Hello
Artur Makówka wrote:
> Hans Reiser wrote:
>> fsync can be dramatically better optimized, and it will be after the
>> kernel merge work is completed. This optimization will likely consist
>> of reducing the tendency to merge atoms and handling fsync by using
>> write twice algorithms to a fixed journal area. Other improvements will
>> doubtless be found when time is spent on it. I am sorry that vim and
>> evolution are suffering so much from our neglecting fsync until after
>> the merge. fsync is one of the things I would have us working on if I
>> had my choice of what we improved in reiser4 rather than other persons
>> making that choice for us at the moment. Oh well, such is life in the
>> society of men.;-)
>>
>> It looks like akpm is going to start reading the reiser4 code. I
>> suspect his remarks will be a step above the ones made so far, he wrote
>> such nice readahead code.
>>
>
> Just want to add, that for desktop systems its only vim and evolution,
> but for my free hosting server it was very frequent system crashes
> (because of that i lost part of my database) and so on. Just want to
> warn anyone deciding to use reiser4 on server, to use 2.6.12 kernels or
> lower as this bug is almost not existent there.
>
> For some uses of reiser4 this bug is very dangerous. Not just slow work
> of some application, but like i said data loss, system instability (few
> crashes every day), and so on.
>
> I would say such a bug/design choice should be top priority, number one.
> Of course thats not true if reiser4 is meant to be only for home use.
> Just want to point that out, because it seems everybody is using reiser4
> only at home, and i am the only one on earth using it on server
> environment (i guess that wasn't the best idea...)
>
> Thanks in advance for consideration of taking this bug to top of your
> TODO list.
>
Please try whether the attached patch improves anything. It simplifies fsync by
avoid commiting of transactions which do not modify file being fsync-ed.
The patch applied to 2.6.14-mm2 with warnings, but that can be ignored.
This patch simplifies reiser4's fsync.
It is an experimental patch to test whether it helps against slowdowns reported
by users.
fs/reiser4/plugin/file/file.c | 14 ++++++++++++++
fs/reiser4/txnmgr.c | 22 +++++++++++++++-------
fs/reiser4/txnmgr.h | 1 +
3 files changed, 30 insertions(+), 7 deletions(-)
diff -puN fs/reiser4/plugin/file/file.c~reiser4-fix-fsync
fs/reiser4/plugin/file/file.c
--- linux-2.6.14-mm2/fs/reiser4/plugin/file/file.c~reiser4-fix-fsync
2005-11-17 13:42:26.000000000 +0300
+++ linux-2.6.14-mm2-vs/fs/reiser4/plugin/file/file.c 2005-11-17
13:42:26.000000000 +0300
@@ -1633,11 +1633,25 @@ int sync_unix_file(struct file *file, st
{
int result;
reiser4_context *ctx;
+ txn_atom *atom;
+ reiser4_block_nr reserve;
ctx = init_context(dentry->d_inode->i_sb);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
+ reserve = estimate_update_common(dentry->d_inode);
+ if (reiser4_grab_space(reserve, BA_CAN_COMMIT))
+ return RETERR(-ENOSPC);
+ write_sd_by_inode_common(dentry->d_inode);
+
+ atom = get_current_atom_locked();
+ spin_lock_txnh(ctx->trans);
+ force_commit_atom(ctx->trans);
+ reiser4_exit_context(ctx);
+ return 0;
+
+
assert("nikita-3486", ctx->trans->atom == NULL);
result = commit_file_atoms(dentry->d_inode);
assert("nikita-3484", ergo(result == 0, ctx->trans->atom == NULL));
diff -puN fs/reiser4/txnmgr.c~reiser4-fix-fsync fs/reiser4/txnmgr.c
--- linux-2.6.14-mm2/fs/reiser4/txnmgr.c~reiser4-fix-fsync 2005-11-17
13:42:26.000000000 +0300
+++ linux-2.6.14-mm2-vs/fs/reiser4/txnmgr.c 2005-11-17 13:42:26.000000000
+0300
@@ -1173,9 +1173,14 @@ static int commit_current_atom(long *nr_
/* TXN_TXNH */
-/* commit current atom and wait commit completion; atom and txn_handle should
be
- * locked before call, this function unlocks them on exit. */
-static int force_commit_atom_nolock(txn_handle * txnh)
+/**
+ * force_commit_atom - commit current atom and wait commit completion
+ * @txnh:
+ *
+ * Commits current atom and wait commit completion; current atom and @txnh have
+ * to be spinlocked before call, this function unlocks them on exit.
+ */
+int force_commit_atom(txn_handle *txnh)
{
txn_atom *atom;
@@ -1188,14 +1193,17 @@ static int force_commit_atom_nolock(txn_
assert("zam-834", atom != NULL);
assert_spin_locked(&(atom->alock));
- /* Set flags for atom and txnh: forcing atom commit and waiting for
- * commit completion */
+ /*
+ * Set flags for atom and txnh: forcing atom commit and waiting for
+ * commit completion
+ */
txnh->flags |= TXNH_WAIT_COMMIT;
atom->flags |= ATOM_FORCE_COMMIT;
spin_unlock_txnh(txnh);
spin_unlock_atom(atom);
+ /* commit is here */
txn_restart_current();
return 0;
}
@@ -1240,7 +1248,7 @@ int txnmgr_force_commit_all(struct super
spin_lock_txnh(txnh);
/* Add force-context txnh */
capture_assign_txnh_nolock(atom, txnh);
- ret = force_commit_atom_nolock(txnh);
+ ret = force_commit_atom(txnh);
if (ret)
return ret;
} else
@@ -2541,7 +2549,7 @@ int sync_atom(txn_atom * atom)
if (atom->stage < ASTAGE_PRE_COMMIT) {
spin_lock_txnh(txnh);
capture_assign_txnh_nolock(atom, txnh);
- result = force_commit_atom_nolock(txnh);
+ result = force_commit_atom(txnh);
} else if (atom->stage < ASTAGE_POST_COMMIT) {
/* wait atom commit */
atom_wait_event(atom);
diff -puN fs/reiser4/txnmgr.h~reiser4-fix-fsync fs/reiser4/txnmgr.h
--- linux-2.6.14-mm2/fs/reiser4/txnmgr.h~reiser4-fix-fsync 2005-11-17
13:42:26.000000000 +0300
+++ linux-2.6.14-mm2-vs/fs/reiser4/txnmgr.h 2005-11-17 13:42:26.000000000
+0300
@@ -416,6 +416,7 @@ extern int current_atom_should_commit(vo
extern jnode *find_first_dirty_jnode(txn_atom *, int);
extern int commit_some_atoms(txn_mgr *);
+extern int force_commit_atom(txn_handle *);
extern int flush_current_atom(int, long, long *, txn_atom **, jnode *);
extern int flush_some_atom(jnode *, long *, const struct writeback_control *,
int);
_
