So far we have 4 commands to control dedup behaviour,
- btrfs dedup enable
Create the dedup tree, and it's the very first step when you're going to use
the dedup feature.
- btrfs dedup disable
Delete the dedup tree, after this we're not able to use dedup any more unless
you enable it again.
- btrfs dedup on [-b]
Switch on the dedup feature temporarily, and it's the second step of applying
dedup with writes. Option '-b' is used to set dedup blocksize.
The default blocksize is 8192(no special reason, you may argue), and the current
limit is [4096, 128 * 1024], because 4K is the generic page size and 128K is the
upper limit of btrfs's compression.
- btrfs dedup off
Switch off the dedup feature temporarily, but the dedup tree remains.
Signed-off-by: Liu Bo <bo.li....@oracle.com>
---
fs/btrfs/ctree.h | 3 +
fs/btrfs/disk-io.c | 1 +
fs/btrfs/ioctl.c | 167 +++++++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/btrfs.h | 12 ++++
4 files changed, 183 insertions(+)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ca1b516..feebfab 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1740,6 +1740,9 @@ struct btrfs_fs_info {
u64 dedup_bs;
int dedup_type;
+
+ /* protect user change for dedup operations */
+ struct mutex dedup_ioctl_mutex;
};
struct btrfs_subvolume_writers {
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a2586ac..3be947f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2362,6 +2362,7 @@ int open_ctree(struct super_block *sb,
mutex_init(&fs_info->dev_replace.lock_finishing_cancel_unmount);
mutex_init(&fs_info->dev_replace.lock_management_lock);
mutex_init(&fs_info->dev_replace.lock);
+ mutex_init(&fs_info->dedup_ioctl_mutex);
spin_lock_init(&fs_info->qgroup_lock);
mutex_init(&fs_info->qgroup_ioctl_lock);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0401397..45c183c 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4820,6 +4820,171 @@ static int btrfs_ioctl_set_features(struct file *file,
void __user *arg)
return btrfs_commit_transaction(trans, root);
}
+static long btrfs_enable_dedup(struct btrfs_root *root)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_trans_handle *trans = NULL;
+ struct btrfs_root *dedup_root;
+ int ret = 0;
+
+ mutex_lock(&fs_info->dedup_ioctl_mutex);
+ if (fs_info->dedup_root) {
+ pr_info("btrfs: dedup has already been enabled\n");
+ mutex_unlock(&fs_info->dedup_ioctl_mutex);
+ return 0;
+ }
+
+ trans = btrfs_start_transaction(root, 2);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ mutex_unlock(&fs_info->dedup_ioctl_mutex);
+ return ret;
+ }
+
+ dedup_root = btrfs_create_tree(trans, fs_info,
+ BTRFS_DEDUP_TREE_OBJECTID);
+ if (IS_ERR(dedup_root))
+ ret = PTR_ERR(dedup_root);
+
+ if (ret)
+ btrfs_end_transaction(trans, root);
+ else
+ ret = btrfs_commit_transaction(trans, root);
+
+ if (!ret) {
+ pr_info("btrfs: dedup enabled\n");
+ fs_info->dedup_root = dedup_root;
+ fs_info->dedup_root->block_rsv = &fs_info->global_block_rsv;
+ btrfs_set_fs_incompat(fs_info, DEDUP);
+ }
+
+ mutex_unlock(&fs_info->dedup_ioctl_mutex);
+ return ret;
+}
+
+static long btrfs_disable_dedup(struct btrfs_root *root)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_root *dedup_root;
+ int ret;
+
+ mutex_lock(&fs_info->dedup_ioctl_mutex);
+ if (!fs_info->dedup_root) {
+ pr_info("btrfs: dedup has been disabled\n");
+ mutex_unlock(&fs_info->dedup_ioctl_mutex);
+ return 0;
+ }
+
+ if (fs_info->dedup_bs != 0) {
+ pr_info("btrfs: cannot disable dedup until switching off
dedup!\n");
+ mutex_unlock(&fs_info->dedup_ioctl_mutex);
+ return -EBUSY;
+ }
+
+ dedup_root = fs_info->dedup_root;
+
+ ret = btrfs_drop_snapshot(dedup_root, NULL, 1, 0);
+
+ if (!ret) {
+ fs_info->dedup_root = NULL;
+ pr_info("btrfs: dedup disabled\n");
+ }
+
+ mutex_unlock(&fs_info->dedup_ioctl_mutex);
+ WARN_ON(ret < 0 && ret != -EAGAIN && ret != -EROFS);
+ return ret;
+}
+
+static long btrfs_set_dedup_bs(struct btrfs_root *root, u64 bs)
+{
+ struct btrfs_fs_info *info = root->fs_info;
+ int ret = 0;
+
+ mutex_lock(&info->dedup_ioctl_mutex);
+ if (!info->dedup_root) {
+ pr_info("btrfs: dedup is disabled, we cannot switch on/off
dedup\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ bs = ALIGN(bs, root->sectorsize);
+ bs = min_t(u64, bs, (128 * 1024ULL));
+
+ if (bs == info->dedup_bs) {
+ if (info->dedup_bs == 0)
+ pr_info("btrfs: switch OFF dedup(it's already off)\n");
+ else
+ pr_info("btrfs: switch ON dedup(its bs is already
%llu)\n",
+ bs);
+ goto out;
+ }
+
+ /*
+ * The dedup works similar to compression, both use async workqueue to
+ * reach better performance. We drain the on-going async works here
+ * so that new dedup writes will apply with the new dedup blocksize.
