We recently fixed the writeback of pages prior to performing
direct i/o, however the initial fix was perhaps a bit heavy
handed. There is no need to invalidate pages if the direct i/o
is only a read, since they will be identical to what has been
flushed to disk anyway.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Spotted by Andy Price. This should fix the odd messages from
lockdep caused by 70d4ee94Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Price <anprice@redhat.com>

This patch adds four new fields to directory leaf blocks.
The intent is not to use them in the kernel itself, although
perhaps we may be able to use them as hints at some later date,
but instead to provide more information for debug/fsck use.

One new field adds a pointer to the inode to which the leaf
belongs. This can be useful if the pointer to the leaf block
has become corrupt, as it will allow us to know which inode
this block should be associated with. This field is set when
the leaf is created and never changed over its lifetime.

The second field is a "distance from the hash table" field.
The meaning is as follows:
 0  = An old leaf in which this value has not been set
 1  = This leaf is pointed to directly from the hash table
 2+ = This leaf is part of a chain, pointed to by another leaf
      block, the value gives the position in the chain.

The third and fourth fields combine to give a time stamp of
the most recent directory insertion or deletion from this
leaf block. The time stamp is not updated when a new leaf
block is chained from the current one. The code is currently
written such that the timestamp on the dir inode will match
that of the leaf block for the most recent insertion/deletion.

For backwards compatibility, any of these new fields which is
zero should be considered to be "unknown".
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

For most cases, only a single new block is needed when we reach
the point of converting from stuffed to exhash directory. The
exception being when the file name is so long that it will not
fit within the new leaf block.

So this patch adds a simple test for that situation so that we
do not need to request the full reservation size in this case.

Potentially we could calculate more accurately the value to use
in other cases too, but that is much more complicated to do and
it is doubtful that the benefit would outweigh the extra cost
in code complexity.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch calls get_write_access in function gfs2_setattr_chown,
which merely increases inode->i_writecount for the duration of the
function. That will ensure that any file closes won't delete the
inode's multi-block reservation while the function is running.
It also ensures that a multi-block reservation exists when needed
for quota change operations during the chown.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

When we look to see if there is enough space to add a dir
entry without allocation, we have then been repeating the
same search later when we do the actual insertion. This
patch caches the details of the location in the gfs2_diradd
structure, so that we do not have to repeat the search.

This will provide a performance improvement which will be
greater as the size of the directory increases.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

There are three cases where we need to calculate the number of
blocks to reserve in a transaction involving linking an inode
into a directory. The one in rename is a bit more complicated,
but the basis of it is the same as for link and create. So it
makes sense to move this calculation into a single function
rather than repeating it three times.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

The intent is that this structure will hold the information
required when adding entries to a directory (linking). To
start with, it will contain only the number of blocks which
are required to link the new entry into the directory. The
current calculation returns either 0 or the maximim number of
blocks that can ever be requested by such a transaction.

The intent is that in a later patch, we can update the dir
code to calculate this value more accurately. In addition
further patches will also add further fields to the new
structure to increase its utility.

In addition this patch fixes a bug where the link used during
inode creation was adding requesting too many blocks in
some cases. This is harmless unless the fs is close to being
full.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Prior to this patch, GFS2 had one address space for each rgrp,
stored in the glock. This patch changes them to use a single
address space in the super block. This therefore saves
(sizeof(struct address_space) * nr_of_rgrps) bytes of memory
and for large filesystems, that can be significant.

It would be nice to be able to do something similar and merge
the inode metadata address space into the same global
address space. However, that is rather more complicated as the
on-disk location doesn't have a 1:1 mapping with the inodes in
general. So while it could be done, it will be a more complicated
operation as it requires changing a lot more code paths.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Each rgrp header is represented as a single extent on disk, so we
can calculate the position within the address space, since we are
using address spaces mapped 1:1 to the disk. This means that it
is possible to use the range based versions of filemap_fdatawrite/wait
and for invalidating the page cache.

Our eventual intent is to then be able to merge the address spaces
used for rgrps into a single address space, rather than to have
one for each glock, saving memory and reducing complexity.

