On Wed, May 15, 2019 at 04:45:42PM +0300, Nikolay Borisov wrote: > > > On 15.05.19 г. 16:31 ч., David Sterba wrote: > > btrfs_check_shared looks up parents of a given extent and uses ulists > > for that. These are allocated and freed repeatedly. Preallocation in the > > caller will avoid the overhead and also allow us to use the GFP_KERNEL > > as it is happens before the extent locks are taken. > > > > Signed-off-by: David Sterba <[email protected]> > > Looks good, one minor nit worth considering below, otherwise: > > > Reviewed-by: Nikolay Borisov <[email protected]> > > > > --- > > fs/btrfs/backref.c | 17 ++++++----------- > > fs/btrfs/backref.h | 3 ++- > > fs/btrfs/extent_io.c | 15 +++++++++++++-- > > 3 files changed, 21 insertions(+), 14 deletions(-) > > > > diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c > > index 982152d3f920..89116afda7a2 100644 > > --- a/fs/btrfs/backref.c > > +++ b/fs/btrfs/backref.c > > @@ -1465,12 +1465,11 @@ int btrfs_find_all_roots(struct btrfs_trans_handle > > *trans, > > * > > * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error. > > */ > > -int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr) > > +int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr, > > + struct ulist *roots, struct ulist *tmp) > > { > > struct btrfs_fs_info *fs_info = root->fs_info; > > struct btrfs_trans_handle *trans; > > - struct ulist *tmp = NULL; > > - struct ulist *roots = NULL; > > struct ulist_iterator uiter; > > struct ulist_node *node; > > struct seq_list elem = SEQ_LIST_INIT(elem); > > @@ -1481,12 +1480,8 @@ int btrfs_check_shared(struct btrfs_root *root, u64 > > inum, u64 bytenr) > > .share_count = 0, > > }; > > > > - tmp = ulist_alloc(GFP_NOFS); > > - roots = ulist_alloc(GFP_NOFS); > > - if (!tmp || !roots) { > > - ret = -ENOMEM; > > - goto out; > > - } > > + ulist_init(roots); > > + ulist_init(tmp); > > > > trans = btrfs_attach_transaction(root); > > if (IS_ERR(trans)) { > > @@ -1527,8 +1522,8 @@ int btrfs_check_shared(struct btrfs_root *root, u64 > > inum, u64 bytenr) > > up_read(&fs_info->commit_root_sem); > > } > > out: > > - ulist_free(tmp); > > - ulist_free(roots); > > + ulist_release(roots); > > + ulist_release(tmp); > > nit: If we turn these into ulist_reinit there is no need to do ulit_init > at the beginning. Having said that, the only difference between > ulist_release/init is that the latter also does ulist->nnode=0 (apart > form the memory freeing). So ulist_release can really boil down to: > > list_for_each_entry_safe() { > kfree} > ulist_init(ulist)
I think I had the _reinit at the end in one of the versions, but then it looked more clear with the explicit _init at the beginning of the function so that it does not rely on the caller to initialize.
