[PATCH] Btrfs: add support for mixed data+metadata block groups V3

[Josef Bacik <josef@redhat.com>]

There are just a few things that need to be fixed in the kernel to support mixed
data+metadata block groups.  Mostly we just need to make sure that if we are
using mixed block groups that we continue to allocate mixed block groups as we
need them.  Also we need to make sure __find_space_info will find our space info
if we search for DATA or METADATA only.  Tested this with xfstests and it works
nicely.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
V2->V3: Add btrfs_mixed_space_info helper

V1->V2: In do_chunk_alloc I was changing flags to == space_info->flags, which
isn't right since space_info doesn't carry the RAID profiles anymore, so instead
check to see if the space info has DATA and METADATA set and if so set that in
the flags as well.
 fs/btrfs/ctree.h       |    6 ++++++
 fs/btrfs/extent-tree.c |   22 +++++++++++++++++++---
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1ecd8f6..86a4f4b 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2043,6 +2043,12 @@ static inline struct dentry *fdentry(struct file *file)
 	return file->f_path.dentry;
 }
 
+static inline bool btrfs_mixed_space_info(struct btrfs_space_info *space_info)
+{
+	return ((space_info->flags & BTRFS_BLOCK_GROUP_METADATA) &&
+		(space_info->flags & BTRFS_BLOCK_GROUP_DATA));
+}
+
 /* extent-tree.c */
 void btrfs_put_block_group(struct btrfs_block_group_cache *cache);
 int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 91a0a41..ed84271 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -547,7 +547,7 @@ static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info,
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(found, head, list) {
-		if (found->flags == flags) {
+		if (found->flags & flags) {
 			rcu_read_unlock();
 			return found;
 		}
@@ -3267,6 +3267,13 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
 	spin_unlock(&space_info->lock);
 
 	/*
+	 * If we have mixed data/metadata chunks we want to make sure we keep
+	 * allocating mixed chunks instead of individual chunks.
+	 */
+	if (btrfs_mixed_space_info(space_info))
+		flags |= (BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA);
+
+	/*
 	 * if we're doing a data chunk, go ahead and make sure that
 	 * we keep a reasonable number of metadata chunks allocated in the
 	 * FS as well.
@@ -4793,6 +4800,7 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
 	bool found_uncached_bg = false;
 	bool failed_cluster_refill = false;
 	bool failed_alloc = false;
+	bool use_cluster = true;
 	u64 ideal_cache_percent = 0;
 	u64 ideal_cache_offset = 0;
 
@@ -4807,16 +4815,24 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
 		return -ENOSPC;
 	}
 
+	/*
+	 * If the space info is for both data and metadata it means we have a
+	 * small filesystem and we can't use the clustering stuff.
+	 */
+	if (btrfs_mixed_space_info(space_info))
+		use_cluster = false;
+
 	if (orig_root->ref_cows || empty_size)
 		allowed_chunk_alloc = 1;
 
-	if (data & BTRFS_BLOCK_GROUP_METADATA) {
+	if (data & BTRFS_BLOCK_GROUP_METADATA && use_cluster) {
 		last_ptr = &root->fs_info->meta_alloc_cluster;
 		if (!btrfs_test_opt(root, SSD))
 			empty_cluster = 64 * 1024;
 	}
 
-	if ((data & BTRFS_BLOCK_GROUP_DATA) && btrfs_test_opt(root, SSD)) {
+	if ((data & BTRFS_BLOCK_GROUP_DATA) && use_cluster &&
+	    btrfs_test_opt(root, SSD)) {
 		last_ptr = &root->fs_info->data_alloc_cluster;
 	}
 
-- 
1.6.6.1