This removes the extra filldir callback which gfs2 was using to
enclose an attempt at readahead for inodes during readdir. The
code was too complicated and also hurts performance badly in the
case that the getdents64/readdir call isn't being followed by
stat() and it wasn't even getting it right all the time when it
was.

As a result, on my test box an "ls" of a directory containing 250000
files fell from about 7mins (freshly mounted, so nothing cached) to
between about 15 to 25 seconds. When the directory content was cached,
the time taken fell from about 3mins to about 4 or 5 seconds.

Interestingly in the cached case, running "ls -l" once reduced the time
taken for subsequent runs of "ls" to about 6 secs even without this
patch. Now it turns out that there was a special case of glocks being
used for prefetching the metadata, but because of the timeouts for these
locks (set to 10 secs) the metadata was being timed out before it was
being used and this the prefetch code was constantly trying to prefetch
the same data over and over.

Calling "ls -l" meant that the inodes were brought into memory and once
the inodes are cached, the glocks are not disposed of until the inodes
are pushed out of the cache, thus extending the lifetime of the glocks,
and thus bringing down the time for subsequent runs of "ls"
considerably.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Fix function parameter typing:
fs/gfs2/glock.c:100: warning: function declaration isn't a prototype
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This fixes a bug which resulted in poor performance due to flushing
the journal too often. The code path in question was via the inode_go_sync()
function in glops.c. The solution is not to flush the journal immediately
when inodes are ejected from memory, but batch up the work for glockd to
deal with later on. This means that glocks may now live on beyond the end of
the lifetime of their inodes (but not very much longer in the normal case).

Also fixed in this patch is a bug (which was hidden by the bug mentioned above) in
calculation of the number of free journal blocks.

The gfs2_logd process has been altered to be more responsive to the journal
filling up. We now wake it up when the number of uncommitted journal blocks
has reached the threshold level rather than trying to flush directly at the
end of each transaction. This again means doing fewer, but larger, log
flushes in general.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

The go_sync callback took two flags, but one of them was set on every
call, so this patch removes once of the flags and makes the previously
conditional operations (on this flag), unconditional.

The go_inval callback took three flags, each of which was set on every
call to it. This patch removes the flags and makes the operations
unconditional, which makes the logic rather more obvious.

Two now unused flags are also removed from incore.h.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Change from GFP_KERNEL to GFP_NOFS as this was causing a
slow down when trying to push inodes from cache.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

There is no way to set the GL_DUMP flag, and in any case the
same thing can be done with systemtap if required for debugging,
so this removes it.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This removes the duplicate di_mode field in favour of using the
inode->i_mode field. This saves 4 bytes.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Fix up for make allyesconfig.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>

As per Andrew Morton's request, removed trailing whitespace.

Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

lm_interface.h has a few out of the tree clients such as GFS1
and userland tools.

Right now, these clients keeps a copy of the file in their build tree
that can go out of sync.

Move lm_interface.h to include/linux, export it to userland and
clean up fs/gfs2 to use the new location.
Signed-off-by: NFabio M. Di Nitto <fabbione@ubuntu.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

A one liner bug fix to prevent the return value being
wrong when more than one superblock is mounted.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Use atomic_t as the ref count in glocks rather than a kref.
This is another step towards using RCU for the glock hash.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This results in smaller list heads, so that we can have more chains
in the same amount of memory (twice as many). I've multiplied the
size of the table by four though - this is because we are saving
memory by not having one lock per chain any more. So we land up
using about the same amount of memory for the hash table as we
did before I started these changes, the difference being that we
now have four times as many hash chains.

The reason that I say "about the same amount of memory" is that the
actual amount now depends upon the NR_CPUS and some of the config
variables, so that its not exact and in some cases we do use more
memory. Eventually we might want to scale the hash table size
according to the size of physical ram as measured on module load.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

The existing implementation of this function in glock.c was not
very efficient as it relied upon keeping a cursor element upon the
hash chain in question and moving it along. This new version improves
upon this by using the current element as a cursor. This is possible
since we only look at the "next" element in the list after we've
taken the read_lock() subsequent to calling the examiner function.
Obviously we have to eventually drop the ref count that we are then
left with and we cannot do that while holding the read_lock, so we
do that next time we drop the lock. That means either just before
we examine another glock, or when the loop has terminated.

The new implementation has several advantages: it uses only a
read_lock() rather than a write_lock(), so it can run simnultaneously
with other code, it doesn't need a "plug" element, so that it removes
a test not only from this list iterator, but from all the other glock
list iterators too. So it makes things faster and smaller.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

The callback for iopen locks is unused, so this removes
it.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Add back the consts which were casted away in the glock sorting
function. Also add early exit code.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Make the number of locks used for hash chains in glock.c
proportional to NR_CPUS. Also move constants for the number
of hash chains into glock.c from incore.h since they are
not used outside of glock.c.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This splits the rwlocks guarding the hash chains of the glock hash
table into their own array. This will reduce memory usage in some
cases due to better alignment, although the real reason for doing it
is to allow the two tables to be different sizes in future (i.e.
the locks will be sized proportionally with the max number of CPUs
and the hash chains sized proportinally with the size of physical memory)

In order to allow this, the gl_bucket member of struct gfs2_glock has
now become gl_hash, so we record the hash rather than a pointer to the
bucket itself.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

As requested by Jan Engelhardt, this removes the typedefs in the
locking module interface and replaces them with void *. Also
since we are changing the interface, I've added a few consts
as well.

Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Cc: David Teigland <teigland@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This removes one of the typedefs from the locking interface. It
is replaced by a forward declaration of the gfs2 superblock. The
other two are not so easy to solve since in their case, they
can refer to one of two possible structures.

Cc: David Teigland <teigland@redhat.com>
Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

There are several reasons why we want to do this:
 - Firstly its large and thus we'll scale better with multiple
   GFS2 fs mounted at the same time
 - Secondly its easier to scale its size as required (thats a plan
   for later patches)
 - Thirdly, we can use kzalloc rather than vmalloc when allocating
   the superblock (its now only 4888 bytes)
 - Fourth its all part of my plan to eventually be able to use RCU
   with the glock hash.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This is another patch preparing for sharing of the glock hash
table between different gfs2 mounts.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This makes all fixed size types have consistent names.

Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This makes everything consistent.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

As per Jan Engelhardt's second email, this removes some unused code,
and fixes up indenting in various places.

Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

As per comments from Jan Engelhardt <jengelh@linux01.gwdg.de> this
updates the copyright message to say "version" in full rather than
"v.2". Also incore.h has been updated to remove forward structure
declarations which are not required.

The gfs2_quota_lvb structure has now had endianess annotations added
to it. Also quota.c has been updated so that we now store the
lvb data locally in endian independant format to avoid needing
a structure in host endianess too. As a result the endianess
conversions are done as required at various points and thus the
conversion routines in lvb.[ch] are no longer required. I've
moved the one remaining constant in lvb.h thats used into lm.h
and removed the unused lvb.[ch].

I have not changed the HIF_ constants. That is left to a later patch
which I hope will unify the gh_flags and gh_iflags fields of the
struct gfs2_holder.

Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This adds the superblock as a key for glock lookups. Since the glocks
are already stored in a per-superblock table, this has no effect at
the moment. Later on this will change though.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Use const for the glock name which is being used as a lookup key
in the glock hash table.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

We can take advantage of the slab allocator to ensure that all the list
heads and the spinlock (plus one or two other fields) are initialised
by slab to speed up allocation of glocks.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Remove the unused sync feature from glocks. This is currently done by
calling the required functions to sync pages/blocks directly so this
code isn't needed.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

For all the usual reasons of enforcing correctness and potentially
reducing code size, this patch makes the glock operations const.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch allows the simultaneous mounting of gfs2meta and gfs2
filesystems. A restriction however is that a gfs2meta fs may only be
mounted if its corresponding gfs2 filesystem is also mounted. Also, a
gfs2 filesystem cannot be unmounted before its gfs2meta filesystem.
Signed-off-by: NAbhijith Das <adas@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

I noticed the gfs2_scand seemed to be taking a lot of CPU,
so in order to cut that down a bit, here is a patch. Firstly
the type of a glock is a constant during its lifetime, so that
its possible to check this without needing locking. I've moved
the (common) case of testing for an inode glock outside of
the glmutex lock.

Also there was a mutex left over from when the glock cache was
master of the inode cache. That isn't required any more so I've
removed that too.

There is probably scope for further speed ups in the future
in this area.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

recovery.c add a brelse to deal with gfs2_replay_read_block being called
twice on the same block.

add a dput to drop the ref count on the root inode.
This was causing lingering glocks and thus causing
a mount failure to hang.

Fix a endian conversion macro that was was swizzling
16bits when it should have been swizzling 32.
Signed-off-by: NRussell Cattelan <cattelan@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

We should have been waiting for lock demotion to finish in
clear_inode.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This means that we don't need to create a special inode just to contain
a struct address_space in order to read a single disk block. Instead
we read the disk block directly. Its slightly faster, and uses slightly
less memory, but the real reason for doing this is that it removes a
special case from the glock code.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This really is the correct fix this time. We just ignore all
glocks associated with inodes until the inodes are pushed
from the inode cache. At that point the glocks are queued for
reclaim, so we don't need to do it here.

Also fix one or two other minor bugs.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Under certain circumstances the glock scanning logic would
demote locks which ought not to have been selected for
demotion.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This removes one instance of GFP_NOFAIL from the glock callback
function. It also fixes a bug where a , was used at a line end
rather than ; causing unintended results.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch fixes the way we have been dealing with unlinked,
but still open files. It removes all limits (other than memory
for inodes, as per every other filesystem) on numbers of these
which we can support on GFS2. It also means that (like other
fs) its the responsibility of the last process to close the file
to deallocate the storage, rather than the person who did the
unlinking. Note that with GFS2, those two events might take place
on different nodes.

Also there are a number of other changes:

 o We use the Linux inode subsystem as it was intended to be
used, wrt allocating GFS2 inodes
 o The Linux inode cache is now the point which we use for
local enforcement of only holding one copy of the inode in
core at once (previous to this we used the glock layer).
 o We no longer use the unlinked "special" file. We just ignore it
completely. This makes unlinking more efficient.
 o We now use the 4th block allocation state. The previously unused
state is used to track unlinked but still open inodes.
 o gfs2_inoded is no longer needed
 o Several fields are now no longer needed (and removed) from the in
core struct gfs2_inode
 o Several fields are no longer needed (and removed) from the in core
superblock

There are a number of future possible optimisations and clean ups
which have been made possible by this patch.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>