tree bb7d2dc93f26e9f8cefe00b590304755a07558eb
parent d555438b6e1dad139d26ab807f0af68a1fa47a86
author Josef Bacik <jbacik@fusionio.com> 1379019508 -0400
committer Chris Mason <chris.mason@fusionio.com> 1379775926 -0400

Btrfs: improve replacing nocow extents

Various people have hit a deadlock when running btrfs/011.  This is because when
replacing nocow extents we will take the i_mutex to make sure nobody messes with
the file while we are replacing the extent.  The problem is we are already
holding a transaction open, which is a locking inversion, so instead we need to
save these inodes we find and then process them outside of the transaction.

Further we can't just lock the inode and assume we are good to go.  We need to
lock the extent range and then read back the extent cache for the inode to make
sure the extent really still points at the physical block we want.  If it
doesn't we don't have to copy it.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>