[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here is a set of small fixes for GFS2. There is a fix to drop
s_umount which is copied in from the core vfs, two patches
relate to a hard to hit "use after free" and memory leak.
Two patches related to using DIO and buffered I/O on the same
file to ensure correct operation in relation to glock state
changes. The final patch adds an RCU read lock to ensure
correct locking on an error path,

Steve.

[Cluster-devel] [PATCH 1/6] GFS2: don't hold s_umount over blkdev_put

[Steven Whitehouse]

This is a GFS2 version of Tejun's patch:
4f331f01b9c43bf001d3ffee578a97a1e0633eac
vfs: don't hold s_umount over close_bdev_exclusive() call

In this case its blkdev_put itself that is the issue and this
patch uses the same solution of dropping and retaking s_umount.

Reported-by: Tejun Heo <tj@kernel.org>
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 82303b4..52fa883 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -1366,8 +1366,18 @@ static struct dentry *gfs2_mount(struct file_system_type *fs_type, int flags,
 	if (IS_ERR(s))
 		goto error_bdev;
 
-	if (s->s_root)
+	if (s->s_root) {
+		/*
+		 * s_umount nests inside bd_mutex during
+		 * __invalidate_device().  blkdev_put() acquires
+		 * bd_mutex and can't be called under s_umount.  Drop
+		 * s_umount temporarily.  This is safe as we're
+		 * holding an active reference.
+		 */
+		up_write(&s->s_umount);
 		blkdev_put(bdev, mode);
+		down_write(&s->s_umount);
+	}
 
 	memset(&args, 0, sizeof(args));
 	args.ar_quota = GFS2_QUOTA_DEFAULT;
-- 
1.8.3.1

[Cluster-devel] [PATCH 2/6] GFS2: Fix use-after-free race when calling gfs2_remove_from_ail

[Steven Whitehouse]

From: Bob Peterson <rpeterso@redhat.com>

Function gfs2_remove_from_ail drops the reference on the bh via
brelse. This patch fixes a race condition whereby bh is deferenced
after the brelse when setting bd->bd_blkno = bh->b_blocknr;
Under certain rare circumstances, bh might be gone or reused,
and bd->bd_blkno is set to whatever that memory happens to be,
which is often 0. Later, in gfs2_trans_add_unrevoke, that bd fails
the test "bd->bd_blkno >= blkno" which causes it to never be freed.
The end result is that the bd is never freed from the bufdata cache,
which results in this error:
slab error in kmem_cache_destroy(): cache `gfs2_bufdata': Can't free all objects

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

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 610613f..9dcb977 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -551,10 +551,10 @@ void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
 	struct buffer_head *bh = bd->bd_bh;
 	struct gfs2_glock *gl = bd->bd_gl;
 
-	gfs2_remove_from_ail(bd);
-	bd->bd_bh = NULL;
 	bh->b_private = NULL;
 	bd->bd_blkno = bh->b_blocknr;
+	gfs2_remove_from_ail(bd); /* drops ref on bh */
+	bd->bd_bh = NULL;
 	bd->bd_ops = &gfs2_revoke_lops;
 	sdp->sd_log_num_revoke++;
 	atomic_inc(&gl->gl_revokes);
-- 
1.8.3.1

[Cluster-devel] [PATCH 3/6] GFS2: Fix slab memory leak in gfs2_bufdata

[Steven Whitehouse]

From: Bob Peterson <rpeterso@redhat.com>

This patch fixes a slab memory leak that sometimes can occur
for files with a very short lifespan. The problem occurs when
a dinode is deleted before it has gotten to the journal properly.
In the leak scenario, the bd object is pinned for journal
committment (queued to the metadata buffers queue: sd_log_le_buf)
but is subsequently unpinned and dequeued before it finds its way
to the ail or the revoke queue. In this rare circumstance, the bd
object needs to be freed from slab memory, or it is forgotten.
We have to be very careful how we do it, though, because
multiple processes can call gfs2_remove_from_journal. In order to
avoid double-frees, only the process that does the unpinning is
allowed to free the bd.

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

diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 9324150..52f177b 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -258,6 +258,7 @@ void gfs2_remove_from_journal(struct buffer_head *bh, struct gfs2_trans *tr, int
 	struct address_space *mapping = bh->b_page->mapping;
 	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
 	struct gfs2_bufdata *bd = bh->b_private;
+	int was_pinned = 0;
 
 	if (test_clear_buffer_pinned(bh)) {
 		trace_gfs2_pin(bd, 0);
@@ -273,12 +274,16 @@ void gfs2_remove_from_journal(struct buffer_head *bh, struct gfs2_trans *tr, int
 			tr->tr_num_databuf_rm++;
 		}
 		tr->tr_touched = 1;
+		was_pinned = 1;
 		brelse(bh);
 	}
 	if (bd) {
 		spin_lock(&sdp->sd_ail_lock);
 		if (bd->bd_tr) {
 			gfs2_trans_add_revoke(sdp, bd);
+		} else if (was_pinned) {
+			bh->b_private = NULL;
+			kmem_cache_free(gfs2_bufdata_cachep, bd);
 		}
 		spin_unlock(&sdp->sd_ail_lock);
 	}
-- 
1.8.3.1

