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block: create the request_queue debugfs_dir on registration

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We were only creating the request_queue debugfs_dir only
for make_request block drivers (multiqueue), but never for
request-based block drivers. We did this as we were only
creating non-blktrace additional debugfs files on that directory
for make_request drivers. However, since blktrace *always* creates
that directory anyway, we special-case the use of that directory
on blktrace. Other than this being an eye-sore, this exposes
request-based block drivers to the same debugfs fragile
race that used to exist with make_request block drivers
where if we start adding files onto that directory we can later
run a race with a double removal of dentries on the directory
if we don't deal with this carefully on blktrace.

Instead, just simplify things by always creating the request_queue
debugfs_dir on request_queue registration. Rename the mutex also to
reflect the fact that this is used outside of the blktrace context.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Luis Chamberlain
2020-06-19 20:47:30 +00:00
committed by Jens Axboe
parent b431ef837e
commit 85e0cbbb8a
6 changed files with 39 additions and 48 deletions
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58
kernel/trace/blktrace.c
View File

@@ -348,7 +348,7 @@ static int __blk_trace_remove(struct request_queue *q)
struct blk_trace *bt;
bt = rcu_replace_pointer(q->blk_trace, NULL,
lockdep_is_held(&q->blk_trace_mutex));
lockdep_is_held(&q->debugfs_mutex));
if (!bt)
return -EINVAL;
@@ -362,9 +362,9 @@ int blk_trace_remove(struct request_queue *q)
{
int ret;
mutex_lock(&q->blk_trace_mutex);
mutex_lock(&q->debugfs_mutex);
ret = __blk_trace_remove(q);
mutex_unlock(&q->blk_trace_mutex);
mutex_unlock(&q->debugfs_mutex);
return ret;
}
@@ -483,14 +483,11 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
struct dentry *dir = NULL;
int ret;
lockdep_assert_held(&q->blk_trace_mutex);
lockdep_assert_held(&q->debugfs_mutex);
if (!buts->buf_size || !buts->buf_nr)
return -EINVAL;
if (!blk_debugfs_root)
return -ENOENT;
strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
@@ -505,7 +502,7 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
* we can be.
*/
if (rcu_dereference_protected(q->blk_trace,
lockdep_is_held(&q->blk_trace_mutex))) {
lockdep_is_held(&q->debugfs_mutex))) {
pr_warn("Concurrent blktraces are not allowed on %s\n",
buts->name);
return -EBUSY;
@@ -524,18 +521,15 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (!bt->msg_data)
goto err;
#ifdef CONFIG_BLK_DEBUG_FS
/*
* When tracing whole make_request drivers (multiqueue) block devices,
* reuse the existing debugfs directory created by the block layer on
* init. For request-based block devices, all partitions block devices,
* When tracing the whole disk reuse the existing debugfs directory
* created by the block layer on init. For partitions block devices,
* and scsi-generic block devices we create a temporary new debugfs
* directory that will be removed once the trace ends.
*/
if (queue_is_mq(q) && bdev && bdev == bdev->bd_contains)
if (bdev && bdev == bdev->bd_contains)
dir = q->debugfs_dir;
else
#endif
bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
/*
@@ -617,9 +611,9 @@ int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
{
int ret;
mutex_lock(&q->blk_trace_mutex);
mutex_lock(&q->debugfs_mutex);
ret = __blk_trace_setup(q, name, dev, bdev, arg);
mutex_unlock(&q->blk_trace_mutex);
mutex_unlock(&q->debugfs_mutex);
return ret;
}
@@ -665,7 +659,7 @@ static int __blk_trace_startstop(struct request_queue *q, int start)
struct blk_trace *bt;
bt = rcu_dereference_protected(q->blk_trace,
lockdep_is_held(&q->blk_trace_mutex));
lockdep_is_held(&q->debugfs_mutex));
if (bt == NULL)
return -EINVAL;
@@ -705,9 +699,9 @@ int blk_trace_startstop(struct request_queue *q, int start)
{
int ret;
mutex_lock(&q->blk_trace_mutex);
mutex_lock(&q->debugfs_mutex);
ret = __blk_trace_startstop(q, start);
mutex_unlock(&q->blk_trace_mutex);
mutex_unlock(&q->debugfs_mutex);
return ret;
}
@@ -736,7 +730,7 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
if (!q)
return -ENXIO;
mutex_lock(&q->blk_trace_mutex);
mutex_lock(&q->debugfs_mutex);
switch (cmd) {
case BLKTRACESETUP:
@@ -763,7 +757,7 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
break;
}
mutex_unlock(&q->blk_trace_mutex);
mutex_unlock(&q->debugfs_mutex);
return ret;
}
@@ -774,14 +768,14 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
**/
void blk_trace_shutdown(struct request_queue *q)
{
mutex_lock(&q->blk_trace_mutex);
mutex_lock(&q->debugfs_mutex);
if (rcu_dereference_protected(q->blk_trace,
lockdep_is_held(&q->blk_trace_mutex))) {
lockdep_is_held(&q->debugfs_mutex))) {
__blk_trace_startstop(q, 0);
__blk_trace_remove(q);
}
mutex_unlock(&q->blk_trace_mutex);
mutex_unlock(&q->debugfs_mutex);
}
#ifdef CONFIG_BLK_CGROUP
@@ -1662,7 +1656,7 @@ static int blk_trace_remove_queue(struct request_queue *q)
struct blk_trace *bt;
bt = rcu_replace_pointer(q->blk_trace, NULL,
lockdep_is_held(&q->blk_trace_mutex));
lockdep_is_held(&q->debugfs_mutex));
if (bt == NULL)
return -EINVAL;
@@ -1837,10 +1831,10 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
if (q == NULL)
goto out_bdput;
mutex_lock(&q->blk_trace_mutex);
mutex_lock(&q->debugfs_mutex);
bt = rcu_dereference_protected(q->blk_trace,
lockdep_is_held(&q->blk_trace_mutex));
lockdep_is_held(&q->debugfs_mutex));
if (attr == &dev_attr_enable) {
ret = sprintf(buf, "%u\n", !!bt);
goto out_unlock_bdev;
@@ -1858,7 +1852,7 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
ret = sprintf(buf, "%llu\n", bt->end_lba);
out_unlock_bdev:
mutex_unlock(&q->blk_trace_mutex);
mutex_unlock(&q->debugfs_mutex);
out_bdput:
bdput(bdev);
out:
@@ -1901,10 +1895,10 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
if (q == NULL)
goto out_bdput;
mutex_lock(&q->blk_trace_mutex);
mutex_lock(&q->debugfs_mutex);
bt = rcu_dereference_protected(q->blk_trace,
lockdep_is_held(&q->blk_trace_mutex));
lockdep_is_held(&q->debugfs_mutex));
if (attr == &dev_attr_enable) {
if (!!value == !!bt) {
ret = 0;
@@ -1921,7 +1915,7 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
if (bt == NULL) {
ret = blk_trace_setup_queue(q, bdev);
bt = rcu_dereference_protected(q->blk_trace,
lockdep_is_held(&q->blk_trace_mutex));
lockdep_is_held(&q->debugfs_mutex));
}
if (ret == 0) {
@@ -1936,7 +1930,7 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
}
out_unlock_bdev:
mutex_unlock(&q->blk_trace_mutex);
mutex_unlock(&q->debugfs_mutex);
out_bdput:
bdput(bdev);
out: