Btrfs: only use the existing eb if it's count isn't 0

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We can run into a problem where we find an eb for our existing page already on
the radix tree but it has a ref count of 0.  It hasn't yet been removed by RCU
yet so this can cause issues where we will use the EB after free.  So do
atomic_inc_not_zero on the exists->refs and if it is zero just do
synchronize_rcu() and try again.  We won't have to worry about new allocators
coming in since they will block on the page lock at this point.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

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Josef Bacik 2012-03-09 09:51:43 -05:00 • committed by Chris Mason

parent 4f2de97ace

commit 115391d231

1 changed files with 8 additions and 2 deletions

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fs/btrfs/extent_io.c

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