When dfuse sees I/O as well-aligned 128k reads then read MB at
a time and cache the result allowing for faster read bandwidth
for well behaved applicaions and large files.

Create a new in-memory descriptor for file contents, pull in a
whole descriptor on first read and perform all other reads from
the same result.

This should give much higher bandwidth for well behaved applications
and should be easy to extend to proper readahead in future.

Test-tag: test_dfuse_caching_check

Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Test-tag: dfuse

Test-tag: dfuse

Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Test-tag: dfuse

Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Test-tag: test_dfuse_caching_check

Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Skip-unit-tests: true
Skip-fault-injection-test: true
Test-tag: test_dfuse_caching_check

Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Skip-unit-tests: true
Skip-fault-injection-test: true
Test-tag: test_dfuse_caching_check

Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Skip-unit-tests: true
Skip-fault-injection-test: true
Test-tag: test_dfuse_caching_check
Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Skip-unit-tests: true
Skip-fault-injection-test: true
Test-tag: test_dfuse_caching_check
Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Skip-unit-tests: true
Skip-fault-injection-test: true
Test-tag: test_dfuse_caching_check
Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Skip-unit-tests: true
Skip-fault-injection-test: true
Test-tag: dfuse
Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Skip-unit-tests: true
Skip-fault-injection-test: true
Test-tag: test_dfuse_caching_check

Features: dfuse,-test_dfuse_find

Features: dfuse,-test_dfuse_find,-test_dfuse_daos_build_wt_pil4dfs
Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Features: dfuse

Signed-off-by: Ashley Pittman <ashley.m.pittman@intel.com>

Required-githooks: true

Signed-off-by: Jeff Olivier <jeffolivier@google.com>

Allow-unstable-test: true

Required-githooks: true

Signed-off-by: Jeff Olivier <jeffolivier@google.com>

Features: dfuse