Revert "dynamic fsync: don't disable fdatasync()"

This reverts commit a6c9f1195647a7403a38be5913164f7a3751e9f1.
Revert "writeback: fix occasional slow sync(1)"

This reverts commit 36f67737d6111fee755c0eb2e5967a3c06e2c23d.
Revert "Dynamic FSync control 1.1"

This reverts commit 983f39cf6403717ed41fc58655b58fd416671979.
Revert "Revert "Dynamic FSync control""

This reverts commit 5f04ad773e67b5fdab1cc2865d995d33045721a3.
eliminados script libera_ram.sh y relax.sh