Since during umount, the rgrp structures are disposed of before
the glocks, we need to store the extent information in the glock
so that is is available for a final invalidation. This patch uses
a field which is otherwise unused in rgrp glocks to do that, so
that we do not have to expand the size of a glock.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Since gfs2_inplace_reserve() is always called with a valid
alloc parms structure, there is no need to test for this
within the function itself - and in any case, after we've
all ready dereferenced it anyway.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

There is only one place this is used, when reading in the quota
changes at mount time. It is not really required and much
simpler to just convert the fields from the on-disk structure
as required.

There should be no functional change as a result of this patch.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

For historical reasons, we drop and retake the log lock in ->releasepage()
however, since there is no reason why we cannot hold the log lock over
the whole function, this allows some simplification. In particular,
pinning a buffer is only ever done under the log lock, so it is possible
here to remove the test for pinned buffers in the second loop, since it
is impossible for that to happen (it is also tested in the first loop).

As a result, two tests made later in the second loop become constants
and can also be reduced to the only possible branch. So the net result
is to remove various bits of unreachable code and make this more
readable.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

With the preceding patch, we started accepting block reservations
smaller than the ideal size, which requires a lot more parsing of the
bitmaps. To reduce the amount of bitmap searching, this patch
implements a scheme whereby each rgrp keeps track of the point
at this multi-block reservations will fail.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This is just basically a resend of a patch I posted earlier.
It didn't change from its original, except in diff offsets, etc:

This patch fixes a bug in the GFS2 block allocation code. The problem
starts if a process already has a multi-block reservation, but for
some reason, another process disqualifies it from further allocations.
For example, the other process might set on the GFS2_RDF_ERROR bit.
The process holding the reservation jumps to label skip_rgrp, but
that label comes after the code that removes the reservation from the
tree. Therefore, the no longer usable reservation is not removed from
the rgrp's reservations tree; it's lost. Eventually, the lost reservation
causes the count of reserved blocks to get off, and eventually that
causes a BUG_ON(rs->rs_rbm.rgd->rd_reserved < rs->rs_free) to trigger.
This patch moves the call to after label skip_rgrp so that the
disqualified reservation is properly removed from the tree, thus keeping
the rgrp rd_reserved count sane.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Here is a second try at a patch I posted earlier, which also implements
suggestions Steve made:

Before this patch, GFS2 would keep searching through all the rgrps
until it found one that had a chunk of free blocks big enough to
satisfy the size hint, which is based on the file write size,
regardless of whether the chunk was big enough to perform the write.
However, when doing big writes there may not be a large enough
chunk of free blocks in any rgrp, due to file system fragmentation.
The largest chunk may be big enough to satisfy the write request,
but it may not meet the ideal reservation size from the "size hint".
The writes would slow to a crawl because every write would search
every rgrp, then finally give up and default to a single-block write.
In my case, performance would drop from 425MB/s to 18KB/s, or 24000
times slower.

This patch basically makes it so that if we can't find a contiguous
chunk of blocks big enough to satisfy the sizehint, we'll use the
largest chunk of blocks we found that will still contain the write.
It does so by keeping track of the largest run of blocks within the
rgrp.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

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

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: NSteven Whitehouse <swhiteho@redhat.com>

In patch 209806ab 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: NSteven Whitehouse <swhiteho@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: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@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: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This is a GFS2 version of Tejun's patch:
4f331f01
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: NTejun Heo <tj@kernel.org>
Reported-by: NAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

In the case that atomic_open calls finish_no_open() with
the dentry that was supplied to gfs2_atomic_open() an
extra reference count is required. This patch fixes that
issue preventing a bug trap triggering at umount time.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Commit [e66cf161: GFS2: Use lockref for glocks] replaced call:
    atomic_read(&gi->gl->gl_ref) == 0
with:
    __lockref_is_dead(&gl->gl_lockref)
therefore changing how gl is accessed, from gi->gl to plan gl.
However, gl can be a NULL pointer, and so gi->gl needs to be
used instead (which is guaranteed not to be NULL because fo
the while loop checking that condition).
Signed-off-by: NMichal Nazarewicz <mina86@mina86.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

By using the generic list_lru code, we can now separate the
per sb quota list locking from the lru locking. The lru
lock is made into the inner-most lock.

As a result of this new lock order, we may occasionally see
items on the per-sb quota list which are "dead" so that the
two places where we traverse that list are updated to take
account of that.

