1 // vim: ts=8 sw=2 smarttab
3 * Ceph - scalable distributed file system
5 * Copyright (C) 2015 Red Hat
7 * This is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License version 2.1, as published by the Free Software
10 * Foundation. See file COPYING.
14 #ifndef STRAY_MANAGER_H
15 #define STRAY_MANAGER_H
17 #include "include/elist.h"
19 #include "mds/PurgeQueue.h"
29 // Has passed through eval_stray and still has refs
30 elist<CDentry*> delayed_eval_stray;
32 // strays that have been trimmed from cache
33 std::set<std::string> trimmed_strays;
35 // Global references for doing I/O
41 // Stray dentries for this rank (including those not in cache)
45 uint64_t num_strays_delayed;
47 // Entries that have entered enqueue() but not been persistently
48 // recorded by PurgeQueue yet
49 uint64_t num_strays_enqueuing;
51 PurgeQueue &purge_queue;
53 void truncate(CDentry *dn);
56 * Purge a dentry from a stray directory. This function
57 * is called once eval_stray is satisfied and StrayManager
58 * throttling is also satisfied. There is no going back
61 void purge(CDentry *dn);
64 * Completion handler for a Filer::purge on a stray inode.
66 void _purge_stray_purged(CDentry *dn, bool only_head);
68 void _purge_stray_logged(CDentry *dn, version_t pdv, LogSegment *ls);
71 * Callback: we have logged the update to an inode's metadata
72 * reflecting it's newly-zeroed length.
74 void _truncate_stray_logged(CDentry *dn, LogSegment *ls);
76 friend class StrayManagerIOContext;
77 friend class StrayManagerLogContext;
78 friend class StrayManagerContext;
80 friend class C_StraysFetched;
81 friend class C_OpenSnapParents;
82 friend class C_PurgeStrayLogged;
83 friend class C_TruncateStrayLogged;
84 friend class C_IO_PurgeStrayPurged;
87 // Call this on a dentry that has been identified as
88 // elegible for purging. It will be passed on to PurgeQueue.
89 void enqueue(CDentry *dn, bool trunc);
91 // Final part of enqueue() which we may have to retry
92 // after opening snap parents.
93 void _enqueue(CDentry *dn, bool trunc);
97 * When hard links exist to an inode whose primary dentry
98 * is unlinked, the inode gets a stray primary dentry.
100 * We may later "reintegrate" the inode into a remaining
101 * non-stray dentry (one of what was previously a remote
102 * dentry) by issuing a rename from the stray to the other
105 void reintegrate_stray(CDentry *dn, CDentry *rlink);
108 * Evaluate a stray dentry for purging or reintegration.
110 * purging: If the inode has no linkage, and no more references, then
111 * we may decide to purge it.
113 * reintegration: If the inode still has linkage, then it means someone else
114 * (a hard link) is still referring to it, and we should
115 * think about reintegrating that inode into the remote dentry.
117 * @returns true if the dentry will be purged (caller should never
118 * take more refs after this happens), else false.
120 bool _eval_stray(CDentry *dn, bool delay=false);
122 void _eval_stray_remote(CDentry *stray_dn, CDentry *remote_dn);
124 // My public interface is for consumption by MDCache
126 explicit StrayManager(MDSRank *mds, PurgeQueue &purge_queue_);
127 void set_logger(PerfCounters *l) {logger = l;}
130 bool eval_stray(CDentry *dn, bool delay=false);
132 void set_num_strays(uint64_t num);
133 uint64_t get_num_strays() const { return num_strays; }
136 * Where eval_stray was previously invoked with delay=true, call
137 * eval_stray again for any dentries that were put on the
138 * delayed_eval_stray list as a result of the original call.
140 * Used so that various places can call eval_stray(delay=true) during
141 * an operation to identify dentries of interest, and then call
142 * this function later during trim in order to do the final
143 * evaluation (and resulting actions) while not in the middle of another
144 * metadata operation.
146 void advance_delayed();
149 * Remote dentry potentially points to a stray. When it is touched,
150 * call in here to evaluate it for migration (move a stray residing
151 * on another MDS to this MDS) or reintegration (move a stray dentry's
152 * inode into a non-stray hardlink dentry and clean up the stray).
154 * @param stray_dn a stray dentry whose inode has been referenced
156 * @param remote_dn (optional) which remote dentry was touched
157 * in an operation that led us here: this is used
158 * as a hint for which remote to reintegrate into
159 * if there are multiple remotes.
161 void eval_remote(CDentry *remote_dn);
164 * Given a dentry within one of my stray directories,
165 * send it off to a stray directory in another MDS.
168 * * Case A: when shutting down a rank, we migrate strays
169 * away from ourselves rather than waiting for purge
170 * * Case B: when a client request has a trace that refers to
171 * a stray inode on another MDS, we migrate that inode from
172 * there to here, in order that we can later re-integrate it
175 * In case B, the receiver should be calling into eval_stray
176 * on completion of mv (i.e. inode put), resulting in a subsequent
179 void migrate_stray(CDentry *dn, mds_rank_t dest);
182 * Update stats to reflect a newly created stray dentry. Needed
183 * because stats on strays live here, but creation happens
184 * in Server or MDCache. For our purposes "creation" includes
185 * loading a stray from a dirfrag and migrating a stray from
186 * another MDS, in addition to creations per-se.
188 void notify_stray_created();
191 * Update stats to reflect a removed stray dentry. Needed because
192 * stats on strays live here, but removal happens in Server or
193 * MDCache. Also includes migration (rename) of strays from
194 * this MDS to another MDS.
196 void notify_stray_removed();
199 #endif // STRAY_MANAGER_H