[PATCH 10/22] btrfs: alloc space cache inode with GFP_NOFS

[Josef Bacik]

If we're allocating a new space cache inode it's likely going to be
under a transaction handle, so we need to use GFP_NOFS to keep from
deadlocking.  Otherwise GFP_KERNEL is fine.

Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
---
 fs/btrfs/free-space-cache.c | 5 +++++
 fs/btrfs/inode.c            | 3 ++-
 fs/btrfs/transaction.h      | 1 +
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index d5f80cb300be..13bc514e4e16 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -68,7 +68,12 @@ static struct inode *__lookup_free_space_inode(struct 
btrfs_root *root,
        btrfs_disk_key_to_cpu(&location, &disk_key);
        btrfs_release_path(path);
 
+       /* We need this set so that we use GFP_NOFS when allocating our inode. 
*/
+       if (current->journal_info == NULL)
+               current->journal_info = BTRFS_TRANS_STUB;
        inode = btrfs_iget(fs_info->sb, &location, root, NULL);
+       if (current->journal_info == BTRFS_TRANS_STUB)
+               current->journal_info = NULL;
        if (IS_ERR(inode))
                return inode;
        if (is_bad_inode(inode)) {
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index eba61bcb9bb3..14ecfe5d6110 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9211,8 +9211,9 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
        struct btrfs_fs_info *fs_info = btrfs_sb(sb);
        struct btrfs_inode *ei;
        struct inode *inode;
+       gfp_t flags = (current->journal_info) ? GFP_NOFS : GFP_KERNEL;
 
-       ei = kmem_cache_alloc(btrfs_inode_cachep, GFP_KERNEL);
+       ei = kmem_cache_alloc(btrfs_inode_cachep, flags);
        if (!ei)
                return NULL;
 
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 94439482a0ec..172ff923bf15 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -106,6 +106,7 @@ struct btrfs_transaction {
 #define TRANS_EXTWRITERS       (__TRANS_START | __TRANS_ATTACH)
 
 #define BTRFS_SEND_TRANS_STUB  ((void *)1)
+#define BTRFS_TRANS_STUB       ((void *)2)
 
 struct btrfs_trans_handle {
        u64 transid;
-- 
2.14.3

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