btrfs: use kvcalloc in btrfs_get_dev_zone_info

Otherwise the kernel memory allocator seems to be unhappy about failing
order 6 allocations for the zones array, that cause 100% reproducible
mount failures in my qemu setup:

  [26.078981] mount: page allocation failure: order:6, mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), nodemask=(null)
  [26.079741] CPU: 0 PID: 2965 Comm: mount Not tainted 6.1.0-rc5+ #185
  [26.080181] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
  [26.080950] Call Trace:
  [26.081132]  <TASK>
  [26.081291]  dump_stack_lvl+0x56/0x6f
  [26.081554]  warn_alloc+0x117/0x140
  [26.081808]  ? __alloc_pages_direct_compact+0x1b5/0x300
  [26.082174]  __alloc_pages_slowpath.constprop.0+0xd0e/0xde0
  [26.082569]  __alloc_pages+0x32a/0x340
  [26.082836]  __kmalloc_large_node+0x4d/0xa0
  [26.083133]  ? trace_kmalloc+0x29/0xd0
  [26.083399]  kmalloc_large+0x14/0x60
  [26.083654]  btrfs_get_dev_zone_info+0x1b9/0xc00
  [26.083980]  ? _raw_spin_unlock_irqrestore+0x28/0x50
  [26.084328]  btrfs_get_dev_zone_info_all_devices+0x54/0x80
  [26.084708]  open_ctree+0xed4/0x1654
  [26.084974]  btrfs_mount_root.cold+0x12/0xde
  [26.085288]  ? lock_is_held_type+0xe2/0x140
  [26.085603]  legacy_get_tree+0x28/0x50
  [26.085876]  vfs_get_tree+0x1d/0xb0
  [26.086139]  vfs_kern_mount.part.0+0x6c/0xb0
  [26.086456]  btrfs_mount+0x118/0x3a0
  [26.086728]  ? lock_is_held_type+0xe2/0x140
  [26.087043]  legacy_get_tree+0x28/0x50
  [26.087323]  vfs_get_tree+0x1d/0xb0
  [26.087587]  path_mount+0x2ba/0xbe0
  [26.087850]  ? _raw_spin_unlock_irqrestore+0x38/0x50
  [26.088217]  __x64_sys_mount+0xfe/0x140
  [26.088506]  do_syscall_64+0x35/0x80
  [26.088776]  entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: 5b31646 ("btrfs: get zone information of zoned block devices")
CC: [email protected] # 5.15+
Reviewed-by: Damien Le Moal <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: Christoph Hellwig

fs/btrfs/zoned.c

@@ -467,7 +467,7 @@ int btrfs_get_dev_zone_info(struct btrfs_device *device, bool populate_cache)
 		goto out;
 	}
 
-	zones = kcalloc(BTRFS_REPORT_NR_ZONES, sizeof(struct blk_zone), GFP_KERNEL);
+	zones = kvcalloc(BTRFS_REPORT_NR_ZONES, sizeof(struct blk_zone), GFP_KERNEL);
 	if (!zones) {
 		ret = -ENOMEM;
 		goto out;
@@ -586,7 +586,7 @@ int btrfs_get_dev_zone_info(struct btrfs_device *device, bool populate_cache)
 	}
 
 
-	kfree(zones);
+	kvfree(zones);
 
 	switch (bdev_zoned_model(bdev)) {
 	case BLK_ZONED_HM:
@@ -618,7 +618,7 @@ int btrfs_get_dev_zone_info(struct btrfs_device *device, bool populate_cache)
 	return 0;
 
 out:
-	kfree(zones);
+	kvfree(zones);
 out_free_zone_info:
 	btrfs_destroy_dev_zone_info(device);