We cannot call grab_cache_page() when holding filesystem locks or with
a transaction started as grab_cache_page() calls page allocation with
GFP_KERNEL flag and thus page reclaim can recurse back into the filesystem
causing deadlocks or various assertion failures. We have to use
find_or_create_page() instead and pass it GFP_NOFS as we do with other
allocations.
Acked-by: NMark Fasheh <mfasheh@suse.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTao Ma <tao.ma@oracle.com>

The original idea to pull ocfs2_find_cpos_for_left_leaf() out of
alloc.c is to benefit punching-holes optimization patch, it however,
can also be referred by other funcs in the future who want to do the
same job.
Signed-off-by: NTristan Ye <tristan.ye@oracle.com>
Acked-by: NMark Fasheh <mfasheh@suse.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Truncate is just a special case of punching holes(from new i_size to
end), we therefore could take advantage of the existing
ocfs2_remove_btree_range() to reduce the comlexity and redundancy in
alloc.c.  The goal here is to make truncate more generic and
straightforward.

Several functions only used by ocfs2_commit_truncate() will smiply be
removed.

ocfs2_remove_btree_range() was originally used by the hole punching
code, which didn't take refcount trees into account (definitely a bug).
We therefore need to change that func a bit to handle refcount trees.
It must take the refcount lock, calculate and reserve blocks for
refcount tree changes, and decrease refcounts at the end.  We replace 
ocfs2_lock_allocators() here by adding a new func
ocfs2_reserve_blocks_for_rec_trunc() which accepts some extra blocks to
reserve.  This will not hurt any other code using
ocfs2_remove_btree_range() (such as dir truncate and hole punching).

I merged the following steps into one patch since they may be
logically doing one thing, though I know it looks a little bit fat
to review.

1). Remove redundant code used by ocfs2_commit_truncate(), since we're
    moving to ocfs2_remove_btree_range anyway.

2). Add a new func ocfs2_reserve_blocks_for_rec_trunc() for purpose of
    accepting some extra blocks to reserve.

3). Change ocfs2_prepare_refcount_change_for_del() a bit to fit our
    needs.  It's safe to do this since it's only being called by
    truncate.

4). Change ocfs2_remove_btree_range() a bit to take refcount case into
    account.

5). Finally, we change ocfs2_commit_truncate() to call
    ocfs2_remove_btree_range() in a proper way.

The patch has been tested normally for sanity check, stress tests
with heavier workload will be expected.

Based on this patch, fixing the punching holes bug will be fairly easy.
Signed-off-by: NTristan Ye <tristan.ye@oracle.com>
Acked-by: NMark Fasheh <mfasheh@suse.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

In ocfs2, we use ocfs2_extend_trans() to extend a journal handle's
blocks. But if jbd2_journal_extend() fails, it will only restart
with the the new number of blocks.  This tends to be awkward since
in most cases we want additional reserved blocks. It makes our code
harder to mantain since the caller can't be sure all the original
blocks will not be accessed and dirtied again.  There are 15 callers
of ocfs2_extend_trans() in fs/ocfs2, and 12 of them have to add
h_buffer_credits before they call ocfs2_extend_trans().  This makes
ocfs2_extend_trans() really extend atop the original block count.
Signed-off-by: NTao Ma <tao.ma@oracle.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Add a per-inode reservations structure and pass it through to the
reservations code.
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

jbd[2]_journal_dirty_metadata() only returns 0.  It's been returning 0
since before the kernel moved to git.  There is no point in checking
this error.

ocfs2_journal_dirty() has been faithfully returning the status since the
beginning.  All over ocfs2, we have blocks of code checking this can't
fail status.  In the past few years, we've tried to avoid adding these
checks, because they are pointless.  But anyone who looks at our code
assumes they are needed.

Finally, ocfs2_journal_dirty() is made a void function.  All error
checking is removed from other files.  We'll BUG_ON() the status of
jbd2_journal_dirty_metadata() just in case they change it someday.  They
won't.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

In case the block we are going to free is allocated from
a discontiguous block group, we have to use suballoc_loc
to be the right group.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

Get the suballoc_loc from ocfs2_claim_new_inode() or
ocfs2_claim_metadata().  Store it on the appropriate field of the block
we just allocated.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

They all take an ocfs2_alloc_context, which has the allocation inode.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NTao Ma <tao.ma@oracle.com>

Get rid of the alloc_space, free_space, reserve_space, claim_space and
release_rsv dquot operations - they are always called from the filesystem
and if a filesystem really needs their own (which none currently does)
it can just call into it's own routine directly.

