![Tejun Heo](/assets/img/avatar_default.png)
bdi's are initialized in two steps, bdi_init() and bdi_register(), but destroyed in a single step by bdi_destroy() which, for a bdi embedded in a request_queue, is called during blk_cleanup_queue() which makes the queue invisible and starts the draining of remaining usages. A request_queue's user can access the congestion state of the embedded bdi as long as it holds a reference to the queue. As such, it may access the congested state of a queue which finished blk_cleanup_queue() but hasn't reached blk_release_queue() yet. Because the congested state was embedded in backing_dev_info which in turn is embedded in request_queue, accessing the congested state after bdi_destroy() was called was fine. The bdi was destroyed but the memory region for the congested state remained accessible till the queue got released.a13f35e871
("writeback: don't embed root bdi_writeback_congested in bdi_writeback") changed the situation. Now, the root congested state which is expected to be pinned while request_queue remains accessible is separately reference counted and the base ref is put during bdi_destroy(). This means that the root congested state may go away prematurely while the queue is between bdi_dstroy() and blk_cleanup_queue(), which was detected by Andrey's KASAN tests. The root cause of this problem is that bdi doesn't distinguish the two steps of destruction, unregistration and release, and now the root congested state actually requires a separate release step. To fix the issue, this patch separates out bdi_unregister() and bdi_exit() from bdi_destroy(). bdi_unregister() is called from blk_cleanup_queue() and bdi_exit() from blk_release_queue(). bdi_destroy() is now just a simple wrapper calling the two steps back-to-back. While at it, the prototype of bdi_destroy() is moved right below bdi_setup_and_register() so that the counterpart operations are located together. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes:a13f35e871
("writeback: don't embed root bdi_writeback_congested in bdi_writeback") Cc: stable@vger.kernel.org # v4.2+ Reported-and-tested-by: Andrey Konovalov <andreyknvl@google.com> Link: http://lkml.kernel.org/g/CAAeHK+zUJ74Zn17=rOyxacHU18SgCfC6bsYW=6kCY5GXJBwGfQ@mail.gmail.com Reviewed-by: Jan Kara <jack@suse.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
656 lines
17 KiB
C
656 lines
17 KiB
C
/*
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* Functions related to sysfs handling
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/backing-dev.h>
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#include <linux/blktrace_api.h>
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#include <linux/blk-mq.h>
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#include <linux/blk-cgroup.h>
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#include "blk.h"
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#include "blk-mq.h"
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struct queue_sysfs_entry {
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struct attribute attr;
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ssize_t (*show)(struct request_queue *, char *);
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ssize_t (*store)(struct request_queue *, const char *, size_t);
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};
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static ssize_t
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queue_var_show(unsigned long var, char *page)
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{
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return sprintf(page, "%lu\n", var);
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}
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static ssize_t
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queue_var_store(unsigned long *var, const char *page, size_t count)
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{
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int err;
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unsigned long v;
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err = kstrtoul(page, 10, &v);
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if (err || v > UINT_MAX)
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return -EINVAL;
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*var = v;
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return count;
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}
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static ssize_t queue_requests_show(struct request_queue *q, char *page)
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{
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return queue_var_show(q->nr_requests, (page));
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}
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static ssize_t
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queue_requests_store(struct request_queue *q, const char *page, size_t count)
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{
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unsigned long nr;
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int ret, err;
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if (!q->request_fn && !q->mq_ops)
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return -EINVAL;
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ret = queue_var_store(&nr, page, count);
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if (ret < 0)
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return ret;
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if (nr < BLKDEV_MIN_RQ)
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nr = BLKDEV_MIN_RQ;
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if (q->request_fn)
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err = blk_update_nr_requests(q, nr);
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else
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err = blk_mq_update_nr_requests(q, nr);
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if (err)
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return err;
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return ret;
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}
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static ssize_t queue_ra_show(struct request_queue *q, char *page)
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{
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unsigned long ra_kb = q->backing_dev_info.ra_pages <<
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(PAGE_CACHE_SHIFT - 10);
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return queue_var_show(ra_kb, (page));
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}
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static ssize_t
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queue_ra_store(struct request_queue *q, const char *page, size_t count)
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{
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unsigned long ra_kb;
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ssize_t ret = queue_var_store(&ra_kb, page, count);
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if (ret < 0)
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return ret;
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q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
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return ret;
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}
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static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
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{
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int max_sectors_kb = queue_max_sectors(q) >> 1;
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return queue_var_show(max_sectors_kb, (page));
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}
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static ssize_t queue_max_segments_show(struct request_queue *q, char *page)
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{
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return queue_var_show(queue_max_segments(q), (page));
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}
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static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *page)
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{
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return queue_var_show(q->limits.max_integrity_segments, (page));
