From: Tom Yan <tom.ty89@xxxxxxxxx>
In commit 5c79097a28c2 ("libata-scsi: reject WRITE SAME (16) with
n_block that exceeds limit"), it is made sure that
ata_set_lba_range_entries() will never be called with a request
size (n_block) that is larger than the number of blocks that a
512-byte block TRIM payload can describe (65535 * 64 = 4194240),
in addition to acknowlegding the SCSI/block layer with the same
limit by advertising it as the Maximum Write Same Length.
Therefore, it is unnecessary to hard code the same limit in
ata_set_lba_range_entries() itself, which would only cost extra
maintenance effort. Such effort can be noticed in, for example,
commit 2983860c7668 ("libata-scsi: avoid repeated calculation of
number of TRIM ranges").
Signed-off-by: Tom Yan <tom.ty89@xxxxxxxxx>
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index be9c76c..9b74ecb 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3322,7 +3322,7 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
buf = page_address(sg_page(scsi_sglist(scmd)));
if (n_block <= 65535 * ATA_MAX_TRIM_RNUM) {
- size = ata_set_lba_range_entries(buf, ATA_MAX_TRIM_RNUM, block, n_block);
+ size = ata_set_lba_range_entries(buf, block, n_block);
} else {
fp = 2;
goto invalid_fld;
diff --git a/include/linux/ata.h b/include/linux/ata.h
index adbc812..5e2e9ad 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -1077,19 +1077,19 @@ static inline void ata_id_to_hd_driveid(u16 *id)
* TO NV CACHE PINNED SET.
*/
static inline unsigned ata_set_lba_range_entries(void *_buffer,
- unsigned num, u64 sector, unsigned long count)
+ u64 sector, unsigned long count)
{
__le64 *buffer = _buffer;
unsigned i = 0, used_bytes;
- while (i < num) {
- u64 entry = sector |
- ((u64)(count > 0xffff ? 0xffff : count) << 48);
+ while (count > 0) {
+ u64 range, entry;
+
+ range = count > 0xffff ? 0xffff : count;
+ entry = sector | (range << 48);
buffer[i++] = __cpu_to_le64(entry);
- if (count <= 0xffff)
- break;
- count -= 0xffff;
- sector += 0xffff;
+ count -= range;
+ sector += range;
}
used_bytes = ALIGN(i * 8, 512);
--
2.9.3
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