[PATCH v6 1/4] libata: Safely overwrite attached page in WRITE SAME xlat

Shaun Tancheff
2016-08-22T04:23:18Z

Safely overwriting the attached page to ATA format from the SCSI formatted
variant.

Signed-off-by: Shaun Tancheff <shaun.tancheff@seagate.com>
---
v6:
- Fix bisect bug reported by Tom Yan <tom.ty89@gmail.com>
- Change to use sg_copy_from_buffer as per Christoph Hellwig <hch@lst.de>
v5:
- Added prep patch to work with non-page aligned scatterlist pages
and use kmap_atomic() to lock page during modification.

drivers/ata/libata-scsi.c | 56 ++++++++++++++++++++++++++++++++++++++++++-----
include/linux/ata.h | 26 ----------------------
2 files changed, 51 insertions(+), 31 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index e207b33..7990cb2 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3282,6 +3282,54 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
return 1;
}

+/**
+ * ata_format_dsm_trim_descr() - SATL Write Same to DSM Trim
+ * @cmd: SCSI command being translated
+ * @num: Maximum number of entries (nominally 64).
+ * @sector: Starting sector
+ * @count: Total Range of request
+ *
+ * Rewrite the WRITE SAME descriptor to be a DSM TRIM little-endian formatted
+ * descriptor.
+ *
+ * Upto 64 entries of the format:
+ * 63:48 Range Length
+ * 47:0 LBA
+ *
+ * Range Length of 0 is ignored.
+ * LBA's should be sorted order and not overlap.
+ *
+ * NOTE: this is the same format as ADD LBA(S) TO NV CACHE PINNED SET
+ */
+static unsigned int ata_format_dsm_trim_descr(struct scsi_cmnd *cmd, u32 num,
+ u64 sector, u32 count)
+{
+ __le64 *buffer;
+ u32 i = 0, used_bytes;
+ unsigned long flags;
+
+ BUILD_BUG_ON(512 > ATA_SCSI_RBUF_SIZE);
+
+ spin_lock_irqsave(&ata_scsi_rbuf_lock, flags);
+ buffer = ((void *)ata_scsi_rbuf);
+ while (i < num) {
+ u64 entry = sector |
+ ((u64)(count > 0xffff ? 0xffff : count) << 48);
+ buffer[i++] = __cpu_to_le64(entry);
+ if (count <= 0xffff)
+ break;
+ count -= 0xffff;
+ sector += 0xffff;
+ }
+
+ used_bytes = ALIGN(i * 8, 512);
+ memset(buffer + i, 0, used_bytes - i * 8);
+ sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd), buffer, 512);
+ spin_unlock_irqrestore(&ata_scsi_rbuf_lock, flags);
+
+ return used_bytes;
+}
+
static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
{
struct ata_taskfile *tf = &qc->tf;
@@ -3290,8 +3338,8 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
const u8 *cdb = scmd->cmnd;
u64 block;
u32 n_block;
+ const u32 trmax = ATA_MAX_TRIM_RNUM;
u32 size;
- void *buf;
u16 fp;
u8 bp = 0xff;

@@ -3319,10 +3367,8 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
if (!scsi_sg_count(scmd))
goto invalid_param_len;

- 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);
+ if (n_block <= 0xffff * trmax) {
+ size = ata_format_dsm_trim_descr(scmd, trmax, block, n_block);
} else {
fp = 2;
goto invalid_fld;
diff --git a/include/linux/ata.h b/include/linux/ata.h
index adbc812..45a1d71 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -1071,32 +1071,6 @@ static inline void ata_id_to_hd_driveid(u16 *id)
#endif
}

-/*
- * Write LBA Range Entries to the buffer that will cover the extent from
- * sector to sector + count. This is used for TRIM and for ADD LBA(S)
- * TO NV CACHE PINNED SET.
- */
-static inline unsigned ata_set_lba_range_entries(void *_buffer,
- unsigned num, 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);
- buffer[i++] = __cpu_to_le64(entry);
- if (count <= 0xffff)
- break;
- count -= 0xffff;
- sector += 0xffff;
- }
-
- used_bytes = ALIGN(i * 8, 512);
- memset(buffer + i, 0, used_bytes - i * 8);
- return used_bytes;
-}
-
static inline bool ata_ok(u8 status)
{
return ((status & (ATA_BUSY | ATA_DRDY | ATA_DF | ATA_DRQ | ATA_ERR))
--
2.9.3