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 ?
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 ?
>
> 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++;
>> }
>>
>
--
Damien Le Moal
Western Digital Research
