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author | Jens Axboe <axboe@fb.com> | 2016-04-12 12:32:46 -0600 |
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committer | Jens Axboe <axboe@fb.com> | 2016-04-12 15:46:27 -0600 |
commit | 93e9d8e836cb1a9a58b33eb6643bf061c6119ef2 (patch) | |
tree | 17a50abdadaa58686983510230932323bf5d123c /block/blk-sysfs.c | |
parent | e0489487ec9cd79ee1fa0dc5d3789c08b0e51a2c (diff) | |
download | linux-stable-93e9d8e836cb1a9a58b33eb6643bf061c6119ef2.tar.gz linux-stable-93e9d8e836cb1a9a58b33eb6643bf061c6119ef2.tar.bz2 linux-stable-93e9d8e836cb1a9a58b33eb6643bf061c6119ef2.zip |
block: add ability to flag write back caching on a device
Add an internal helper and flag for setting whether a queue has
write back caching, or write through (or none). Add a sysfs file
to show this as well, and make it changeable from user space.
This will replace the (awkward) blk_queue_flush() interface that
drivers currently use to inform the block layer of write cache state
and capabilities.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'block/blk-sysfs.c')
-rw-r--r-- | block/blk-sysfs.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 995b58d46ed1..99205965f559 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -347,6 +347,38 @@ static ssize_t queue_poll_store(struct request_queue *q, const char *page, return ret; } +static ssize_t queue_wc_show(struct request_queue *q, char *page) +{ + if (test_bit(QUEUE_FLAG_WC, &q->queue_flags)) + return sprintf(page, "write back\n"); + + return sprintf(page, "write through\n"); +} + +static ssize_t queue_wc_store(struct request_queue *q, const char *page, + size_t count) +{ + int set = -1; + + if (!strncmp(page, "write back", 10)) + set = 1; + else if (!strncmp(page, "write through", 13) || + !strncmp(page, "none", 4)) + set = 0; + + if (set == -1) + return -EINVAL; + + spin_lock_irq(q->queue_lock); + if (set) + queue_flag_set(QUEUE_FLAG_WC, q); + else + queue_flag_clear(QUEUE_FLAG_WC, q); + spin_unlock_irq(q->queue_lock); + + return count; +} + static struct queue_sysfs_entry queue_requests_entry = { .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR }, .show = queue_requests_show, @@ -478,6 +510,12 @@ static struct queue_sysfs_entry queue_poll_entry = { .store = queue_poll_store, }; +static struct queue_sysfs_entry queue_wc_entry = { + .attr = {.name = "write_cache", .mode = S_IRUGO | S_IWUSR }, + .show = queue_wc_show, + .store = queue_wc_store, +}; + static struct attribute *default_attrs[] = { &queue_requests_entry.attr, &queue_ra_entry.attr, @@ -503,6 +541,7 @@ static struct attribute *default_attrs[] = { &queue_iostats_entry.attr, &queue_random_entry.attr, &queue_poll_entry.attr, + &queue_wc_entry.attr, NULL, }; |