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}
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static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
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{
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if (blk_queue_cluster(q))
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return queue_var_show(queue_max_segment_size(q), (page));
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return queue_var_show(PAGE_CACHE_SIZE, (page));
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}
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static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)
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{
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return queue_var_show(queue_logical_block_size(q), page);
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}
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static ssize_t queue_physical_block_size_show(struct request_queue *q, char *page)
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{
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return queue_var_show(queue_physical_block_size(q), page);
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}
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static ssize_t queue_io_min_show(struct request_queue *q, char *page)
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{
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return queue_var_show(queue_io_min(q), page);
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}
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static ssize_t queue_io_opt_show(struct request_queue *q, char *page)
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{
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return queue_var_show(queue_io_opt(q), page);
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}
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static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
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{
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return queue_var_show(q->limits.discard_granularity, page);
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}
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static ssize_t queue_discard_max_hw_show(struct request_queue *q, char *page)
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{
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unsigned long long val;
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val = q->limits.max_hw_discard_sectors << 9;
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return sprintf(page, "%llu\n", val);
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}
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static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
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{
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return sprintf(page, "%llu\n",
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(unsigned long long)q->limits.max_discard_sectors << 9);
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}
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static ssize_t queue_discard_max_store(struct request_queue *q,
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const char *page, size_t count)
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{
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unsigned long max_discard;
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ssize_t ret = queue_var_store(&max_discard, page, count);
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if (ret < 0)
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return ret;
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if (max_discard & (q->limits.discard_granularity - 1))
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return -EINVAL;
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max_discard >>= 9;
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if (max_discard > UINT_MAX)
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return -EINVAL;
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if (max_discard > q->limits.max_hw_discard_sectors)
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max_discard = q->limits.max_hw_discard_sectors;
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q->limits.max_discard_sectors = max_discard;
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return ret;
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}
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static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
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{
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return queue_var_show(queue_discard_zeroes_data(q), page);
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}
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static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
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{
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return sprintf(page, "%llu\n",
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(unsigned long long)q->limits.max_write_same_sectors << 9);
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}
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static ssize_t
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queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
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{
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unsigned long max_sectors_kb,
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max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1,
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page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
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ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
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if (ret < 0)
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return ret;
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if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
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return -EINVAL;
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spin_lock_irq(q->queue_lock);
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q->limits.max_sectors = max_sectors_kb << 1;
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spin_unlock_irq(q->queue_lock);
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return ret;
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}
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static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
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{
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int max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1;
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return queue_var_show(max_hw_sectors_kb, (page));
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}
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#define QUEUE_SYSFS_BIT_FNS(name, flag, neg) \
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static ssize_t \
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queue_show_##name(struct request_queue *q, char *page) \
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{ \
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int bit; \
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bit = test_bit(QUEUE_FLAG_##flag, &q->queue_flags); \
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return queue_var_show(neg ? !bit : bit, page); \
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} \
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static ssize_t \
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queue_store_##name(struct request_queue *q, const char *page, size_t count) \
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{ \
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unsigned long val; \
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ssize_t ret; \
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ret = queue_var_store(&val, page, count); \
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if (ret < 0) \
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return ret; \
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if (neg) \
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val = !val; \
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\
