This patch adds an ioctl for cancelling a btrfs balance operation
mid-flight. The ioctl simply sets a flag, and the operation terminates
after the current block group move has completed.
Signed-off-by: Hugo Mills <hugo@xxxxxxxxxxxxx>
---
fs/btrfs/ctree.h | 1 +
fs/btrfs/ioctl.c | 28 ++++++++++++++++++++++++++++
fs/btrfs/ioctl.h | 1 +
fs/btrfs/volumes.c | 7 ++++++-
4 files changed, 36 insertions(+), 1 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 25aa3cf..5031085 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -876,6 +876,7 @@ struct btrfs_block_group_cache {
struct btrfs_balance_info {
u32 expected;
u32 completed;
+ int cancel_pending;
};
struct reloc_control;
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 5ddf816..d4458d0 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2868,6 +2868,32 @@ error:
return ret;
}
+/*
+ * Cancel a running balance operation
+ */
+long btrfs_ioctl_balance_cancel(struct btrfs_fs_info *fs_info)
+{
+ int err = 0;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ spin_lock(&fs_info->balance_info_lock);
+ if (!fs_info->balance_info) {
+ err = -EINVAL;
+ goto error;
+ }
+ if (fs_info->balance_info->cancel_pending) {
+ err = -ECANCELED;
+ goto error;
+ }
+ fs_info->balance_info->cancel_pending = 1;
+
+error:
+ spin_unlock(&fs_info->balance_info_lock);
+ return err;
+}
+
long btrfs_ioctl(struct file *file, unsigned int
cmd, unsigned long arg)
{
@@ -2915,6 +2941,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_balance(root->fs_info->dev_root);
case BTRFS_IOC_BALANCE_PROGRESS:
return btrfs_ioctl_balance_progress(root->fs_info, argp);
+ case BTRFS_IOC_BALANCE_CANCEL:
+ return btrfs_ioctl_balance_cancel(root->fs_info);
case BTRFS_IOC_CLONE:
return btrfs_ioctl_clone(file, arg, 0, 0, 0);
case BTRFS_IOC_CLONE_RANGE:
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 575b25f..edcbe61 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -255,4 +255,5 @@ struct btrfs_ioctl_balance_progress {
struct btrfs_ioctl_fs_info_args)
#define BTRFS_IOC_BALANCE_PROGRESS _IOR(BTRFS_IOCTL_MAGIC, 32, \
struct btrfs_ioctl_balance_progress)
+#define BTRFS_IOC_BALANCE_CANCEL _IO(BTRFS_IOCTL_MAGIC, 33)
#endif
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 4c0a386..f38b231 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2049,6 +2049,7 @@ int btrfs_balance(struct btrfs_root *dev_root)
bal_info->expected = -1; /* One less than actually counted,
because chunk 0 is special */
bal_info->completed = 0;
+ bal_info->cancel_pending = 0;
spin_unlock(&dev_root->fs_info->balance_info_lock);
/* step one make some room on all the devices */
@@ -2109,7 +2110,7 @@ int btrfs_balance(struct btrfs_root *dev_root)
key.offset = (u64)-1;
key.type = BTRFS_CHUNK_ITEM_KEY;
- while (1) {
+ while (!bal_info->cancel_pending) {
ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
if (ret < 0)
goto error;
@@ -2149,6 +2150,10 @@ int btrfs_balance(struct btrfs_root *dev_root)
bal_info->completed, bal_info->expected);
}
ret = 0;
+ if (bal_info->cancel_pending) {
+ printk(KERN_INFO "btrfs: balance cancelled\n");
+ ret = -EINTR;
+ }
error:
btrfs_free_path(path);
spin_lock(&dev_root->fs_info->balance_info_lock);
--
1.7.2.5
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