iSCSI initiators can issue read and write requests that target
overlapping areas. In such a case, current sheepdog driver cannot
serialize these requests so the semantics of virtual drive will be
corrupt. This patch implements a mechanism for serializing such
requests.
Cc: Teruaki Ishizaki <ishizaki.teruaki@xxxxxxxxxxxxx>
Cc: Takashi Menjo <menjo.takashi@xxxxxxxxxxxxx>
Tested-by: Takashi Menjo <menjo.takashi@xxxxxxxxxxxxx>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@xxxxxxxxxxxxx>
---
usr/bs_sheepdog.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 68 insertions(+)
diff --git a/usr/bs_sheepdog.c b/usr/bs_sheepdog.c
index 21d7dac..be6d321 100644
--- a/usr/bs_sheepdog.c
+++ b/usr/bs_sheepdog.c
@@ -294,6 +294,10 @@ struct sheepdog_access_info {
pthread_mutex_t inode_version_mutex;
uint64_t inode_version;
+
+ struct list_head inflight_list_head;
+ pthread_mutex_t inflight_list_mutex;
+ pthread_cond_t inflight_list_cond;
};
static inline int is_data_obj_writeable(struct sheepdog_inode *inode,
@@ -1252,6 +1256,11 @@ trans_to_expect_nothing:
goto out;
ret = 0;
+
+ INIT_LIST_HEAD(&ai->inflight_list_head);
+ pthread_mutex_init(&ai->inflight_list_mutex, NULL);
+ pthread_cond_init(&ai->inflight_list_cond, NULL);
+
out:
strcpy(filename, orig_filename);
free(orig_filename);
@@ -1349,6 +1358,41 @@ out:
return ret;
}
+struct inflight_thread {
+ unsigned long min_idx, max_idx;
+ struct list_head list;
+};
+
+static void inflight_block(struct sheepdog_access_info *ai,
+ struct inflight_thread *myself)
+{
+ struct inflight_thread *inflight;
+
+ pthread_mutex_lock(&ai->inflight_list_mutex);
+
+retry:
+ list_for_each_entry(inflight, &ai->inflight_list_head, list) {
+ if (!(myself->max_idx < inflight->min_idx ||
+ inflight->max_idx < myself->min_idx)) {
+ pthread_cond_wait(&ai->inflight_list_cond,
+ &ai->inflight_list_mutex);
+ goto retry;
+ }
+ }
+
+ list_add_tail(&myself->list, &ai->inflight_list_head);
+ pthread_mutex_unlock(&ai->inflight_list_mutex);
+}
+ void inflight_release(struct sheepdog_access_info *ai,
+ struct inflight_thread *myself)
+{
+ pthread_mutex_lock(&ai->inflight_list_mutex);
+ list_del(&myself->list);
+ pthread_mutex_unlock(&ai->inflight_list_mutex);
+
+ pthread_cond_signal(&ai->inflight_list_cond);
+}
+
static void bs_sheepdog_request(struct scsi_cmd *cmd)
{
int ret = 0;
@@ -1360,6 +1404,13 @@ static void bs_sheepdog_request(struct scsi_cmd *cmd)
struct sheepdog_access_info *ai =
(struct sheepdog_access_info *)(info + 1);
+ uint32_t object_size = (UINT32_C(1) << ai->inode.block_size_shift);
+ struct inflight_thread myself;
+ int inflight = 0;
+
+ memset(&myself, 0, sizeof(myself));
+ INIT_LIST_HEAD(&myself.list);
+
switch (cmd->scb[0]) {
case SYNCHRONIZE_CACHE:
case SYNCHRONIZE_CACHE_16:
@@ -1383,6 +1434,13 @@ static void bs_sheepdog_request(struct scsi_cmd *cmd)
}
length = scsi_get_out_length(cmd);
+
+ myself.min_idx = cmd->offset / object_size;
+ myself.max_idx = (cmd->offset + length + (object_size - 1))
+ / object_size;
+ inflight_block(ai, &myself);
+ inflight = 1;
+
ret = sd_io(ai, 1, scsi_get_out_buffer(cmd),
length, cmd->offset);
@@ -1394,6 +1452,13 @@ static void bs_sheepdog_request(struct scsi_cmd *cmd)
case READ_12:
case READ_16:
length = scsi_get_in_length(cmd);
+
+ myself.min_idx = cmd->offset / object_size;
+ myself.max_idx = (cmd->offset + length + (object_size - 1))
+ / object_size;
+ inflight_block(ai, &myself);
+ inflight = 1;
+
ret = sd_io(ai, 0, scsi_get_in_buffer(cmd),
length, cmd->offset);
if (ret)
@@ -1413,6 +1478,9 @@ static void bs_sheepdog_request(struct scsi_cmd *cmd)
cmd, cmd->scb[0], ret, length, cmd->offset);
sense_data_build(cmd, key, asc);
}
+
+ if (inflight)
+ inflight_release(ai, &myself);
}
static int bs_sheepdog_open(struct scsi_lu *lu, char *path,
--
2.7.4
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