Move shared logic into the common __dquot_alloc_space,
dquot_claim_space_nodirty and __dquot_free_space low-level methods,
and rationalize the wrappers around it to move as much as possible
code into the common block for CONFIG_QUOTA vs not.  Also rename
all these helpers to be named dquot_* instead of vfs_dq_*.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJan Kara <jack@suse.cz>

This patch add extent block (metadata) stealing mechanism for
extent allocation. This mechanism is same as the inode stealing.
if no room in slot specific extent_alloc, we will try to
allocate extent block from the next slot.
Signed-off-by: NTiger Yang <tiger.yang@oracle.com>
Acked-by: NTao Ma <tao.ma@oracle.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

do_sync_mapping_range(..., SYNC_FILE_RANGE_WRITE) is a very awkward way
to perform a filemap_fdatawrite_range.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

That is "success", "unknown", "through", "performance", "[re|un]mapping"
, "access", "default", "reasonable", "[con]currently", "temperature"
, "channel", "[un]used", "application", "example","hierarchy", "therefore"
, "[over|under]flow", "contiguous", "threshold", "enough" and others.
Signed-off-by: NAndré Goddard Rosa <andre.goddard@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

ocfs2 refcount tree is stored as an extent tree while
the leaf ocfs2_refcount_rec points to a refcount block.

The following step can trip a kernel panic.
mkfs.ocfs2 -b 512 -C 1M --fs-features=refcount $DEVICE
mount -t ocfs2 $DEVICE $MNT_DIR
FILE_NAME=$RANDOM
FILE_NAME_1=$RANDOM
FILE_REF="${FILE_NAME}_ref"
FILE_REF_1="${FILE_NAME}_ref_1"
for((i=0;i<305;i++))
do
# /mnt/1048576 is a file with 1048576 sizes.
cat /mnt/1048576 >> $MNT_DIR/$FILE_NAME
cat /mnt/1048576 >> $MNT_DIR/$FILE_NAME_1
done
for((i=0;i<3;i++))
do
cat /mnt/1048576 >> $MNT_DIR/$FILE_NAME
done

for((i=0;i<2;i++))
do
cat /mnt/1048576 >> $MNT_DIR/$FILE_NAME
cat /mnt/1048576 >> $MNT_DIR/$FILE_NAME_1
done

cat /mnt/1048576 >> $MNT_DIR/$FILE_NAME

for((i=0;i<11;i++))
do
cat /mnt/1048576 >> $MNT_DIR/$FILE_NAME
cat /mnt/1048576 >> $MNT_DIR/$FILE_NAME_1
done
reflink $MNT_DIR/$FILE_NAME $MNT_DIR/$FILE_REF
# write_f is a program which will write some bytes to a file at offset.
# write_f -f file_name -l offset -w write_bytes.
./write_f -f $MNT_DIR/$FILE_REF -l $[310*1048576] -w 4096
./write_f -f $MNT_DIR/$FILE_REF -l $[306*1048576] -w 4096
./write_f -f $MNT_DIR/$FILE_REF -l $[311*1048576] -w 4096
./write_f -f $MNT_DIR/$FILE_NAME -l $[310*1048576] -w 4096
./write_f -f $MNT_DIR/$FILE_NAME -l $[311*1048576] -w 4096
reflink $MNT_DIR/$FILE_NAME $MNT_DIR/$FILE_REF_1
./write_f -f $MNT_DIR/$FILE_NAME -l $[311*1048576] -w 4096
#kernel panic here.