[Cluster-devel] [PATCH 4/6] GFS2: Fix incorrect invalidation for DIO/buffered I/O

[Steven Whitehouse]

In patch 209806aba9d540dde3db0a5ce72307f85f33468f we allowed
local deferred locks to be granted against a cached exclusive
lock. That opened up a corner case which this patch now
fixes.

The solution to the problem is to check whether we have cached
pages each time we do direct I/O and if so to unmap, flush
and invalidate those pages. Since the glock state machine
normally does that for us, mostly the code will be a no-op.

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

diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index b7fc035..73f3e4e 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -986,6 +986,7 @@ static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
+	struct address_space *mapping = inode->i_mapping;
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_holder gh;
 	int rv;
@@ -1006,6 +1007,35 @@ static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 	if (rv != 1)
 		goto out; /* dio not valid, fall back to buffered i/o */
 
+	/*
+	 * Now since we are holding a deferred (CW) lock at this point, you
+	 * might be wondering why this is ever needed. There is a case however
+	 * where we've granted a deferred local lock against a cached exclusive
+	 * glock. That is ok provided all granted local locks are deferred, but
+	 * it also means that it is possible to encounter pages which are
+	 * cached and possibly also mapped. So here we check for that and sort
+	 * them out ahead of the dio. The glock state machine will take care of
+	 * everything else.
+	 *
+	 * If in fact the cached glock state (gl->gl_state) is deferred (CW) in
+	 * the first place, mapping->nr_pages will always be zero.
+	 */
+	if (mapping->nrpages) {
+		loff_t lstart = offset & (PAGE_CACHE_SIZE - 1);
+		loff_t len = iov_length(iov, nr_segs);
+		loff_t end = PAGE_ALIGN(offset + len) - 1;
+
+		rv = 0;
+		if (len == 0)
+			goto out;
+		if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
+			unmap_shared_mapping_range(ip->i_inode.i_mapping, offset, len);
+		rv = filemap_write_and_wait_range(mapping, lstart, end);
+		if (rv)
+			return rv;
+		truncate_inode_pages_range(mapping, lstart, end);
+	}
+
 	rv = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
 				  offset, nr_segs, gfs2_get_block_direct,
 				  NULL, NULL, 0);
-- 
1.8.3.1

[Cluster-devel] [PATCH 5/6] GFS2: Wait for async DIO in glock state changes

[Steven Whitehouse]

We need to wait for any outstanding DIO to complete in a couple
of situations. Firstly, in case we are changing out of deferred
mode (in inode_go_sync) where GLF_DIRTY will not be set. That
call could be prefixed with a test for gl_state == LM_ST_DEFERRED
but it doesn't seem worth it bearing in mind that the test for
outstanding DIO is very quick anyway, in the usual case that there
is none.

The second case is in inode_go_lock which will catch the cases
where we have a cached EX lock, but where we grant deferred locks
against it so that there is no glock state transistion. We only
need to wait if the state is not deferred, since DIO is valid
anyway in that state.

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

diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index db908f6..f88dcd9 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -192,8 +192,11 @@ static void inode_go_sync(struct gfs2_glock *gl)
 
 	if (ip && !S_ISREG(ip->i_inode.i_mode))
 		ip = NULL;
-	if (ip && test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
-		unmap_shared_mapping_range(ip->i_inode.i_mapping, 0, 0);
+	if (ip) {
+		if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
+			unmap_shared_mapping_range(ip->i_inode.i_mapping, 0, 0);
+		inode_dio_wait(&ip->i_inode);
+	}
 	if (!test_and_clear_bit(GLF_DIRTY, &gl->gl_flags))
 		return;
 
@@ -410,6 +413,9 @@ static int inode_go_lock(struct gfs2_holder *gh)
 			return error;
 	}
 
+	if (gh->gh_state != LM_ST_DEFERRED)
+		inode_dio_wait(&ip->i_inode);
+
 	if ((ip->i_diskflags & GFS2_DIF_TRUNC_IN_PROG) &&
 	    (gl->gl_state == LM_ST_EXCLUSIVE) &&
 	    (gh->gh_state == LM_ST_EXCLUSIVE)) {
-- 
1.8.3.1

[Cluster-devel] [PATCH 6/6] GFS2: Fix unsafe dereference in dump_holder()

[Steven Whitehouse]

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

GLOCK_BUG_ON() might call this function without RCU read lock. Make sure that
RCU read lock is held when using task_struct returned from pid_task().

