 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -341,7 +341,6 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
         INIT_LIST_HEAD(&ci->i_cap_snaps);
         ci->i_head_snapc = NULL;
         ci->i_snap_caps = 0;
-        ci->i_cap_exporting_issued = 0;
 
         for (i = 0; i < CEPH_FILE_MODE_NUM; i++)
                 ci->i_nr_by_mode[i] = 0;
@@ -407,7 +406,7 @@ void ceph_destroy_inode(struct inode *inode)
 
         /*
          * we may still have a snap_realm reference if there are stray
-         * caps in i_cap_exporting_issued or i_snap_caps.
+         * caps in i_snap_caps.
          */
         if (ci->i_snap_realm) {
                 struct ceph_mds_client *mdsc =
@@ -582,6 +581,7 @@ static int fill_inode(struct inode *inode,
                       unsigned long ttl_from, int cap_fmode,
                       struct ceph_cap_reservation *caps_reservation)
 {
+        struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
         struct ceph_mds_reply_inode *info = iinfo->in;
         struct ceph_inode_info *ci = ceph_inode(inode);
         int i;
@@ -591,7 +591,9 @@ static int fill_inode(struct inode *inode,
         struct ceph_inode_frag *frag;
         struct rb_node *rb_node;
         struct ceph_buffer *xattr_blob = NULL;
+        struct ceph_cap *new_cap = NULL;
         int err = 0;
+        bool wake = false;
         bool queue_trunc = false;
         bool new_version = false;
 
@@ -599,6 +601,10 @@ static int fill_inode(struct inode *inode,
              inode, ceph_vinop(inode), le64_to_cpu(info->version),
              ci->i_version);
 
+        /* prealloc new cap struct */
+        if (info->cap.caps && ceph_snap(inode) == CEPH_NOSNAP)
+                new_cap = ceph_get_cap(mdsc, caps_reservation);
+
         /*
          * prealloc xattr data, if it looks like we'll need it.  only
          * if len > 4 (meaning there are actually xattrs; the first 4
@@ -762,8 +768,37 @@ static int fill_inode(struct inode *inode,
                 dout(" marking %p complete (empty)\n", inode);
                 __ceph_dir_set_complete(ci, atomic_read(&ci->i_release_count));
         }
+
+        /* were we issued a capability? */
+        if (info->cap.caps) {
+                if (ceph_snap(inode) == CEPH_NOSNAP) {
+                        ceph_add_cap(inode, session,
+                                     le64_to_cpu(info->cap.cap_id),
+                                     cap_fmode,
+                                     le32_to_cpu(info->cap.caps),
+                                     le32_to_cpu(info->cap.wanted),
+                                     le32_to_cpu(info->cap.seq),
+                                     le32_to_cpu(info->cap.mseq),
+                                     le64_to_cpu(info->cap.realm),
+                                     info->cap.flags, &new_cap);
+                        wake = true;
+                } else {
+                        dout(" %p got snap_caps %s\n", inode,
+                             ceph_cap_string(le32_to_cpu(info->cap.caps)));
+                        ci->i_snap_caps |= le32_to_cpu(info->cap.caps);
+                        if (cap_fmode >= 0)
+                                __ceph_get_fmode(ci, cap_fmode);
+                }
+        } else if (cap_fmode >= 0) {
+                pr_warning("mds issued no caps on %llx.%llx\n",
+                           ceph_vinop(inode));
+                __ceph_get_fmode(ci, cap_fmode);
+        }
         spin_unlock(&ci->i_ceph_lock);
 
+        if (wake)
+                wake_up_all(&ci->i_cap_wq);
+
         /* queue truncate if we saw i_size decrease */
         if (queue_trunc)
                 ceph_queue_vmtruncate(inode);
@@ -806,41 +841,14 @@ static int fill_inode(struct inode *inode,
         }
         mutex_unlock(&ci->i_fragtree_mutex);
 
-        /* were we issued a capability? */
-        if (info->cap.caps) {
-                if (ceph_snap(inode) == CEPH_NOSNAP) {
-                        ceph_add_cap(inode, session,
-                                     le64_to_cpu(info->cap.cap_id),
-                                     cap_fmode,
-                                     le32_to_cpu(info->cap.caps),
-                                     le32_to_cpu(info->cap.wanted),
-                                     le32_to_cpu(info->cap.seq),
-                                     le32_to_cpu(info->cap.mseq),
-                                     le64_to_cpu(info->cap.realm),
-                                     info->cap.flags,
-                                     caps_reservation);
-                } else {
-                        spin_lock(&ci->i_ceph_lock);
-                        dout(" %p got snap_caps %s\n", inode,
-                             ceph_cap_string(le32_to_cpu(info->cap.caps)));
-                        ci->i_snap_caps |= le32_to_cpu(info->cap.caps);
-                        if (cap_fmode >= 0)
-                                __ceph_get_fmode(ci, cap_fmode);
-                        spin_unlock(&ci->i_ceph_lock);
-                }
-        } else if (cap_fmode >= 0) {
-                pr_warning("mds issued no caps on %llx.%llx\n",
-                           ceph_vinop(inode));
-                __ceph_get_fmode(ci, cap_fmode);
-        }
-
         /* update delegation info? */
         if (dirinfo)
                 ceph_fill_dirfrag(inode, dirinfo);
 
         err = 0;
-
 out:
+        if (new_cap)
+                ceph_put_cap(mdsc, new_cap);
         if (xattr_blob)
                 ceph_buffer_put(xattr_blob);
         return err;
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index ead05cc1f447..12b20744e386 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -292,7 +292,6 @@ struct ceph_inode_info {
         struct ceph_snap_context *i_head_snapc;  /* set if wr_buffer_head > 0 or
                                                     dirty|flushing caps */
         unsigned i_snap_caps;           /* cap bits for snapped files */
-        unsigned i_cap_exporting_issued;
 
         int i_nr_by_mode[CEPH_FILE_MODE_NUM];  /* open file counts */
 
@@ -775,11 +774,13 @@ static inline void ceph_forget_all_cached_acls(struct inode *inode)
 extern const char *ceph_cap_string(int c);
 extern void ceph_handle_caps(struct ceph_mds_session *session,
                              struct ceph_msg *msg);
-extern int ceph_add_cap(struct inode *inode,
-                        struct ceph_mds_session *session, u64 cap_id,
-                        int fmode, unsigned issued, unsigned wanted,
-                        unsigned cap, unsigned seq, u64 realmino, int flags,
-                        struct ceph_cap_reservation *caps_reservation);
+extern struct ceph_cap *ceph_get_cap(struct ceph_mds_client *mdsc,
+                                     struct ceph_cap_reservation *ctx);
+extern void ceph_add_cap(struct inode *inode,
+                         struct ceph_mds_session *session, u64 cap_id,
+                         int fmode, unsigned issued, unsigned wanted,
+                         unsigned cap, unsigned seq, u64 realmino, int flags,
+                         struct ceph_cap **new_cap);
 extern void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release);
 extern void ceph_put_cap(struct ceph_mds_client *mdsc,
                          struct ceph_cap *cap);