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Commit 63432cd3 authored by David Anderson's avatar David Anderson
Browse files

remount: Prevent error spam when remounting fails. 

Cuttlefish's combined fstab has two entries for every partition, which
causes a lot of error spam when remount fails. Fix this by only
remounting entries that match an actual mount point (if such a mount
point exists).

Bug: 241179247
Test: remount on broken kernel
Change-Id: I3ddab553706f98b45f83221fd195f481dfdcc5c0
parent 9e8c41c5

fs_mgr/fs_mgr_overlayfs.cpp

+37 −22
Original line number Diff line number Diff line
@@ -370,28 +370,6 @@ bool fs_mgr_rw_access(const std::string& path) { 
    return ret;

}



bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only = true) {

    Fstab fstab;

    auto save_errno = errno;

    if (!ReadFstabFromFile("/proc/mounts", &fstab)) {

        return false;

    }

    errno = save_errno;

    const auto lowerdir = kLowerdirOption + mount_point;

    for (const auto& entry : fstab) {

        if (overlay_only && "overlay" != entry.fs_type && "overlayfs" != entry.fs_type) continue;

        if (mount_point != entry.mount_point) continue;

        if (!overlay_only) return true;

        const auto options = android::base::Split(entry.fs_options, ",");

        for (const auto& opt : options) {

            if (opt == lowerdir) {

                return true;

            }

        }

    }

    return false;

}



constexpr char kOverlayfsFileContext[] = "u:object_r:overlayfs_file:s0";



bool fs_mgr_overlayfs_setup_dir(const std::string& dir, std::string* overlay, bool* change) {
@@ -1290,8 +1268,23 @@ bool fs_mgr_wants_overlayfs(FstabEntry* entry) { 
}



Fstab fs_mgr_overlayfs_candidate_list(const Fstab& fstab) {

    android::fs_mgr::Fstab mounts;

    if (!android::fs_mgr::ReadFstabFromFile("/proc/mounts", &mounts)) {

        PLOG(ERROR) << "Failed to read /proc/mounts";

        return {};

    }



    Fstab candidates;

    for (const auto& entry : fstab) {

        // Filter out partitions whose type doesn't match what's mounted.

        // This avoids spammy behavior on devices which can mount different

        // filesystems for each partition.

        auto proc_mount_point = (entry.mount_point == "/system") ? "/" : entry.mount_point;

        auto mounted = GetEntryForMountPoint(&mounts, proc_mount_point);

        if (!mounted || mounted->fs_type != entry.fs_type) {

            continue;

        }



        FstabEntry new_entry = entry;

        if (!fs_mgr_overlayfs_already_mounted(entry.mount_point) &&

            !fs_mgr_wants_overlayfs(&new_entry)) {
@@ -1698,6 +1691,28 @@ void TeardownAllOverlayForMountPoint(const std::string& mount_point) { 


#endif  // ALLOW_ADBD_DISABLE_VERITY != 0



bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only) {

    Fstab fstab;

    auto save_errno = errno;

    if (!ReadFstabFromFile("/proc/mounts", &fstab)) {

        return false;

    }

    errno = save_errno;

    const auto lowerdir = kLowerdirOption + mount_point;

    for (const auto& entry : fstab) {

        if (overlay_only && "overlay" != entry.fs_type && "overlayfs" != entry.fs_type) continue;

        if (mount_point != entry.mount_point) continue;

        if (!overlay_only) return true;

        const auto options = android::base::Split(entry.fs_options, ",");

        for (const auto& opt : options) {

            if (opt == lowerdir) {

                return true;

            }

        }

    }

    return false;

}



bool fs_mgr_has_shared_blocks(const std::string& mount_point, const std::string& dev) {

    struct statfs fs;

    if ((statfs((mount_point + "/lost+found").c_str(), &fs) == -1) ||

fs_mgr/fs_mgr_remount.cpp

+20 −8
Original line number Diff line number Diff line
@@ -186,8 +186,8 @@ static bool IsRemountable(Fstab& candidates, const FstabEntry& entry) { 
    if (entry.fs_type == "vfat") {

        return false;

    }

    if (GetEntryForMountPoint(&candidates, entry.mount_point)) {

        return true;

    if (auto candidate_entry = GetEntryForMountPoint(&candidates, entry.mount_point)) {

        return candidate_entry->fs_type == entry.fs_type;

    }

    if (GetWrappedEntry(candidates, entry)) {

        return false;
@@ -196,13 +196,22 @@ static bool IsRemountable(Fstab& candidates, const FstabEntry& entry) { 
}



static Fstab::const_iterator FindPartition(const Fstab& fstab, const std::string& partition) {

    Fstab mounts;

    if (!android::fs_mgr::ReadFstabFromFile("/proc/mounts", &mounts)) {

        LOG(ERROR) << "Failed to read /proc/mounts";

        return fstab.end();

    }



    for (auto iter = fstab.begin(); iter != fstab.end(); iter++) {

        const auto mount_point = system_mount_point(*iter);

        if (partition == mount_point) {

        if (partition == mount_point || partition == android::base::Basename(mount_point)) {

            // In case fstab has multiple entries, pick the one that matches the

            // actual mounted filesystem type.

            auto proc_mount_point = (iter->mount_point == "/system") ? "/" : iter->mount_point;

            auto mounted = GetEntryForMountPoint(&mounts, proc_mount_point);

            if (mounted && mounted->fs_type == iter->fs_type) {

                return iter;

            }

        if (partition == android::base::Basename(mount_point)) {

            return iter;

        }

    }

    return fstab.end();
@@ -243,7 +252,10 @@ static RemountStatus GetRemountList(const Fstab& fstab, const std::vector<std::s 
            entry = wrap;

        }



        if (!IsRemountable(candidates, *entry)) {

        // If it's already remounted, include it so it gets gracefully skipped

        // later on.

        if (!fs_mgr_overlayfs_already_mounted(entry->mount_point) &&

            !IsRemountable(candidates, *entry)) {

            LOG(ERROR) << "Invalid partition " << arg;

            return INVALID_PARTITION;

        }

fs_mgr/include/fs_mgr_overlayfs.h

+1 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ bool fs_mgr_overlayfs_setup(const char* backing = nullptr, const char* mount_poi 
bool fs_mgr_overlayfs_teardown(const char* mount_point = nullptr, bool* change = nullptr);

bool fs_mgr_overlayfs_is_setup();

bool fs_mgr_has_shared_blocks(const std::string& mount_point, const std::string& dev);

bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only = true);

std::string fs_mgr_get_context(const std::string& mount_point);



enum class OverlayfsValidResult {