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authorFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>2009-07-09 14:46:53 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2009-07-30 14:39:45 -0700
commitc637cbe1701c396f8c3dbf0b11c0c77d70980618 (patch)
treed2102fbc88a3416f61982e021e94d19c6549782d
parentc242f9dd84db9159fd64b9d254660eabd90503b0 (diff)
downloadlinux-linaro-stable-c637cbe1701c396f8c3dbf0b11c0c77d70980618.tar.gz
block: fix sg SG_DXFER_TO_FROM_DEV regression
commit ecb554a846f8e9d2a58f6d6c118168a63ac065aa upstream. I overlooked SG_DXFER_TO_FROM_DEV support when I converted sg to use the block layer mapping API (2.6.28). Douglas Gilbert explained SG_DXFER_TO_FROM_DEV: http://www.spinics.net/lists/linux-scsi/msg37135.html = The semantics of SG_DXFER_TO_FROM_DEV were: - copy user space buffer to kernel (LLD) buffer - do SCSI command which is assumed to be of the DATA_IN (data from device) variety. This would overwrite some or all of the kernel buffer - copy kernel (LLD) buffer back to the user space. The idea was to detect short reads by filling the original user space buffer with some marker bytes ("0xec" it would seem in this report). The "resid" value is a better way of detecting short reads but that was only added this century and requires co-operation from the LLD. = This patch changes the block layer mapping API to support this semantics. This simply adds another field to struct rq_map_data and enables __bio_copy_iov() to copy data from user space even with READ requests. It's better to add the flags field and kills null_mapped and the new from_user fields in struct rq_map_data but that approach makes it difficult to send this patch to stable trees because st and osst drivers use struct rq_map_data (they were converted to use the block layer in 2.6.29 and 2.6.30). Well, I should clean up the block layer mapping API. zhou sf reported this regiression and tested this patch: http://www.spinics.net/lists/linux-scsi/msg37128.html http://www.spinics.net/lists/linux-scsi/msg37168.html Reported-by: zhou sf <sxzzsf@gmail.com> Tested-by: zhou sf <sxzzsf@gmail.com> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/scsi/sg.c4
-rw-r--r--fs/bio.c22
-rw-r--r--include/linux/blkdev.h1
3 files changed, 17 insertions, 10 deletions
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index e1716f14cd47..ff63279b40ea 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1656,6 +1656,10 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd)
md->nr_entries = req_schp->k_use_sg;
md->offset = 0;
md->null_mapped = hp->dxferp ? 0 : 1;
+ if (dxfer_dir == SG_DXFER_TO_FROM_DEV)
+ md->from_user = 1;
+ else
+ md->from_user = 0;
}
if (iov_count) {
diff --git a/fs/bio.c b/fs/bio.c
index 98711647ece4..78b05093a104 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -706,14 +706,13 @@ static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count,
}
static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
- struct sg_iovec *iov, int iov_count, int uncopy,
- int do_free_page)
+ struct sg_iovec *iov, int iov_count,
+ int to_user, int from_user, int do_free_page)
{
int ret = 0, i;
struct bio_vec *bvec;
int iov_idx = 0;
unsigned int iov_off = 0;
- int read = bio_data_dir(bio) == READ;
__bio_for_each_segment(bvec, bio, i, 0) {
char *bv_addr = page_address(bvec->bv_page);
@@ -728,13 +727,14 @@ static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
iov_addr = iov[iov_idx].iov_base + iov_off;
if (!ret) {
- if (!read && !uncopy)
- ret = copy_from_user(bv_addr, iov_addr,
- bytes);
- if (read && uncopy)
+ if (to_user)
ret = copy_to_user(iov_addr, bv_addr,
bytes);
+ if (from_user)
+ ret = copy_from_user(bv_addr, iov_addr,
+ bytes);
+
if (ret)
ret = -EFAULT;
}
@@ -771,7 +771,8 @@ int bio_uncopy_user(struct bio *bio)
if (!bio_flagged(bio, BIO_NULL_MAPPED))
ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
- bmd->nr_sgvecs, 1, bmd->is_our_pages);
+ bmd->nr_sgvecs, bio_data_dir(bio) == READ,
+ 0, bmd->is_our_pages);
bio_free_map_data(bmd);
bio_put(bio);
return ret;
@@ -876,8 +877,9 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
/*
* success
*/
- if (!write_to_vm && (!map_data || !map_data->null_mapped)) {
- ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 0);
+ if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
+ (map_data && map_data->from_user)) {
+ ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 1, 0);
if (ret)
goto cleanup;
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b4f71f1a4af7..e590df0bbb37 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -723,6 +723,7 @@ struct rq_map_data {
int nr_entries;
unsigned long offset;
int null_mapped;
+ int from_user;
};
struct req_iterator {