As a result of this patch, the gfs2 quota shrinker is now
NUMA zone aware, and we are also laying the foundations for
further improvments in due course.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Signed-off-by: NAbhijith Das <adas@redhat.com>
Tested-by: NAbhijith Das <adas@redhat.com>
Cc: Dave Chinner <dchinner@redhat.com>

This is a straight forward rename which is in preparation for
introducing the generic list_lru infrastructure in the
following patch.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Signed-off-by: NAbhijith Das <adas@redhat.com>
Tested-by: NAbhijith Das <adas@redhat.com>

This patch adds reflink support to the quota data cache. It
looks a bit strange because we still don't have a sensible
split in the lookup by id and the lru list. That is coming in
later patches though.

The intent here is just to swap the current ref count for
reflinks in all cases with as little as possible other change.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Signed-off-by: NAbhijith Das <adas@redhat.com>
Tested-by: NAbhijith Das <adas@redhat.com>

duplicated to hell and back...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Currently glocks have an atomic reference count and also a spinlock
which covers various internal fields, such as the state. This intent of
this patch is to replace the spinlock and the atomic reference count
with a lockref structure. This contains a spinlock which we can continue
to use as before, and a reference counter which is used in conjuction
with the spinlock to replace the previous atomic counter.

As a result of this there are some new rules for reference counting on
glocks. We need to distinguish between reference count changes under
gl_spin (which are now just increment or decrement of the new counter,
provided the count cannot hit zero) and those which are outside of
gl_spin, but which now take gl_spin internally.

The conversion is relatively straight forward. There is probably some
further clean up which can be done, but the priority at this stage is to
make the change in as simple a manner as possible.

A consequence of this change is that the reference count is being
decoupled from the lru list processing. This should allow future
adoption of the lru_list code with glocks in due course.

The reason for using the "dead" state and not just relying on 0 being
the "invalid state" is so that in due course 0 ref counts can be
allowable. The intent is to eventually be able to remove the ref count
changes which are currently hidden away in state_change().
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Now that gfs2_quota_sync can be potentially called from multiple
threads, we should protect this bit of code, and the sync generation
number in particular in order to ensure that there are no races
when syncing quotas.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>

The function qd_trylock was not a trylock despite its name and
can be inlined into gfs2_quota_unlock in order to make the
code a bit clearer. There should be no functional change as a
result of this patch.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>

There should be no functional change bar the removal of a
test of the MS_READONLY flag which would never be reachable.
This merges the common code from qd_fish and qd_trylock into
a single function and calls it from both those places.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>

There is no need for a paramater which relates to the internals
of quota to be exposed to users. The only possible use would be
to turn it up so large that the memory allocation fails. So lets
remove it and set it to a sensible value which ensures that we
don't ask for multipage allocations.

Currently the size of struct gfs2_holder means that the caluclated
value is identical to the previous default value, so there should
be no functional change.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>

This function is only called twice, and both callers are
quota related, so lets move this function into quota.c and
make it static.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

When setting the starting point for block allocation, there were calls
to both gfs2_rbm_to_block() and gfs2_rbm_from_block() in the common case
of there being an active reservation. The gfs2_rbm_from_block() function
can be quite slow, and since the two conversions were effectively a
no-op, it makes sense to avoid them entirely in this case.

There is no functional change here, but the code should be a bit more
efficient after this patch.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch adds a structure to contain allocation parameters with
the intention of future expansion of this structure. The idea is
that we should be able to add more information about the allocation
in the future in order to allow the allocator to make a better job
of placing the requests on-disk.

There is no functional difference from applying this patch.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

The reservation for an inode should be cleared when it is truncated so
that we can start again at a different offset for future allocations.
We could try and do better than that, by resetting the search based on
where the truncation started from, but this is only a first step.

In addition, there are three callers of gfs2_rs_delete() but only one
of those should really be testing the value of i_writecount. While
we get away with that in the other cases currently, I think it would
be better if we made that test specific to the one case which
requires it.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

We need to dput() the result of d_splice_alias(), unless it is passed to
finish_no_open().

Edited by Steven Whitehouse in order to make it apply to the current
GFS2 git tree, and taking account of a prerequisite patch which hasn't
been applied.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Cc: stable@vger.kernel.org

Since the previous patch eliminated bi in favor of bii, this follow-on
patch needed to be adjusted accordingly. Here is the revised version.

This patch adds a new function, gfs2_rbm_incr, which increments
an rbm structure. This is more efficient than calling gfs2_rbm_to_block,
incrementing, then calling gfs2_rbm_from_block.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>