btrfs: qgroup: Use root::qgroup_meta_rsv_* to record qgroup meta reserved space

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For quota disabled->enable case, it's possible that at reservation time
quota was not enabled so no bytes were really reserved, while at release
time, quota was enabled so we will try to release some bytes we didn't
really own.

Such situation can cause metadata reserveation underflow, for both types,
also less possible for per-trans type since quota enable will commit
transaction.

To address this, record qgroup meta reserved bytes into
root::qgroup_meta_rsv_pertrans and ::prealloc.
So at releasing time we won't free any bytes we didn't reserve.

For DATA, it's already handled by io_tree, so nothing needs to be done
there.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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This commit is contained in:

Qu Wenruo 2017-12-12 15:34:34 +08:00 • committed by David Sterba

parent 4f5427ccce

commit 8287475a20

3 changed files with 68 additions and 4 deletions

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5

fs/btrfs/ctree.h

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1

fs/btrfs/disk-io.c

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66

fs/btrfs/qgroup.c

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