[v2,06/13] btrfs: create helper function __check_raid_min_devices()

Commit Message

Anand Jain Feb. 13, 2016, 2:01 a.m. UTC

move a section of btrfs_rm_device() code to check for min number of the
devices into the function __check_raid_min_devices()

Signed-off-by: Anand Jain <[e-mail]>
---
v2: commit update and title renamed from
    Btrfs: move check for min number of devices to a function
 fs/btrfs/volumes.c | 51 ++++++++++++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 19 deletions(-)

Comments

David Sterba Feb. 15, 2016, 2:51 p.m. UTC | #1

On Sat, Feb 13, 2016 at 10:01:33AM +0800, Anand Jain wrote:
> move a section of btrfs_rm_device() code to check for min number of the
> devices into the function __check_raid_min_devices()

But this also changes the semantics a bit. In context of device remove
we check if there are going to be enough devices after removal, while
the new helper __check_raid_min_devices should verify that a given
number of devices is OK.

In a pseudo code:

__check_raid_min_devices(fs_info, num_devices) {
	/* check the device constraints */
}

btrfs_rm_device() {
	num_devices = <read number of devices>;

	if (!__check_raid_min_devices(num_devices - 1))
		goto error;
}

As there's only one user of the __check_raid_min_devices function, this
would not break bisection etc, but I'm going to clean it up in followup
patches. There are more changes, I'll send it to the mailing list when
done.
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 76133e0..506d1fd 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1703,23 +1703,20 @@  out:
 	return ret;
 }
 
-int btrfs_rm_device(struct btrfs_root *root, char *device_path)
+static int __check_raid_min_devices(struct btrfs_root *root)
 {
-	struct btrfs_device *device;
-	struct btrfs_device *next_device;
-	struct block_device *bdev;
-	struct buffer_head *bh = NULL;
-	struct btrfs_super_block *disk_super;
-	struct btrfs_fs_devices *cur_devices;
 	u64 all_avail;
-	u64 devid;
 	u64 num_devices;
-	u8 *dev_uuid;
 	unsigned seq;
 	int ret = 0;
-	bool clear_super = false;
 
-	mutex_lock(&uuid_mutex);
+	num_devices = root->fs_info->fs_devices->num_devices;
+	btrfs_dev_replace_lock(&root->fs_info->dev_replace);
+	if (btrfs_dev_replace_is_ongoing(&root->fs_info->dev_replace)) {
+		WARN_ON(num_devices < 1);
+		num_devices--;
+	}
+	btrfs_dev_replace_unlock(&root->fs_info->dev_replace);
 
 	do {
 		seq = read_seqbegin(&root->fs_info->profiles_lock);
@@ -1729,14 +1726,6 @@  int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 			    root->fs_info->avail_metadata_alloc_bits;
 	} while (read_seqretry(&root->fs_info->profiles_lock, seq));
 
-	num_devices = root->fs_info->fs_devices->num_devices;
-	btrfs_dev_replace_lock(&root->fs_info->dev_replace);
-	if (btrfs_dev_replace_is_ongoing(&root->fs_info->dev_replace)) {
-		WARN_ON(num_devices < 1);
-		num_devices--;
-	}
-	btrfs_dev_replace_unlock(&root->fs_info->dev_replace);
-
 	if ((all_avail & BTRFS_BLOCK_GROUP_RAID10) && num_devices <= 4) {
 		ret = BTRFS_ERROR_DEV_RAID10_MIN_NOT_MET;
 		goto out;
@@ -1758,6 +1747,30 @@  int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 		goto out;
 	}
 
+out:
+	return ret;
+}
+
+int btrfs_rm_device(struct btrfs_root *root, char *device_path)
+{
+	struct btrfs_device *device;
+	struct btrfs_device *next_device;
+	struct block_device *bdev;
+	struct buffer_head *bh = NULL;
+	struct btrfs_super_block *disk_super;
+	struct btrfs_fs_devices *cur_devices;
+	u64 devid;
+	u64 num_devices;
+	u8 *dev_uuid;
+	int ret = 0;
+	bool clear_super = false;
+
+	mutex_lock(&uuid_mutex);
+
+	ret = __check_raid_min_devices(root);
+	if (ret)
+		goto out;
+
 	if (strcmp(device_path, "missing") == 0) {
 		struct list_head *devices;
 		struct btrfs_device *tmp;