blkcg: Restructure blkg_conf_prep() and friends
We want to support lazy init of rq-qos policies so that iolatency is enabled
lazily on configuration instead of gendisk initialization. The way blkg
config helpers are structured now is a bit awkward for that. Let's
restructure:
* blkcg_conf_open_bdev() is renamed to blkg_conf_open_bdev(). The blkcg_
prefix was used because the bdev opening step is blkg-independent.
However, the distinction is too subtle and confuses more than helps. Let's
switch to blkg prefix so that it's consistent with the type and other
helper names.
* struct blkg_conf_ctx now remembers the original input string and is always
initialized by the new blkg_conf_init().
* blkg_conf_open_bdev() is updated to take a pointer to blkg_conf_ctx like
blkg_conf_prep() and can be called multiple times safely. Instead of
modifying the double pointer to input string directly,
blkg_conf_open_bdev() now sets blkg_conf_ctx->body.
* blkg_conf_finish() is renamed to blkg_conf_exit() for symmetry and now
must be called on all blkg_conf_ctx's which were initialized with
blkg_conf_init().
Combined, this allows the users to either open the bdev first or do it
altogether with blkg_conf_prep() which will help implementing lazy init of
rq-qos policies.
blkg_conf_init/exit() will also be used implement synchronization against
device removal. This is necessary because iolat / iocost are configured
through cgroupfs instead of one of the files under /sys/block/DEVICE. As
cgroupfs operations aren't synchronized with block layer, the lazy init and
other configuration operations may race against device removal. This patch
makes blkg_conf_init/exit() used consistently for all cgroup-orginating
configurations making them a good place to implement explicit
synchronization.
Users are updated accordingly. No behavior change is intended by this patch.
v2: bfq wasn't updated in v1 causing a build error. Fixed.
v3: Update the description to include future use of blkg_conf_init/exit() as
synchronization points.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Yu Kuai <yukuai1@huaweicloud.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230413000649.115785-3-tj@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo
Jens Axboe
parent
83462a6c97
commit
faffaab289
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@ -1105,9 +1105,11 @@ static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
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struct bfq_group *bfqg;
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u64 v;
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ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, buf, &ctx);
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blkg_conf_init(&ctx, buf);
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ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, &ctx);
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if (ret)
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return ret;
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goto out;
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if (sscanf(ctx.body, "%llu", &v) == 1) {
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/* require "default" on dfl */
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@ -1129,7 +1131,7 @@ static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
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ret = 0;
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}
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out:
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blkg_conf_finish(&ctx);
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blkg_conf_exit(&ctx);
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return ret ?: nbytes;
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}
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@ -653,69 +653,93 @@ u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v)
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EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
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/**
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* blkcg_conf_open_bdev - parse and open bdev for per-blkg config update
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* @inputp: input string pointer
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* blkg_conf_init - initialize a blkg_conf_ctx
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* @ctx: blkg_conf_ctx to initialize
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* @input: input string
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*
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* Parse the device node prefix part, MAJ:MIN, of per-blkg config update
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* from @input and get and return the matching bdev. *@inputp is
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* updated to point past the device node prefix. Returns an ERR_PTR()
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* value on error.
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*
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* Use this function iff blkg_conf_prep() can't be used for some reason.
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* Initialize @ctx which can be used to parse blkg config input string @input.
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* Once initialized, @ctx can be used with blkg_conf_open_bdev() and
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* blkg_conf_prep(), and must be cleaned up with blkg_conf_exit().
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*/
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struct block_device *blkcg_conf_open_bdev(char **inputp)
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void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input)
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{
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char *input = *inputp;
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*ctx = (struct blkg_conf_ctx){ .input = input };
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}
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EXPORT_SYMBOL_GPL(blkg_conf_init);
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/**
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* blkg_conf_open_bdev - parse and open bdev for per-blkg config update
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* @ctx: blkg_conf_ctx initialized with blkg_conf_init()
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*
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* Parse the device node prefix part, MAJ:MIN, of per-blkg config update from
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* @ctx->input and get and store the matching bdev in @ctx->bdev. @ctx->body is
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* set to point past the device node prefix.
