diff options
Diffstat (limited to 'fs/ceph/snap.c')
-rw-r--r-- | fs/ceph/snap.c | 96 |
1 files changed, 59 insertions, 37 deletions
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 4ac0606dcbd4..b41e6724c591 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -67,19 +67,19 @@ void ceph_get_snap_realm(struct ceph_mds_client *mdsc, { lockdep_assert_held(&mdsc->snap_rwsem); - dout("get_realm %p %d -> %d\n", realm, - atomic_read(&realm->nref), atomic_read(&realm->nref)+1); /* - * since we _only_ increment realm refs or empty the empty - * list with snap_rwsem held, adjusting the empty list here is - * safe. we do need to protect against concurrent empty list - * additions, however. + * The 0->1 and 1->0 transitions must take the snap_empty_lock + * atomically with the refcount change. Go ahead and bump the + * nref here, unless it's 0, in which case we take the spinlock + * and then do the increment and remove it from the list. */ - if (atomic_inc_return(&realm->nref) == 1) { - spin_lock(&mdsc->snap_empty_lock); + if (atomic_inc_not_zero(&realm->nref)) + return; + + spin_lock(&mdsc->snap_empty_lock); + if (atomic_inc_return(&realm->nref) == 1) list_del_init(&realm->empty_item); - spin_unlock(&mdsc->snap_empty_lock); - } + spin_unlock(&mdsc->snap_empty_lock); } static void __insert_snap_realm(struct rb_root *root, @@ -208,28 +208,28 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc, { lockdep_assert_held_write(&mdsc->snap_rwsem); - dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm, - atomic_read(&realm->nref), atomic_read(&realm->nref)-1); + /* + * We do not require the snap_empty_lock here, as any caller that + * increments the value must hold the snap_rwsem. + */ if (atomic_dec_and_test(&realm->nref)) __destroy_snap_realm(mdsc, realm); } /* - * caller needn't hold any locks + * See comments in ceph_get_snap_realm. Caller needn't hold any locks. */ void ceph_put_snap_realm(struct ceph_mds_client *mdsc, struct ceph_snap_realm *realm) { - dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm, - atomic_read(&realm->nref), atomic_read(&realm->nref)-1); - if (!atomic_dec_and_test(&realm->nref)) + if (!atomic_dec_and_lock(&realm->nref, &mdsc->snap_empty_lock)) return; if (down_write_trylock(&mdsc->snap_rwsem)) { + spin_unlock(&mdsc->snap_empty_lock); __destroy_snap_realm(mdsc, realm); up_write(&mdsc->snap_rwsem); } else { - spin_lock(&mdsc->snap_empty_lock); list_add(&realm->empty_item, &mdsc->snap_empty); spin_unlock(&mdsc->snap_empty_lock); } @@ -487,6 +487,9 @@ static void ceph_queue_cap_snap(struct ceph_inode_info *ci) pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode); return; } + capsnap->cap_flush.is_capsnap = true; + INIT_LIST_HEAD(&capsnap->cap_flush.i_list); + INIT_LIST_HEAD(&capsnap->cap_flush.g_list); spin_lock(&ci->i_ceph_lock); used = __ceph_caps_used(ci); @@ -846,6 +849,43 @@ static void flush_snaps(struct ceph_mds_client *mdsc) dout("flush_snaps done\n"); } +/** + * ceph_change_snap_realm - change the snap_realm for an inode + * @inode: inode to move to new snap realm + * @realm: new realm to move inode into (may be NULL) + * + * Detach an inode from its old snaprealm (if any) and attach it to + * the new snaprealm (if any). The old snap realm reference held by + * the inode is put. If realm is non-NULL, then the caller's reference + * to it is taken over by the inode. + */ +void ceph_change_snap_realm(struct inode *inode, struct ceph_snap_realm *realm) +{ + struct ceph_inode_info *ci = ceph_inode(inode); + struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc; + struct ceph_snap_realm *oldrealm = ci->i_snap_realm; + + lockdep_assert_held(&ci->i_ceph_lock); + + if (oldrealm) { + spin_lock(&oldrealm->inodes_with_caps_lock); + list_del_init(&ci->i_snap_realm_item); + if (oldrealm->ino == ci->i_vino.ino) + oldrealm->inode = NULL; + spin_unlock(&oldrealm->inodes_with_caps_lock); + ceph_put_snap_realm(mdsc, oldrealm); + } + + ci->i_snap_realm = realm; + + if (realm) { + spin_lock(&realm->inodes_with_caps_lock); + list_add(&ci->i_snap_realm_item, &realm->inodes_with_caps); + if (realm->ino == ci->i_vino.ino) + realm->inode = inode; + spin_unlock(&realm->inodes_with_caps_lock); + } +} /* * Handle a snap notification from the MDS. @@ -932,7 +972,6 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, }; struct inode *inode = ceph_find_inode(sb, vino); struct ceph_inode_info *ci; - struct ceph_snap_realm *oldrealm; if (!inode) continue; @@ -957,27 +996,10 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, } dout(" will move %p to split realm %llx %p\n", inode, realm->ino, realm); - /* - * Move the inode to the new realm - */ - oldrealm = ci->i_snap_realm; - spin_lock(&oldrealm->inodes_with_caps_lock); - list_del_init(&ci->i_snap_realm_item); - spin_unlock(&oldrealm->inodes_with_caps_lock); - - spin_lock(&realm->inodes_with_caps_lock); - list_add(&ci->i_snap_realm_item, - &realm->inodes_with_caps); - ci->i_snap_realm = realm; - if (realm->ino == ci->i_vino.ino) - realm->inode = inode; - spin_unlock(&realm->inodes_with_caps_lock); - - spin_unlock(&ci->i_ceph_lock); ceph_get_snap_realm(mdsc, realm); - ceph_put_snap_realm(mdsc, oldrealm); - + ceph_change_snap_realm(inode, realm); + spin_unlock(&ci->i_ceph_lock); iput(inode); continue; |