For a zoned block device mount, an array of zone types for the 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
equivalent information, that is, if a zone is sequential or not. This
reduces the memory usage for the device mount 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 function
f2fs_blkz_is_seq(), which is a rewrite of the function get_blkz_type().

Signed-off-by: Damien Le Moal <damien.lem...@wdc.com>
---
 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 6300ac5bcbe4..c5700f63ebe7 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1000,8 +1000,8 @@ 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
 };
 
@@ -3213,16 +3213,17 @@ static inline int f2fs_sb_has_inode_crtime(struct 
super_block *sb)
 }
 
 #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;
 }
 #endif
 
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index b16a8e6625aa..1abf951abeb1 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1447,19 +1447,8 @@ 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);
 
@@ -1474,10 +1463,12 @@ 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 8173ae688814..205be76d6e53 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -881,7 +881,7 @@ 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
-               kfree(FDEV(i).blkz_type);
+               kfree(FDEV(i).blkz_seq);
 #endif
        }
        kfree(sbi->devs);
@@ -2222,9 +2222,11 @@ 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
@@ -2249,7 +2251,8 @@ 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++;
                }
-- 
2.14.3


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