[PATCH 5/5] btrfs: use fs netlink interface for ENOSPC conditions

[Lukas Czerner <lczerner@redhat.com>]

Register fs netlink interface and send proper warning if ENOSPC is
encountered. Note that we differentiate between enospc for metadata and
enospc for data.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: linux-btrfs@vger.kernel.org
---
 fs/btrfs/extent-tree.c |   13 ++++++++++---
 fs/btrfs/super.c       |    1 +
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 66bac22..a47d9b9 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3029,13 +3029,14 @@ int btrfs_check_data_free_space(struct inode *inode, u64 bytes)
 {
 	struct btrfs_space_info *data_sinfo;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
 	u64 used;
 	int ret = 0, committed = 0, alloc_chunk = 1;
 
 	/* make sure bytes are sectorsize aligned */
 	bytes = (bytes + root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 
-	if (root == root->fs_info->tree_root ||
+	if (root == fs_info->tree_root ||
 	    BTRFS_I(inode)->location.objectid == BTRFS_FREE_INO_OBJECTID) {
 		alloc_chunk = 0;
 		committed = 1;
@@ -3070,7 +3071,7 @@ alloc:
 			if (IS_ERR(trans))
 				return PTR_ERR(trans);
 
-			ret = do_chunk_alloc(trans, root->fs_info->extent_root,
+			ret = do_chunk_alloc(trans, fs_info->extent_root,
 					     bytes + 2 * 1024 * 1024,
 					     alloc_target,
 					     CHUNK_ALLOC_NO_FORCE);
@@ -3100,7 +3101,7 @@ alloc:
 		/* commit the current transaction and try again */
 commit_trans:
 		if (!committed &&
-		    !atomic_read(&root->fs_info->open_ioctl_trans)) {
+		    !atomic_read(&fs_info->open_ioctl_trans)) {
 			committed = 1;
 			trans = btrfs_join_transaction(root);
 			if (IS_ERR(trans))
@@ -3111,6 +3112,8 @@ commit_trans:
 			goto again;
 		}
 
+		fs_nl_send_warning(fs_info->fs_devices->latest_bdev->bd_dev,
+				   FS_NL_ENOSPC_WARN);
 		return -ENOSPC;
 	}
 	data_sinfo->bytes_may_use += bytes;
@@ -3522,6 +3525,10 @@ again:
 	}
 
 out:
+	if (unlikely(-ENOSPC == ret)) {
+		dev_t bdev = root->fs_info->fs_devices->latest_bdev->bd_dev;
+		fs_nl_send_warning(bdev, FS_NL_META_ENOSPC_WARN);
+	}
 	if (flushing) {
 		spin_lock(&space_info->lock);
 		space_info->flush = 0;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 15634d4..8ac9e01 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1266,6 +1266,7 @@ static int __init init_btrfs_fs(void)
 	if (err)
 		goto unregister_ioctl;
 
+	init_fs_nl_family();
 	printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 	return 0;
 
-- 
1.7.4.4