btrfs: Return EXDEV for cross file system snapshot

EXDEV seems an appropriate error if an operation fails bacause it
crosses file system boundaries.

Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Kusanagi Kouichi <slash@ac.auone-net.jp>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: fix unprotected alloc list insertion during the finishing procedure of replace

the alloc list of the filesystem is protected by ->chunk_mutex, we need
get that mutex when we insert the new device into the list.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: fix use-after-free in the finishing procedure of the device replace

During device replace test, we hit a null pointer deference (It was very easy
to reproduce it by running xfstests' btrfs/011 on the devices with the virtio
scsi driver). There were two bugs that caused this problem:
- We might allocate new chunks on the replaced device after we updated
  the mapping tree. And we forgot to replace the source device in those
  mapping of the new chunks.
- We might get the mapping information which including the source device
  before the mapping information update. And then submit the bio which was
  based on that mapping information after we freed the source device.

For the first bug, we can fix it by doing mapping tree update and source
device remove in the same context of the chunk mutex. The chunk mutex is
used to protect the allocable device list, the above method can avoid
the new chunk allocation, and after we remove the source device, all
the new chunks will be allocated on the new device. So it can fix
the first bug.

For the second bug, we need make sure all flighting bios are finished and
no new bios are produced during we are removing the source device. To fix
this problem, we introduced a global @bio_counter, we not only inc/dec
@bio_counter outsize of map_blocks, but also inc it before submitting bio
and dec @bio_counter when ending bios.

Since Raid56 is a little different and device replace dosen't support raid56
yet, it is not addressed in the patch and I add comments to make sure we will
fix it in the future.

Reported-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: add missing error check in incremental send

Function wait_for_parent_move() returns negative value if an error
happened, 0 if we don't need to wait for the parent's move, and
1 if the wait is needed.
Before this change an error return value was being treated like the
return value 1, which was not correct.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: Fix 32/64-bit problem with BTRFS_SET_RECEIVED_SUBVOL ioctl

The structure for BTRFS_SET_RECEIVED_IOCTL packs differently on 32-bit
and 64-bit systems. This means that it is impossible to use btrfs
receive on a system with a 64-bit kernel and 32-bit userspace, because
the structure size (and hence the ioctl number) is different.

This patch adds a compatibility structure and ioctl to deal with the
above case.

Signed-off-by: Hugo Mills <hugo@carfax.org.uk>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: switch to btrfs_previous_extent_item()

Since we have introduced btrfs_previous_extent_item() to search previous
extent item, just switch into it.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: only add roots if necessary in find_parent_nodes()

find_all_leafs() dosen't need add all roots actually, add roots only
if we need, this can avoid unnecessary ulist dance.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: fix send dealing with file renames and directory moves

This fixes a case that the commit titled:

   Btrfs: fix infinite path build loops in incremental send

didn't cover. If the parent-child relationship between 2 directories
is inverted, both get renamed, and the former parent has a file that
got renamed too (but remains a child of that directory), the incremental
send operation would use the file's old path after sending an unlink
operation for that old path, causing receive to fail on future operations
like changing owner, permissions or utimes of the corresponding inode.

This is not a regression from the commit mentioned before, as without
that commit we would fall into the issues that commit fixed, so it's
just one case that wasn't covered before.

Simple steps to reproduce this issue are:

      $ mkfs.btrfs -f /dev/sdb3
      $ mount /dev/sdb3 /mnt/btrfs
      $ mkdir -p /mnt/btrfs/a/b/c/d
      $ touch /mnt/btrfs/a/b/c/d/file
      $ mkdir -p /mnt/btrfs/a/b/x
      $ btrfs subvol snapshot -r /mnt/btrfs /mnt/btrfs/snap1
      $ mv /mnt/btrfs/a/b/x /mnt/btrfs/a/b/c/x2
      $ mv /mnt/btrfs/a/b/c/d /mnt/btrfs/a/b/c/x2/d2
      $ mv /mnt/btrfs/a/b/c/x2/d2/file /mnt/btrfs/a/b/c/x2/d2/file2
      $ btrfs subvol snapshot -r /mnt/btrfs /mnt/btrfs/snap2
      $ btrfs send -p /mnt/btrfs/snap1 /mnt/btrfs/snap2 > /tmp/incremental.send

A patch to update the test btrfs/030 from xfstests, so that it covers
this case, will be submitted soon.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: more send support for parent/child dir relationship inversion

The commit titled "Btrfs: fix infinite path build loops in incremental send"
didn't cover a particular case where the parent-child relationship inversion
of directories doesn't imply a rename of the new parent directory. This was
due to a simple logic mistake, a logical and instead of a logical or.