+ */
+ atomic_inc(&info->async_submit_draining);
+ while (atomic_read(&info->nr_async_submits) ||
+ atomic_read(&info->async_delalloc_pages)) {
+ wait_event(info->async_submit_wait,
+ (atomic_read(&info->nr_async_submits) == 0 &&
+ atomic_read(&info->async_delalloc_pages) == 0));
+ }
+
+ /*
+ * dedup_bs = 0: dedup off;
+ * dedup_bs > 0: dedup on;
+ */
+ info->dedup_bs = bs;
+ if (info->dedup_bs == 0) {
+ pr_info("btrfs: switch OFF dedup\n");
+ } else {
+ info->dedup_bs = bs;
+ pr_info("btrfs: switch ON dedup(dedup blocksize %llu)\n",
+ info->dedup_bs);
+ }
+ atomic_dec(&info->async_submit_draining);
+
+out:
+ mutex_unlock(&info->dedup_ioctl_mutex);
+ return ret;
+}
+
+static long btrfs_ioctl_dedup_ctl(struct btrfs_root *root, void __user *args)
+{
+ struct btrfs_ioctl_dedup_args *dargs;
+ int ret;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ dargs = memdup_user(args, sizeof(*dargs));
+ if (IS_ERR(dargs)) {
+ ret = PTR_ERR(dargs);
+ goto out;
+ }
+
+ switch (dargs->cmd) {
+ case BTRFS_DEDUP_CTL_ENABLE:
+ ret = btrfs_enable_dedup(root);
+ break;
+ case BTRFS_DEDUP_CTL_DISABLE:
+ ret = btrfs_disable_dedup(root);
+ break;
+ case BTRFS_DEDUP_CTL_SET_BS:
+ /* dedup on/off */
+ ret = btrfs_set_dedup_bs(root, dargs->bs);
+ break;
+ default:
+ ret = -EINVAL;
+ }
+
+ kfree(dargs);
+out:
+ return ret;
+}
+
long btrfs_ioctl(struct file *file, unsigned int
cmd, unsigned long arg)
{
@@ -4942,6 +5107,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_set_fslabel(file, argp);
case BTRFS_IOC_FILE_EXTENT_SAME:
return btrfs_ioctl_file_extent_same(file, argp);
+ case BTRFS_IOC_DEDUP_CTL:
+ return btrfs_ioctl_dedup_ctl(root, argp);
case BTRFS_IOC_GET_SUPPORTED_FEATURES:
return btrfs_ioctl_get_supported_features(file, argp);
case BTRFS_IOC_GET_FEATURES:
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index b4d6909..a300b27 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -405,6 +405,16 @@ struct btrfs_ioctl_get_dev_stats {
__u64 unused[128 - 2 - BTRFS_DEV_STAT_VALUES_MAX]; /* pad to 1k */
};
+/* deduplication control ioctl modes */
+#define BTRFS_DEDUP_CTL_ENABLE 1
+#define BTRFS_DEDUP_CTL_DISABLE 2
+#define BTRFS_DEDUP_CTL_SET_BS 3
+struct btrfs_ioctl_dedup_args {
+ __u64 cmd;
+ __u64 bs;
+ __u64 unused[14];
+};
+
#define BTRFS_QUOTA_CTL_ENABLE 1
#define BTRFS_QUOTA_CTL_DISABLE 2
#define BTRFS_QUOTA_CTL_RESCAN__NOTUSED 3
@@ -612,6 +622,8 @@ static inline char *btrfs_err_str(enum btrfs_err_code
err_code)
struct btrfs_ioctl_dev_replace_args)
#define BTRFS_IOC_FILE_EXTENT_SAME _IOWR(BTRFS_IOCTL_MAGIC, 54, \
struct btrfs_ioctl_same_args)
+#define BTRFS_IOC_DEDUP_CTL _IOWR(BTRFS_IOCTL_MAGIC, 55, \
+ struct btrfs_ioctl_dedup_args)
#define BTRFS_IOC_GET_FEATURES _IOR(BTRFS_IOCTL_MAGIC, 57, \
struct btrfs_ioctl_feature_flags)
#define BTRFS_IOC_SET_FEATURES _IOW(BTRFS_IOCTL_MAGIC, 57, \
--
1.8.1.4
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