The argument 'tree_mod_log' is not necessary since all of callers enable it.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Since we don't use MOD_LOG_KEY_REMOVE_WHILE_MOVING to add nritems
during rewinding, we should insert a MOD_LOG_KEY_REMOVE operation first.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Key MOD_LOG_KEY_REMOVE_WHILE_MOVING means that we're doing memmove inside
an extent buffer node, and the node's number of items remains unchanged
(unless we are inserting a single pointer, but we have MOD_LOG_KEY_ADD for that).

So we don't need to increase node's number of items during rewinding,
otherwise we may get an node larger than leafsize and cause general protection
errors later.

Here is the details,
- If we do memory move for inserting a single pointer, we need to
  add node's nritems by one, and we honor MOD_LOG_KEY_ADD for adding.

- If we do memory move for deleting a single pointer, we need to
  decrease node's nritems by one, and we honor MOD_LOG_KEY_REMOVE for
  deleting.

- If we do memory move for balance left/right, we need to decrease
  node's nritems, and we honor MOD_LOG_KEY_REMOVE for balaning.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

After cloning root's node, we forgot to dec the src's ref
which can lead to a memory leak.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Emphasis the way tree_mod_log_insert_move avoids adding
MOD_LOG_KEY_REMOVE_WHILE_MOVING operations, depending on the direction of
the move operation.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

In get_old_root we grab a lock on the extent buffer before we obtain a
reference on that buffer. That order is changed now.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

In btrfs_find_all_roots' termination condition, we compare the level of the
old buffer we got from btrfs_search_old_slot to the level of the current
root node. We'd better compare it to the level of the rewinded root node.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Tree mod log treated old root buffers as always empty buffers when starting
the rewind operations. However, the old root may still be part of the
current tree at a lower level, with still some valid entries.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Avoid the implicit free by tree_mod_log_set_root_pointer, which is wrong in
two places. Where needed, we call tree_mod_log_free_eb explicitly now.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Independant of the check (push_items < src_items) tree_mod_log_eb_copy did
log the removal of the old data entries from the source buffer. Therefore,
we must not call tree_mod_log_eb_move if the check evaluates to true, as
that would log the removal twice, finally resulting in (rewinded) buffers
with wrong values for header_nritems.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

The function btrfs_insert_some_items() would not be called by any other functions,
so remove it.
Signed-off-by: Robin Dong <sanbai@taobao.com>

The btrfs send code was assuming the offset of the file item into the
extent translated to bytes on disk.  If we're compressed, this isn't
true, and so it was off into extents owned by other files.

It was also improperly handling inline extents.  This solves a crash
where we may have gone past the end of the file extent item by not
testing early enough for an inline extent.  It also solves problems
where we have a whole between the end of the inline item and the start
of the full extent.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

When we split a leaf, we may end up inserting a new root on top of that
leaf.  The reflog code was incorrectly assuming the old root was always
a node.  This makes sure we skip over leaves.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Commit a168650c introduced a waiting mechanism to prevent busy waiting in
btrfs_run_delayed_refs. This can deadlock with btrfs_run_ordered_operations,
where a tree_mod_seq is held while waiting for the io to complete, while
the end_io calls btrfs_run_delayed_refs.
This whole mechanism is unnecessary. If not enough runnable refs are
available to satisfy count, just return as count is more like a guideline
than a strict requirement.
In case we have to run all refs, commit transaction makes sure that no
other threads are working in the transaction anymore, so we just assert
here that no refs are blocked.
Signed-off-by: Arne Jansen <sensille@gmx.net>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

This function is used to find the differences between
two trees. The tree compare skips whole subtrees if it
detects shared tree blocks and thus is pretty fast.
Signed-off-by: Alexander Block <ablock84@googlemail.com>
Reviewed-by: David Sterba <dave@jikos.cz>
Reviewed-by: Arne Jansen <sensille@gmx.net>
Reviewed-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Reviewed-by: Alex Lyakas <alex.bolshoy.btrfs@gmail.com>

Often no exact match is wanted but just the next lower or
higher item. There's a lot of duplicated code throughout
btrfs to deal with the corner cases. This patch adds a
helper function that can facilitate searching.
Signed-off-by: Arne Jansen <sensille@gmx.net>

When calling btrfs_next_old_leaf, we were leaking an extent buffer in the
rare case of using the deadlock avoidance code needed for the tree mod log.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

Often no exact match is wanted but just the next lower or
higher item. There's a lot of duplicated code throughout
btrfs to deal with the corner cases. This patch adds a
helper function that can facilitate searching.
Signed-off-by: Arne Jansen <sensille@gmx.net>

We've got two mechanisms both required for reliable backref resolving (tree
mod log and holding back delayed refs). You cannot make use of one without
the other. So instead of requiring the user of this mechanism to setup both
correctly, we join them into a single interface.

Additionally, we stop inserting non-blockers into fs_info->tree_mod_seq_list
as we did before, which was of no value.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

When calling btrfs_next_old_leaf, we were leaking an extent buffer in the
rare case of using the deadlock avoidance code needed for the tree mod log.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

With the tree mod log, we may end up with two roots (the current root and a
rewinded version of it) both pointing to two leaves, l1 and l2, of which l2
had already been cow-ed in the current transaction. If we don't rewind any
tree blocks, we cannot have two roots both pointing to an already cowed tree
block.

