On 2019/3/7 2:15, Damien Le Moal wrote:
> On 2019/03/06 23:32, Chao Yu wrote:
>> On 2019-3-6 14:27, Damien Le Moal wrote:
>>> For zoned block devices, an array of zone types for each device is
>>> allocated and initialized in order to determine if a section is stored
>>> on a sequential zone (zone reset needed) or a conventional zone (no
>>> zone reset needed and regular discard applies). Considering this usage,
>>> the zone types stored in memory can be replaced with a bitmap to
>>> indicate an equivalent information, that is, if a zone is sequential or
>>> not. This reduces the memory usage for each zoned device by roughly 8:
>>> on a 14TB disk with zones of 256 MB, the zone type array consumes
>>> 13x4KB pages while the bitmap uses only 2x4KB pages.
>>>
>>> This patch changes the f2fs_dev_info structure blkz_type field to the
>>> bitmap blkz_seq. Access to this bitmap is done using the helper
>>> function f2fs_blkz_is_seq(), which is a rewrite of the function
>>> get_blkz_type().
>>>
>>> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
>>> ---
>>> Changes from v1:
>>> * Use kvfree() instead of kfree() to free the zone bitmap
>>>
>>> fs/f2fs/f2fs.h | 13 +++++++------
>>> fs/f2fs/segment.c | 23 +++++++----------------
>>> fs/f2fs/super.c | 13 ++++++++-----
>>> 3 files changed, 22 insertions(+), 27 deletions(-)
>>>
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index 12fabd6735dd..d7b2de930352 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -1067,8 +1067,8 @@ struct f2fs_dev_info {
>>> block_t start_blk;
>>> block_t end_blk;
>>> #ifdef CONFIG_BLK_DEV_ZONED
>>> - unsigned int nr_blkz; /* Total number of zones */
>>> - u8 *blkz_type; /* Array of zones type */
>>> + unsigned int nr_blkz; /* Total number of zones */
>>> + unsigned long *blkz_seq; /* Bitmap indicating sequential zones */
>>> #endif
>>> };
>>>
>>> @@ -3508,16 +3508,17 @@ F2FS_FEATURE_FUNCS(lost_found, LOST_FOUND);
>>> F2FS_FEATURE_FUNCS(sb_chksum, SB_CHKSUM);
>>>
>>> #ifdef CONFIG_BLK_DEV_ZONED
>>> -static inline int get_blkz_type(struct f2fs_sb_info *sbi,
>>> - struct block_device *bdev, block_t blkaddr)
>>> +static inline bool f2fs_blkz_is_seq(struct f2fs_sb_info *sbi,
>>> + struct block_device *bdev, block_t blkaddr)
>>> {
>>> unsigned int zno = blkaddr >> sbi->log_blocks_per_blkz;
>>> int i;
>>>
>>> for (i = 0; i < sbi->s_ndevs; i++)
>>> if (FDEV(i).bdev == bdev)
>>> - return FDEV(i).blkz_type[zno];
>>> - return -EINVAL;
>>> + return test_bit(zno, FDEV(i).blkz_seq);
>>> + WARN_ON_ONCE(1);
>>> + return false;
>>
>> How about just handling this case as previous instead of treating device as
>> conventional zone?
>
> Before this patch, if the device is not found, an error was returned, which was
> propagated up by __f2fs_issue_discard_zone() as an -EIO. Do you mean to do the
> same here too ?
Yes.
>
> Now that I look at this again, another possible change that I think actually may
> make more sense is to pass the devi (device index) variable set by
> __f2fs_issue_discard_zone() to this function. No need for the device search loop
> doing so and invalid block numbers leading to invalid device indexes can/should
> be handled in __f2fs_issue_discard_zone().
>
> What do you think ?
