[Cluster-devel] GFS2: Pre-pull patch posting

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

Hi,

Here are four small bug fixes for GFS2. There is no common theme here
really, just a few items that were fixed recently. The first fixes
lock name generation when the glock number is 0. The second fixes a
race allocating reservation structures and the final two fix a performance
issue by making small changes in the allocation code,

Steve.

[Cluster-devel] [PATCH 1/4] GFS2: Initialize hex string to '0'

[Steven Whitehouse]

From: Nathan Straz <nstraz@redhat.com>

When generating the DLM lock name, a value of 0 would skip
the loop and leave the string unchanged.  This left locks with
a value of 0 unlabeled.  Initializing the string to '0' fixes this.

Signed-off-by: Nathan Straz <nstraz@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c
index 8dad6b0..b906ed1 100644
--- a/fs/gfs2/lock_dlm.c
+++ b/fs/gfs2/lock_dlm.c
@@ -241,6 +241,7 @@ static u32 make_flags(struct gfs2_glock *gl, const unsigned int gfs_flags,
 
 static void gfs2_reverse_hex(char *c, u64 value)
 {
+	*c = '0';
 	while (value) {
 		*c-- = hex_asc[value & 0x0f];
 		value >>= 4;
-- 
1.7.4

[Cluster-devel] [PATCH 2/4] GFS2: Fix race in gfs2_rs_alloc

[Steven Whitehouse]

From: Abhijith Das <adas@redhat.com>

QE aio tests uncovered a race condition in gfs2_rs_alloc where it's possible
to come out of the function with a valid ip->i_res allocation but it gets
freed before use resulting in a NULL ptr dereference.

This patch envelopes the initial short-circuit check for non-NULL ip->i_res
into the mutex lock. With this patch, I was able to successfully run the
reproducer test multiple times.

Resolves: rhbz#878476
Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 37ee061..738b388 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -557,22 +557,20 @@ void gfs2_free_clones(struct gfs2_rgrpd *rgd)
  */
 int gfs2_rs_alloc(struct gfs2_inode *ip)
 {
-	struct gfs2_blkreserv *res;
+	int error = 0;
 
+	down_write(&ip->i_rw_mutex);
 	if (ip->i_res)
-		return 0;
-
-	res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
-	if (!res)
-		return -ENOMEM;
+		goto out;
 
-	RB_CLEAR_NODE(&res->rs_node);
+	ip->i_res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
+	if (!ip->i_res) {
+		error = -ENOMEM;
+		goto out;
+	}
 
-	down_write(&ip->i_rw_mutex);
-	if (ip->i_res)
-		kmem_cache_free(gfs2_rsrv_cachep, res);
-	else
-		ip->i_res = res;
+	RB_CLEAR_NODE(&ip->i_res->rs_node);
+out:
 	up_write(&ip->i_rw_mutex);
 	return 0;
 }
-- 
1.7.4

[Cluster-devel] [PATCH 3/4] GFS2: Stop looking for free blocks at end of rgrp

[Steven Whitehouse]

From: Bob Peterson <rpeterso@redhat.com>

This patch adds a return code check after calling function
gfs2_rbm_from_block while determining the free extent size.
That way, when the end of an rgrp is reached, it won't try
to process unaligned blocks after the end.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 738b388..712dd4f 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -350,10 +350,14 @@ static u32 gfs2_free_extlen(const struct gfs2_rbm *rrbm, u32 len)
 		BUG_ON(len < chunk_size);
 		len -= chunk_size;
 		block = gfs2_rbm_to_block(&rbm);
-		gfs2_rbm_from_block(&rbm, block + chunk_size);
-		n_unaligned = 3;
-		if (ptr)
+		if (gfs2_rbm_from_block(&rbm, block + chunk_size)) {
+			n_unaligned = 0;
 			break;
+		}
+		if (ptr) {
+			n_unaligned = 3;
+			break;
+		}
 		n_unaligned = len & 3;
 	}
 
-- 
1.7.4

[Cluster-devel] [PATCH 4/4] GFS2: Reset rd_last_alloc when it reaches the end of the rgrp

[Steven Whitehouse]

From: Bob Peterson <rpeterso@redhat.com>

In function rg_mblk_search, it's searching for multiple blocks in
a given state (e.g. "free"). If there's an active block reservation
its goal is the next free block of that. If the resource group
contains the dinode's goal block, that's used for the search. But
if neither is the case, it uses the rgrp's last allocated block.
That way, consecutive allocations appear after one another on media.
The problem comes in when you hit the end of the rgrp; it would never
start over and search from the beginning. This became a problem,
since if you deleted all the files and data from the rgrp, it would
never start over and find free blocks. So it had to keep searching
further out on the media to allocate blocks. This patch resets the
rd_last_alloc after it does an unsuccessful search at the end of
the rgrp.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 712dd4f..b7eff07 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -1426,6 +1426,9 @@ static void rg_mblk_search(struct gfs2_rgrpd *rgd, struct gfs2_inode *ip,
 		rs->rs_free = extlen;
 		rs->rs_inum = ip->i_no_addr;
 		rs_insert(ip);
+	} else {
+		if (goal == rgd->rd_last_alloc + rgd->rd_data0)
+			rgd->rd_last_alloc = 0;
 	}
 }
 
