[PATCH v2 1/2] Btrfs: Check INCOMPAT flags on remount with lzo compression

[Mitch Harder <mitch.harder@sabayonlinux.org>]

In support of the recently added capability to remount with lzo
compression, check the compression INCOMPAT flags when remounting
with lzo compression, and set the flags if necessary.

Signed-off-by: Mitch Harder <mitch.harder@sabayonlinux.org>
---
v1-v2:
- Remove extraneous formatting change.

 fs/btrfs/ctree.h |    1 +
 fs/btrfs/super.c |   18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a0ee2f8..8bee032 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3094,6 +3094,7 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size);
 
 /* super.c */
 int btrfs_parse_options(struct btrfs_root *root, char *options);
+void btrfs_chk_lzo_incompat(struct btrfs_root *root);
 int btrfs_sync_fs(struct super_block *sb, int wait);
 void btrfs_printk(struct btrfs_fs_info *fs_info, const char *fmt, ...);
 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 26da344..f3a5967 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -401,6 +401,7 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 				compress_type = "lzo";
 				info->compress_type = BTRFS_COMPRESS_LZO;
 				btrfs_set_opt(info->mount_opt, COMPRESS);
+				btrfs_chk_lzo_incompat(root);
 			} else if (strncmp(args[0].from, "no", 2) == 0) {
 				compress_type = "no";
 				info->compress_type = BTRFS_COMPRESS_NONE;
@@ -587,6 +588,23 @@ out:
 }
 
 /*
+ * Check the INCOMPAT features in the super block, and set the
+ * LZO INCOMPAT flag if it has not been set.
+ */
+void btrfs_chk_lzo_incompat(struct btrfs_root *root)
+{
+	struct btrfs_super_block *disk_super;
+	u64 features;
+
+	disk_super = root->fs_info->super_copy;
+	features = btrfs_super_incompat_flags(disk_super);
+	if (!(features & BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO)) {
+		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
+		btrfs_set_super_incompat_flags(disk_super, features);
+	}
+}
+
+/*
  * Parse mount options that are required early in the mount process.
  *
  * All other options will be parsed on much later in the mount process and
-- 
1.7.8.6