Not all services involved in block I/O go through VM to access the
blocks they need. As a result, the blocks in VM may become stale,
possibly causing corruption when the stale copy is restored by a
service that does go through VM later on. This patch restores support
for forgetting cached blocks that belong to a particular device, and
makes the relevant file systems use this functionality 1) when
requested by VFS through REQ_FLUSH, and 2) upon unmount.
Change-Id: I0758c5ed8fe4b5ba81d432595d2113175776aff8
Primary purpose of change: to support the mmap implementation, VM must
know both (a) about some block metadata for FS cache blocks, i.e.
inode numbers and inode offsets where applicable; and (b) know about
*all* cache blocks, i.e. also of the FS primary caches and not just
the blocks that spill into the secondary one. This changes the
interface and VM data structures.
This change is only for the interface (libminixfs) and VM data
structures; the filesystem code is unmodified, so although the
secondary cache will be used as normal, blocks will not be annotated
with inode information until the FS is modified to provide this
information. Until it is modified, mmap of files will fail gracefully
on such filesystems.
This is indicated to VFS/VM by returning ENOSYS for REQ_PEEK.
Change-Id: I1d2df6c485e6c5e89eb28d9055076cc02629594e
. test70: regression test for m_out vfs race condition
The following tests use testcache.c to generate test i/o
patterns, generate random write data and verify the reads.
. test71: blackbox full-stack test of FS operation, testing
using the regular VFS interface crazy i/o patterns
with various working set sizes, triggering only
primary cache, also secondary cache, and finally
disk i/o and verifying contents all the time
. test72: unit test of libminixfs, implementing
functions it needs from -lsys and -lblockdriver
and the client in order to simulate a working
cache client and backend environment.
. test73: blackbox test of secondary vm cache in isolation
Change-Id: I1287e9753182b8719e634917ad158e3c1e079ceb
