[PATCH] Btrfs: fix allocationg memory failure for btrfsic_state structure

[Wang Shilong <wangshilong1991@gmail.com>]

size of @btrfsic_state needs more than 2M, it is very likely to
fail allocating memory using kzalloc(). see following mesage:

[91428.902148] Call Trace:
[<ffffffff816f6e0f>] dump_stack+0x4d/0x66
[<ffffffff811b1c7f>] warn_alloc_failed+0xff/0x170
[<ffffffff811b66e1>] __alloc_pages_nodemask+0x951/0xc30
[<ffffffff811fd9da>] alloc_pages_current+0x11a/0x1f0
[<ffffffff811b1e0b>] ? alloc_kmem_pages+0x3b/0xf0
[<ffffffff811b1e0b>] alloc_kmem_pages+0x3b/0xf0
[<ffffffff811d1018>] kmalloc_order+0x18/0x50
[<ffffffff811d1074>] kmalloc_order_trace+0x24/0x140
[<ffffffffa06c097b>] btrfsic_mount+0x8b/0xae0 [btrfs]
[<ffffffff810af555>] ? check_preempt_curr+0x85/0xa0
[<ffffffff810b2de3>] ? try_to_wake_up+0x103/0x430
[<ffffffffa063d200>] open_ctree+0x1bd0/0x2130 [btrfs]
[<ffffffffa060fdde>] btrfs_mount+0x62e/0x8b0 [btrfs]
[<ffffffff811fd9da>] ? alloc_pages_current+0x11a/0x1f0
[<ffffffff811b0a5e>] ? __get_free_pages+0xe/0x50
[<ffffffff81230429>] mount_fs+0x39/0x1b0
[<ffffffff812509fb>] vfs_kern_mount+0x6b/0x150
[<ffffffff812537fb>] do_mount+0x27b/0xc30
[<ffffffff811b0a5e>] ? __get_free_pages+0xe/0x50
[<ffffffff812544f6>] SyS_mount+0x96/0xf0
[<ffffffff81701970>] system_call_fastpath+0x16/0x1b

Since we are allocating memory for hash table array, so
it will be good if we could allocate continuous pages here.

Fix this problem by firstly trying kzalloc(), if we fail,
use vzalloc() instead.

Signed-off-by: Wang Shilong <wangshilong1991@gmail.com>
---
 fs/btrfs/check-integrity.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index cb7f3fe..66e820f 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -3130,10 +3130,13 @@ int btrfsic_mount(struct btrfs_root *root,
 		       root->sectorsize, PAGE_CACHE_SIZE);
 		return -1;
 	}
-	state = kzalloc(sizeof(*state), GFP_NOFS);
-	if (NULL == state) {
-		printk(KERN_INFO "btrfs check-integrity: kmalloc() failed!\n");
-		return -1;
+	state = kzalloc(sizeof(*state), GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
+	if (!state) {
+		state = vzalloc(sizeof(*state));
+		if (!state) {
+			printk(KERN_INFO "btrfs check-integrity: vzalloc() failed!\n");
+			return -1;
+		}
 	}
 
 	if (!btrfsic_is_initialized) {
@@ -3277,5 +3280,8 @@ void btrfsic_unmount(struct btrfs_root *root,
 
 	mutex_unlock(&btrfsic_mutex);
 
-	kfree(state);
+	if (is_vmalloc_addr(state))
+		vfree(state);
+	else
+		kfree(state);
 }
-- 
1.8.3.1