bcachefs: statfs resports incorrect avail blocks

The current implementation of bch_statfs does not scale the number of
available blocks provided in f_bavail by the reserve factor. This causes
an allocation of a file of this size to fail.
Signed-off-by: Dan Robertson <dan@dlrobertson.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/buckets.c

@@ -261,18 +261,11 @@ void bch2_fs_usage_to_text(struct printbuf *out,
 	}
 }
 
-#define RESERVE_FACTOR	6
-
 static u64 reserve_factor(u64 r)
 {
 	return r + (round_up(r, (1 << RESERVE_FACTOR)) >> RESERVE_FACTOR);
 }
 
-static u64 avail_factor(u64 r)
-{
-	return div_u64(r << RESERVE_FACTOR, (1 << RESERVE_FACTOR) + 1);
-}
-
 u64 bch2_fs_sectors_used(struct bch_fs *c, struct bch_fs_usage_online *fs_usage)
 {
 	return min(fs_usage->u.hidden +

fs/bcachefs/buckets.h

@@ -294,6 +294,13 @@ static inline int bch2_disk_reservation_get(struct bch_fs *c,
 	return bch2_disk_reservation_add(c, res, sectors * nr_replicas, flags);
 }
 
+#define RESERVE_FACTOR	6
+
+static inline u64 avail_factor(u64 r)
+{
+	return div_u64(r << RESERVE_FACTOR, (1 << RESERVE_FACTOR) + 1);
+}
+
 int bch2_dev_buckets_resize(struct bch_fs *, struct bch_dev *, u64);
 void bch2_dev_buckets_free(struct bch_dev *);
 int bch2_dev_buckets_alloc(struct bch_fs *, struct bch_dev *);

fs/bcachefs/fs.c

@@ -1274,8 +1274,8 @@ static int bch2_statfs(struct dentry *dentry, struct kstatfs *buf)
 	buf->f_type	= BCACHEFS_STATFS_MAGIC;
 	buf->f_bsize	= sb->s_blocksize;
 	buf->f_blocks	= usage.capacity >> shift;
-	buf->f_bfree	= (usage.capacity - usage.used) >> shift;
-	buf->f_bavail	= buf->f_bfree;
+	buf->f_bfree	= usage.free >> shift;
+	buf->f_bavail	= avail_factor(usage.free) >> shift;
 
 	buf->f_files	= usage.nr_inodes + avail_inodes;
 	buf->f_ffree	= avail_inodes;