-- 
1.7.4

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

This time we have mostly clean ups. There is a bug fix for a NULL dereference
relating to ACLs, and another which improves (but does not fix entirely) an
allocation fall-back code path. The other three patches are small clean ups.

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

Hi,

Here are a few GFS2 fixes which are pending. There are two patches
which fix up a couple of minor issues in the DLM interface code,
a missing error path in gfs2_rs_alloc(), two patches which fix problems
during "withdraw" and a fix for discards/FITRIM when using 4k sector
sized devices,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

Hi,

I know the merge window isn't open yet, but at this stage I'm going to
hold off on any larger patches until the following merge window so this
patch set isn't likely to change much, hence kicking it out a bit early
for review.

There are a few interesting points to note in this patch set:
 o GFS2 is updated to use the new truncate sequence
 o Support for fallocate is added
 o Clean up of some unused/obsolete mount options

I'm currently working on a patch to allow the glock hash table
to use RCU. That is currently a work-in-progress and that will
hopefully be ready for the succeeding merge window.

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

Hi,

Here is the current content of the GFS2 -nmw git tree. Mostly its
just clean up and bug fixes this time. There is one exception which
is the "wait for journal id" patch which is a new feature aimed
at (eventually) allowing us to simplify the userland support which
GFS2 requires,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

Hi,

Nothing very exciting this time.... mostly minor bug fixes and
a docs update. The gfs2_logd patch has been hanging around for
a long time and is now finally integrated. It is the first step
towards a longer term goal of improving performance in that
area,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

Here are three small (but important!) fixes to GFS2.

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

Hi,

Not so many patches for GFS2 this merge window. The bulk of the changes are
aimed at reducing overheads when caching large numbers of inodes and
the consequent simplification of the umount code,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

As merge time is approaching, here is the current content of the
GFS2 -nmw git tree. I'm not expecting to take any more patches
now for the current merge window unless any last minute bugs
are discovered.

There is not a huge amount new this time. Some extra context for
uevent messages, better error handling during block allocation,
and a clean up of extended attribute support. There is still more
to do on the extended attribute side of things, but this is a good
start I think.

There are a few bug fixes as well. Once these patches are merged
I'm intending to start off the next -nmw tree with a patch to
remove some of the (now unused) sysfs files as per the message
on cluster-devel a few weeks back.

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

Hi,

As the merge window is more or less upon us, here is the content
of the GFS2 -nmw tree. There is nothing too startling this time
as the focus has very much been bug fixes and clean up.

We have a new mount option, commit= which does exactly the same
thing as the ext3 equivalent option. We have a long term plan to
make all the tunable parameters available as mount options and
thus to be able to eventually drop the sysfs interface to these
parameters.

Another long term plan is to get rid of the files named
ops_somethingorother and to either merge them into other
files, or rename them to not have the ops_ prefix. This
patch series makes a start on that, and does all the easy
ones. As a result some functions with only one caller are
moved to the same file as their caller and made static.

The docs are also updated to reflect the fact that the
lock_dlm interface module no longer exists and that interface is
now built into GFS2.

Steve.

[Cluster-devel] [GFS2] Pre-pull patch posting

[swhiteho]

Hi,

So as the merge window draws closer, here is the current content of the
GFS2 git tree. The major item this time is patch 5 in the series. This
contians by far the majority of the changes, and the majority of those
changes are actually removal of code. The patch merges the lock_dlm
module (not the dlm itself, but GFS2's interface to the dlm) into
GFS2 itself. This means that a number of optimisations are then
possible in terms of merging strucutures resulting in a considerable
saving in memory.

Since that patch is so large (I'm afraid that it really doesn't make
any sense to split it up) its been in the -nmw git tree for the whole
period since the last merge window and has also been posted for review
on cluster-devel on a number of occasions before that. We've run a
number of tests on it as well in that period, so I believe that its
pretty stable now. It certainly makes the code a lot cleaner and
easier to follow in that area.

The remainder of the patches are mostly bug fixes, but there are one
or two other interesting features, those being:

 o GFS2 now supports the discard I/O requests for thin provisioning, etc
 o A new "demote a glock" interface is added to sysfs to help in
   testing GFS2
 o With a new mkfs.gfs2 which writes UUIDs, the UUID is now included
   in uevent messages (with older filesystems which don't have UUIDs,
   we just don't send that information)

The GFS2 tracing patches which I posted a little while back are not
included in this patch set. I think I can see what I need to do in
order to avoid patching blktrace now, so my plan is to look at those
patches again after this merge window, and when all the queued patches
for the tracing subsystem have been merged.

