Pull GFS2 updates from Steven Whitehouse.
* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-3.0-nmw:
GFS2: Eliminate 64-bit divides
GFS2: Reduce file fragmentation
GFS2: kernel panic with small gfs2 filesystems - 1 RG
GFS2: Fixing double brelse'ing bh allocated in gfs2_meta_read when EIO occurs
GFS2: Combine functions get_local_rgrp and gfs2_inplace_reserve
GFS2: Add kobject release method
GFS2: Size seq_file buffer more carefully
GFS2: Use seq_vprintf for glocks debugfs file
seq_file: Add seq_vprintf function and export it
GFS2: Use lvbs for storing rgrp information with mount option
GFS2: Cache last hash bucket for glock seq_files
GFS2: Increase buffer size for glocks and glstats debugfs files
GFS2: Fix error handling when reading an invalid block from the journal
GFS2: Add "top dir" flag support
GFS2: Fold quota data into the reservations struct
GFS2: Extend the life of the reservations
Since the moment writes to quota files are using block device page cache and
space for quota structures is reserved at the moment they are first accessed we
have no reason to sync quota before inode writeback. In fact this order is now
only harmful since quota information can easily change during inode writeback
(either because conversion of delayed-allocated extents or simply because of
allocation of new blocks for simple filesystems not using page_mkwrite).
So move syncing of quota information after writeback of inodes into ->sync_fs
method. This way we do not have to use ->quota_sync callback which is primarily
intended for use by quotactl syscall anyway and we get rid of calling
->sync_fs() twice unnecessarily. We skip quota syncing for OCFS2 since it does
proper quota journalling in all cases (unlike ext3, ext4, and reiserfs which
also support legacy non-journalled quotas) and thus there are no dirty quota
structures.
CC: "Theodore Ts'o" <tytso@mit.edu>
CC: Joel Becker <jlbec@evilplan.org>
CC: reiserfs-devel@vger.kernel.org
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Dave Kleikamp <shaggy@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Split off part of dquot_quota_sync() which writes dquots into a quota file
to a separate function. In the next patch we will use the function from
filesystems and we do not want to abuse ->quota_sync quotactl callback more
than necessary.
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch reduces GFS2 file fragmentation by pre-reserving blocks. The
resulting improved on disk layout greatly speeds up operations in cases
which would have resulted in interlaced allocation of blocks previously.
A typical example of this is 10 parallel dd processes, each writing to a
file in a common dirctory.
The implementation uses an rbtree of reservations attached to each
resource group (and each inode).
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Instead of reading in the resource groups when gfs2 is checking
for free space to allocate from, gfs2 can store the necessary infromation
in the resource group's lvb. Also, instead of searching for unlinked
inodes in every resource group that's checked for free space, gfs2 can
store the number of unlinked but inodes in the lvb, and only check for
unlinked inodes if it will find some.
The first time a resource group is locked, the lvb must initialized.
Since this involves counting the unlinked inodes in the resource group,
this takes a little extra time. But after that, if the resource group
is locked with GL_SKIP, the buffer head won't be read in unless it's
actually needed.
Enabling the resource groups lvbs is done via the rgrplvb mount option. If
this option isn't set, the lvbs will still be set and updated, but they won't
be verfied or used by the filesystem. To safely turn on this option, all of
the nodes mounting the filesystem must be running code with this patch, and
the filesystem must have been completely unmounted since they were updated.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch moves the ancillary quota data structures into the
block reservations structure. This saves GFS2 some time and
effort in allocating and deallocating the qadata structure.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch lengthens the lifespan of the reservations structure for
inodes. Before, they were allocated and deallocated for every write
operation. With this patch, they are allocated when the first write
occurs, and deallocated when the last process closes the file.
It's more efficient to do it this way because it saves GFS2 a lot of
unnecessary allocates and frees. It also gives us more flexibility
for the future: (1) we can now fold the qadata structure back into
the structure and save those alloc/frees, (2) we can use this for
multi-block reservations.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
After we moved inode_sync_wait() from end_writeback() it doesn't make sense
to call the function end_writeback() anymore. Rename it to clear_inode()
which well says what the function really does - set I_CLEAR flag.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
This ensures that we will not try to access the inode thats
being flushed via the glock after it has been freed.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
The FITRIM ioctl provides an alternative way to send discard requests to
the underlying device. Using the discard mount option results in every
freed block generating a discard request to the block device. This can
be slow, since many block devices can only process discard requests of
larger sizes, and also such operations can be time consuming.