Steps to reproduce:

  $ mkfs.btrfs -f /dev/sdb3
  $ mount /dev/sdb3 /mnt/btrfs
  $ mkdir -p /mnt/btrfs/a/b/bar1/bar2/bar3/bar4
  $ btrfs subvol snapshot -r /mnt/btrfs /mnt/btrfs/snap1
  $ mv /mnt/btrfs/a/b/bar1/bar2/bar3/bar4 /mnt/btrfs/a/b/k44
  $ mv /mnt/btrfs/a/b/bar1/bar2/bar3 /mnt/btrfs/a/b/k44
  $ mv /mnt/btrfs/a/b/bar1/bar2 /mnt/btrfs/a/b/k44/bar3
  $ mv /mnt/btrfs/a/b/bar1 /mnt/btrfs/a/b/k44/bar3/bar2/k11
  $ btrfs subvol snapshot -r /mnt/btrfs /mnt/btrfs/snap2
  $ btrfs send -p /mnt/btrfs/snap1 /mnt/btrfs/snap2 > /tmp/incremental.send

A patch to update the test btrfs/030 from xfstests, so that it covers
this case, will be submitted soon.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: send: replace check with an assert in gen_unique_name

The buffer passed to snprintf can hold the fully expanded format string,
64 = 3x largest ULL + 3x char + trailing null.  I don't think that removing the
check entirely is a good idea, hence the ASSERT.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: send: remove prepared member from fs_path

The member is used only to return value back from
fs_path_prepare_for_add, we can do it locally and save 8 bytes for the
inline_buf path.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: send: remove virtual_mem member from fs_path

We don't need to keep track of that, it's available via is_vmalloc_addr.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: send: squeeze bitfilelds in fs_path

We know that buf_len is at most PATH_MAX, 4k, and can merge it with the
reversed member. This saves 3 bytes in favor of inline_buf.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: send: remove BUG from process_all_refs

There are only 2 static callers, the BUG would normally be never
reached, but let's be nice.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: send: remove BUG_ON from name_cache_delete

If cleaning the name cache fails, we could try to proceed at the cost of
some memory leak. This is not expected to happen often.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: fix assert screwup for the pending move stuff

Wang noticed that he was failing btrfs/030 even though me and Filipe couldn't
reproduce.  Turns out this is because Wang didn't have CONFIG_BTRFS_ASSERT set,
which meant that a key part of Filipe's original patch was not being built in.
This appears to be a mess up with merging Filipe's patch as it does not exist in
his original patch.  Fix this by changing how we make sure del_waiting_dir_move
asserts that it did not error and take the function out of the ifdef check.
This makes btrfs/030 pass with the assert on or off.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: use right extent item position in send when finding extent clones

This was a leftover from the commit:

   74dd17fbe3d65829e75d84f00a9525b2ace93998
   (Btrfs: fix btrfs send for inline items and compression)

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Btrfs: make some tree searches in send.c more efficient

We have this pattern where we do search for a contiguous group of
items in a tree and everytime we find an item, we process it, then
we release our path, increment the offset of the search key, do
another full tree search and repeat these steps until a tree search
can't find more items we're interested in.

Instead of doing these full tree searches after processing each item,
just process the next item/slot in our leaf and don't release the path.
Since all these trees are read only and we always use the commit root
for a search and skip node/leaf locks, we're not affecting concurrency
on the trees.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: send: lower memory requirements in common case

The fs_path structure uses an inline buffer and falls back to a chain of
allocations, but vmalloc is not necessary because PATH_MAX fits into
PAGE_SIZE.

The size of fs_path has been reduced to 256 bytes from PAGE_SIZE,
usually 4k. Experimental measurements show that most paths on a single
filesystem do not exceed 200 bytes, and these get stored into the inline
buffer directly, which is now 230 bytes. Longer paths are kmalloced when
needed.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
btrfs: add simple debugfs interface

Help during debugging to export various interesting infromation and
tunables without the need of extra mount options or ioctls.

Usage:
* declare your variable in sysfs.h, and include where you need it
* define the variable in sysfs.c and make it visible via
  debugfs_create_TYPE

Depends on CONFIG_DEBUG_FS.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>