As always, please let us know if you spot any issues in the patches,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[swhiteho]

In preparation for the next merge window, here is the current content
of the GFS2 git tree. Firstly, we have one new feature, which is
support for the FIEMAP ioctl. That patch does touch some code
outside of GFS2 itself, but its the only patch in this series which
does so.

The remaining patches are mostly clean up and bug fixes, as usual.
They are working towards a point where I can submit a patch to finally
merge the lock_dlm module (not dlm itself I should emphasise) into
GFS2. That is a large patch and a preliminary version has already been
posted to cluster-devel. My plan is to put that patch into my -nmw
git tree as the first patch for the following merge window to give
it maximum exposure.

The other highlight of this patch series, is a patch which removes
the two daemons (gfs2_scand and gfs2_glockd) and replaces them with
a "shrinker" routine registered with the VM. As expected, this also
reduces the code size. We are also expecting do do a similar thing
with the GFS2 quota data strucutures at some point in the future.

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting

[Steven Whitehouse]

I'm guessing that the merge window opening might not be too far
away now, and in any case, I won't have quite my normal internet
access next week. So I'm pushing out the current GFS2 tree so
that (I hope) there will be time to fix any issues.

Again, there are fewer patches here. A lot of them are fairly small
too. The most noteable item deals with the meta filesystem which
was in response to Al Viro's suggestions concerning a better way
to structure that code. It certainly results in a much cleaner
implementation, so thanks go to Al for pointing that out.

A couple of new features: I/O barrier support (needs no user
configuration, see the patch for details) and UUID support
(no code changes, its all userland but we reserve space in
the super block, again details in the patch itself).

I know that I hardly need say, but please let me know if you have any
comments :-)

Steve.

[Cluster-devel] [GFS2] Pre-pull patch posting

[swhiteho]

So, although the merge window isn't yet open, I'm guessing that its
probably not too far away, hence this posting of the contents of
the current GFS2 -nmw git tree.

This time the big news is locking changes, although having said that,
there are far fewer queued patches in total than I've had for previous
merge windows and I believe that this is an indication of the
growing maturity of GFS2.

The first patch in the series is really the main change and is
a big clean up of the core of the glocks, which are really the
core of GFS2 in a lot of ways. Further through the series is
a documentation patch, which explains the fine detail of how
glocks work and the assumptions made by the glock core when
calling the functions relating to individual glock types.

Other notable changes include merging the lock_nolock module
into the core of GFS2 since there is little point in retaining
it separately. There is a plan to do the same to lock_dlm as
well in the future (not the DLM itself obviously, just the
interface module thats part of GFS2).

Most of the remaing changes are bug fixes or futher optimisations
over the initial glock changes, plus one or two minor clean ups
along the way.

Steve.

[Cluster-devel] [GFS2] Pre-pull patch posting

[swhiteho]

This is the current content of the GFS2 -nmw git tree. Mostly bug
fixes, there are some changes relating to block mapping which are
working towards cleaning up this code and allowing more efficient
block mapping. There is a second part to that work which is not
included in this patch set - the plan is that it will be in the
next patch set and its currently undergoing testing.

There are a number of clean up patches in the series too. We have
been continuing the work of gradually reducing the fields in the
various ..._host structures with a view to eventually eliminating
them completely. They were introduced as a stop-gap measure to fix
the endianess annotation and the fields are now gradually being moved
to other structures (or eliminated).

Bob Peterson's new improved "bitfit" algorithm provides a nice
speed up when we are allocating blocks as well as cleaning up
that area of the code.

Steve.

[Cluster-devel] [GFS2] Pre-pull patch posting

[swhiteho]

Hi,

Here is the current GFS2 patch queue. You'll notice that this time
there are no DLM patches in this list. That is because the DLM team
are setting up their own git tree and this future DLM patches will
be sent directly by them rather than via the GFS2 tree.

Most of this set of patches is clean up and bug fixes, there is really
not a lot new this time. I guess the most significant thing is the
patch to use ->page_mkwrite which will greatly increase efficiency
when files opened r/w are mostly only accessed for reading across a
cluster.

There are a number of cleanups related to journalling which is really
where the largest number of changes in terms of code lines is. The
indirect blocks for the journal are now scanned once only at mount
time and the bmap information is retained in the form of an extent
list. Since we expect journals to consist of only a single extent
in the normal case, this should generally be quite a short list :-)

In addition some of the tunables relating to the journal have been
removed in favour of autotuning those variables.

Steve.