Rather than using the discard mount option, FITRIM allows a sweep of the
filesystem on an occasional basis, and also to optionally avoid sending
down discard requests for smaller regions.
In GFS2 FITRIM will work at resource group granularity. There is a flag
for each resource group which keeps track of which resource groups have
been trimmed. This flag is reset whenever a deallocation occurs in the
resource group, and set whenever a successful FITRIM of that resource
group has taken place. This helps to reduce repeated discard requests
for the same block ranges, again improving performance.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-3.0-nmw:
GFS2: local functions should be static
GFS2: We only need one ACL getting function
GFS2: Fix multi-block allocation
GFS2: decouple quota allocations from block allocations
GFS2: split function rgblk_search
GFS2: Fix up "off by one" in the previous patch
GFS2: move toward a generic multi-block allocator
GFS2: O_(D)SYNC support for fallocate
GFS2: remove vestigial al_alloced
GFS2: combine gfs2_alloc_block and gfs2_alloc_di
GFS2: Add non-try locks back to get_local_rgrp
GFS2: f_ra is always valid in dir readahead function
GFS2: Fix very unlikley memory leak in ACL xattr code
GFS2: More automated code analysis fixes
GFS2: Add readahead to sequential directory traversal
GFS2: Fix up REQ flags
Seeing that just about every destructor got that INIT_LIST_HEAD() copied into
it, there is no point whatsoever keeping this INIT_LIST_HEAD in inode_init_once();
the cost of taking it into inode_init_always() will be negligible for pipes
and sockets and negative for everything else. Not to mention the removal of
boilerplate code from ->destroy_inode() instances...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch separates the code pertaining to allocations into two
parts: quota-related information and block reservations.
This patch also moves all the block reservation structure allocations to
function gfs2_inplace_reserve to simplify the code, and moves
the frees to function gfs2_inplace_release.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Unfortunately, it is not enough to just ignore locked buffers during
the AIL flush from fsync. We need to be able to ignore all buffers
which are locked, dirty or pinned at this stage as they might have
been added subsequent to the log flush earlier in the fsync function.
In addition, this means that we no longer need to rely on i_mutex to
keep out writes during fsync, so we can, as a side-effect, remove
that protection too.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Tested-By: Abhijith Das <adas@redhat.com>
This means that after the initial allocation for any inode, the
last used resource group is cached in the inode for future use.
This drastically reduces the number of lookups of resource
groups in the common case, and this the contention on that
data structure.
The allocation algorithm is the same as previously, except that we
always check to see if the goal block is within the cached rgrp
first before going to the rbtree to look one up.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Since we have ruled out supporting online filesystem shrink,
it is possible to make the resource group list append only
during the life of a super block. This gives several benefits:
Firstly, we only need to read new rindex elements as they are added
rather than needing to reread the whole rindex file each time one
element is added.
Secondly, the rindex glock can be held for much shorter periods of
time, and is completely removed from the fast path for allocations.
The lock is taken in shared mode only when updating the resource
groups when the first allocation occurs, and after a grow has
taken place.
Thirdly, this results in a reduction in code size, and everything
gets a lot simpler to understand in this area.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
The aim of this patch is to use the newly enhanced ->dirty_inode()
super block operation to deal with atime updates, rather than
piggy backing that code into ->write_inode() as is currently
done.
The net result is a simplification of the code in various places
and a reduction of the number of gfs2_dinode_out() calls since
this is now implied by ->dirty_inode().
Some of the mark_inode_dirty() calls have been moved under glocks
in order to take advantage of then being able to avoid locking in
->dirty_inode() when we already have suitable locks.
One consequence is that generic_write_end() now correctly deals
with file size updates, so that we do not need a separate check
for that afterwards. This also, indirectly, means that fdatasync
should work correctly on GFS2 - the current code always syncs the
metadata whether it needs to or not.
Has survived testing with postmark (with and without atime) and
also fsx.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
If we have got far enough through the inode allocation code
path that an inode has already been allocated, then we must
call iput to dispose of it, if an error occurs during a
later part of the process. This will always be the final iput
since there will be no other references to the inode.
