linux-stable.git/fs/btrfs/relocation.c, branch linux-3.14.y

Btrfs: fix build_backref_tree issue with multiple shared blocks

2014-10-30T16:38:18+00:00

commit bbe9051441effce51c9a533d2c56440df64db2d7 upstream.

Marc Merlin sent me a broken fs image months ago where it would blow up in the
upper->checked BUG_ON() in build_backref_tree.  This is because we had a
scenario like this

block a -- level 4 (not shared)
   |
block b -- level 3 (reloc block, shared)
   |
block c -- level 2 (not shared)
   |
block d -- level 1 (shared)
   |
block e -- level 0 (shared)

We go to build a backref tree for block e, we notice block d is shared and add
it to the list of blocks to lookup it's backrefs for.  Now when we loop around
we will check edges for the block, so we will see we looked up block c last
time.  So we lookup block d and then see that the block that points to it is
block c and we can just skip that edge since we've already been up this path.
The problem is because we clear need_check when we see block d (as it is shared)
we never add block b as needing to be checked.  And because block c is in our
path already we bail out before we walk up to block b and add it to the backref
check list.

To fix this we need to reset need_check if we trip over a block that doesn't
need to be checked.  This will make sure that any subsequent blocks in the path
as we're walking up afterwards are added to the list to be processed.  With this
patch I can now mount Marc's fs image and it'll complete the balance without
panicing.  Thanks,

Reported-by: Marc MERLIN 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason 
Signed-off-by: Greg Kroah-Hartman

Btrfs: cleanup error handling in build_backref_tree

2014-10-30T16:38:18+00:00

commit 75bfb9aff45e44625260f52a5fd581b92ace3e62 upstream.

When balance panics it tends to panic in the

BUG_ON(!upper->checked);

test, because it means it couldn't build the backref tree properly.  This is
annoying to users and frankly a recoverable error, nothing in this function is
actually fatal since it is just an in-memory building of the backrefs for a
given bytenr.  So go through and change all the BUG_ON()'s to ASSERT()'s, and
fix the BUG_ON(!upper->checked) thing to just return an error.

This patch also fixes the error handling so it tears down the work we've done
properly.  This code was horribly broken since we always just panic'ed instead
of actually erroring out, so it needed to be completely re-worked.  With this
patch my broken image no longer panics when I mount it.  Thanks,

Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason 
Signed-off-by: Greg Kroah-Hartman

Btrfs: fix an oops when we fail to relocate tree blocks

2014-01-28T21:20:14+00:00

During balance test, we hit an oops:
[ 2013.841551] kernel BUG at fs/btrfs/relocation.c:1174!

The problem is that if we fail to relocate tree blocks, we should
update backref cache, otherwise, some pending nodes are not updated
while snapshot check @cache->last_trans is within one transaction
and won't update it and then oops happen.

Signed-off-by: Wang Shilong 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: fix an oops when we fail to merge reloc roots

2014-01-28T21:20:13+00:00

Previously, we will free reloc root memory and then force filesystem
to be readonly. The problem is that there may be another thread commiting
transaction which will try to access freed reloc root during merging reloc
roots process.

To keep consistency snapshots shared space, we should allow snapshot
finished if possible, so here we don't free reloc root memory.

signed-off-by: Wang Shilong 

Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: remove unused argument from select_reloc_root()

2014-01-28T21:20:12+00:00

@nr is no longer used, remove it from select_reloc_root()

Signed-off-by: Wang Shilong 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: convert printk to btrfs_ and fix BTRFS prefix

2014-01-28T21:20:05+00:00

Convert all applicable cases of printk and pr_* to the btrfs_* macros.

Fix all uses of the BTRFS prefix.

Signed-off-by: Frank Holton 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: remove unnecessary filemap writting and waiting after block group relocation

2014-01-28T21:19:57+00:00

We have commited transaction before, remove redundant filemap writting and
waiting here, it can speed up balance relocation process.

Signed-off-by: Wang Shilong 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: improve forever loop when doing balance relocation

2014-01-28T21:19:43+00:00

We hit a forever loop when doing balance relocation,the reason
is that we firstly reserve 4M(node size is 16k).and within transaction
we will try to add extra reservation for snapshot roots,this will
return -EAGAIN if there has been a thread flushing space to reserve
space.We will do this again and again with filesystem becoming nearly
full.

If the above '-EAGAIN' case happens, we try to refill reservation more
outsize of transaction, and this will return eariler in enospc case,however,
this dosen't really hurt because it makes no sense doing balance relocation
with the filesystem nearly full.

Miao Xie helped a lot to track this issue, thanks.

Signed-off-by: Wang Shilong 
Signed-off-by: Miao Xie 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: make sure we cleanup all reloc roots if error happens

2013-12-12T15:12:51+00:00

I hit an oops when merging reloc roots fails, the reason is that
new reloc roots may be added and we should make sure we cleanup
all reloc roots.

Signed-off-by: Wang Shilong 
Signed-off-by: Chris Mason

Btrfs: skip building backref tree for uuid and quota tree when doing balance relocation

2013-12-12T15:12:36+00:00

Quota tree and UUID Tree is only cowed, they can not be snapshoted.

Signed-off-by: Wang Shilong 
Signed-off-by: Chris Mason