Btrfs: disallow mutually exclusive admin operations from user mode

Btrfs admin operations that are manually started from user mode
and that cannot be executed at the same time return -EINPROGRESS.
A common way to enter and leave this locked section is introduced
since it used to be specific to the balance operation.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 147406d..e9dc780 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1527,6 +1527,8 @@ struct btrfs_fs_info {
 
        /* device replace state */
        struct btrfs_dev_replace dev_replace;
+
+       atomic_t mutually_exclusive_operation_running;
 };
 
 /*

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b40b827..26f46da 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1317,13 +1317,13 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
 
-       mutex_lock(&root->fs_info->volume_mutex);
-       if (root->fs_info->balance_ctl) {
-               printk(KERN_INFO "btrfs: balance in progress\n");
-               ret = -EINVAL;
-               goto out;
+       if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
+                       1)) {
+               pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+               return -EINPROGRESS;
        }
 
+       mutex_lock(&root->fs_info->volume_mutex);
        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args)) {
                ret = PTR_ERR(vol_args);
@@ -1419,6 +1419,7 @@ out_free:
        kfree(vol_args);
 out:
        mutex_unlock(&root->fs_info->volume_mutex);
+       atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
        return ret;
 }
 
@@ -2160,9 +2161,17 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
        if (btrfs_root_readonly(root))
                return -EROFS;
 
+       if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
+                       1)) {
+               pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+               return -EINPROGRESS;
+       }
        ret = mnt_want_write_file(file);
-       if (ret)
+       if (ret) {
+               atomic_set(&root->fs_info->mutually_exclusive_operation_running,
+                          0);
                return ret;
+       }
 
        switch (inode->i_mode & S_IFMT) {
        case S_IFDIR:
@@ -2214,6 +2223,7 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
        }
 out:
        mnt_drop_write_file(file);
+       atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
        return ret;
 }
 
@@ -2225,13 +2235,13 @@ static long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
 
-       mutex_lock(&root->fs_info->volume_mutex);
-       if (root->fs_info->balance_ctl) {
-               printk(KERN_INFO "btrfs: balance in progress\n");
-               ret = -EINVAL;
-               goto out;
+       if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
+                       1)) {
+               pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+               return -EINPROGRESS;
        }
 
+       mutex_lock(&root->fs_info->volume_mutex);
        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args)) {
                ret = PTR_ERR(vol_args);
@@ -2244,6 +2254,7 @@ static long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
        kfree(vol_args);
 out:
        mutex_unlock(&root->fs_info->volume_mutex);
+       atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
        return ret;
 }
 
@@ -2258,13 +2269,13 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
        if (root->fs_info->sb->s_flags & MS_RDONLY)
                return -EROFS;
 
-       mutex_lock(&root->fs_info->volume_mutex);
-       if (root->fs_info->balance_ctl) {
-               printk(KERN_INFO "btrfs: balance in progress\n");
-               ret = -EINVAL;
-               goto out;
+       if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
+                       1)) {
+               pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+               return -EINPROGRESS;
        }
 
+       mutex_lock(&root->fs_info->volume_mutex);
        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args)) {
                ret = PTR_ERR(vol_args);
@@ -2277,6 +2288,7 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
        kfree(vol_args);
 out:
        mutex_unlock(&root->fs_info->volume_mutex);
+       atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
        return ret;
 }
 
@@ -3319,6 +3331,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
        struct btrfs_ioctl_balance_args *bargs;
        struct btrfs_balance_control *bctl;
        int ret;
+       int need_to_clear_lock = 0;
 
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
@@ -3354,10 +3367,13 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
                bargs = NULL;
        }
 
-       if (fs_info->balance_ctl) {
+       if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
+                       1)) {
+               pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
                ret = -EINPROGRESS;
                goto out_bargs;
        }
+       need_to_clear_lock = 1;
 
        bctl = kzalloc(sizeof(*bctl), GFP_NOFS);
        if (!bctl) {
@@ -3391,6 +3407,9 @@ do_balance:
 out_bargs:
        kfree(bargs);
 out:
+       if (need_to_clear_lock)
+               atomic_set(&root->fs_info->mutually_exclusive_operation_running,
+                          0);
        mutex_unlock(&fs_info->balance_mutex);
        mutex_unlock(&fs_info->volume_mutex);
        mnt_drop_write_file(file);

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index d2c0bcc..33ca36b 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2952,6 +2952,7 @@ static int balance_kthread(void *data)
                ret = btrfs_balance(fs_info->balance_ctl, NULL);
        }
 
+       atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
        mutex_unlock(&fs_info->balance_mutex);
        mutex_unlock(&fs_info->volume_mutex);
 
@@ -2974,6 +2975,7 @@ int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info)
                return 0;
        }
 
+       WARN_ON(atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1));
        tsk = kthread_run(balance_kthread, fs_info, "btrfs-balance");
        if (IS_ERR(tsk))
                return PTR_ERR(tsk);