Chris Mason 65b51a009e btrfs_search_slot: reduce lock contention by cowing in two stages ... A btree block cow has two parts, the first is to allocate a destination block and the second is to copy the old bock over. The first part needs locks in the extent allocation tree, and may need to do IO. This changeset splits that into a separate function that can be called without any tree locks held. btrfs_search_slot is changed to drop its path and start over if it has to COW a contended block. This often means that many writers will pre-alloc a new destination for a the same contended block, but they cache their prealloc for later use on lower levels in the tree. Signed-off-by: Chris Mason <chris.mason@oracle.com>		2008-09-25 11:04:06 -04:00
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btrfs	btrfs_search_slot: reduce lock contention by cowing in two stages	2008-09-25 11:04:06 -04:00