From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch fixes a double completion bug where ibr->pending = 2 usage
plus the extra callback to iblock_complete_cmd() invoked after bio
submission in iblock_execute_rw() can interfere with the normal
bio->bi_done() -> iblock_bio_done() -> iblock_complete_cmd() completion
path, causing a double target_complete_cmd() call to occur.
This bug was introduced during v3.4-rc2 code with:
commit 5787cacd0bd5ee016ad807b244550d34fe2beebe
Author: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Tue Apr 24 00:25:06 2012 -0400
target: remove struct se_task
Also drop the bio_cnt >= IBLOCK_MAX_BIO_PER_TASK rolling call to
iblock_submit_bios() to avoid the exception case where outstanding
bios completing via iblock_bio_done() are not accounted for when
returning returning non zero from iblock_execute_rw().
This bug was originally reported by Kelsey when a single se_cmd
descriptor required more than one bio to complete.
Reported-by: Kelsey Prantis <kelsey.prantis@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_iblock.c | 11 +----------
1 files changed, 1 insertions(+), 10 deletions(-)
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 57d7674..d066932 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -47,7 +47,6 @@
#include "target_core_iblock.h"
-#define IBLOCK_MAX_BIO_PER_TASK 32 /* max # of bios to submit at a time */
#define IBLOCK_BIO_POOL_SIZE 128
static struct se_subsystem_api iblock_template;
@@ -602,7 +601,6 @@ static int iblock_execute_rw(struct se_cmd *cmd)
struct scatterlist *sg;
u32 sg_num = sgl_nents;
sector_t block_lba;
- unsigned bio_cnt;
int rw;
int i;
@@ -658,8 +656,7 @@ static int iblock_execute_rw(struct se_cmd *cmd)
bio_list_init(&list);
bio_list_add(&list, bio);
- atomic_set(&ibr->pending, 2);
- bio_cnt = 1;
+ atomic_set(&ibr->pending, 1);
for_each_sg(sgl, sg, sgl_nents, i) {
/*
@@ -669,10 +666,6 @@ static int iblock_execute_rw(struct se_cmd *cmd)
*/
while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
!= sg->length) {
- if (bio_cnt >= IBLOCK_MAX_BIO_PER_TASK) {
- iblock_submit_bios(&list, rw);
- bio_cnt = 0;
- }
bio = iblock_get_bio(cmd, block_lba, sg_num);
if (!bio)
@@ -680,7 +673,6 @@ static int iblock_execute_rw(struct se_cmd *cmd)
atomic_inc(&ibr->pending);
bio_list_add(&list, bio);
- bio_cnt++;
}
/* Always in 512 byte units for Linux/Block */
@@ -689,7 +681,6 @@ static int iblock_execute_rw(struct se_cmd *cmd)
}
iblock_submit_bios(&list, rw);
- iblock_complete_cmd(cmd);
return 0;
fail_put_bios:
--
1.7.2.5
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