Pass flags to more DMU write/hold functions #17872
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Over the time many of DMU functions got flags argument to control prefetch, caching, etc. Few functions though left without it, even though closer look shown that many of them do not require prefetch due to their access pattern. This patch adds the flags argument to dmu_write(), dmu_buf_hold_array() and dmu_buf_hold_array_by_bonus(), passing DMU_READ_NO_PREFETCH where applicable. I am going to also pass DMU_UNCACHEDIO to some of them later. Signed-off-by: Alexander Motin <[email protected]>
behlendorf
reviewed
Oct 28, 2025
| void | ||
| dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size, | ||
| const void *buf, dmu_tx_t *tx) | ||
| const void *buf, dmu_tx_t *tx, dmu_flags_t flags) |
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My only concern is Lustre makes use of this interface so it'll break that build. We could instead create a dmu_write_flags wrapper like we've done elsewhere. That said, Lustre already makes use of the _by_dnode() variant so I don't think it'd be a big deal for them to switch to that.
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Most of other functions already take the flags argument, while dmu_buf_will_dirty_flags() is the only exception when we have a separate function for that. I could make what you ask, but it would be an oddity.
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Over the time many of DMU functions got flags argument to control prefetch, caching, etc. Few functions though left without it, even though closer look shown that many of them do not benefit from prefetch due to their access pattern. This patch adds the flags argument to
dmu_write(),dmu_buf_hold_array()anddmu_buf_hold_array_by_bonus(), passingDMU_READ_NO_PREFETCHwhere applicable.I am going to also pass
DMU_UNCACHEDIOto some of them later.How Has This Been Tested?
Build-tested on FreeBSD. I don't expect any effects visible without precise instrumentation.
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Signed-off-by.