Messages in this thread | | | Date | Tue, 14 Jul 2009 22:24:56 +0400 | From | Vladislav Bolkhovitin <> | Subject | Re: [PATCH v2]: New implementation of scsi_execute_async() |
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Vladislav Bolkhovitin, on 07/14/2009 08:17 PM wrote: > This patch reimplements scsi_execute_async(). In the new version it's a lot less > hackish and also has additional features. Namely: > > 1. Possibility to insert commands both in tail and in head of the queue. > > 2. Possibility to explicitly specify if the last SG element has space for padding. > > This patch based on the previous patches posted by Tejun Heo. Comparing to them > it has the following improvements: > > 1. It uses BIOs chaining instead of kmalloc()ing the whole bio. > > 2. It uses SGs chaining instead of kmalloc()ing one big SG in case if direct > mapping failed (e.g. because of DMA alignment or padding). > > 3. If direct mapping failed, if possible, it copies only the last SG element, > not the whole SG. > > 4. When needed, copy_page() is used instead of memcpy() to copy the whole pages. > > Also this patch adds and exports functions sg_copy() and sg_copy_elem(), which > cop one SG to another and one SG element to another respectively. > > At the moment SCST is the only user of this functionality. It needs it, because > its target drivers, which are, basically, SCSI drivers, can deal only with SGs, > not with BIOs. But, according the latest discussions, there are other potential > users for of this functionality, so I'm sending this patch in a hope that it will be > also useful for them and eventually will be merged in the mainline kernel. > > This patch requires previously sent patch with subject "[PATCH]: Rename REQ_COPY_USER > to more descriptive REQ_HAS_TAIL_SPACE_FOR_PADDING". > > It's against 2.6.30.1, but if necessary, I can update it to any necessary > kernel version. > > Signed-off-by: Vladislav Bolkhovitin <vst@vlnb.net> > > block/blk-map.c | 408 ++++++++++++++++++++++++++++++++++++++++++++ > drivers/scsi/scsi_lib.c | 108 +++++++++++ > include/linux/blkdev.h | 3 > include/linux/scatterlist.h | 7 > include/scsi/scsi_device.h | 11 + > lib/scatterlist.c | 147 +++++++++++++++ > 6 files changed, 683 insertions(+), 1 deletion(-)
Oops, sorry, forgot to write the change log from v1. V2 has fixes according to comments made by Joe Eykholt and Boaz Harrosh.
Vlad
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