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Message-ID: <20140317095653.GA1014@kernel.org>
Date: Mon, 17 Mar 2014 17:56:53 +0800
From: Shaohua Li <shli@...nel.org>
To: Mike Snitzer <snitzer@...hat.com>
Cc: axboe@...nel.dk, dm-devel@...hat.com, linux-kernel@...r.kernel.org,
agk@...hat.com
Subject: Re: [patch v3]DM: dm-insitu-comp: a compressed DM target for SSD
On Fri, Mar 14, 2014 at 06:44:45PM -0400, Mike Snitzer wrote:
> On Fri, Mar 14 2014 at 5:40am -0400,
> Shaohua Li <shli@...nel.org> wrote:
>
> > On Mon, Mar 10, 2014 at 09:52:56AM -0400, Mike Snitzer wrote:
> > > On Fri, Mar 07 2014 at 2:57am -0500,
> > > Shaohua Li <shli@...nel.org> wrote:
> > >
> > > > ping!
> > >
> > > Hi,
> > >
> > > I intend to get dm-insitu-comp reviewed for 3.15. Sorry I haven't
> > > gotten back with you before now, been busy tending to 3.14-rc issues.
> > >
> > > I took a quick first pass over your code a couple weeks ago. Looks to
> > > be in great shape relative to coding conventions and the more DM
> > > specific conventions. Clearly demonstrates you have a good command of
> > > DM concepts and quirks.
>
> Think I need to eat my words from above at least partially. Given you
> haven't implemented any of the target suspend or resume hooks this
> target will _not_ work properly across suspend + resume cycles that all
> DM targets must support.
>
> But we can obviously work through it with urgency for 3.15.
>
> I've pulled your v3 patch into git and have overlayed edits from my
> first pass. Lots of funky wrapping to conform to 80 columns. But
> whitespace aside, I've added FIXME:s in the relevant files. If you work
> on any of these FIXMEs please send follow-up patches so that we don't
> step on each others' toes.
>
> Please see the 'for-3.15-insitu-comp' branch of this git repo:
> git://git.kernel.org/pub/scm/linux/kernel/git/snitzer/linux.git
Thanks for your to look at it. I fixed them against your tree. Please check below patch.
Subject: dm-insitu-comp: fix different issues
Fix different issues pointed out by Mike and add suspend/resume support.
Signed-off-by: Shaohua Li <shli@...ionio.com>
---
drivers/md/dm-insitu-comp.c | 108 ++++++++++++++++++++++++++++++--------------
drivers/md/dm-insitu-comp.h | 8 +++
2 files changed, 84 insertions(+), 32 deletions(-)
Index: linux/drivers/md/dm-insitu-comp.c
===================================================================
--- linux.orig/drivers/md/dm-insitu-comp.c 2014-03-17 12:37:37.850751341 +0800
+++ linux/drivers/md/dm-insitu-comp.c 2014-03-17 17:40:01.106660303 +0800
@@ -17,6 +17,7 @@
#include "dm-insitu-comp.h"
#define DM_MSG_PREFIX "insitu-comp"
+#define DEFAULT_WRITEBACK_DELAY 5
static inline int lzo_comp_len(int comp_len)
{
@@ -40,6 +41,10 @@ static struct kmem_cache *insitu_comp_me
static struct insitu_comp_io_worker insitu_comp_io_workers[NR_CPUS];
static struct workqueue_struct *insitu_comp_wq;
+#define BYTE_BITS 8
+#define BYTE_BITS_SHIFT 3
+#define BYTE_BITS_MASK (BYTE_BITS - 1)
+
/* each block has 5 bits of metadata */
static u8 insitu_comp_get_meta(struct insitu_comp_info *info, u64 block_index)
{
