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: NJan Schmidt <list.btrfs@jan-o-sch.net>

When resolving indirect refs, we used to call btrfs_next_leaf in case we
didn't find an exact match. While we should find exact matches most of the
time, in case we don't, we must continue searching. Treating those matches
differently depending on the level we're searching doesn't make sense.

Even worse, we might end up searching for a key larger than the largest, in
which case there is no next_leaf and subsequent jobs would fail. This commit
drops the bogous lines.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

We must build up the inode list with the extent lock held after following
indirect refs.

This also requires an extension to ulists, which allows to modify the stored
aux value in case a key already exists in the list.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

This enables backref resolving on life trees while they are changing. This
is a prerequisite for quota groups and just nice to have for everything
else.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

Before this patch we called find_all_leafs for a data extent, then called
find_all_roots and then looked into the extent to grab the information
we were seeking. This was done without holding the leaves locked to avoid
deadlocks. However, this can obviouly race with concurrent tree
modifications.

Instead, we now look into the extent while we're holding the lock during
find_all_leafs and store this information together with the leaf list.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

The key we store with a tree block backref is only a hint. It is set when
the ref is created and can remain correct for a long time. As the tree is
rebalanced, however, eventually the key no longer points to the correct
destination.

With this patch, we change find_parent_nodes to no longer add keys unless it
knows for sure they're correct (e.g. because they're for an extent data
backref). Then when we later encounter a backref ref with no parent and no
key set, we grab the block and take the first key from the block itself.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

That one has been around since the addition of backref.c. Due to the way we
calculate our slot numbers, after adding inline refs we're missing one keyed
ref unless it's located at the beginning of a new leaf.
Reported-by: NAlexander Block <ablock84@googlemail.com>
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

ulist_next gets the pointer to the previously returned element to find the
next element from there. However, when we call ulist_add while iteration
with ulist_next is in progress (ulist explicitly supports this), we can
realloc the ulist internal memory, which makes the pointer to the previous
element useless.

Instead, we now use an iterator parameter that's independent from the
internal pointers.
Reported-by: NAlexander Block <ablock84@googlemail.com>
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

iref_to_path and iterate_irefs both increment the eb's refcount to use it
after releasing the path. Both depend on consistent data remaining in the
extent buffer and need a read lock to protect it.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

Avoid calling free_extent_buffer more than once when the iterator function
returns non-zero. The only code that uses this is scrub repair for corrupted
nodatasum blocks.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

Make free_ipath() behave like most other freeing functions in the
kernel and gracefully do nothing when passed a NULL pointer.

Besides this making the bahaviour consistent with functions such as
kfree(), vfree(), btrfs_free_path() etc etc, it also fixes a real NULL
deref issue in fs/btrfs/ioctl.c::btrfs_ioctl_ino_to_path(). In that
function we have this code:

...
        ipath = init_ipath(size, root, path);
        if (IS_ERR(ipath)) {
                ret = PTR_ERR(ipath);
                ipath = NULL;
                goto out;
        }
...
out:
        btrfs_free_path(path);
        free_ipath(ipath);
...

If we ever take the true branch of that 'if' statement we'll end up
passing a NULL pointer to free_ipath() which will subsequently
dereference it and we'll go "Boom" :-(
This patch will avoid that.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>

init_ipath() allocates btrfs_data_container which is never freed.  Free
it in free_ipath() and nuke the comment for init_data_container() - we
can safely free it with kfree().
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

In commit 4692cf58 we introduced new backref walking code for btrfs. This
assumes we're searching live roots, which requires a transaction context.
While scrubbing, however, we must not join a transaction because this could
deadlock with the commit path. Additionally, what scrub really wants to do
is resolving a logical address in the commit root it's currently checking.

This patch adds support for logical to path resolving on commit roots and
makes scrub use that.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

- We might unlock head->mutex while it was not locked
- We might leave the function without unlocking delayed_refs->lock
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

inode_ref_info() returns 1 when the element wasn't found and < 0 on error,
just like btrfs_search_slot(). In iref_to_path() it's an error when the
inode ref can't be found, thus we return ERR_PTR(ret) in that case. In order
to avoid ERR_PTR(1), we now set ret to -ENOENT in that case.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

Added initialization with the declaration of ret. It isn't set later on the
switch-default branch (which should never be taken).
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

The old backref iteration code could only safely be used on commit roots.
Besides this limitation, it had bugs in finding the roots for these
references. This commit replaces large parts of it by btrfs_find_all_roots()
which a) really finds all roots and the correct roots, b) works correctly
under heavy file system load, c) considers delayed refs.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

This function gets a byte number (a data extent), collects all the leafs
pointing to it and walks up the trees to find all fs roots pointing to those
leafs. It also returns the list of all leafs pointing to that extent.

It does proper locking for the involved trees, can be used on busy file
systems and honors delayed refs.
Signed-off-by: NArne Jansen <sensille@gmx.net>
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

 This patch casts to unsigned long before casting to a pointer and fixes
 the following warnings:
fs/btrfs/extent_io.c:2289:20: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
fs/btrfs/ioctl.c:2933:37: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
fs/btrfs/ioctl.c:2937:21: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
fs/btrfs/ioctl.c:3020:21: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
fs/btrfs/scrub.c:275:4: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
fs/btrfs/backref.c:686:27: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
Signed-off-by: NJeff Mahoney <jeffm@suse.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

The new ioctls to follow backrefs are not clean for 32/64 bit
compat.  This reworks them for u64s everywhere.  They are brand new, so
there are no problems with changing the interface now.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

These helper functions iterate back references and call a function for each
backref. There is also a function to resolve an inode to a path in the
file system.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>