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Merge "fs_mgr: Change scratch margin to 3 X logical_block_size."

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Treehugger Robot 2018-12-04 16:30:25 +00:00 committed by Gerrit Code Review
commit a30cff7f89
2 changed files with 20 additions and 3 deletions
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5
fs_mgr/README.overlayfs.md
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@ -89,4 +89,9 @@ Caveats
if higher than 4.6.
- *adb enable-verity* will free up overlayfs and as a bonus the
device will be reverted pristine to before any content was updated.
- If dynamic partitions runs out of space, resizing a logical
partition larger may fail because of the scratch partition.
If this happens, either fastboot flashall or adb enable-verity can
be used to clear scratch storage to permit the flash.
Then reinstate the overrides and continue.
- File bugs or submit fixes for review.

18
fs_mgr/fs_mgr_overlayfs.cpp
View file

@ -675,14 +675,26 @@ bool fs_mgr_overlayfs_setup_scratch(const fstab* fstab, bool* change) {
}
changed = true;
}
// Take half of free space, minimum 512MB or free space - 256KB margin.
// Take half of free space, minimum 512MB or maximum free - margin.
static constexpr auto kMinimumSize = uint64_t(512 * 1024 * 1024);
static constexpr auto kMarginSize = uint64_t(256 * 1024);
if (partition->size() < kMinimumSize) {
auto partition_size =
builder->AllocatableSpace() - builder->UsedSpace() + partition->size();
if ((partition_size > kMinimumSize) || !partition->size()) {
partition_size = std::max(std::min(kMinimumSize, partition_size - kMarginSize),
// Leave some space for free space jitter of a few erase
// blocks, in case they are needed for any individual updates
// to any other partition that needs to be flashed while
// overlayfs is in force. Of course if margin_size is not
// enough could normally get a flash failure, so
// ResizePartition() will delete the scratch partition in
// order to fulfill. Deleting scratch will destroy all of
// the adb remount overrides :-( .
auto margin_size = uint64_t(3 * 256 * 1024);
BlockDeviceInfo info;
if (builder->GetBlockDeviceInfo(partition_name, &info)) {
margin_size = 3 * info.logical_block_size;
}
partition_size = std::max(std::min(kMinimumSize, partition_size - margin_size),
partition_size / 2);
if (partition_size > partition->size()) {
if (!builder->ResizePartition(partition, partition_size)) {