diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 27a9342cd91c5..2118c22625cad 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -5027,6 +5027,132 @@ int btrfs_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) return -EINVAL; } +static int btrfs_ioctl_subvol_sync(struct btrfs_fs_info *fs_info, void __user *argp) +{ + struct btrfs_root *root; + struct btrfs_ioctl_subvol_wait args = { 0 }; + signed long sched_ret; + int refs; + u64 root_flags; + bool wait_for_deletion = false; + bool found = false; + + if (copy_from_user(&args, argp, sizeof(args))) + return -EFAULT; + + switch (args.mode) { + case BTRFS_SUBVOL_SYNC_WAIT_FOR_QUEUED: + /* + * Wait for the first one deleted that waits until all previous + * are cleaned. + */ + spin_lock(&fs_info->trans_lock); + if (!list_empty(&fs_info->dead_roots)) { + root = list_last_entry(&fs_info->dead_roots, + struct btrfs_root, root_list); + args.subvolid = btrfs_root_id(root); + found = true; + } + spin_unlock(&fs_info->trans_lock); + if (!found) + return -ENOENT; + + fallthrough; + case BTRFS_SUBVOL_SYNC_WAIT_FOR_ONE: + if ((0 < args.subvolid && args.subvolid < BTRFS_FIRST_FREE_OBJECTID) || + BTRFS_LAST_FREE_OBJECTID < args.subvolid) + return -EINVAL; + break; + case BTRFS_SUBVOL_SYNC_COUNT: + spin_lock(&fs_info->trans_lock); + args.count = list_count_nodes(&fs_info->dead_roots); + spin_unlock(&fs_info->trans_lock); + if (copy_to_user(argp, &args, sizeof(args))) + return -EFAULT; + return 0; + case BTRFS_SUBVOL_SYNC_PEEK_FIRST: + spin_lock(&fs_info->trans_lock); + /* Last in the list was deleted first. */ + if (!list_empty(&fs_info->dead_roots)) { + root = list_last_entry(&fs_info->dead_roots, + struct btrfs_root, root_list); + args.subvolid = btrfs_root_id(root); + } else { + args.subvolid = 0; + } + spin_unlock(&fs_info->trans_lock); + if (copy_to_user(argp, &args, sizeof(args))) + return -EFAULT; + return 0; + case BTRFS_SUBVOL_SYNC_PEEK_LAST: + spin_lock(&fs_info->trans_lock); + /* First in the list was deleted last. */ + if (!list_empty(&fs_info->dead_roots)) { + root = list_first_entry(&fs_info->dead_roots, + struct btrfs_root, root_list); + args.subvolid = btrfs_root_id(root); + } else { + args.subvolid = 0; + } + spin_unlock(&fs_info->trans_lock); + if (copy_to_user(argp, &args, sizeof(args))) + return -EFAULT; + return 0; + default: + return -EINVAL; + } + + /* 32bit limitation: fs_roots_radix key is not wide enough. */ + if (sizeof(unsigned long) != sizeof(u64) && args.subvolid > U32_MAX) + return -EOVERFLOW; + + while (1) { + /* Wait for the specific one. */ + if (down_read_interruptible(&fs_info->subvol_sem) == -EINTR) + return -EINTR; + refs = -1; + spin_lock(&fs_info->fs_roots_radix_lock); + root = radix_tree_lookup(&fs_info->fs_roots_radix, + (unsigned long)args.subvolid); + if (root) { + spin_lock(&root->root_item_lock); + refs = btrfs_root_refs(&root->root_item); + root_flags = btrfs_root_flags(&root->root_item); + spin_unlock(&root->root_item_lock); + } + spin_unlock(&fs_info->fs_roots_radix_lock); + up_read(&fs_info->subvol_sem); + + /* Subvolume does not exist. */ + if (!root) + return -ENOENT; + + /* Subvolume not deleted at all. */ + if (refs > 0) + return -EEXIST; + /* We've waited and now the subvolume is gone. */ + if (wait_for_deletion && refs == -1) { + /* Return the one we waited for as the last one. */ + if (copy_to_user(argp, &args, sizeof(args))) + return -EFAULT; + return 0; + } + + /* Subvolume not found on the first try (deleted or never existed). */ + if (refs == -1) + return -ENOENT; + + wait_for_deletion = true; + ASSERT(root_flags & BTRFS_ROOT_SUBVOL_DEAD); + sched_ret = schedule_timeout_interruptible(HZ); + /* Early wake up or error. */ + if (sched_ret != 0) + return -EINTR; + } + + return 0; +} + long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { @@ -5178,6 +5304,8 @@ long btrfs_ioctl(struct file *file, unsigned int case BTRFS_IOC_ENCODED_WRITE_32: return btrfs_ioctl_encoded_write(file, argp, true); #endif + case BTRFS_IOC_SUBVOL_SYNC_WAIT: + return btrfs_ioctl_subvol_sync(fs_info, argp); } return -ENOTTY; diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h index cdf6ad872149c..d3b222d7af240 100644 --- a/include/uapi/linux/btrfs.h +++ b/include/uapi/linux/btrfs.h @@ -1049,6 +1049,29 @@ struct btrfs_ioctl_encoded_io_args { #define BTRFS_ENCODED_IO_ENCRYPTION_NONE 0 #define BTRFS_ENCODED_IO_ENCRYPTION_TYPES 1 +/* + * Wait for subvolume cleaning process. This queries the kernel queue and it + * can change between the calls. + * + * - FOR_ONE - specify the subvolid + * - FOR_QUEUED - wait for all currently queued + * - COUNT - count number of queued + * - PEEK_FIRST - read which is the first in the queue (to be cleaned or being + * cleaned already), or 0 if the queue is empty + * - PEEK_LAST - read the last subvolid in the queue, or 0 if the queue is empty + */ +struct btrfs_ioctl_subvol_wait { + __u64 subvolid; + __u32 mode; + __u32 count; +}; + +#define BTRFS_SUBVOL_SYNC_WAIT_FOR_ONE (0) +#define BTRFS_SUBVOL_SYNC_WAIT_FOR_QUEUED (1) +#define BTRFS_SUBVOL_SYNC_COUNT (2) +#define BTRFS_SUBVOL_SYNC_PEEK_FIRST (3) +#define BTRFS_SUBVOL_SYNC_PEEK_LAST (4) + /* Error codes as returned by the kernel */ enum btrfs_err_code { BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET = 1, @@ -1181,6 +1204,8 @@ enum btrfs_err_code { struct btrfs_ioctl_encoded_io_args) #define BTRFS_IOC_ENCODED_WRITE _IOW(BTRFS_IOCTL_MAGIC, 64, \ struct btrfs_ioctl_encoded_io_args) +#define BTRFS_IOC_SUBVOL_SYNC_WAIT _IOW(BTRFS_IOCTL_MAGIC, 65, \ + struct btrfs_ioctl_subvol_wait) #ifdef __cplusplus }