On Fri, Apr 6, 2018 at 6:21 AM, David Sterba <dste...@suse.cz> wrote: > On Thu, Apr 05, 2018 at 11:58:16AM -0700, Liu Bo wrote: >> On Thu, Apr 5, 2018 at 9:48 AM, David Sterba <dste...@suse.cz> wrote: >> > On Sat, Mar 31, 2018 at 06:11:55AM +0800, Liu Bo wrote: >> >> This is running in a typical write path, not inside a critical path >> >> where we have to abort the running transaction, so it's OK to return >> >> errors to callers and eventually to userspace. >> > >> > I'm not sure this is entierly correct, several other places do not abort >> > after btrfs_drop_extents as there's nothing that would leave the >> > structres in some half-state. >> > >> >> Signed-off-by: Liu Bo <bo....@linux.alibaba.com> >> >> --- >> >> fs/btrfs/inode.c | 5 +---- >> >> 1 file changed, 1 insertion(+), 4 deletions(-) >> >> >> >> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c >> >> index c7b75dd..b9310f8 100644 >> >> --- a/fs/btrfs/inode.c >> >> +++ b/fs/btrfs/inode.c >> >> @@ -4939,16 +4939,13 @@ static int maybe_insert_hole(struct btrfs_root >> >> *root, struct inode *inode, >> >> >> >> ret = btrfs_drop_extents(trans, root, inode, offset, offset + len, >> >> 1); >> >> if (ret) { >> >> - btrfs_abort_transaction(trans, ret); >> >> btrfs_end_transaction(trans); >> >> return ret; >> >> } >> >> >> >> ret = btrfs_insert_file_extent(trans, root, >> >> btrfs_ino(BTRFS_I(inode)), >> >> offset, 0, 0, len, 0, len, 0, 0, 0); >> > >> > But here the extents have been already dropped and missing to insert the >> > items does not seem to lead to a consistent state. >> > >> > It's possible that I'm missing something. In a call path that can be >> > safely rolled back even with a started transaction, we don't need to >> > abort in all cases. But if the rollback requires some non-trivial >> > modifications, I don't see options how to avoid the abort. >> > >> > __btrfs_drop_extents does a lot of state changes and can itself fail >> > in the middle of dropping the range, aborting looks like the safest >> > option. >> > >> >> As maybe_insert_hole is only called by btrfs_cont_expand here, which >> means it's a really hole, I don't expect drop_extents would drop >> anything, we can remove this drop_extents and put an assert after >> btrfs_insert_file_extent for checking EEXIST. > > Sounds good. >
Let me make a v2 and have a fstests run. thanks, liubo >> It's different from punch hole where we need to explicitly drop an >> actual extent and replace it with a hole range. > > Right, that's what I didn't see at first. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html