The reason is that if the ocfs2_extent_rec is the last record
in a leaf extent block, the old solution fails to find the
suitable end cpos. So this patch try to walk through the b-tree,
find the next sub root and get the c_pos the next sub-tree starts
from.

btw, I have runned tristan's test case against the patched kernel
for several days and this type of kernel panic never happens again.
Signed-off-by: NTao Ma <tao.ma@oracle.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

In ocfs2_extend_rotate_transaction, op_credits is the orignal
credits in the handle and we only want to extend the credits
for the rotation, but the old solution always double it. It
is harmless for some minor operations, but for actions like
reflink we may rotate tree many times and cause the credits
increase dramatically. So this patch try to only increase
the desired credits.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

During CoW, if the old extent record is refcounted, we allocate
som new clusters and do CoW. Actually we can have some improvement
here. If the old extent has refcount=1, that means now it is only
used by this file. So we don't need to allocate new clusters, just
remove the refcounted flag and it is OK. We also have to remove
it from the refcount tree while not deleting it.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

This patch try CoW support for a refcounted record.

the whole process will be:
1. Calculate how many clusters we need to CoW and where we start.
   Extents that are not completely encompassed by the write will
   be broken on 1MB boundaries.
2. Do CoW for the clusters with the help of page cache.
3. Change the b-tree structure with the new allocated clusters.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

Add 'Decrement refcount for delete' in to the normal truncate
process. So for a refcounted extent record, call refcount rec
decrementation instead of cluster free.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

Add function ocfs2_mark_extent_refcounted which can mark
an extent refcounted.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

    Given a physical cpos and length, decrement the refcount
in the tree. If the refcount for any portion of the extent goes
to zero, that portion is queued for freeing.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

Now fs/ocfs2/alloc.c has more than 7000 lines. It contains our
basic b-tree operation. Although we have already make our b-tree
operation generic, the basic structrue ocfs2_path which is used
to iterate one b-tree branch is still static and limited to only
used in alloc.c. As refcount tree need them and I don't want to
add any more b-tree unrelated code to alloc.c, export them out.

Signed-off-by: Tao Ma <tao.ma@oracle.com> 

Add refcount b-tree as a new extent tree so that it can
use the b-tree to store and maniuplate ocfs2_refcount_rec.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

ocfs2_mark_extent_written actually does the following things:
1. check the parameters.
2. initialize the left_path and split_rec.
3. call __ocfs2_mark_extent_written. it will do:
   1) check the flags of unwritten
   2) do the real split work.
The whole process is packed tightly somehow. So this patch
will abstract 2 different functions so that future b-tree
operation can work with it.

1. __ocfs2_split_extent will accept path and split_rec and do
  the real split work.
2. ocfs2_change_extent_flag will accept a new flag and initialize
   path and split_rec.

So now ocfs2_mark_extent_written will do:
1. check the parameters.
2. call ocfs2_change_extent_flag.
   1) initalize the left_path and split_rec.
   2) check whether the new flags conflict with the old one.
   3) call __ocfs2_split_extent to do the split.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

Add a new operation eo_ocfs2_extent_contig int the extent tree's
operations vector. So that with the new refcount tree, We want
this so that refcount trees can always return CONTIG_NONE and
prevent extent merging.
Signed-off-by: NTao Ma <tao.ma@oracle.com>

With this commit, extent tree operations are divorced from inodes and
rely on ocfs2_caching_info.  Phew!
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

We only allow unwritten extents on data, so the toplevel
ocfs2_mark_extent_written() can use an inode all it wants.  But the
subfunction isn't even using the inode argument.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Don't use a struct inode anymore.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

It already has an extent_tree.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

One more generic btree function that is isolated from struct inode.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

One more function that doesn't need a struct inode to pass to its
children.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

One more function down, no inode in the entire insert-extent chain.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

ocfs2_insert_extent() wants to insert a record into the extent map if
it's an inode data extent.  But since many btrees can call that
function, let's make it an op on ocfs2_extent_tree.  Other tree types
can leave it empty.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

It's not using it, so remove it from the parameter list.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

It already has an ocfs2_extent_tree and doesn't need the inode.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

We don't want struct inode in generic btree operations.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Don't pass the inode in.  We don't want it around for generic btree
operations.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

They aren't using it, so remove it from their parameter lists.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Another on the way to generic btree functions.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Give it an ocfs2_extent_tree and it is happy.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

ocfs2_remove_extent() wants to truncate the extent map if it's
truncating an inode data extent.  But since many btrees can call that
function, let's make it an op on ocfs2_extent_tree.  Other tree types
can leave it empty.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>