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Fix a bug introduced in r291716:

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"The problem with the approach taken both in _bus_dmamap_load_pages and
bus_dmamap_load_ma_triv is that they split the request buffer into
arbitrary chunks based on page boundaries, creating segments that no
longer have a size that's a multiple of the sector size. This breaks
drivers like blkfront (and probably other stuff)." [1]

This was most easily triggered by running `fsck /` on a system running
in Xen (e.g. Amazon EC2) but also showed up via growfs(8) and probably
many other userland tools which access the disk directly.

Patch by:	royger [1]
"Thinks this should be fine" by:	ken
This commit is contained in:
cperciva 2016-01-11 20:38:39 +00:00
parent 8bb6f22f29
commit 9ca3584fdd
1 changed files with 2 additions and 24 deletions
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26
sys/kern/subr_bus_dma.c
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@ -130,28 +130,6 @@ _bus_dmamap_load_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map,
return (error);
}
/*
* Load tlen data starting at offset within a region specified by a list of
* physical pages.
*/
static int
_bus_dmamap_load_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
vm_page_t *pages, bus_size_t tlen, int offset, int *nsegs, int flags)
{
vm_paddr_t paddr;
bus_size_t len;
int error, i;
for (i = 0, error = 0; error == 0 && tlen > 0; i++, tlen -= len) {
len = min(PAGE_SIZE - offset, tlen);
paddr = VM_PAGE_TO_PHYS(pages[i]) + offset;
error = _bus_dmamap_load_phys(dmat, map, paddr, len,
flags, NULL, nsegs);
offset = 0;
}
return (error);
}
/*
* Load from block io.
*/
@ -168,8 +146,8 @@ _bus_dmamap_load_bio(bus_dma_tag_t dmat, bus_dmamap_t map, struct bio *bio,
}
if ((bio->bio_flags & BIO_UNMAPPED) != 0)
return (_bus_dmamap_load_pages(dmat, map, bio->bio_ma,
bio->bio_bcount, bio->bio_ma_offset, nsegs, flags));
return (_bus_dmamap_load_ma(dmat, map, bio->bio_ma,
bio->bio_bcount, bio->bio_ma_offset, flags, NULL, nsegs));
return (_bus_dmamap_load_buffer(dmat, map, bio->bio_data,
bio->bio_bcount, kernel_pmap, flags, NULL, nsegs));