Btrfs: fix race between send and deduplication that lead to failures and crashes

[tomoyo/tomoyo-test1.git] / fs / btrfs / ioctl.c

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 19b0ee4..7755b50 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3262,6 +3262,19 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
 {
        int ret;
        u64 i, tail_len, chunk_count;
+       struct btrfs_root *root_dst = BTRFS_I(dst)->root;
+
+       spin_lock(&root_dst->root_item_lock);
+       if (root_dst->send_in_progress) {
+               btrfs_warn_rl(root_dst->fs_info,
+"cannot deduplicate to root %llu while send operations are using it (%d in progress)",
+                             root_dst->root_key.objectid,
+                             root_dst->send_in_progress);
+               spin_unlock(&root_dst->root_item_lock);
+               return -EAGAIN;
+       }
+       root_dst->dedupe_in_progress++;
+       spin_unlock(&root_dst->root_item_lock);
 
        tail_len = olen % BTRFS_MAX_DEDUPE_LEN;
        chunk_count = div_u64(olen, BTRFS_MAX_DEDUPE_LEN);
@@ -3270,7 +3283,7 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
                ret = btrfs_extent_same_range(src, loff, BTRFS_MAX_DEDUPE_LEN,
                                              dst, dst_loff);
                if (ret)
-                       return ret;
+                       goto out;
 
                loff += BTRFS_MAX_DEDUPE_LEN;
                dst_loff += BTRFS_MAX_DEDUPE_LEN;
@@ -3279,6 +3292,10 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
        if (tail_len > 0)
                ret = btrfs_extent_same_range(src, loff, tail_len, dst,
                                              dst_loff);
+out:
+       spin_lock(&root_dst->root_item_lock);
+       root_dst->dedupe_in_progress--;
+       spin_unlock(&root_dst->root_item_lock);
 
        return ret;
 }