bsg: fix a blocking read bug
This patch fixes a bug that read() returns ENODATA even with a
blocking file descriptor when there are no commands pending.
This also includes some cleanups.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/bsg.c b/block/bsg.c
index a333c93..2f78d7d 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -115,9 +115,9 @@
wake_up(&bd->wq_free);
}
-static struct bsg_command *__bsg_alloc_command(struct bsg_device *bd)
+static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
{
- struct bsg_command *bc = NULL;
+ struct bsg_command *bc = ERR_PTR(-EINVAL);
spin_lock_irq(&bd->lock);
@@ -131,6 +131,7 @@
if (unlikely(!bc)) {
spin_lock_irq(&bd->lock);
bd->queued_cmds--;
+ bc = ERR_PTR(-ENOMEM);
goto out;
}
@@ -198,30 +199,6 @@
return ret;
}
-/*
- * get a new free command, blocking if needed and specified
- */
-static struct bsg_command *bsg_get_command(struct bsg_device *bd)
-{
- struct bsg_command *bc;
- int ret;
-
- do {
- bc = __bsg_alloc_command(bd);
- if (bc)
- break;
-
- ret = bsg_io_schedule(bd, TASK_INTERRUPTIBLE);
- if (ret) {
- bc = ERR_PTR(ret);
- break;
- }
-
- } while (1);
-
- return bc;
-}
-
static int blk_fill_sgv4_hdr_rq(request_queue_t *q, struct request *rq,
struct sg_io_v4 *hdr, int has_write_perm)
{
@@ -397,7 +374,7 @@
/*
* Get a finished command from the done list
*/
-static struct bsg_command *__bsg_get_done_cmd(struct bsg_device *bd, int state)
+static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
{
struct bsg_command *bc;
int ret;
@@ -407,9 +384,14 @@
if (bc)
break;
- ret = bsg_io_schedule(bd, state);
+ if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
+ bc = ERR_PTR(-EAGAIN);
+ break;
+ }
+
+ ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
if (ret) {
- bc = ERR_PTR(ret);
+ bc = ERR_PTR(-ERESTARTSYS);
break;
}
} while (1);
@@ -419,18 +401,6 @@
return bc;
}
-static struct bsg_command *
-bsg_get_done_cmd(struct bsg_device *bd, const struct iovec *iov)
-{
- return __bsg_get_done_cmd(bd, TASK_INTERRUPTIBLE);
-}
-
-static struct bsg_command *
-bsg_get_done_cmd_nosignals(struct bsg_device *bd)
-{
- return __bsg_get_done_cmd(bd, TASK_UNINTERRUPTIBLE);
-}
-
static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
struct bio *bio)
{
@@ -496,19 +466,16 @@
*/
ret = 0;
do {
- bc = bsg_get_done_cmd_nosignals(bd);
-
- /*
- * we _must_ complete before restarting, because
- * bsg_release can't handle this failing.
- */
- if (PTR_ERR(bc) == -ERESTARTSYS)
- continue;
- if (IS_ERR(bc)) {
- ret = PTR_ERR(bc);
+ spin_lock_irq(&bd->lock);
+ if (!bd->queued_cmds) {
+ spin_unlock_irq(&bd->lock);
break;
}
+ bc = bsg_get_done_cmd(bd);
+ if (IS_ERR(bc))
+ break;
+
tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio);
if (!ret)
ret = tret;
@@ -519,11 +486,9 @@
return ret;
}
-typedef struct bsg_command *(*bsg_command_callback)(struct bsg_device *bd, const struct iovec *iov);
-
static ssize_t
-__bsg_read(char __user *buf, size_t count, bsg_command_callback get_bc,
- struct bsg_device *bd, const struct iovec *iov, ssize_t *bytes_read)
+__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
+ const struct iovec *iov, ssize_t *bytes_read)
{
struct bsg_command *bc;
int nr_commands, ret;
@@ -534,7 +499,7 @@
ret = 0;
nr_commands = count / sizeof(struct sg_io_v4);
while (nr_commands) {
- bc = get_bc(bd, iov);
+ bc = bsg_get_done_cmd(bd);
if (IS_ERR(bc)) {
ret = PTR_ERR(bc);
break;
@@ -598,8 +563,7 @@
bsg_set_block(bd, file);
bytes_read = 0;
- ret = __bsg_read(buf, count, bsg_get_done_cmd,
- bd, NULL, &bytes_read);
+ ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
*ppos = bytes_read;
if (!bytes_read || (bytes_read && err_block_err(ret)))
@@ -625,9 +589,7 @@
while (nr_commands) {
request_queue_t *q = bd->queue;
- bc = bsg_get_command(bd);
- if (!bc)
- break;
+ bc = bsg_alloc_command(bd);
if (IS_ERR(bc)) {
ret = PTR_ERR(bc);
bc = NULL;