That will be better, please go ahead. :)
Thanks,
>
>>
>> Thanks,
>>
>>> }
>>> #endif
>>>
>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>> index 9b79056d705d..65941070776c 100644
>>> --- a/fs/f2fs/segment.c
>>> +++ b/fs/f2fs/segment.c
>>> @@ -1703,19 +1703,8 @@ static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
>>> blkstart -= FDEV(devi).start_blk;
>>> }
>>>
>>> - /*
>>> - * We need to know the type of the zone: for conventional zones,
>>> - * use regular discard if the drive supports it. For sequential
>>> - * zones, reset the zone write pointer.
>>> - */
>>> - switch (get_blkz_type(sbi, bdev, blkstart)) {
>>> -
>>> - case BLK_ZONE_TYPE_CONVENTIONAL:
>>> - if (!blk_queue_discard(bdev_get_queue(bdev)))
>>> - return 0;
>>> - return __queue_discard_cmd(sbi, bdev, lblkstart, blklen);
>>> - case BLK_ZONE_TYPE_SEQWRITE_REQ:
>>> - case BLK_ZONE_TYPE_SEQWRITE_PREF:
>>> + /* For sequential zones, reset the zone write pointer */
>>> + if (f2fs_blkz_is_seq(sbi, bdev, blkstart)) {
>>> sector = SECTOR_FROM_BLOCK(blkstart);
>>> nr_sects = SECTOR_FROM_BLOCK(blklen);
>>>
>>> @@ -1730,10 +1719,12 @@ static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
>>> trace_f2fs_issue_reset_zone(bdev, blkstart);
>>> return blkdev_reset_zones(bdev, sector,
>>> nr_sects, GFP_NOFS);
>>> - default:
>>> - /* Unknown zone type: broken device ? */
>>> - return -EIO;
>>> }
>>> +
>>> + /* For conventional zones, use regular discard if supported */
>>> + if (!blk_queue_discard(bdev_get_queue(bdev)))
>>> + return 0;
>>> + return __queue_discard_cmd(sbi, bdev, lblkstart, blklen);
>>> }
>>> #endif
>>>
>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>> index c46a1d4318d4..91d7429be554 100644
>>> --- a/fs/f2fs/super.c
>>> +++ b/fs/f2fs/super.c
>>> @@ -1017,7 +1017,7 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
>>> for (i = 0; i < sbi->s_ndevs; i++) {
>>> blkdev_put(FDEV(i).bdev, FMODE_EXCL);
>>> #ifdef CONFIG_BLK_DEV_ZONED
>>> - kvfree(FDEV(i).blkz_type);
>>> + kvfree(FDEV(i).blkz_seq);
>>> #endif
>>> }
>>> kvfree(sbi->devs);
>>> @@ -2765,9 +2765,11 @@ static int init_blkz_info(struct f2fs_sb_info *sbi, int devi)
>>> if (nr_sectors & (bdev_zone_sectors(bdev) - 1))
>>> FDEV(devi).nr_blkz++;
>>>
>>> - FDEV(devi).blkz_type = f2fs_kmalloc(sbi, FDEV(devi).nr_blkz,
>>> - GFP_KERNEL);
>>> - if (!FDEV(devi).blkz_type)
>>> + FDEV(devi).blkz_seq = f2fs_kzalloc(sbi,
>>> + BITS_TO_LONGS(FDEV(devi).nr_blkz)
>>> + * sizeof(unsigned long),
>>> + GFP_KERNEL);
>>> + if (!FDEV(devi).blkz_seq)
>>> return -ENOMEM;
>>>
>>> #define F2FS_REPORT_NR_ZONES 4096
>>> @@ -2794,7 +2796,8 @@ static int init_blkz_info(struct f2fs_sb_info *sbi, int devi)
>>> }
>>>
>>> for (i = 0; i < nr_zones; i++) {
>>> - FDEV(devi).blkz_type[n] = zones[i].type;
>>> + if (zones[i].type != BLK_ZONE_TYPE_CONVENTIONAL)
>>> + set_bit(n, FDEV(devi).blkz_seq);
>>> sector += zones[i].len;
>>> n++;
>>> }
>>>
>>
>
>