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spin_lock_irq(q->queue_lock); \
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if (val) \
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queue_flag_set(QUEUE_FLAG_##flag, q); \
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else \
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queue_flag_clear(QUEUE_FLAG_##flag, q); \
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spin_unlock_irq(q->queue_lock); \
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return ret; \
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}
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QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1);
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QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
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QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
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#undef QUEUE_SYSFS_BIT_FNS
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static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
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{
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return queue_var_show((blk_queue_nomerges(q) << 1) |
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blk_queue_noxmerges(q), page);
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}
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static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
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size_t count)
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{
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unsigned long nm;
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ssize_t ret = queue_var_store(&nm, page, count);
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if (ret < 0)
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return ret;
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spin_lock_irq(q->queue_lock);
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queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
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queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
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if (nm == 2)
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queue_flag_set(QUEUE_FLAG_NOMERGES, q);
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else if (nm)
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queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
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spin_unlock_irq(q->queue_lock);
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return ret;
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}
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static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
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{
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bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
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bool force = test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags);
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return queue_var_show(set << force, page);
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}
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static ssize_t
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queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
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{
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ssize_t ret = -EINVAL;
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#ifdef CONFIG_SMP
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unsigned long val;
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ret = queue_var_store(&val, page, count);
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if (ret < 0)
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return ret;
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spin_lock_irq(q->queue_lock);
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if (val == 2) {
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queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
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queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
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} else if (val == 1) {
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queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
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queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
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} else if (val == 0) {
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queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
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queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
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}
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spin_unlock_irq(q->queue_lock);
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#endif
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return ret;
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}
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static struct queue_sysfs_entry queue_requests_entry = {
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.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
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.show = queue_requests_show,
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.store = queue_requests_store,
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};
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static struct queue_sysfs_entry queue_ra_entry = {
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.attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
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.show = queue_ra_show,
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.store = queue_ra_store,
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};
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static struct queue_sysfs_entry queue_max_sectors_entry = {
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.attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
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.show = queue_max_sectors_show,
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.store = queue_max_sectors_store,
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};
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static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
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.attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
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.show = queue_max_hw_sectors_show,
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};
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static struct queue_sysfs_entry queue_max_segments_entry = {
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.attr = {.name = "max_segments", .mode = S_IRUGO },
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.show = queue_max_segments_show,
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};
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static struct queue_sysfs_entry queue_max_integrity_segments_entry = {
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.attr = {.name = "max_integrity_segments", .mode = S_IRUGO },
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.show = queue_max_integrity_segments_show,
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};
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static struct queue_sysfs_entry queue_max_segment_size_entry = {
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.attr = {.name = "max_segment_size", .mode = S_IRUGO },
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.show = queue_max_segment_size_show,
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};
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static struct queue_sysfs_entry queue_iosched_entry = {
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.attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
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.show = elv_iosched_show,
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.store = elv_iosched_store,
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};
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static struct queue_sysfs_entry queue_hw_sector_size_entry = {
