On 17.11.2017 21:50, Josef Bacik wrote: > From: Josef Bacik <[email protected]> > > We discovered a box that had double allocations, and suspected the space > cache may be to blame. While auditing the write out path I noticed that > if we've already setup the space cache we will just carry on. This > means that any error we hit after cache_save_setup before we go to > actually write the cache out we won't reset the inode generation, so > whatever was already written will be considered correct, except it'll be > stale. Fix this by _always_ resetting the generation on the block group > inode, this way we only ever have valid or invalid cache. > > With this patch I was no longer able to reproduce cache corruption with > dm-log-writes and my bpf error injection tool. >
Is it normal that no function checks the return value of cache_save_setup ? > Cc: [email protected] > Signed-off-by: Josef Bacik <[email protected]> > --- > fs/btrfs/extent-tree.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index e2d7e86b51d1..67b26b209e23 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -3526,13 +3526,6 @@ static int cache_save_setup(struct > btrfs_block_group_cache *block_group, > goto again; > } > > - /* We've already setup this transaction, go ahead and exit */ > - if (block_group->cache_generation == trans->transid && > - i_size_read(inode)) { > - dcs = BTRFS_DC_SETUP; > - goto out_put; > - } > - > /* > * We want to set the generation to 0, that way if anything goes wrong > * from here on out we know not to trust this cache when we load up next > @@ -3556,6 +3549,13 @@ static int cache_save_setup(struct > btrfs_block_group_cache *block_group, > } > WARN_ON(ret); > > + /* We've already setup this transaction, go ahead and exit */ > + if (block_group->cache_generation == trans->transid && > + i_size_read(inode)) { > + dcs = BTRFS_DC_SETUP; > + goto out_put; > + } > + > if (i_size_read(inode) > 0) { > ret = btrfs_check_trunc_cache_free_space(fs_info, > &fs_info->global_block_rsv); > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