Unlike when the inode has been unlinked, its block state will
be GFS2_BLKST_INODE rather than GFS2_BLKST_UNLINKED so we need
to skip the test in ->evict_inode() for this one case in order
to ensure that it will be deallocated correctly. This patch adds
a new flag in order to ensure that this will happen correctly.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
We do not need to start a transaction unless the atime
check has proved positive. Also if we are going to flush
the complete ail list anyway, we might as well skip the
writeback for this specific inode's metadata, since that
will be done as part of the ail writeback process in an
order offering potentially more efficient I/O.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch adds a cache for the hash table to the directory code
in order to help simplify the way in which the hash table is
accessed. This is intended to be a first step towards introducing
some performance improvements in the directory code.
There are two follow ups that I'm hoping to see fairly shortly. One
is to simplify the hash table reading code now that we always read the
complete hash table, whether we want one entry or all of them. The
other is to introduce readahead on the heads of the hash chains
which are referred to from the table.
The hash table is a maximum of 128k in size, so it is not worth trying
to read it in small chunks.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch contains a few misc fixes which resolve a recently
reported issue. This patch has been a real team effort and has
received a lot of testing.
The first issue is that the ail lock needs to be held over a few
more operations. The lock thats added into gfs2_releasepage() may
possibly be a candidate for replacing with RCU at some future
point, but at this stage we've gone for the obvious fix.
The second issue is that gfs2_write_inode() can end up calling
a glock recursively when called from gfs2_evict_inode() via the
syncing code, so it needs a guard added.
The third issue is that we either need to not truncate the metadata
pages of inodes which have zero link count, but which we cannot
deallocate due to them still being in use by other nodes, or we need
to ensure that those pages have all made it through the journal and
ail lists first. This patch takes the former approach, but the
latter has also been tested and there is nothing to choose between
them performance-wise. So again, we could revise that decision
in the future.
Also, the inode eviction process is now better documented.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Tested-by: Bob Peterson <rpeterso@redhat.com>
Tested-by: Abhijith Das <adas@redhat.com>
Reported-by: Barry J. Marson <bmarson@redhat.com>
Reported-by: David Teigland <teigland@redhat.com>
This function was intended for debugging purposes, but it is not very
useful. If we want to know what is on disk then all we need is a
block number and gfs2_edit can give us much better information about
what is there. Otherwise, if we are interested in what is stored in
the in-core inode, it doesn't help us out there either.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch adds writeback_control to writing back the AIL
list. This means that we can then take advantage of the
information we get in ->write_inode() in order to set off
some pre-emptive writeback.
In addition, the AIL code is cleaned up a bit to make it
a bit simpler to understand.
There is still more which can usefully be done in this area,
but this is a good start at least.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
The GLF_LRU flag introduced in the previous patch can be
used to check if a glock is on the lru list when a new
holder is queued and if so remove it, without having first
to get the lru_lock.
The main purpose of this patch however is to optimise the
glocks left over when an inode at end of life is being
evicted. Previously such glocks were left with the GLF_LFLUSH
flag set, so that when reclaimed, each one required a log flush.
This patch resets the GLF_LFLUSH flag when there is nothing
left to flush thus preventing later log flushes as glocks are
reused or demoted.
In order to do this, we need to keep track of the number of
revokes which are outstanding, and also to clear the GLF_LFLUSH
bit after a log commit when only revokes have been processed.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Rather than allowing the glocks to be scheduled for possible
reclaim as soon as they have exited the journal, this patch
delays their entry to the list until the glocks in question
are no longer in use.
This means that we will rely on the vm for writeback of all
dirty data and metadata from now on. When glocks are added
to the lru list they should be freeable much faster since all
the I/O required to free them should have already been completed.
This should lead to much better I/O patterns under low memory
conditions.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
The GFS2 ->write_inode function should be more aggressive at writing
back to the filesystem. This adopts the XFS system of returning
-EAGAIN when the writeback has not been completely done. Also, we
now kick off in-place writeback when called with WB_SYNC_NONE,
but we only wait for it and flush the log when WB_SYNC_ALL is
requested.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch fixes a deadlock in GFS2 where two processes are trying
to reclaim an unlinked dinode:
One holds the inode glock and calls gfs2_lookup_by_inum trying to look
up the inode, which it can't, due to I_FREEING. The other has set
I_FREEING from vfs and is at the beginning of gfs2_delete_inode
waiting for the glock, which is held by the first. The solution is to
add a new non_block parameter to the gfs2_iget function that causes it
to return -ENOENT if the inode is being freed.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This adds a couple of missing tests to avoid read-only nodes
from attempting to deallocate unlinked inodes.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Reported-by: Michel Andre de la Porte <madelaporte@ubi.com>
When a file gets deleted on GFS2, if a node can't get an exclusive lock on the
file's iopen glock, it punts on actually freeing up the space, because another
node is using the file. When it does this, it needs to drop the iopen glock
from its cache so that the other node can get an exclusive lock on it. Now,
gfs2_delete_inode() sets GL_NOCACHE before dropping the shared lock on the
iopen glock in preparation for grabbing it in the exclusive state. Since the
node needs the glock in the exclusive state, dropping the shared lock from the
cache doesn't slow down the case where no other nodes are using the file.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
RCU free the struct inode. This will allow:
- Subsequent store-free path walking patch. The inode must be consulted for
permissions when walking, so an RCU inode reference is a must.