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index c8420f7..6f7a47c 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1655,6 +1655,7 @@ static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
 	struct task_struct *gh_owner = NULL;
 	char flags_buf[32];
 
+	rcu_read_lock();
 	if (gh->gh_owner_pid)
 		gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
 	gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
@@ -1664,6 +1665,7 @@ static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
 		       gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
 		       gh_owner ? gh_owner->comm : "(ended)",
 		       (void *)gh->gh_ip);
+	rcu_read_unlock();
 	return 0;
 }
 
-- 
1.8.3.1

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are a number of small fixes for GFS2. There is a fix for FIEMAP
on large sparse files, a negative dentry hashing fix, a fix for
flock, and a bug fix relating to d_splice_alias usage. There are
also (patches 1 and 5) a couple of updates which are less
critical, but small and low risk.

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are the current set of small fixes relating to GFS2.

This patch set contains two minor docs/spelling fixes, some fixes for
flock, a change to use GFP_NOFS to avoid recursion on a rarely used code
path and a fix for a race relating to the glock lru,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are a couple of very small, but important, fixes,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Out of these fives patches, the one for ensuring that the number of
revokes is not exceeded, and the one for checking the glock is not
already held in gfs2_getxattr are the two most important. The latter
can be triggered by selinux.

The other three patches are very small and fix mostly fairly
trivial issues,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

There are four patches this time. The first fixes a problem where the
wrong descriptor type was being written into the log for journaled data
blocks. The second fixes a race relating to the deallocation of allocator
data. The third provides a fallback if kmalloc is unable to satisfy a
request to allocate a directory hash table. The fourth fixes the iopen
glock caching so that inodes are deleted in a more timely manner after
rmdir/unlink,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

This time there are just four fixes. There are a couple of minor updates
to the quota code, a fix for KConfig to ensure that only valid combinations
including GFS2 can be built, and a fix for a typo affecting end i/o
processing when writing the journal.

Also, there is a temporary fix for a performance regression relating to
block reservations and directories. A longer fix will be applied in
due course, but this deals with the most immediate problem for now,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are a number of GFS2 bug fixes. There are three from Andy Price
which fix various issues spotted by automated code analysis. There are two
from Lukas Czerner fixing my mistaken assumptions as to how FITRIM
should work. Finally Ben Marzinski has fixed a bug relating to mmap and
atime and also a bug relating to a locking issue in the transaction code.

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are three GFS2 fixes for the current kernel tree. These are all
related to the block reservation code which was added at the merge
window. That code will be getting an update at the forthcoming merge
window too. In the mean time though there are a few smaller issues
which should be fixed.

The first patch resolves an issue with write sizes of greater than
32 bits with the size hinting code. The second ensures that the
allocation data structure is initialised when using xattrs and the
third takes into account allocations which may have been made by
other nodes which affect a reservation on the local node,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are four fixes for issues that have come up since the last
merge window,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are four patches which provided fixes for bugs found in the
current upstream code. Please see individual patches for
descriptions,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

The following three fixes should help ensure that 3.0 is the best
release yet, GFS2-wise at least. I've had the first two queued for
some time waiting for the final one of this set. All three are relatively
short, although the third is a bit longer than the others, mainly
due to the extra comments added describing the inode eviction process,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are a couple of small fixes which just missed the previous pull
request. Both fairly short and self-explanatory,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are four fixes for GFS2. See the individual patches for the detailed
descriptions,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are a few small fixes for GFS2,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

These are three important, but relatively small, bug fixes for GFS2.
The first prevents a kernel BUG triggering in a relatively unlikely
(but possible) scenario when a log flush caused by glock demotion
races with a log flush from some other initiator (e.g. fsync).

The second and third patches add extra conditions to two areas
of code. This makes their behaviour match ext3 in those cases,

Steve.

[Cluster-devel] [GFS2] Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are a couple of GFS2 fixes. Both are one-liners,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here are a couple of patches which between them fix a problem where
occasionally it was possible for the GFS2 module to be unloaded
before all the glocks were deallocated, which, needless to say, made
the slab allocator unhappy,

Steve.

[Cluster-devel] [GFS2] Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here is the latest set of GFS2 fixes. They are all fairly small,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Here are four small fixes for GFS2. Assuming that nobody spots
any errors, I'll be sending a pull request for these shortly,

Steve.

[Cluster-devel] GFS2: Pre-pull patch posting (fixes)

[Steven Whitehouse]

Hi,

Here is the current content of the GFS2 -fixes git tree. Nothing
very exciting this time... some fixes for issues we've
had relating to flushing glocks/memory usage, plus a couple of
other fixes relating to statfs and the timely removal of inodes
which have been unlinked on a remote node,

Steve.