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mds: use scatter pins for migration instead of rd/wrlocks

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This is simpler (for the migrator), and wrlocks allow scatter_writebehind,
which is a no-no for a frozen tree.  By pinning the frozen dir's parent
inode, we prevent any scatter or unscatter operations from implicitly
updating metadata within the frozen root dirfrag.
This commit is contained in:
Sage Weil 2010-09-22 15:42:52 -07:00
parent 961e186d47
commit d715338110
2 changed files with 11 additions and 51 deletions
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58
src/mds/Migrator.cc
View File

@ -548,33 +548,6 @@ public:
* public method to initiate an export.
* will fail if the directory is freezing, frozen, unpinnable, or root.
*/
static void rd_or_wr_lock(ScatterLock *lock, int *rd, int *wr)
{
if (lock->can_rdlock(-1)) {
lock->get_rdlock();
*rd |= lock->get_type();
} else {
lock->get_wrlock();
*wr |= lock->get_type();
}
}
static void rd_or_wr_unlock(MDS *mds, ScatterLock *lock, int rd, int wr)
{
if (rd & lock->get_type())
mds->locker->rdlock_finish(lock, NULL);
else
mds->locker->wrlock_finish(lock, NULL);
}
void Migrator::drop_parent_rd_wr_locks(CInode *in, int rd, int wr)
{
rd_or_wr_unlock(mds, &in->filelock, rd, wr);
rd_or_wr_unlock(mds, &in->nestlock, rd, wr);
rd_or_wr_unlock(mds, &in->dirfragtreelock, rd, wr);
}
void Migrator::export_dir(CDir *dir, int dest)
{
dout(7) << "export_dir " << *dir << " to " << dest << dendl;
@ -616,10 +589,8 @@ void Migrator::export_dir(CDir *dir, int dest)
}
// pin parent scatterlocks?
CInode *diri = dir->inode;
if ((!diri->filelock.can_rdlock(-1) && !diri->filelock.can_wrlock(diri->get_loner())) ||
(!diri->nestlock.can_rdlock(-1) && !diri->nestlock.can_wrlock(diri->get_loner())) ||
(!diri->dirfragtreelock.can_rdlock(-1) && !diri->dirfragtreelock.can_wrlock(diri->get_loner()))) {
dout(7) << "export_dir couldn't rd|wrlock parent inode file+nest+dftlock, failing. " << *diri << dendl;
if (!diri->can_scatter_pin()) {
dout(7) << "export_dir couldn't pin parent inode scatterlocks, failing. " << *diri << dendl;
return;
}
@ -689,9 +660,7 @@ void Migrator::export_frozen(CDir *dir)
CInode *diri = dir->inode;
if (!mds->locker->dentry_can_rdlock_trace(trace) ||
(!diri->filelock.can_rdlock(-1) && !diri->filelock.can_wrlock(diri->get_loner())) ||
(!diri->nestlock.can_rdlock(-1) && !diri->nestlock.can_wrlock(diri->get_loner())) ||
(!diri->dirfragtreelock.can_rdlock(-1) && !diri->dirfragtreelock.can_wrlock(diri->get_loner()))) {
!diri->can_scatter_pin()) {
dout(7) << "export_dir couldn't rdlock path or rd|wrlock parent inode file+nest+dftlock, failing. "
<< *diri << dendl;
@ -711,16 +680,10 @@ void Migrator::export_frozen(CDir *dir)
dout(10) << " taking locks on path, parent inode scatterlocks" << dendl;
// rdlock path
mds->locker->dentry_anon_rdlock_trace_start(trace);
// rd or wrlock parent inode scatterlocks
// this prevents accounted_fragstat updates while we are frozen
int rdlocked = 0, wrlocked = 0;
rd_or_wr_lock(&diri->filelock, &rdlocked, &wrlocked);
rd_or_wr_lock(&diri->nestlock, &rdlocked, &wrlocked);
rd_or_wr_lock(&diri->dirfragtreelock, &rdlocked, &wrlocked);
export_parent_rdlocked[dir] = rdlocked;
export_parent_wrlocked[dir] = wrlocked;
dout(10) << " dir inode now locked " << *diri << dendl;
// pin scatterlocks
diri->get_scatter_pin();
dout(10) << " dir inode now scatter pinned " << *diri << dendl;
cache->show_subtrees();
@ -1407,9 +1370,10 @@ void Migrator::export_unlock(CDir *dir)
vector<CDentry*> trace;
cache->make_trace(trace, dir->inode);
mds->locker->dentry_anon_rdlock_trace_finish(trace);
drop_parent_rd_wr_locks(dir->inode, export_parent_rdlocked[dir], export_parent_wrlocked[dir]);
export_parent_rdlocked.erase(dir);
export_parent_wrlocked.erase(dir);
list<Context*> ls;
dir->inode->put_scatter_pin(ls);
mds->queue_waiters(ls);
}
void Migrator::export_finish(CDir *dir)

4
src/mds/Migrator.h
View File

@ -81,8 +81,6 @@ protected:
// export fun
map<CDir*,int> export_state;
map<CDir*,int> export_peer;
map<CDir*,int> export_parent_rdlocked; // bit set => rdlocked
map<CDir*,int> export_parent_wrlocked; // bit set => wrlocked
//map<CDir*,list<bufferlist> > export_data; // only during EXPORTING state
map<CDir*,set<int> > export_warning_ack_waiting;
map<CDir*,set<int> > export_notify_ack_waiting;
@ -167,8 +165,6 @@ public:
}
void drop_parent_rd_wr_locks(CInode *in, int rd, int wr);
// -- misc --
void handle_mds_failure_or_stop(int who);