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*
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* This function may be called multiple times on @ctx and the extra calls become
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* NOOPs. blkg_conf_prep() implicitly calls this function. Use this function
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* explicitly if bdev access is needed without resolving the blkcg / policy part
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* of @ctx->input. Returns -errno on error.
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*/
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int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
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{
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char *input = ctx->input;
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unsigned int major, minor;
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struct block_device *bdev;
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int key_len;
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if (ctx->bdev)
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return 0;
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if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2)
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return ERR_PTR(-EINVAL);
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return -EINVAL;
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input += key_len;
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if (!isspace(*input))
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return ERR_PTR(-EINVAL);
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return -EINVAL;
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input = skip_spaces(input);
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bdev = blkdev_get_no_open(MKDEV(major, minor));
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if (!bdev)
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return ERR_PTR(-ENODEV);
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return -ENODEV;
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if (bdev_is_partition(bdev)) {
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blkdev_put_no_open(bdev);
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return ERR_PTR(-ENODEV);
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return -ENODEV;
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}
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*inputp = input;
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return bdev;
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ctx->body = input;
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ctx->bdev = bdev;
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return 0;
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}
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/**
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* blkg_conf_prep - parse and prepare for per-blkg config update
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* @blkcg: target block cgroup
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* @pol: target policy
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* @input: input string
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* @ctx: blkg_conf_ctx to be filled
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* @ctx: blkg_conf_ctx initialized with blkg_conf_init()
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*
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* Parse per-blkg config update from @input and initialize @ctx with the
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* result. @ctx->blkg points to the blkg to be updated and @ctx->body the
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* part of @input following MAJ:MIN. This function returns with queue lock
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* held and must be paired with blkg_conf_finish().
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* Parse per-blkg config update from @ctx->input and initialize @ctx
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* accordingly. On success, @ctx->body points to the part of @ctx->input
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* following MAJ:MIN, @ctx->bdev points to the target block device and
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* @ctx->blkg to the blkg being configured.
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*
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* blkg_conf_open_bdev() may be called on @ctx beforehand. On success, this
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* function returns with queue lock held and must be followed by
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* blkg_conf_exit().
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*/
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int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
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char *input, struct blkg_conf_ctx *ctx)
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struct blkg_conf_ctx *ctx)
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__acquires(&bdev->bd_queue->queue_lock)
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{
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struct block_device *bdev;
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struct gendisk *disk;
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struct request_queue *q;
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struct blkcg_gq *blkg;
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int ret;
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bdev = blkcg_conf_open_bdev(&input);
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if (IS_ERR(bdev))
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return PTR_ERR(bdev);
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disk = bdev->bd_disk;
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ret = blkg_conf_open_bdev(ctx);
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if (ret)
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return ret;
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disk = ctx->bdev->bd_disk;
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q = disk->queue;
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/*
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@ -793,9 +817,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
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}
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success:
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blk_queue_exit(q);
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ctx->bdev = bdev;
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ctx->blkg = blkg;
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ctx->body = input;
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return 0;
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fail_preloaded:
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@ -805,7 +827,6 @@ fail_unlock:
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fail_exit_queue:
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blk_queue_exit(q);
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fail:
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blkdev_put_no_open(bdev);
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/*
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* If queue was bypassing, we should retry. Do so after a
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* short msleep(). It isn't strictly necessary but queue
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@ -821,19 +842,27 @@ fail:
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EXPORT_SYMBOL_GPL(blkg_conf_prep);
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/**
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* blkg_conf_finish - finish up per-blkg config update
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* @ctx: blkg_conf_ctx initialized by blkg_conf_prep()
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* blkg_conf_exit - clean up per-blkg config update
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* @ctx: blkg_conf_ctx initialized with blkg_conf_init()
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*
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* Finish up after per-blkg config update. This function must be paired
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* with blkg_conf_prep().
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* Clean up after per-blkg config update. This function must be called on all
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* blkg_conf_ctx's initialized with blkg_conf_init().
