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blktrace: split do_blk_trace_setup into two functions

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Split do_blk_trace_setup into two functions, this is done to prepare for
an incoming new BLKTRACESETUP2 ioctl(2) which can receive extended
parameters from user-space.

Also move the size verification logic to the callers in preparation for
using a new internal structure later.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Johannes Thumshirn
2025-10-22 13:41:05 +02:00
committed by Jens Axboe
parent 370cd70a40
commit 42da88a724
1 changed files with 56 additions and 38 deletions
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94
kernel/trace/blktrace.c
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@@ -518,9 +518,10 @@ static void blk_trace_setup_lba(struct blk_trace *bt,
/*
* Setup everything required to start tracing
*/
static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
struct block_device *bdev,
struct blk_user_trace_setup *buts)
static struct blk_trace *blk_trace_setup_prepare(struct request_queue *q,
char *name, dev_t dev,
u32 buf_size, u32 buf_nr,
struct block_device *bdev)
{
struct blk_trace *bt = NULL;
struct dentry *dir = NULL;
@@ -528,31 +529,19 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
lockdep_assert_held(&q->debugfs_mutex);
if (!buts->buf_size || !buts->buf_nr)
return -EINVAL;
strscpy_pad(buts->name, name, BLKTRACE_BDEV_SIZE);
/*
* some device names have larger paths - convert the slashes
* to underscores for this to work as expected
*/
strreplace(buts->name, '/', '_');
/*
* bdev can be NULL, as with scsi-generic, this is a helpful as
* we can be.
*/
if (rcu_dereference_protected(q->blk_trace,
lockdep_is_held(&q->debugfs_mutex))) {
pr_warn("Concurrent blktraces are not allowed on %s\n",
buts->name);
return -EBUSY;
pr_warn("Concurrent blktraces are not allowed on %s\n", name);
return ERR_PTR(-EBUSY);
}
bt = kzalloc(sizeof(*bt), GFP_KERNEL);
if (!bt)
return -ENOMEM;
return ERR_PTR(-ENOMEM);
ret = -ENOMEM;
bt->sequence = alloc_percpu(unsigned long);
@@ -572,7 +561,7 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (bdev && !bdev_is_partition(bdev))
dir = q->debugfs_dir;
else
bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
bt->dir = dir = debugfs_create_dir(name, blk_debugfs_root);
/*
* As blktrace relies on debugfs for its interface the debugfs directory
@@ -580,8 +569,7 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
* files or directories.
*/
if (IS_ERR_OR_NULL(dir)) {
pr_warn("debugfs_dir not present for %s so skipping\n",
buts->name);
pr_warn("debugfs_dir not present for %s so skipping\n", name);
ret = -ENOENT;
goto err;
}
@@ -593,17 +581,38 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);
debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
bt->rchan = relay_open("trace", dir, buts->buf_size,
buts->buf_nr, &blk_relay_callbacks, bt);
bt->rchan = relay_open("trace", dir, buf_size, buf_nr,
&blk_relay_callbacks, bt);
if (!bt->rchan)
goto err;
blk_trace_setup_lba(bt, bdev);
return bt;
err:
blk_trace_free(q, bt);
return ERR_PTR(ret);
}
static void blk_trace_setup_finalize(struct request_queue *q,
char *name, struct blk_trace *bt,
struct blk_user_trace_setup *buts)
{
strscpy_pad(buts->name, name, BLKTRACE_BDEV_SIZE);
/*
* some device names have larger paths - convert the slashes
* to underscores for this to work as expected
*/
strreplace(buts->name, '/', '_');
bt->act_mask = buts->act_mask;
if (!bt->act_mask)
bt->act_mask = (u16) -1;
blk_trace_setup_lba(bt, bdev);
/* overwrite with user settings */
if (buts->start_lba)
bt->start_lba = buts->start_lba;
@@ -615,12 +624,6 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
rcu_assign_pointer(q->blk_trace, bt);
get_probe_ref();
ret = 0;
err:
if (ret)
blk_trace_free(q, bt);
return ret;
}
int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
@@ -628,17 +631,25 @@ int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
char __user *arg)
{
struct blk_user_trace_setup buts;
struct blk_trace *bt;
int ret;
ret = copy_from_user(&buts, arg, sizeof(buts));
if (ret)
return -EFAULT;
if (!buts.buf_size || !buts.buf_nr)
return -EINVAL;
mutex_lock(&q->debugfs_mutex);
ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
bt = blk_trace_setup_prepare(q, name, dev, buts.buf_size, buts.buf_nr,
bdev);
if (IS_ERR(bt)) {
mutex_unlock(&q->debugfs_mutex);
return PTR_ERR(bt);
}
blk_trace_setup_finalize(q, name, bt, &buts);
mutex_unlock(&q->debugfs_mutex);
if (ret)
return ret;
if (copy_to_user(arg, &buts, sizeof(buts))) {
blk_trace_remove(q);
@@ -655,11 +666,14 @@ static int compat_blk_trace_setup(struct request_queue *q, char *name,
{
struct blk_user_trace_setup buts;
struct compat_blk_user_trace_setup cbuts;
int ret;
struct blk_trace *bt;
if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
return -EFAULT;
if (!cbuts.buf_size || !cbuts.buf_nr)
return -EINVAL;
buts = (struct blk_user_trace_setup) {
.act_mask = cbuts.act_mask,
.buf_size = cbuts.buf_size,
@@ -670,10 +684,14 @@ static int compat_blk_trace_setup(struct request_queue *q, char *name,
};
mutex_lock(&q->debugfs_mutex);
ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
bt = blk_trace_setup_prepare(q, name, dev, buts.buf_size, buts.buf_nr,
bdev);
if (IS_ERR(bt)) {
mutex_unlock(&q->debugfs_mutex);
return PTR_ERR(bt);
}
blk_trace_setup_finalize(q, name, bt, &buts);
mutex_unlock(&q->debugfs_mutex);
if (ret)
return ret;
if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
blk_trace_remove(q);