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dm: add WRITE SAME support

WRITE SAME bios have a payload that contain a single page. When cloning WRITE SAME bios DM has no need to modify the bi_io_vec attributes (and doing so would be detrimental). DM need only alter the start and end of the WRITE SAME bio accordingly. Rather than duplicate __clone_and_map_discard, factor out a common function that is also used by __clone_and_map_write_same.

Mike Snitzer committed 13 years ago

Commit 23508a91 parent d54eaa51 file · +39 −5Browse files

Unified · Split

drivers/md/dm.c+39−5
@@ -1174,7 +1174,28 @@ static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti) · 1173 unmodified lines
1174 ci->sector_count = 0;1174 ci->sector_count = 0;
1175}1175}
1176 1176
1177static int __clone_and_map_discard(struct clone_info *ci)1177typedef unsigned (*get_num_requests_fn)(struct dm_target *ti);
1178
1179static unsigned get_num_discard_requests(struct dm_target *ti)
1180{
1181 return ti->num_discard_requests;
1182}
1183
1184static unsigned get_num_write_same_requests(struct dm_target *ti)
1185{
1186 return ti->num_write_same_requests;
1187}
1188
1189typedef bool (*is_split_required_fn)(struct dm_target *ti);
1190
1191static bool is_split_required_for_discard(struct dm_target *ti)
1192{
1193 return ti->split_discard_requests;
1194}
1195
1196static int __clone_and_map_changing_extent_only(struct clone_info *ci,
1197 get_num_requests_fn get_num_requests,
1198 is_split_required_fn is_split_required)
1178{1199{
1179 struct dm_target *ti;1200 struct dm_target *ti;
1180 sector_t len;1201 sector_t len;
@@ -1185,15 +1206,15 @@ static int __clone_and_map_discard(struct clone_info *ci) · 4 unmodified lines
1185 return -EIO;1206 return -EIO;
1186 1207
1187 /*1208 /*
1188 * Even though the device advertised discard support,1209 * Even though the device advertised support for this type of
1189 * that does not mean every target supports it, and1210 * request, that does not mean every target supports it, and
1190 * reconfiguration might also have changed that since the1211 * reconfiguration might also have changed that since the
1191 * check was performed.1212 * check was performed.
1192 */1213 */
1193 if (!ti->num_discard_requests)1214 if (!get_num_requests || !get_num_requests(ti))
1194 return -EOPNOTSUPP;1215 return -EOPNOTSUPP;
1195 1216
1196 if (!ti->split_discard_requests)1217 if (is_split_required && !is_split_required(ti))
1197 len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));1218 len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
1198 else1219 else
1199 len = min(ci->sector_count, max_io_len(ci->sector, ti));1220 len = min(ci->sector_count, max_io_len(ci->sector, ti));
@@ -1206,6 +1227,17 @@ static int __clone_and_map_discard(struct clone_info *ci) · 6 unmodified lines
1206 return 0;1227 return 0;
1207}1228}
1208 1229
1230static int __clone_and_map_discard(struct clone_info *ci)
1231{
1232 return __clone_and_map_changing_extent_only(ci, get_num_discard_requests,
1233 is_split_required_for_discard);
1234}
1235
1236static int __clone_and_map_write_same(struct clone_info *ci)
1237{
1238 return __clone_and_map_changing_extent_only(ci, get_num_write_same_requests, NULL);
1239}
1240
1209static int __clone_and_map(struct clone_info *ci)1241static int __clone_and_map(struct clone_info *ci)
1210{1242{
1211 struct bio *bio = ci->bio;1243 struct bio *bio = ci->bio;
@@ -1215,6 +1247,8 @@ static int __clone_and_map(struct clone_info *ci) · 3 unmodified lines
1215 1247
1216 if (unlikely(bio->bi_rw & REQ_DISCARD))1248 if (unlikely(bio->bi_rw & REQ_DISCARD))
1217 return __clone_and_map_discard(ci);1249 return __clone_and_map_discard(ci);
1250 else if (unlikely(bio->bi_rw & REQ_WRITE_SAME))
1251 return __clone_and_map_write_same(ci);
1218 1252
1219 ti = dm_table_find_target(ci->map, ci->sector);1253 ti = dm_table_find_target(ci->map, ci->sector);
1220 if (!dm_target_is_valid(ti))1254 if (!dm_target_is_valid(ti))