btrfs: account for non-CoW'd blocks in btrfs_abort_transaction

commit 64c12921e11b3a0c10d088606e328c58e29274d8 upstream.

The test for !trans->blocks_used in btrfs_abort_transaction is
insufficient to determine whether it's safe to drop the transaction
handle on the floor.  btrfs_cow_block, informed by should_cow_block,
can return blocks that have already been CoW'd in the current
transaction.  trans->blocks_used is only incremented for new block
allocations. If an operation overlaps the blocks in the current
transaction entirely and must abort the transaction, we'll happily
let it clean up the trans handle even though it may have modified
the blocks and will commit an incomplete operation.

In the long-term, I'd like to do closer tracking of when the fs
is actually modified so we can still recover as gracefully as possible,
but that approach will need some discussion.  In the short term,
since this is the only code using trans->blocks_used, let's just
switch it to a bool indicating whether any blocks were used and set
it when should_cow_block returns false.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index ec7928a27aaad4c2241ef5b9dcd2048401861085..234707cc419c3d2c4d016a332dfcd37181eff5a1 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1552,6 +1552,7 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
                       trans->transid, root->fs_info->generation);
 
        if (!should_cow_block(trans, root, buf)) {
+               trans->dirty = true;
                *cow_ret = buf;
                return 0;
        }
@@ -2773,8 +2774,10 @@ again:
                         * then we don't want to set the path blocking,
                         * so we test it here
                         */
-                       if (!should_cow_block(trans, root, b))
+                       if (!should_cow_block(trans, root, b)) {
+                               trans->dirty = true;
                                goto cow_done;
+                       }
 
                        /*
                         * must have write locks on this node and the

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 84e060eb0de8c6aca562bcfb537f5236a71e9e66..78f1b57d0b46c4190e87f84374fffc4baf852182 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7929,7 +7929,7 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
                         buf->start + buf->len - 1, GFP_NOFS);
        }
-       trans->blocks_used++;
+       trans->dirty = true;
        /* this returns a buffer locked for blocking */
        return buf;
 }

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 00b8f37cc306df540989a9a888f0fb6cf0eb8a0e..d7c138f42bdf082e0818923da0c3ea1e37a5c446 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -239,7 +239,7 @@ void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
        trans->aborted = errno;
        /* Nothing used. The other threads that have joined this
         * transaction may be able to continue. */
-       if (!trans->blocks_used && list_empty(&trans->new_bgs)) {
+       if (!trans->dirty && list_empty(&trans->new_bgs)) {
                const char *errstr;
 
                errstr = btrfs_decode_error(errno);

diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 72be51f7ca2fbf92507f2e2f36344a6b0a45f1a8..c0b501a5a3531ba8db95dd9e924df12f0aae6640 100644 (file)
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -110,7 +110,6 @@ struct btrfs_trans_handle {
        u64 chunk_bytes_reserved;
        unsigned long use_count;
        unsigned long blocks_reserved;
-       unsigned long blocks_used;
        unsigned long delayed_ref_updates;
        struct btrfs_transaction *transaction;
        struct btrfs_block_rsv *block_rsv;
@@ -121,6 +120,7 @@ struct btrfs_trans_handle {
        bool can_flush_pending_bgs;
        bool reloc_reserved;
        bool sync;
+       bool dirty;
        unsigned int type;
        /*
         * this root is only needed to validate that the root passed to