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*/
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void blkg_conf_finish(struct blkg_conf_ctx *ctx)
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void blkg_conf_exit(struct blkg_conf_ctx *ctx)
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__releases(&ctx->bdev->bd_queue->queue_lock)
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{
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spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock);
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blkdev_put_no_open(ctx->bdev);
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if (ctx->blkg) {
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spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock);
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ctx->blkg = NULL;
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}
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if (ctx->bdev) {
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blkdev_put_no_open(ctx->bdev);
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ctx->body = NULL;
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ctx->bdev = NULL;
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}
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}
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EXPORT_SYMBOL_GPL(blkg_conf_finish);
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EXPORT_SYMBOL_GPL(blkg_conf_exit);
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static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src)
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{
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@ -206,15 +206,17 @@ void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
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u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
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struct blkg_conf_ctx {
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char *input;
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char *body;
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struct block_device *bdev;
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struct blkcg_gq *blkg;
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char *body;
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};
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struct block_device *blkcg_conf_open_bdev(char **inputp);
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void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
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int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx);
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int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
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char *input, struct blkg_conf_ctx *ctx);
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void blkg_conf_finish(struct blkg_conf_ctx *ctx);
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struct blkg_conf_ctx *ctx);
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void blkg_conf_exit(struct blkg_conf_ctx *ctx);
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/**
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* bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
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@ -3106,9 +3106,11 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
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return nbytes;
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}
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ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, buf, &ctx);
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blkg_conf_init(&ctx, buf);
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ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, &ctx);
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if (ret)
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return ret;
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goto err;
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iocg = blkg_to_iocg(ctx.blkg);
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@ -3127,12 +3129,14 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
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weight_updated(iocg, &now);
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spin_unlock(&iocg->ioc->lock);
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blkg_conf_finish(&ctx);
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blkg_conf_exit(&ctx);
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return nbytes;
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einval:
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blkg_conf_finish(&ctx);
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return -EINVAL;
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ret = -EINVAL;
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err:
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blkg_conf_exit(&ctx);
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return ret;
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}
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static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
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@ -3189,19 +3193,22 @@ static const match_table_t qos_tokens = {
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static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
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size_t nbytes, loff_t off)
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{
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struct block_device *bdev;
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struct blkg_conf_ctx ctx;
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struct gendisk *disk;
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struct ioc *ioc;
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u32 qos[NR_QOS_PARAMS];
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bool enable, user;
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char *p;
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char *body, *p;
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int ret;
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bdev = blkcg_conf_open_bdev(&input);
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if (IS_ERR(bdev))
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return PTR_ERR(bdev);
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blkg_conf_init(&ctx, input);
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disk = bdev->bd_disk;
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ret = blkg_conf_open_bdev(&ctx);
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if (ret)
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goto err;
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body = ctx.body;
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disk = ctx.bdev->bd_disk;
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if (!queue_is_mq(disk->queue)) {
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ret = -EOPNOTSUPP;
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goto err;
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@ -3223,7 +3230,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
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enable = ioc->enabled;
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user = ioc->user_qos_params;
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while ((p = strsep(&input, " \t\n"))) {
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while ((p = strsep(&body, " \t\n"))) {
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substring_t args[MAX_OPT_ARGS];
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char buf[32];
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int tok;