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.attr = {.name = "hw_sector_size", .mode = S_IRUGO },
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.show = queue_logical_block_size_show,
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};
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static struct queue_sysfs_entry queue_logical_block_size_entry = {
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.attr = {.name = "logical_block_size", .mode = S_IRUGO },
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.show = queue_logical_block_size_show,
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};
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static struct queue_sysfs_entry queue_physical_block_size_entry = {
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.attr = {.name = "physical_block_size", .mode = S_IRUGO },
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.show = queue_physical_block_size_show,
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};
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static struct queue_sysfs_entry queue_io_min_entry = {
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.attr = {.name = "minimum_io_size", .mode = S_IRUGO },
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.show = queue_io_min_show,
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};
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static struct queue_sysfs_entry queue_io_opt_entry = {
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.attr = {.name = "optimal_io_size", .mode = S_IRUGO },
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.show = queue_io_opt_show,
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};
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static struct queue_sysfs_entry queue_discard_granularity_entry = {
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.attr = {.name = "discard_granularity", .mode = S_IRUGO },
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.show = queue_discard_granularity_show,
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};
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static struct queue_sysfs_entry queue_discard_max_hw_entry = {
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.attr = {.name = "discard_max_hw_bytes", .mode = S_IRUGO },
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.show = queue_discard_max_hw_show,
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};
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static struct queue_sysfs_entry queue_discard_max_entry = {
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.attr = {.name = "discard_max_bytes", .mode = S_IRUGO | S_IWUSR },
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.show = queue_discard_max_show,
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.store = queue_discard_max_store,
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};
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static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
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.attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
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.show = queue_discard_zeroes_data_show,
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};
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static struct queue_sysfs_entry queue_write_same_max_entry = {
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.attr = {.name = "write_same_max_bytes", .mode = S_IRUGO },
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.show = queue_write_same_max_show,
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};
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static struct queue_sysfs_entry queue_nonrot_entry = {
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.attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
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.show = queue_show_nonrot,
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.store = queue_store_nonrot,
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};
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static struct queue_sysfs_entry queue_nomerges_entry = {
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.attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
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.show = queue_nomerges_show,
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.store = queue_nomerges_store,
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};
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static struct queue_sysfs_entry queue_rq_affinity_entry = {
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.attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
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.show = queue_rq_affinity_show,
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.store = queue_rq_affinity_store,
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};
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static struct queue_sysfs_entry queue_iostats_entry = {
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.attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
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.show = queue_show_iostats,
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.store = queue_store_iostats,
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};
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static struct queue_sysfs_entry queue_random_entry = {
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.attr = {.name = "add_random", .mode = S_IRUGO | S_IWUSR },
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.show = queue_show_random,
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.store = queue_store_random,
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};
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static struct attribute *default_attrs[] = {
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&queue_requests_entry.attr,
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&queue_ra_entry.attr,
|
|
&queue_max_hw_sectors_entry.attr,
|
|
&queue_max_sectors_entry.attr,
|
|
&queue_max_segments_entry.attr,
|
|
&queue_max_integrity_segments_entry.attr,
|
|
&queue_max_segment_size_entry.attr,
|
|
&queue_iosched_entry.attr,
|
|
&queue_hw_sector_size_entry.attr,
|
|
&queue_logical_block_size_entry.attr,
|
|
&queue_physical_block_size_entry.attr,
|
|
&queue_io_min_entry.attr,
|
|
&queue_io_opt_entry.attr,
|
|
&queue_discard_granularity_entry.attr,
|
|
&queue_discard_max_entry.attr,
|
|
&queue_discard_max_hw_entry.attr,
|
|
&queue_discard_zeroes_data_entry.attr,
|
|
&queue_write_same_max_entry.attr,
|
|
&queue_nonrot_entry.attr,
|
|
&queue_nomerges_entry.attr,
|
|
&queue_rq_affinity_entry.attr,
|
|
&queue_iostats_entry.attr,
|
|
&queue_random_entry.attr,
|
|
NULL,
|
|
};
|
|
|
|
#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
|
|
|
|
static ssize_t
|
|
queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
|
|
{
|
|
struct queue_sysfs_entry *entry = to_queue(attr);
|
|
struct request_queue *q =
|
|
container_of(kobj, struct request_queue, kobj);
|
|
ssize_t res;
|
|
|
|
if (!entry->show)
|
|
return -EIO;
|
|
mutex_lock(&q->sysfs_lock);
|
|
if (blk_queue_dying(q)) {
|
|
mutex_unlock(&q->sysfs_lock);
|
|
return -ENOENT;
|
|
}
|
|
res = entry->show(q, page);
|
|
mutex_unlock(&q->sysfs_lock);
|
|
return res;
|
|
}
|
|
|
|
static ssize_t
|
|
queue_attr_store(struct kobject *kobj, struct attribute *attr,
|
|
const char *page, size_t length)
|
|
{
|
|
struct queue_sysfs_entry *entry = to_queue(attr);
|
|
struct request_queue *q;
|
|
ssize_t res;
|
|
|
|
if (!entry->store)
|
|
return -EIO;
|
|
|
|
q = container_of(kobj, struct request_queue, kobj);
|
|
mutex_lock(&q->sysfs_lock);
|
|
if (blk_queue_dying(q)) {
|
|
mutex_unlock(&q->sysfs_lock);
|
|
return -ENOENT;
|
|
}
|
|
res = entry->store(q, page, length);
|
|
mutex_unlock(&q->sysfs_lock);
|
|
return res;
|
|
}
|
|
|
|
static void blk_free_queue_rcu(struct rcu_head *rcu_head)
|
|
{
|
|
struct request_queue *q = container_of(rcu_head, struct request_queue,
|
|
rcu_head);
|
|
kmem_cache_free(blk_requestq_cachep, q);
|
|
}
|
|
|
|
/**
|
|
* blk_release_queue: - release a &struct request_queue when it is no longer needed
|
|
* @kobj: the kobj belonging to the request queue to be released
|
|
*
|
|
* Description:
|
|
* blk_release_queue is the pair to blk_init_queue() or
|
|
* blk_queue_make_request(). It should be called when a request queue is
|
|
* being released; typically when a block device is being de-registered.
