On Sat, Jan 18, 2014 at 4:58 AM, Wang Shilong
<wangsl.fnst@xxxxxxxxxxxxxx> wrote:
> Steps to reproduce:
> # mkfs.btrfs -f /dev/sda8
> # mount /dev/sda8 /mnt
> # btrfs sub snapshot -r /mnt /mnt/snap1
> # btrfs sub snapshot -r /mnt /mnt/snap2
> # btrfs send /mnt/snap1 -p /mnt/snap2 -f /mnt/1
> # dmesg
>
> The problem is that we will sort clone roots(include @send_root), it
> might push @send_root before thus @send_root's @send_in_progress will
> be decreased twice.
>
> Cc: David Sterba <dsterba@xxxxxxx>
> Signed-off-by: Wang Shilong <wangsl.fnst@xxxxxxxxxxxxxx>
> ---
> changelog
> v2->v3:
> add comments as david addressed.
> v1->v2:
> use right root to check
> ---
> fs/btrfs/send.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
> index bff0b1a..83b6bdb 100644
> --- a/fs/btrfs/send.c
> +++ b/fs/btrfs/send.c
> @@ -4752,6 +4752,7 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
> u32 i;
> u64 *clone_sources_tmp = NULL;
> int clone_sources_to_rollback = 0;
> + int sort_clone_roots = 0;
>
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -4942,6 +4943,7 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
> sort(sctx->clone_roots, sctx->clone_roots_cnt,
> sizeof(*sctx->clone_roots), __clone_root_cmp_sort,
> NULL);
> + sort_clone_roots = 1;
>
> ret = send_subvol(sctx);
> if (ret < 0)
> @@ -4957,11 +4959,22 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
> }
>
> out:
> - for (i = 0; sctx && i < clone_sources_to_rollback; i++)
> - btrfs_root_dec_send_in_progress(sctx->clone_roots[i].root);
> + if (sort_clone_roots) {
> + for (i = 0; i < sctx->clone_roots_cnt; i++)
> + btrfs_root_dec_send_in_progress(
> + sctx->clone_roots[i].root);
sctx can be NULL here, anywhere after the 'out' label.
> + } else {
> + for (i = 0; sctx && i < clone_sources_to_rollback; i++)
> + btrfs_root_dec_send_in_progress(
> + sctx->clone_roots[i].root);
Same here.
> + /*
> + * if we fail to add @send_root in clone roots, we still
> + * need to decrease @send_in_progress count here.
> + */
> + btrfs_root_dec_send_in_progress(send_root);
> + }
> if (sctx && !IS_ERR_OR_NULL(sctx->parent_root))
> btrfs_root_dec_send_in_progress(sctx->parent_root);
> - btrfs_root_dec_send_in_progress(send_root);
>
> kfree(arg);
> vfree(clone_sources_tmp);
> --
> 1.8.3.1
>
> --
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--
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"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."
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