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@ -3313,7 +3320,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
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blk_mq_unquiesce_queue(disk->queue);
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blk_mq_unfreeze_queue(disk->queue);
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blkdev_put_no_open(bdev);
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blkg_conf_exit(&ctx);
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return nbytes;
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einval:
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spin_unlock_irq(&ioc->lock);
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@ -3323,7 +3330,7 @@ einval:
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ret = -EINVAL;
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err:
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blkdev_put_no_open(bdev);
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blkg_conf_exit(&ctx);
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return ret;
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}
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@ -3376,19 +3383,22 @@ static const match_table_t i_lcoef_tokens = {
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static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
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size_t nbytes, loff_t off)
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{
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struct block_device *bdev;
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struct blkg_conf_ctx ctx;
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struct request_queue *q;
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struct ioc *ioc;
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u64 u[NR_I_LCOEFS];
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bool user;
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char *p;
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char *body, *p;
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int ret;
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bdev = blkcg_conf_open_bdev(&input);
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if (IS_ERR(bdev))
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return PTR_ERR(bdev);
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blkg_conf_init(&ctx, input);
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q = bdev_get_queue(bdev);
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ret = blkg_conf_open_bdev(&ctx);
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if (ret)
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goto err;
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body = ctx.body;
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q = bdev_get_queue(ctx.bdev);
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if (!queue_is_mq(q)) {
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ret = -EOPNOTSUPP;
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goto err;
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@ -3396,7 +3406,7 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
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ioc = q_to_ioc(q);
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if (!ioc) {
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ret = blk_iocost_init(bdev->bd_disk);
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ret = blk_iocost_init(ctx.bdev->bd_disk);
|
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if (ret)
|
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goto err;
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ioc = q_to_ioc(q);
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|
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@ -3409,7 +3419,7 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
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memcpy(u, ioc->params.i_lcoefs, sizeof(u));
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user = ioc->user_cost_model;
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while ((p = strsep(&input, " \t\n"))) {
|
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while ((p = strsep(&body, " \t\n"))) {
|
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substring_t args[MAX_OPT_ARGS];
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char buf[32];
|
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int tok;
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@ -3456,7 +3466,7 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
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blk_mq_unquiesce_queue(q);
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blk_mq_unfreeze_queue(q);
|
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|
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blkdev_put_no_open(bdev);
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blkg_conf_exit(&ctx);
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return nbytes;
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einval:
|
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|
@ -3467,7 +3477,7 @@ einval:
|
|||
|
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ret = -EINVAL;
|
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err:
|
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blkdev_put_no_open(bdev);
|
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blkg_conf_exit(&ctx);
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -836,9 +836,11 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
|
|||
u64 oldval;
|
||||
int ret;
|
||||
|
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ret = blkg_conf_prep(blkcg, &blkcg_policy_iolatency, buf, &ctx);
|
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blkg_conf_init(&ctx, buf);
|
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|
||||
ret = blkg_conf_prep(blkcg, &blkcg_policy_iolatency, &ctx);
|
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if (ret)
|
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return ret;
|
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goto out;
|
||||
|
||||
iolat = blkg_to_lat(ctx.blkg);
|
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p = ctx.body;
|
||||
|
|
@ -874,7 +876,7 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
|
|||
iolatency_clear_scaling(blkg);
|
||||
ret = 0;
|
||||
out:
|
||||
blkg_conf_finish(&ctx);
|
||||
blkg_conf_exit(&ctx);
|
||||
return ret ?: nbytes;
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -1368,9 +1368,11 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
|
|||
int ret;
|
||||
u64 v;
|
||||
|
||||
ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
|
||||
blkg_conf_init(&ctx, buf);
|
||||
|
||||
ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx);
|
||||
if (ret)
|
||||
return ret;
|
||||
goto out_finish;
|
||||
|
||||
ret = -EINVAL;
|
||||
if (sscanf(ctx.body, "%llu", &v) != 1)
|
||||
|
|
@ -1389,7 +1391,7 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
|
|||
tg_conf_updated(tg, false);
|
||||
ret = 0;
|
||||
out_finish:
|
||||
blkg_conf_finish(&ctx);
|
||||
blkg_conf_exit(&ctx);
|
||||
return ret ?: nbytes;
|
||||
}
|
||||
|
||||
|
|
@ -1561,9 +1563,11 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
|
|||
int ret;
|
||||
int index = of_cft(of)->private;
|
||||
|
||||
ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
|
||||
blkg_conf_init(&ctx, buf);
|
||||
|
||||
ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx);
|
||||
if (ret)
|
||||
return ret;
|
||||
goto out_finish;
|
||||
|
||||
tg = blkg_to_tg(ctx.blkg);
|
||||
tg_update_carryover(tg);
|
||||
|
|
@ -1662,7 +1666,7 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
|
|||
tg->td->limit_valid[LIMIT_LOW]);
|
||||
ret = 0;
|
||||
out_finish:
|
||||
blkg_conf_finish(&ctx);
|
||||
blkg_conf_exit(&ctx);
|
||||
return ret ?: nbytes;
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue