Update CoW size estimate when replacing entire dynamic partitions #307
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Otherwise, if the partition size increases or the data becomes more incompressible, update_engine might fail to flash the partition due to the CoW block device running out of space. Since all known VABC-enabled OTAs in the wild currently use CoW v2 with lz4 compression, this is the only configuration we support. CoW v3 also exists in AOSP's libsnapshot_cow, but is much more complicated to implement and is not yet used, even in the Android 15 beta OTAs. Fixes: #306 Signed-off-by: Andrew Gunnerson <[email protected]>
lz4_flex appears to compress system images better than the original lz4 implementation used in libsnapshot_cow, so the estimates are too low. Fixes: #306 Signed-off-by: Andrew Gunnerson <[email protected]>
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Jun 22, 2024
Signed-off-by: Andrew Gunnerson <[email protected]>
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Otherwise, if the partition size increases or the data becomes more incompressible, update_engine might fail to flash the partition due to the CoW block device running out of space.
Since all known VABC-enabled OTAs in the wild currently use CoW v2 with lz4 compression, this is the only configuration we support. CoW v3 also exists in AOSP's libsnapshot_cow, but is much more complicated to implement and is not yet used, even in the Android 15 beta OTAs.
Fixes: #306