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Commit 53c96da7 authored by Mark Salyzyn's avatar Mark Salyzyn
Browse files

fs_mgr: add overlayfs for small-space filesystems 

If free space on the systems partition is less than 1%, then we may
use overlayfs to override the filesystem.

Test: manual
Bug: 109821005
Change-Id: I03eb9c7882cfd18db418a51e4964404f73f5ceb7
parent 1e6a318b

fs_mgr/fs_mgr_overlayfs.cpp

+17 −1
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <sys/mount.h>

#include <sys/param.h>

#include <sys/stat.h>

#include <sys/statvfs.h>

#include <sys/types.h>

#include <unistd.h>
@@ -96,9 +97,24 @@ std::string fs_mgr_get_context(const std::string& mount_point) { 
    return "";

}



// At less than 1% free space return value of false,

// means we will try to wrap with overlayfs.

bool fs_mgr_filesystem_has_space(const char* mount_point) {

    // If we have access issues to find out space remaining, return true

    // to prevent us trying to override with overlayfs.

    struct statvfs vst;

    if (statvfs(mount_point, &vst)) return true;



    static constexpr int percent = 1;  // 1%



    return (vst.f_bfree >= (vst.f_blocks * percent / 100));

}



bool fs_mgr_overlayfs_enabled(const struct fstab_rec* fsrec) {

    // readonly filesystem, can not be mount -o remount,rw

    return "squashfs"s == fsrec->fs_type;

    // if squashfs or if free space is (near) zero making

    // such a remount virtually useless.

    return ("squashfs"s == fsrec->fs_type) || !fs_mgr_filesystem_has_space(fsrec->mount_point);

}



constexpr char upper_name[] = "upper";