linux-toradex.git/fs/gfs2/glock.c, branch v4.17

gfs2: Stop using rhashtable_walk_peek

2018-04-12T16:41:19+00:00

Function rhashtable_walk_peek is problematic because there is no
guarantee that the glock previously returned still exists; when that key
is deleted, rhashtable_walk_peek can end up returning a different key,
which will cause an inconsistent glock dump.  Fix this by keeping track
of the current glock in the seq file iterator functions instead.

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Bob Peterson

gfs2: Glock dump performance regression fix

2018-02-01T18:27:11+00:00

Restore an optimization removed in commit 7f19449553 "Fix debugfs glocks
dump": keep the glock hash table iterator active while the glock dump
file is held open.  This avoids having to rescan the hash table from the
start for each read, with quadratically rising runtime.

In addition, use rhastable_walk_peek for resuming a glock dump at the
current position: when a glock doesn't fit in the provided buffer
anymore, the next read must revisit the same glock.

Finally, also restart the dump from the first entry when we notice that
the hash table has been resized in gfs2_glock_seq_start.

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Bob Peterson

rhashtable: Change rhashtable_walk_start to return void

2017-12-11T14:58:38+00:00

Most callers of rhashtable_walk_start don't care about a resize event
which is indicated by a return value of -EAGAIN. So calls to
rhashtable_walk_start are wrapped wih code to ignore -EAGAIN. Something
like this is common:

       ret = rhashtable_walk_start(rhiter);
       if (ret && ret != -EAGAIN)
               goto out;

Since zero and -EAGAIN are the only possible return values from the
function this check is pointless. The condition never evaluates to true.

This patch changes rhashtable_walk_start to return void. This simplifies
code for the callers that ignore -EAGAIN. For the few cases where the
caller cares about the resize event, particularly where the table can be
walked in mulitple parts for netlink or seq file dump, the function
rhashtable_walk_start_check has been added that returns -EAGAIN on a
resize event.

Signed-off-by: Tom Herbert 
Acked-by: Herbert Xu 
Signed-off-by: David S. Miller

gfs2: Fix debugfs glocks dump

2017-09-25T17:32:33+00:00

The switch to rhashtables (commit 88ffbf3e03) broke the debugfs glock
dump (/sys/kernel/debug/gfs2//glocks) for dumps bigger than a
single buffer: the right function for restarting an rhashtable iteration
from the beginning of the hash table is rhashtable_walk_enter;
rhashtable_walk_stop + rhashtable_walk_start will just resume from the
current position.

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Bob Peterson 
Cc: stable@vger.kernel.org # v4.3+

gfs2: constify rhashtable_params

2017-08-30T13:14:39+00:00

rhashtable_params are not supposed to change at runtime. All
Functions rhashtable_* working with const rhashtable_params
provided by . So mark the non-const structs
as const.

Signed-off-by: Arvind Yadav 
Signed-off-by: Bob Peterson

GFS2: Fix up some sparse warnings

2017-08-25T23:47:18+00:00

This patch cleans up various pieces of GFS2 to avoid sparse errors.
This doesn't fix them all, but it fixes several. The first error,
in function glock_hash_walk was a genuine bug where the rhashtable
could be started and not stopped.

Signed-off-by: Bob Peterson

gfs2: Clean up waiting on glocks

2017-08-10T15:51:02+00:00

The prepare_to_wait_on_glock and finish_wait_on_glock functions introduced in
commit 56a365be "gfs2: gfs2_glock_get: Wait on freeing glocks" are
better removed, resulting in cleaner code.

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Bob Peterson

gfs2: gfs2_evict_inode: Put glocks asynchronously

2017-08-10T15:45:21+00:00

gfs2_evict_inode is called to free inodes under memory pressure.  The
function calls into DLM when an inode's last cluster-wide reference goes
away (remote unlink) and to release the glock and associated DLM lock
before finally destroying the inode.  However, if DLM is blocked on
memory to become available, calling into DLM again will deadlock.

Avoid that by decoupling releasing glocks from destroying inodes in that
case: with gfs2_glock_queue_put, glocks will be dequeued asynchronously
in work queue context, when the associated inodes have likely already
been destroyed.

With this change, inodes can end up being unlinked, remote-unlink can be
triggered, and then the inode can be reallocated before all
remote-unlink callbacks are processed.  To detect that, revalidate the
link count in gfs2_evict_inode to make sure we're not deleting an
allocated, referenced inode.

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Bob Peterson

gfs2: gfs2_glock_get: Wait on freeing glocks

2017-08-10T15:39:31+00:00

Keep glocks in their hash table until they are freed instead of removing
them when their last reference is dropped.  This allows to wait for any
previous instances of a glock to go away in gfs2_glock_get before
creating a new glocks.

Special thanks to Andy Price for finding and fixing a problem which also
required us to delete the rcu_read_unlock from the error case in function
gfs2_glock_get.

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Bob Peterson

GFS2: Don't waste time locking lru_lock for non-lru glocks

2017-08-09T14:36:39+00:00

Before this patch, glock_dq would call gfs2_glock_remove_from_lru.
For glocks that are never put on the LRU, such as the transaction
glock, this just takes the spin_lock, determines there's nothing to
be done because the list is empty, then unlocks again. This was
causing unnecessary lock contention on the lru_lock spin_lock.
This patch adds a check for GLOF_LRU in the glops before taking
the spin_lock.

Signed-off-by: Bob Peterson