Now there is btrfs_next_leaf, which has a leaf locked and wants a lock on
the next (right) leaf. And there is push_leaf_left, which has a (cowed!)
leaf locked and wants a lock on the previous (left) leaf.

In order to solve this dead lock situation, we use try_lock in
btrfs_next_leaf (only in case it's called with a tree mod log time_seq
paramter) and if we fail to get a lock on the next leaf, we give up our lock
on the current leaf and retry from the very beginning.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

When a MOD_LOG_KEY_ADD operation is rewinded, we remove the key from the
tree block. If its not the last key, removal involves a move operation.
This move operation was explicitly done before this commit.

However, at insertion time, there's a move operation before the actual
addition to make room for the new key, which is recorded in the tree mod
log as well. This means, we must drop the move operation when rewinding the
add operation, because the next operation we'll be rewinding will be the
corresponding MOD_LOG_MOVE_KEYS operation.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Several callers of insert_ptr set the tree_mod_log parameter to 0 to avoid
addition to the tree mod log. In fact, we need all of those operations. This
commit simply removes the additional parameter and makes addition to the
tree mod log unconditional.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

For the tree mod log, we don't log any operations at leaf level. If the root
is at the leaf level (i.e. the tree consists only of the root), then
__tree_mod_log_oldest_root will find a ROOT_REPLACE operation in the log
(because we always log that one no matter which level), but no other
operations.

With this patch __tree_mod_log_oldest_root exits cleanly instead of
BUGging in this situation. get_old_root checks if its really a root at leaf
level in case we don't have any operations and WARNs if this assumption
breaks.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

gcc was giving an uninit variable warning here.  Strictly
speaking we don't need to init it, but this will make things
much less error prone.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

When adding to the tree modification log, we grab two locks at different
stages. We must not drop the outer lock until we're done with section
protected by the inner lock. This moves the unlock call for the outer lock
to the appropriate position.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

To make sense of the tree mod log, the backref walker not only needs
btrfs_search_old_slot, but it also called btrfs_next_leaf, which in turn was
calling btrfs_search_slot. This obviously didn't give the correct result.

This commit adds btrfs_next_old_leaf, a drop-in replacement for
btrfs_next_leaf with a time_seq parameter. If it is zero, it behaves exactly
like btrfs_next_leaf. If it is non-zero, it will use btrfs_search_old_slot
with this time_seq parameter.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

In __tree_mod_log_oldest_root() we must return the found operation even if
it's not a ROOT_REPLACE operation. Otherwise, the caller assumes that there
are no operations to be rewinded and returns immediately.

The code in the caller is modified to improve readability.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

get_old_root could race with root node updates because we weren't locking
the node early enough. Use btrfs_read_lock_root_node to grab the root locked
in the very beginning and release the lock as soon as possible (just like
btrfs_search_slot does).
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

This is a leftover from cleanup patch 559af821. Before the cleanup,
btrfs_header_nritems was called inside an if condition. As it has no side
effects we need to preserve here, it should simply be dropped.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

When we rewind REMOVE_WHILE_FREEING operations, there's code that allocates
a fresh buffer instead of cloning the old one. Setting that buffer's level
correctly was missing in this case.

When rewinding a MOVE_KEYS operation, btrfs_node_key_ptr_offset(slot) was
missing for memmove_extent_buffer()'s arguments.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Logging for del_ptr when we're not deleting the last pointer was wrong. This
fixes both, duplicate log entries and log sequence.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Replace duplicate code by small inline helper function.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

tree_mod_alloc calls __get_tree_mod_seq and must acquire a spinlock before
doing so.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

btrfs_read_buffer() has the possibility of returning the error.
Therefore, I add the code in which the return value of btrfs_read_buffer()
is checked.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>

The tree modification log together with the current state of the tree gives
a consistent, old version of the tree. btrfs_search_old_slot is used to
search through this old version and return old (dummy!) extent buffers.
Naturally, this function cannot do any tree modifications.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Record all relevant modifications to block pointers in the tree mod log so
that we can rewind them later on for backref walking.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

When running functions that can make changes to the internal trees
(e.g. btrfs_search_slot), we check if somebody may be interested in the
block we're currently modifying. If so, we record our modification to be
able to rewind it later on.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

The tree mod log will log modifications made fs-tree nodes. Most
modifications are done by autobalance of the tree. Such changes are recorded
as long as a block entry exists. When released, the log is cleaned.

With the tree modification log, it's possible to reconstruct a consistent
old state of the tree. This is required to do backref walking on a busy
file system.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Three callers of btrfs_free_tree_block or btrfs_alloc_tree_block passed
parameter for_cow = 1. In fact, these two functions should never mark
their tree modification operations as for_cow, because they can change
the number of blocks referenced by a tree.

Hence, we remove the extra for_cow parameter from these functions and
make them pass a zero down.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>