- sb_inode_list_lock to be moved inside i_lock because sb list walkers who want
to take i_lock no longer need to take sb_inode_list_lock to walk the list in
the first place. This will simplify and optimize locking.
- Could remove some nested trylock loops in dcache code
- Could potentially simplify things a bit in VM land. Do not need to take the
page lock to follow page->mapping.
The downsides of this is the performance cost of using RCU. In a simple
creat/unlink microbenchmark, performance drops by about 10% due to inability to
reuse cache-hot slab objects. As iterations increase and RCU freeing starts
kicking over, this increases to about 20%.
In cases where inode lifetimes are longer (ie. many inodes may be allocated
during the average life span of a single inode), a lot of this cache reuse is
not applicable, so the regression caused by this patch is smaller.
The cache-hot regression could largely be avoided by using SLAB_DESTROY_BY_RCU,
however this adds some complexity to list walking and store-free path walking,
so I prefer to implement this at a later date, if it is shown to be a win in
real situations. I haven't found a regression in any non-micro benchmark so I
doubt it will be a problem.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
In fill_super() we hadn't MS_ACTIVE set yet, so there won't
be any inodes with zero i_count sitting around.
In put_super() we already have MS_ACTIVE removed *and* we
had called invalidate_inodes() since then. So again there
won't be any inodes with zero i_count...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
XFS supports the "norecovery" mount option which is basically the
same as the GFS2 spectator mode. This adds support for "norecovery"
as a synonym for spectator mode, which is hopefully a more obvious
description of what it actually does.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This option has never done anything useful. Also at the same time
this cleans up the sb checks which are done at mount time. The
debug option will be accepted, but ignored in future. Since it
didn't do anything, there didn't seem much point in retaining it.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This option defaulted to on for lock_nolock mounts and off
otherwise. The only function was to avoid the revalidation of
dentries. In the cluster case, that is entirely pointless and
liable to cause coherency problems.
The patch changes the revalidation to depend upon whether the
fs is a local or cluster fs (i.e. it follows the existing default
behaviour). I very much doubt anybody ever used this option as
there is no reason to. Even so we will continue to accept it
on the mount command line, but ignore it.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This is been a no-op for a very long time now. I'm pretty sure
nobody uses it, but just in case we'll still accept it on the
command line, but ignore it.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
With the update of the truncate code, ip->i_disksize and
inode->i_size are merely copies of each other. This means
we can remove ip->i_disksize and use inode->i_size exclusively
reducing the size of a GFS2 inode by 8 bytes.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (96 commits)
no need for list_for_each_entry_safe()/resetting with superblock list
Fix sget() race with failing mount
vfs: don't hold s_umount over close_bdev_exclusive() call
sysv: do not mark superblock dirty on remount
sysv: do not mark superblock dirty on mount
btrfs: remove junk sb_dirt change
BFS: clean up the superblock usage
AFFS: wait for sb synchronization when needed
AFFS: clean up dirty flag usage
cifs: truncate fallout
mbcache: fix shrinker function return value
mbcache: Remove unused features
add f_flags to struct statfs(64)
pass a struct path to vfs_statfs
update VFS documentation for method changes.
All filesystems that need invalidate_inode_buffers() are doing that explicitly
convert remaining ->clear_inode() to ->evict_inode()
Make ->drop_inode() just return whether inode needs to be dropped
fs/inode.c:clear_inode() is gone
fs/inode.c:evict() doesn't care about delete vs. non-delete paths now
...
Fix up trivial conflicts in fs/nilfs2/super.c
Function gfs2_write_alloc_required always returned zero as its
return code. Therefore, it doesn't need to return a return code
at all. Given that, we can use the return value to return whether
or not the dinode needs block allocations rather than passing
that value in, which in turn simplifies a bunch of error checking.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
The following patch adds a message to indicate when barriers have been
disabled due to a block device which doesn't support them. You could
already tell this via the mount options in /proc/mounts, but all the
other filesystems also log a message at the same time.