@@ -47,15 +52,14 @@ static u8 insitu_comp_get_meta(struct in
int bits, offset;
u8 data, ret = 0;
- // FIXME: "magic" numbers in this function (7, 3)
- offset = first_bit & 7;
- bits = min_t(u8, INSITU_COMP_META_BITS, 8 - offset);
+ offset = first_bit & BYTE_BITS_MASK;
+ bits = min_t(u8, INSITU_COMP_META_BITS, BYTE_BITS - offset);
- data = info->meta_bitmap[first_bit >> 3];
+ data = info->meta_bitmap[first_bit >> BYTE_BITS_SHIFT];
ret = (data >> offset) & ((1 << bits) - 1);
if (bits < INSITU_COMP_META_BITS) {
- data = info->meta_bitmap[(first_bit >> 3) + 1];
+ data = info->meta_bitmap[(first_bit >> BYTE_BITS_SHIFT) + 1];
bits = INSITU_COMP_META_BITS - bits;
ret |= (data & ((1 << bits) - 1)) <<
(INSITU_COMP_META_BITS - bits);
@@ -71,14 +75,13 @@ static void insitu_comp_set_meta(struct
u8 data;
struct page *page;
- // FIXME: "magic" numbers in this function (7, 3)
- offset = first_bit & 7;
- bits = min_t(u8, INSITU_COMP_META_BITS, 8 - offset);
+ offset = first_bit & BYTE_BITS_MASK;
+ bits = min_t(u8, INSITU_COMP_META_BITS, BYTE_BITS - offset);
- data = info->meta_bitmap[first_bit >> 3];
+ data = info->meta_bitmap[first_bit >> BYTE_BITS_SHIFT];
data &= ~(((1 << bits) - 1) << offset);
data |= (meta & ((1 << bits) - 1)) << offset;
- info->meta_bitmap[first_bit >> 3] = data;
+ info->meta_bitmap[first_bit >> BYTE_BITS_SHIFT] = data;
/*
* For writethrough, we write metadata directly. For writeback, if
@@ -301,9 +304,24 @@ static int insitu_comp_meta_writeback_th
init_completion(&wb.complete);
while (!kthread_should_stop()) {
- // FIXME: writeback_delay should be in secs
- schedule_timeout_interruptible(msecs_to_jiffies(info->writeback_delay * 1000));
+ schedule_timeout_interruptible(
+ msecs_to_jiffies(info->writeback_delay * MSEC_PER_SEC));
insitu_comp_flush_dirty_meta(info, &wb);
+
+ if (info->wb_thread_suspend_status != WB_THREAD_RESUMED) {
+ writeback_flush_io_done(&wb, 0);
+ wait_for_completion(&wb.complete);
+
+ info->wb_thread_suspend_status = WB_THREAD_SUSPENDED;
+ wake_up_interruptible(&info->wb_thread_suspend_wq);
+
+ wait_event_interruptible(info->wb_thread_suspend_wq,
+ info->wb_thread_suspend_status == WB_THREAD_RESUMED ||
+ kthread_should_stop());
+
+ atomic_set(&wb.cnt, 1);
+ init_completion(&wb.complete);
+ }
}
insitu_comp_flush_dirty_meta(info, &wb);
@@ -357,6 +375,8 @@ static int insitu_comp_init_meta(struct
info->ti->error = "Create writeback thread error";
return -EINVAL;
}
+ info->wb_thread_suspend_status = WB_THREAD_RESUMED;
+ init_waitqueue_head(&info->wb_thread_suspend_wq);
}
return 0;
@@ -410,7 +430,6 @@ static int insitu_comp_read_or_create_su
total_blocks = i_size_read(info->dev->bdev->bd_inode) >> INSITU_COMP_BLOCK_SHIFT;
data_blocks = total_blocks - 1;
- // FIXME: 64bit divide on 32bit? must compile/work on 32bit
rem = do_div(data_blocks, INSITU_COMP_BLOCK_SIZE * 8 + INSITU_COMP_META_BITS);
meta_blocks = data_blocks * INSITU_COMP_META_BITS;
data_blocks *= INSITU_COMP_BLOCK_SIZE * 8;
@@ -507,13 +526,11 @@ out:
*/
static int insitu_comp_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
- // FIXME: add proper feature arg processing.
- // FIXME: pick default metadata write mode.
