first stage mount: removing the requirement of by-name prefix for AVB

Current first stage mount for AVB requires specifying a common prefix of
by-name symlink for all AVB partitions. It limits all AVB partitions to be on
the same block device.

firmware {
    android {
        compatible = "android,firmware";
        vbmeta {
            compatible = "android,vbmeta";
            parts = "vbmeta,boot,system,vendor";
            by_name_prefix="/dev/block/platform/soc.0/f9824900.sdhci/by-name"  <-- *removing this*
        };
        fstab {
            compatible = "android,fstab";
            vendor {
                compatible = "android,vendor";
                dev = "/dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor";
                type = "ext4";
                mnt_flags = "ro,barrier=1,inode_readahead_blks=8";
                fsmgr_flags = "wait,avb";
            };
        };
    };
};

For normal mount with AVB, it extracts the by-name prefix of /misc
partition and use it as the prefix for all other partitions:
    - /dev/block/platform/soc.0/f9824900.sdhci/by-name/misc ->
    - /dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor_a

Fix this by adding an internal map in FsManagerAvbOps to record the mapping
from partition name to its by-name symlink:

    ByNameSymlinkMap["vendor_a"] = "/dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor_a"

Two overloaded factory methods are then provided for FsManagerAvbUniquePtr:
    - FsManagerAvbUniquePtr Open(ByNameSymlinkMap&& by_name_symlink_map):
      for first stage mount, where the by-name symlink map will be
      constructed externally, from the uevents processed by init, before
      invoking this factory method.

    - FsManagerAvbUniquePtr Open(const fstab& fstab): for normal mount,
      where the by-name symlink map will be constructed from the input fstab
      internally.

Bug: 37552224
Test: first stage mount /vendor with vboot 1.0
Test: first stage mount /vendor with vboot 2.0 (AVB)
Test: normal mount /vendor with vboot 2.0 (AVB)
Change-Id: Id17e8566da87ea22b8923fcd6e47db8d45bc7d6a
Merged-In: Id17e8566da87ea22b8923fcd6e47db8d45bc7d6a
(cherry picked from commit 20651f62d081c88596e70b3b589863a75e2a9c35)

0 files changed, 0 insertions, 0 deletions