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author | Andrew Morton <akpm@osdl.org> | 2006-10-20 08:28:16 +0200 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-20 19:26:35 +0200 |
commit | 3fcfab16c5b86eaa3db3a9a31adba550c5b67141 (patch) | |
tree | bd348fa081b8fbec2c79fbf8f173a306d70b2b2c /mm/backing-dev.c | |
parent | [PATCH] export clear_queue_congested and set_queue_congested (diff) | |
download | linux-3fcfab16c5b86eaa3db3a9a31adba550c5b67141.tar.xz linux-3fcfab16c5b86eaa3db3a9a31adba550c5b67141.zip |
[PATCH] separate bdi congestion functions from queue congestion functions
Separate out the concept of "queue congestion" from "backing-dev congestion".
Congestion is a backing-dev concept, not a queue concept.
The blk_* congestion functions are retained, as wrappers around the core
backing-dev congestion functions.
This proper layering is needed so that NFS can cleanly use the congestion
functions, and so that CONFIG_BLOCK=n actually links.
Cc: "Thomas Maier" <balagi@justmail.de>
Cc: "Jens Axboe" <jens.axboe@oracle.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: David Howells <dhowells@redhat.com>
Cc: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/backing-dev.c')
-rw-r--r-- | mm/backing-dev.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c new file mode 100644 index 000000000000..f50a2811f9dc --- /dev/null +++ b/mm/backing-dev.c @@ -0,0 +1,69 @@ + +#include <linux/wait.h> +#include <linux/backing-dev.h> +#include <linux/fs.h> +#include <linux/sched.h> +#include <linux/module.h> + +static wait_queue_head_t congestion_wqh[2] = { + __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), + __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) + }; + + +void clear_bdi_congested(struct backing_dev_info *bdi, int rw) +{ + enum bdi_state bit; + wait_queue_head_t *wqh = &congestion_wqh[rw]; + + bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; + clear_bit(bit, &bdi->state); + smp_mb__after_clear_bit(); + if (waitqueue_active(wqh)) + wake_up(wqh); +} +EXPORT_SYMBOL(clear_bdi_congested); + +void set_bdi_congested(struct backing_dev_info *bdi, int rw) +{ + enum bdi_state bit; + + bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; + set_bit(bit, &bdi->state); +} +EXPORT_SYMBOL(set_bdi_congested); + +/** + * congestion_wait - wait for a backing_dev to become uncongested + * @rw: READ or WRITE + * @timeout: timeout in jiffies + * + * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit + * write congestion. If no backing_devs are congested then just wait for the + * next write to be completed. + */ +long congestion_wait(int rw, long timeout) +{ + long ret; + DEFINE_WAIT(wait); + wait_queue_head_t *wqh = &congestion_wqh[rw]; + + prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); + ret = io_schedule_timeout(timeout); + finish_wait(wqh, &wait); + return ret; +} +EXPORT_SYMBOL(congestion_wait); + +/** + * congestion_end - wake up sleepers on a congested backing_dev_info + * @rw: READ or WRITE + */ +void congestion_end(int rw) +{ + wait_queue_head_t *wqh = &congestion_wqh[rw]; + + if (waitqueue_active(wqh)) + wake_up(wqh); +} +EXPORT_SYMBOL(congestion_end); |