|
|
* Currently, its primary task it to free all the &struct request
|
|
* structures that were allocated to the queue and the queue itself.
|
|
*
|
|
* Note:
|
|
* The low level driver must have finished any outstanding requests first
|
|
* via blk_cleanup_queue().
|
|
**/
|
|
static void blk_release_queue(struct kobject *kobj)
|
|
{
|
|
struct request_queue *q =
|
|
container_of(kobj, struct request_queue, kobj);
|
|
|
|
bdi_exit(&q->backing_dev_info);
|
|
blkcg_exit_queue(q);
|
|
|
|
if (q->elevator) {
|
|
spin_lock_irq(q->queue_lock);
|
|
ioc_clear_queue(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
elevator_exit(q->elevator);
|
|
}
|
|
|
|
blk_exit_rl(&q->root_rl);
|
|
|
|
if (q->queue_tags)
|
|
__blk_queue_free_tags(q);
|
|
|
|
if (!q->mq_ops)
|
|
blk_free_flush_queue(q->fq);
|
|
else
|
|
blk_mq_release(q);
|
|
|
|
blk_trace_shutdown(q);
|
|
|
|
if (q->bio_split)
|
|
bioset_free(q->bio_split);
|
|
|
|
ida_simple_remove(&blk_queue_ida, q->id);
|
|
call_rcu(&q->rcu_head, blk_free_queue_rcu);
|
|
}
|
|
|
|
static const struct sysfs_ops queue_sysfs_ops = {
|
|
.show = queue_attr_show,
|
|
.store = queue_attr_store,
|
|
};
|
|
|
|
struct kobj_type blk_queue_ktype = {
|
|
.sysfs_ops = &queue_sysfs_ops,
|
|
.default_attrs = default_attrs,
|
|
.release = blk_release_queue,
|
|
};
|
|
|
|
int blk_register_queue(struct gendisk *disk)
|
|
{
|
|
int ret;
|
|
struct device *dev = disk_to_dev(disk);
|
|
struct request_queue *q = disk->queue;
|
|
|
|
if (WARN_ON(!q))
|
|
return -ENXIO;
|
|
|
|
/*
|
|
* SCSI probing may synchronously create and destroy a lot of
|
|
* request_queues for non-existent devices. Shutting down a fully
|
|
* functional queue takes measureable wallclock time as RCU grace
|
|
* periods are involved. To avoid excessive latency in these
|
|
* cases, a request_queue starts out in a degraded mode which is
|
|
* faster to shut down and is made fully functional here as
|
|
* request_queues for non-existent devices never get registered.
|
|
*/
|
|
if (!blk_queue_init_done(q)) {
|
|
queue_flag_set_unlocked(QUEUE_FLAG_INIT_DONE, q);
|
|
blk_queue_bypass_end(q);
|
|
if (q->mq_ops)
|
|
blk_mq_finish_init(q);
|
|
}
|
|
|
|
ret = blk_trace_init_sysfs(dev);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
|
|
if (ret < 0) {
|
|
blk_trace_remove_sysfs(dev);
|
|
return ret;
|
|
}
|
|
|
|
kobject_uevent(&q->kobj, KOBJ_ADD);
|
|
|
|
if (q->mq_ops)
|
|
blk_mq_register_disk(disk);
|
|
|
|
if (!q->request_fn)
|
|
return 0;
|
|
|
|
ret = elv_register_queue(q);
|
|
if (ret) {
|
|
kobject_uevent(&q->kobj, KOBJ_REMOVE);
|
|
kobject_del(&q->kobj);
|
|
blk_trace_remove_sysfs(dev);
|
|
kobject_put(&dev->kobj);
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void blk_unregister_queue(struct gendisk *disk)
|
|
{
|
|
struct request_queue *q = disk->queue;
|
|
|
|
if (WARN_ON(!q))
|
|
return;
|
|
|
|
if (q->mq_ops)
|
|
blk_mq_unregister_disk(disk);
|
|
|
|
if (q->request_fn)
|
|
elv_unregister_queue(q);
|
|
|
|
kobject_uevent(&q->kobj, KOBJ_REMOVE);
|
|
kobject_del(&q->kobj);
|
|
blk_trace_remove_sysfs(disk_to_dev(disk));
|
|
kobject_put(&disk_to_dev(disk)->kobj);
|
|
}
|