Also, the same mechanisms are used to indicate when the lock
demote interface has been used (only ever used for debugging)
which is a request from our support team.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch contains various tweaks to how log flushes and active item writeback
work. gfs2_logd is now managed by a waitqueue, and gfs2_log_reseve now waits
for gfs2_logd to do the log flushing. Multiple functions were rewritten to
remove the need to call gfs2_log_lock(). Instead of using one test to see if
gfs2_logd had work to do, there are now seperate tests to check if there
are two many buffers in the incore log or if there are two many items on the
active items list.
This patch is a port of a patch Steve Whitehouse wrote about a year ago, with
some minor changes. Since gfs2_ail1_start always submits all the active items,
it no longer needs to keep track of the first ai submitted, so this has been
removed. In gfs2_log_reserve(), the order of the calls to
prepare_to_wait_exclusive() and wake_up() when firing off the logd thread has
been switched. If it called wake_up first there was a small window for a race,
where logd could run and return before gfs2_log_reserve was ready to get woken
up. If gfs2_logd ran, but did not free up enough blocks, gfs2_log_reserve()
would be left waiting for gfs2_logd to eventualy run because it timed out.
Finally, gt_logd_secs, which controls how long to wait before gfs2_logd times
out, and flushes the log, can now be set on mount with ar_commit.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6: (33 commits)
quota: stop using QUOTA_OK / NO_QUOTA
dquot: cleanup dquot initialize routine
dquot: move dquot initialization responsibility into the filesystem
dquot: cleanup dquot drop routine
dquot: move dquot drop responsibility into the filesystem
dquot: cleanup dquot transfer routine
dquot: move dquot transfer responsibility into the filesystem
dquot: cleanup inode allocation / freeing routines
dquot: cleanup space allocation / freeing routines
ext3: add writepage sanity checks
ext3: Truncate allocated blocks if direct IO write fails to update i_size
quota: Properly invalidate caches even for filesystems with blocksize < pagesize
quota: generalize quota transfer interface
quota: sb_quota state flags cleanup
jbd: Delay discarding buffers in journal_unmap_buffer
ext3: quota_write cross block boundary behaviour
quota: drop permission checks from xfs_fs_set_xstate/xfs_fs_set_xquota
quota: split out compat_sys_quotactl support from quota.c
quota: split out netlink notification support from quota.c
quota: remove invalid optimization from quota_sync_all
...
Fixed trivial conflicts in fs/namei.c and fs/ufs/inode.c
This gives the filesystem more information about the writeback that
is happening. Trond requested this for the NFS unstable write handling,
and other filesystems might benefit from this too by beeing able to
distinguish between the different callers in more detail.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currenly sync_quota_sb does a lot of sync and truncate action that only
applies to "VFS" style quotas and is actively harmful for the sync
performance in XFS. Move it into vfs_quota_sync and add a wait parameter
to ->quota_sync to tell if we need it or not.
My audit of the GFS2 code says it's also not needed given the way GFS2
implements quotas, but I'd be happy if this can get a detailed review.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
As a consequence of the previous patch, we can now remove the
loop which used to be required due to the circular dependency
between the inodes and glocks. Instead we can just invalidate
the inodes, and then clear up any glocks which are left.
Also we no longer need the rwsem since there is no longer any
danger of the inode invalidation calling back into the glock
code (and from there back into the inode code).
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Since the start of GFS2, an "extra" inode has been used to store
the metadata belonging to each inode. The only reason for using
this inode was to have an extra address space, the other fields
were unused. This means that the memory usage was rather inefficient.
The reason for keeping each inode's metadata in a separate address
space is that when glocks are requested on remote nodes, we need to
be able to efficiently locate the data and metadata which relating
to that glock (inode) in order to sync or sync and invalidate it
(depending on the remotely requested lock mode).
This patch adds a new type of glock, which has in addition to
its normal fields, has an address space. This applies to all
inode and rgrp glocks (but to no other glock types which remain
as before). As a result, we no longer need to have the second
inode.
This results in three major improvements:
1. A saving of approx 25% of memory used in caching inodes
2. A removal of the circular dependency between inodes and glocks
3. No confusion between "normal" and "metadata" inodes in super.c
Although the first of these is the more immediately apparent, the
second is just as important as it now enables a number of clean
ups at umount time. Those will be the subject of future patches.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
