nvme/util: don't chain a PRP list page that isn't actually needed - #67
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nvme_map_prp()/nvme_mapv_prp() build the PRP list through a cursor that chains onto the next page as soon as it reaches a page's last slot and another entry follows. It can't tell whether that next entry is really the last one overall, so whenever the transfer size lands exactly on a page boundary (e.g. a 2047K transfer at a 512B LBA size, which needs almost exactly one page's worth of PRP entries) and the caller provides more than one prplist page as a safety margin, the cursor spills the final entry onto the second page even though the first page had room for it. Thread through whether the entry being appended is truly the last one, so the cursor can place it directly instead of reserving a chain link that turns out to be unnecessary. Signed-off-by: Minwoo Im <minwoo.im@samsung.com>
lsgunth
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Jul 30, 2026
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I've reviewed the patch and it looks correct to me. Thanks!
iomartin
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Add Job File Support
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nvme_map_prp()/nvme_mapv_prp() build the PRP list through a cursor that chains onto the next page as soon as it reaches a page's last slot and another entry follows. It can't tell whether that next entry is really the last one overall, so whenever the transfer size lands exactly on a page boundary (e.g. a 2047K transfer at a 512B LBA size, which needs almost exactly one page's worth of PRP entries) and the caller provides more than one prplist page as a safety margin, the cursor spills the final entry onto the second page even though the first page had room for it.
Thread through whether the entry being appended is truly the last one, so the cursor can place it directly instead of reserving a chain link that turns out to be unnecessary.