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scsi_debug: fix do_device_access() with wrap around range

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do_device_access() is a function that abstracts copying SG list from/to
ramdisk storage (fake_storep).

It must deal with the ranges exceeding actual fake_storep size, because
such ranges are valid if virtual_gb is set greater than zero, and they
should be treated as fake_storep is repeatedly mirrored up to virtual
size.

Unfortunately, it can't deal with the range which wraps around the end of
fake_storep.  A wrap around range is copied by two
sg_copy_{from,to}_buffer() calls, but sg_copy_{from,to}_buffer() can't
copy from/to in the middle of SG list, therefore the second call can't
copy correctly.

This fixes it by using sg_pcopy_{from,to}_buffer() that can copy from/to
the middle of SG list.

This also simplifies the assignment of sdb->resid in
fill_from_dev_buffer().  Because fill_from_dev_buffer() is now only called
once per command execution cycle.  So it is not necessary to take care to
decrease sdb->resid if fill_from_dev_buffer() is called more than once.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Horia Geanta <horia.geanta@freescale.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Akinobu Mita 2013-07-08 16:01:57 -07:00 committed by Linus Torvalds
parent d05257238f
commit a451751172
1 changed files with 37 additions and 11 deletions
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48
drivers/scsi/scsi_debug.c
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@ -439,10 +439,7 @@ static int fill_from_dev_buffer(struct scsi_cmnd *scp, unsigned char *arr,
act_len = sg_copy_from_buffer(sdb->table.sgl, sdb->table.nents,
arr, arr_len);
if (sdb->resid)
sdb->resid -= act_len;
else
sdb->resid = scsi_bufflen(scp) - act_len;
sdb->resid = scsi_bufflen(scp) - act_len;
return 0;
}
@ -1693,24 +1690,48 @@ static int check_device_access_params(struct sdebug_dev_info *devi,
return 0;
}
/* Returns number of bytes copied or -1 if error. */
static int do_device_access(struct scsi_cmnd *scmd,
struct sdebug_dev_info *devi,
unsigned long long lba, unsigned int num, int write)
{
int ret;
unsigned long long block, rest = 0;
int (*func)(struct scsi_cmnd *, unsigned char *, int);
struct scsi_data_buffer *sdb;
enum dma_data_direction dir;
size_t (*func)(struct scatterlist *, unsigned int, void *, size_t,
off_t);
func = write ? fetch_to_dev_buffer : fill_from_dev_buffer;
if (write) {
sdb = scsi_out(scmd);
dir = DMA_TO_DEVICE;
func = sg_pcopy_to_buffer;
} else {
sdb = scsi_in(scmd);
dir = DMA_FROM_DEVICE;
func = sg_pcopy_from_buffer;
}
if (!sdb->length)
return 0;
if (!(scsi_bidi_cmnd(scmd) || scmd->sc_data_direction == dir))
return -1;
block = do_div(lba, sdebug_store_sectors);
if (block + num > sdebug_store_sectors)
rest = block + num - sdebug_store_sectors;
ret = func(scmd, fake_storep + (block * scsi_debug_sector_size),
(num - rest) * scsi_debug_sector_size);
if (!ret && rest)
ret = func(scmd, fake_storep, rest * scsi_debug_sector_size);
ret = func(sdb->table.sgl, sdb->table.nents,
fake_storep + (block * scsi_debug_sector_size),
(num - rest) * scsi_debug_sector_size, 0);
if (ret != (num - rest) * scsi_debug_sector_size)
return ret;
if (rest) {
ret += func(sdb->table.sgl, sdb->table.nents,
fake_storep, rest * scsi_debug_sector_size,
(num - rest) * scsi_debug_sector_size);
}
return ret;
}
@ -1849,7 +1870,12 @@ static int resp_read(struct scsi_cmnd *SCpnt, unsigned long long lba,
read_lock_irqsave(&atomic_rw, iflags);
ret = do_device_access(SCpnt, devip, lba, num, 0);
read_unlock_irqrestore(&atomic_rw, iflags);
return ret;
if (ret == -1)
return DID_ERROR << 16;
scsi_in(SCpnt)->resid = scsi_bufflen(SCpnt) - ret;
return 0;
}
void dump_sector(unsigned char *buf, int len)