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udev: generate system-unique storage symlinks using device path
When the same disk image is written to multiple storage units, for example an external SD card and an internal eMMC, the symlinks in /dev/disk/by-{label,uuid,partlabel,partuuid}/ are no longer unique, and will point to the device that is probed last. Adressing partitions via labels and UUIDs is nice to work with, and depending on the use case, it might also be more robust than using the symlinks in /dev/disk/by-path/ containing the partition number. Combine the two approaches to create unique symlinks containing both the device path as well as the respective UUIDs or labels, and throw in a symlink using the devpath and the partition number for the sake of completeness. For an exemplary GPT-partitioned disk at "platform-2198000.mmc" with a partition containing an ext4 file system, this might create symlinks of the following form: /dev/disk/by-path/platform-2198000.mmc-part/by-partnum/1 /dev/disk/by-path/platform-2198000.mmc-part/by-partuuid/e5a75233-3b90-4aec-8075-b4dd7132b48d /dev/disk/by-path/platform-2198000.mmc-part/by-partlabel/rootfs /dev/disk/by-path/platform-2198000.mmc-part/by-uuid/b2c92f24-8215-4680-b931-f423aae5f1c9 /dev/disk/by-path/platform-2198000.mmc-part/by-label/rootfs Signed-off-by: Roland Hieber <rhi@pengutronix.de>
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@ -145,6 +145,19 @@ ENV{ID_WWN_WITH_EXTENSION}=="?*", SYMLINK+="disk/by-id/wwn-$env{ID_WWN_WITH_EXTE
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ENV{ID_PART_ENTRY_UUID}=="?*", SYMLINK+="disk/by-partuuid/$env{ID_PART_ENTRY_UUID}"
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ENV{ID_PART_ENTRY_SCHEME}=="gpt", ENV{ID_PART_ENTRY_NAME}=="?*", SYMLINK+="disk/by-partlabel/$env{ID_PART_ENTRY_NAME}"
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# by-path/<path>/by-* links (path + partition/filesystem metadata)
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ENV{ID_PATH}=="", GOTO="persistent_storage_by-path_parts_end"
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ENV{DEVTYPE}!="partition", GOTO="persistent_storage_by-path_parts_end"
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SYMLINK+="disk/by-path/$env{ID_PATH}-part/by-partnum/%n"
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ENV{ID_PART_ENTRY_UUID}=="?*", SYMLINK+="disk/by-path/$env{ID_PATH}-part/by-partuuid/$env{ID_PART_ENTRY_UUID}"
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ENV{ID_PART_ENTRY_SCHEME}=="gpt", ENV{ID_PART_ENTRY_NAME}=="?*", SYMLINK+="disk/by-path/$env{ID_PATH}-part/by-partlabel/$env{ID_PART_ENTRY_NAME}"
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ENV{ID_FS_USAGE}=="filesystem|other|crypto", ENV{ID_FS_UUID_ENC}=="?*", SYMLINK+="disk/by-path/$env{ID_PATH}-part/by-uuid/$env{ID_FS_UUID_ENC}"
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ENV{ID_FS_USAGE}=="filesystem|other|crypto", ENV{ID_FS_LABEL_ENC}=="?*", SYMLINK+="disk/by-path/$env{ID_PATH}-part/by-label/$env{ID_FS_LABEL_ENC}"
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LABEL="persistent_storage_by-path_parts_end"
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# by-diskseq link (if an app is told to open a path like this, they may parse
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# the diskseq number from the path, then issue BLKGETDISKSEQ to verify they really got
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# the right device, to access specific disks in a race-free fashion)
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