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Blktrace: bail out early if block debugfs is not configured 

Since @blk_debugfs_root couldn't be configured dynamically, we can
save a few memory allocation if it's not there.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Liu Bo 2018-06-29 09:56:08 +08:00 committed by Jens Axboe
parent 1954e9a998
commit e1a413245a
1 changed files with 3 additions and 3 deletions
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6
kernel/trace/blktrace.c
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@ -494,6 +494,9 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
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';
@ -518,9 +521,6 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
ret = -ENOENT;
if (!blk_debugfs_root)
goto err;
dir = debugfs_lookup(buts->name, blk_debugfs_root);
if (!dir)
bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);