On Tue, Apr 12, 2011 at 09:33:03AM +0800, liubo wrote:
> On 04/12/2011 08:30 AM, Josef Bacik wrote:
> > Everytime we try to allocate disk space we try and see if we can pre-emptively
> > allocate a chunk, but in the common case we don't allocate anything, so there is
> > no sense in taking the chunk_mutex at all. So instead if we are allocating a
> > chunk, mark it in the space_info so we don't get two people trying to allocate
> > at the same time. Thanks,
> >
> > Signed-off-by: Josef Bacik <josef@xxxxxxxxxx>
> > ---
> > fs/btrfs/ctree.h | 5 +++--
> > fs/btrfs/extent-tree.c | 24 ++++++++++++++++++++++--
> > 2 files changed, 25 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> > index 0d00a07..a566780 100644
> > --- a/fs/btrfs/ctree.h
> > +++ b/fs/btrfs/ctree.h
> > @@ -740,10 +740,11 @@ struct btrfs_space_info {
> > */
> > unsigned long reservation_progress;
> >
> > - int full; /* indicates that we cannot allocate any more
> > + int full:1; /* indicates that we cannot allocate any more
> > chunks for this space */
> > - int force_alloc; /* set if we need to force a chunk alloc for
> > + int force_alloc:1; /* set if we need to force a chunk alloc for
> > this space */
> > + int chunk_alloc:1; /* set if we are allocating a chunk */
> >
> > struct list_head list;
> >
> > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> > index f619c3c..80c048f 100644
> > --- a/fs/btrfs/extent-tree.c
> > +++ b/fs/btrfs/extent-tree.c
> > @@ -3020,6 +3020,7 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
> > found->bytes_may_use = 0;
> > found->full = 0;
> > found->force_alloc = 0;
> > + found->chunk_alloc = 0;
> > *space_info = found;
> > list_add_rcu(&found->list, &info->space_info);
> > atomic_set(&found->caching_threads, 0);
> > @@ -3273,10 +3274,9 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
> > {
> > struct btrfs_space_info *space_info;
> > struct btrfs_fs_info *fs_info = extent_root->fs_info;
> > + int wait_for_alloc = 0;
> > int ret = 0;
> >
> > - mutex_lock(&fs_info->chunk_mutex);
> > -
> > flags = btrfs_reduce_alloc_profile(extent_root, flags);
> >
> > space_info = __find_space_info(extent_root->fs_info, flags);
> > @@ -3287,6 +3287,7 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
> > }
> > BUG_ON(!space_info);
> >
> > +again:
> > spin_lock(&space_info->lock);
> > if (space_info->force_alloc)
> > force = 1;
> > @@ -3299,9 +3300,27 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
> > alloc_bytes)) {
> > spin_unlock(&space_info->lock);
> > goto out;
>
> hmm, the "goto" will lead to problems, cause in "out" clause there is a mutex_unlock(), which
> we do not have a mutex_lock yet.
>
Hrm I wonder why xfstests didn't trip over that, thats what I get for patching
while watching the kid. Thanks,
Josef
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