libata-scsi: avoid repeated calculation of number of TRIM ranges

Currently libata statically allows only 1-block (512-byte) payload
for each TRIM command. Each payload can carry 64 TRIM ranges since
each range requires 8 bytes.

It is silly to keep doing the calculation (512 / 8) in different
places. Hence, define the new ATA_MAX_TRIM_RNUM for the result.

Signed-off-by: Tom Yan <tom.ty89@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index b0ca322..3dca0d1 100644 (file)
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2319,7 +2319,7 @@ static unsigned int ata_scsiop_inq_b0(struct ata_scsi_args *args, u8 *rbuf)
         * with the unmap bit set.
         */
        if (ata_id_has_trim(args->id)) {
-               put_unaligned_be64(65535 * 512 / 8, &rbuf[36]);
+               put_unaligned_be64(65535 * ATA_MAX_TRIM_RNUM, &rbuf[36]);
                put_unaligned_be32(1, &rbuf[28]);
        }
 
@@ -3311,8 +3311,8 @@ 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 * 512 / 8) {
-               size = ata_set_lba_range_entries(buf, 512, block, n_block);
+       if (n_block <= 65535 * ATA_MAX_TRIM_RNUM) {
+               size = ata_set_lba_range_entries(buf, ATA_MAX_TRIM_RNUM, block, n_block);
        } else {
                fp = 2;
                goto invalid_fld;

diff --git a/include/linux/ata.h b/include/linux/ata.h
index 2d68793..d20b1ee 100644 (file)
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -48,6 +48,7 @@ enum {
        ATA_MAX_SECTORS_1024    = 1024,
        ATA_MAX_SECTORS_LBA48   = 65535,/* TODO: 65536? */
        ATA_MAX_SECTORS_TAPE    = 65535,
+       ATA_MAX_TRIM_RNUM       = 64,   /* 512-byte payload / (6-byte LBA + 2-byte range per entry) */
 
        ATA_ID_WORDS            = 256,
        ATA_ID_CONFIG           = 0,
@@ -1069,12 +1070,12 @@ 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 buf_size, u64 sector, unsigned long count)
+               unsigned num, u64 sector, unsigned long count)
 {
        __le64 *buffer = _buffer;
        unsigned i = 0, used_bytes;
 
-       while (i < buf_size / 8 ) { /* 6-byte LBA + 2-byte range per entry */
+       while (i < num) {
                u64 entry = sector |
                        ((u64)(count > 0xffff ? 0xffff : count) << 48);
                buffer[i++] = __cpu_to_le64(entry);