struct insitu_comp_info *info;
char write_mode[15];
int ret, i;
- if (argc < 2) {
+ if (argc < 1) {
ti->error = "Invalid argument count";
return -EINVAL;
}
@@ -525,19 +542,18 @@ static int insitu_comp_ctr(struct dm_tar
}
info->ti = ti;
+ info->write_mode = INSITU_COMP_WRITE_BACK;
+ info->writeback_delay = DEFAULT_WRITEBACK_DELAY;
+ if (argc == 1)
+ goto skip_optargs;
+
if (sscanf(argv[1], "%s", write_mode) != 1) {
ti->error = "Invalid argument";
ret = -EINVAL;
goto err_para;
}
- if (strcmp(write_mode, "writeback") == 0) {
- if (argc != 3) {
- ti->error = "Invalid argument";
- ret = -EINVAL;
- goto err_para;
- }
- info->write_mode = INSITU_COMP_WRITE_BACK;
+ if (strcmp(write_mode, "writeback") == 0 && argc == 3) {
if (sscanf(argv[2], "%u", &info->writeback_delay) != 1) {
ti->error = "Invalid argument";
ret = -EINVAL;
@@ -551,6 +567,7 @@ static int insitu_comp_ctr(struct dm_tar
goto err_para;
}
+skip_optargs:
if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
&info->dev)) {
ti->error = "Can't get device";
@@ -1348,6 +1365,28 @@ static int insitu_comp_map(struct dm_tar
return DM_MAPIO_SUBMITTED;
}
+static void insitu_comp_postsuspend(struct dm_target *ti)
+{
+ struct insitu_comp_info *info = ti->private;
+ /* all requests are finished already */
+ if (info->write_mode != INSITU_COMP_WRITE_BACK)
+ return;
+ info->wb_thread_suspend_status = WB_THREAD_SUSPENDING;
+ wake_up_process(info->writeback_tsk);
+
+ wait_event_interruptible(info->wb_thread_suspend_wq,
+ info->wb_thread_suspend_status == WB_THREAD_SUSPENDED);
+}
+
+static void insitu_comp_resume(struct dm_target *ti)
+{
+ struct insitu_comp_info *info = ti->private;
+ if (info->write_mode != INSITU_COMP_WRITE_BACK)
+ return;
+ info->wb_thread_suspend_status = WB_THREAD_RESUMED;
+ wake_up_interruptible(&info->wb_thread_suspend_wq);
+}
+
/*
* INFO: uncompressed_data_size compressed_data_size metadata_size
* TABLE: writethrough/writeback commit_delay
@@ -1360,10 +1399,10 @@ static void insitu_comp_status(struct dm
switch (type) {
case STATUSTYPE_INFO:
- DMEMIT("%lu %lu %lu",
- atomic64_read(&info->uncompressed_write_size),
- atomic64_read(&info->compressed_write_size),
- atomic64_read(&info->meta_write_size));
+ DMEMIT("%llu %llu %llu",
+ (long long)atomic64_read(&info->uncompressed_write_size),
+ (long long)atomic64_read(&info->compressed_write_size),
+ (long long)atomic64_read(&info->meta_write_size));
break;
case STATUSTYPE_TABLE:
if (info->write_mode == INSITU_COMP_WRITE_BACK)
@@ -1407,8 +1446,8 @@ static struct target_type insitu_comp_ta
.ctr = insitu_comp_ctr,
.dtr = insitu_comp_dtr,
.map = insitu_comp_map,
- // FIXME: no .postsuspend or .preresume or .resume!?
- // need to flush workqueue at a minimum. what about commit? see pool_target or cache_target
+ .postsuspend = insitu_comp_postsuspend,
+ .resume = insitu_comp_resume,
.status = insitu_comp_status,
.iterate_devices = insitu_comp_iterate_devices,
.io_hints = insitu_comp_io_hints,
@@ -1430,14 +1469,19 @@ static int __init insitu_comp_init(void)
default_compressor = r;
r = -ENOMEM;
- // FIXME: add dm_ prefix to at least these 2 structs so slabs are attributed to dm
- insitu_comp_io_range_cachep = KMEM_CACHE(insitu_comp_io_range, 0);
+ insitu_comp_io_range_cachep = kmem_cache_create("dm_insitu_comp_io_range",
+ sizeof(struct insitu_comp_io_range),
+ __alignof__(struct insitu_comp_io_range),
+ 0, NULL);
if (!insitu_comp_io_range_cachep) {
DMWARN("Can't create io_range cache");
goto err;
}
- insitu_comp_meta_io_cachep = KMEM_CACHE(insitu_comp_meta_io, 0);
+ insitu_comp_meta_io_cachep = kmem_cache_create("dm_insitu_comp_meta_io",
+ sizeof(struct insitu_comp_meta_io),
+ __alignof__(struct insitu_comp_meta_io),
+ 0, NULL);
if (!insitu_comp_meta_io_cachep) {
DMWARN("Can't create meta_io cache");
goto err;
Index: linux/drivers/md/dm-insitu-comp.h
===================================================================
--- linux.orig/drivers/md/dm-insitu-comp.h 2014-03-17 12:37:37.850751341 +0800
+++ linux/drivers/md/dm-insitu-comp.h 2014-03-17 16:22:24.553201921 +0800
@@ -92,6 +92,8 @@ struct insitu_comp_info {
enum INSITU_COMP_WRITE_MODE write_mode;
unsigned int writeback_delay; /* second unit */
struct task_struct *writeback_tsk;
+ int wb_thread_suspend_status;
+ wait_queue_head_t wb_thread_suspend_wq;
struct dm_io_client *io_client;
atomic64_t compressed_write_size;
@@ -99,6 +101,12 @@ struct insitu_comp_info {
atomic64_t meta_write_size;
};
+enum {
+ WB_THREAD_RESUMED = 0,
+ WB_THREAD_SUSPENDING = 1,
+ WB_THREAD_SUSPENDED = 2,
+};
+
struct insitu_comp_meta_io {
struct dm_io_request io_req;
struct dm_io_region io_region;
--
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