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Device mapper sends flush bios to all the targets and the targets send it to the underlying device. That may be inefficient, for example if a table contains 10 linear targets pointing to the same physical device, then device mapper would send 10 flush bios to that device - despite the fact that only one bio would be sufficient. This commit optimizes the flush behavior. It introduces a per-target variable flush_bypasses_map - it is set when the target supports flush optimization - currently, the dm-linear and dm-stripe targets support it. When all the targets in a table have flush_bypasses_map, flush_bypasses_map on the table is set. __send_empty_flush tests if the table has flush_bypasses_map - and if it has, no flush bios are sent to the targets via the "map" method and the list dm_table->devices is iterated and the flush bios are sent to each member of the list. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Mike Snitzer <snitzer@kernel.org> Suggested-by: Yang Yang <yang.yang@vivo.com> |
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| acpi | ||
| asm-generic | ||
| clocksource | ||
| crypto | ||
| drm | ||
| dt-bindings | ||
| keys | ||
| kunit | ||
| kvm | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
| pcmcia | ||
| ras | ||
| rdma | ||
| rv | ||
| scsi | ||
| soc | ||
| sound | ||
| target | ||
| trace | ||
| uapi | ||
| ufs | ||
| vdso | ||
| video | ||
| xen | ||