[PATCH 4/4] zonefs: fix synchronous write to sequential zone files

[Damien Le Moal]

Synchronous writes to sequential zone files cannot use zone append
operations if the underlying zoned device queue limit
max_zone_append_sectors is 0, indicating that the device does not
support this operation. In this case, fall back to using regular write
operations.

Signed-off-by: Damien Le Moal <damien.lem...@wdc.com>
---
 fs/zonefs/super.c  | 16 ++++++++++++----
 fs/zonefs/zonefs.h |  2 ++
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
index 049e36c69ed7..b97566b9dff7 100644
--- a/fs/zonefs/super.c
+++ b/fs/zonefs/super.c
@@ -689,14 +689,15 @@ static ssize_t zonefs_file_dio_append(struct kiocb *iocb, 
struct iov_iter *from)
 {
        struct inode *inode = file_inode(iocb->ki_filp);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
-       struct block_device *bdev = inode->i_sb->s_bdev;
-       unsigned int max;
+       struct super_block *sb = inode->i_sb;
+       struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+       struct block_device *bdev = sb->s_bdev;
+       sector_t max = sbi->s_max_zone_append_sectors;
        struct bio *bio;
        ssize_t size;
        int nr_pages;
        ssize_t ret;
 
-       max = queue_max_zone_append_sectors(bdev_get_queue(bdev));
        max = ALIGN_DOWN(max << SECTOR_SHIFT, inode->i_sb->s_blocksize);
        iov_iter_truncate(from, max);
 
@@ -853,6 +854,8 @@ static ssize_t zonefs_file_dio_write(struct kiocb *iocb, 
struct iov_iter *from)
 
        /* Enforce sequential writes (append only) in sequential zones */
        if (zi->i_ztype == ZONEFS_ZTYPE_SEQ) {
+               struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+
                mutex_lock(&zi->i_truncate_mutex);
                if (iocb->ki_pos != zi->i_wpoffset) {
                        mutex_unlock(&zi->i_truncate_mutex);
@@ -860,7 +863,7 @@ static ssize_t zonefs_file_dio_write(struct kiocb *iocb, 
struct iov_iter *from)
                        goto inode_unlock;
                }
                mutex_unlock(&zi->i_truncate_mutex);
-               append = sync;
+               append = sync && sbi->s_max_zone_append_sectors;
        }
 
        if (append)
@@ -1683,6 +1686,11 @@ static int zonefs_fill_super(struct super_block *sb, 
void *data, int silent)
                sbi->s_mount_opts &= ~ZONEFS_MNTOPT_EXPLICIT_OPEN;
        }
 
+       sbi->s_max_zone_append_sectors =
+               queue_max_zone_append_sectors(bdev_get_queue(sb->s_bdev));
+       if (!sbi->s_max_zone_append_sectors)
+               zonefs_info(sb, "Zone append is not supported: falling back to 
using regular writes\n");
+
        ret = zonefs_read_super(sb);
        if (ret)
                return ret;
diff --git a/fs/zonefs/zonefs.h b/fs/zonefs/zonefs.h
index 51141907097c..2b8c3b1a32ea 100644
--- a/fs/zonefs/zonefs.h
+++ b/fs/zonefs/zonefs.h
@@ -185,6 +185,8 @@ struct zonefs_sb_info {
 
        unsigned int            s_max_open_zones;
        atomic_t                s_open_zones;
+
+       sector_t                s_max_zone_append_sectors;
 };
 
 static inline struct zonefs_sb_info *ZONEFS_SB(struct super_block *sb)
-- 
2.30.2