提交 c7309e88 编写于 作者: L Linus Torvalds

Merge branch 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

Pull btrfs fixes from Chris Mason:
 "The first commit is a fix from Filipe for a very old extent buffer
  reuse race that triggered a BUG_ON.  It hasn't come up often, I looked
  through old logs at FB and we hit it a handful of times over the last
  year.

  The rest are other corners he hit during testing"

* 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix race when reusing stale extent buffers that leads to BUG_ON
  Btrfs: fix race between block group creation and their cache writeout
  Btrfs: fix panic when starting bg cache writeout after IO error
  Btrfs: fix crash after inode cache writeback failure
......@@ -3180,8 +3180,6 @@ static int write_one_cache_group(struct btrfs_trans_handle *trans,
btrfs_mark_buffer_dirty(leaf);
fail:
btrfs_release_path(path);
if (ret)
btrfs_abort_transaction(trans, root, ret);
return ret;
}
......@@ -3487,8 +3485,30 @@ int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans,
ret = 0;
}
}
if (!ret)
if (!ret) {
ret = write_one_cache_group(trans, root, path, cache);
/*
* Our block group might still be attached to the list
* of new block groups in the transaction handle of some
* other task (struct btrfs_trans_handle->new_bgs). This
* means its block group item isn't yet in the extent
* tree. If this happens ignore the error, as we will
* try again later in the critical section of the
* transaction commit.
*/
if (ret == -ENOENT) {
ret = 0;
spin_lock(&cur_trans->dirty_bgs_lock);
if (list_empty(&cache->dirty_list)) {
list_add_tail(&cache->dirty_list,
&cur_trans->dirty_bgs);
btrfs_get_block_group(cache);
}
spin_unlock(&cur_trans->dirty_bgs_lock);
} else if (ret) {
btrfs_abort_transaction(trans, root, ret);
}
}
/* if its not on the io list, we need to put the block group */
if (should_put)
......@@ -3597,8 +3617,11 @@ int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
ret = 0;
}
}
if (!ret)
if (!ret) {
ret = write_one_cache_group(trans, root, path, cache);
if (ret)
btrfs_abort_transaction(trans, root, ret);
}
/* if its not on the io list, we need to put the block group */
if (should_put)
......
......@@ -4772,6 +4772,25 @@ struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
start >> PAGE_CACHE_SHIFT);
if (eb && atomic_inc_not_zero(&eb->refs)) {
rcu_read_unlock();
/*
* Lock our eb's refs_lock to avoid races with
* free_extent_buffer. When we get our eb it might be flagged
* with EXTENT_BUFFER_STALE and another task running
* free_extent_buffer might have seen that flag set,
* eb->refs == 2, that the buffer isn't under IO (dirty and
* writeback flags not set) and it's still in the tree (flag
* EXTENT_BUFFER_TREE_REF set), therefore being in the process
* of decrementing the extent buffer's reference count twice.
* So here we could race and increment the eb's reference count,
* clear its stale flag, mark it as dirty and drop our reference
* before the other task finishes executing free_extent_buffer,
* which would later result in an attempt to free an extent
* buffer that is dirty.
*/
if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) {
spin_lock(&eb->refs_lock);
spin_unlock(&eb->refs_lock);
}
mark_extent_buffer_accessed(eb, NULL);
return eb;
}
......
......@@ -3466,6 +3466,7 @@ int btrfs_write_out_ino_cache(struct btrfs_root *root,
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
int ret;
struct btrfs_io_ctl io_ctl;
bool release_metadata = true;
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return 0;
......@@ -3473,11 +3474,20 @@ int btrfs_write_out_ino_cache(struct btrfs_root *root,
memset(&io_ctl, 0, sizeof(io_ctl));
ret = __btrfs_write_out_cache(root, inode, ctl, NULL, &io_ctl,
trans, path, 0);
if (!ret)
if (!ret) {
/*
* At this point writepages() didn't error out, so our metadata
* reservation is released when the writeback finishes, at
* inode.c:btrfs_finish_ordered_io(), regardless of it finishing
* with or without an error.
*/
release_metadata = false;
ret = btrfs_wait_cache_io(root, trans, NULL, &io_ctl, path, 0);
}
if (ret) {
btrfs_delalloc_release_metadata(inode, inode->i_size);
if (release_metadata)
btrfs_delalloc_release_metadata(inode, inode->i_size);
#ifdef DEBUG
btrfs_err(root->fs_info,
"failed to write free ino cache for root %llu",
......
......@@ -722,6 +722,7 @@ void btrfs_start_ordered_extent(struct inode *inode,
int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
{
int ret = 0;
int ret_wb = 0;
u64 end;
u64 orig_end;
struct btrfs_ordered_extent *ordered;
......@@ -741,9 +742,14 @@ int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
if (ret)
return ret;
ret = filemap_fdatawait_range(inode->i_mapping, start, orig_end);
if (ret)
return ret;
/*
* If we have a writeback error don't return immediately. Wait first
* for any ordered extents that haven't completed yet. This is to make
* sure no one can dirty the same page ranges and call writepages()
* before the ordered extents complete - to avoid failures (-EEXIST)
* when adding the new ordered extents to the ordered tree.
*/
ret_wb = filemap_fdatawait_range(inode->i_mapping, start, orig_end);
end = orig_end;
while (1) {
......@@ -767,7 +773,7 @@ int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
break;
end--;
}
return ret;
return ret_wb ? ret_wb : ret;
}
/*
......
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