| Message ID | bf988d76ebcb9003a16c6b3cd5d25ca94872b93e.1652109795.git.fdmanana@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: do not account twice for inode ref when reserving metadata units | expand |
On Mon, May 09, 2022 at 04:29:14PM +0100, fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > When reserving metadata units for creating an inode, we don't need to > reserve one extra unit for the inode ref item because when creating the > inode, at btrfs_create_new_inode(), we always insert the inode item and > the inode ref item in a single batch (a single btree insert operation, > and both ending up in the same leaf). > > As we have accounted already one unit for the inode item, the extra unit > for the inode ref item is superfluous, it only makes us reserve more > metadata than necessary and often adding more reclaim pressure if we are > low on available metadata space. > > Signed-off-by: Filipe Manana <fdmanana@suse.com> Added to misc-next, thanks.
On 9.05.22 г. 18:29 ч., fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > When reserving metadata units for creating an inode, we don't need to > reserve one extra unit for the inode ref item because when creating the > inode, at btrfs_create_new_inode(), we always insert the inode item and > the inode ref item in a single batch (a single btree insert operation, > and both ending up in the same leaf). > > As we have accounted already one unit for the inode item, the extra unit > for the inode ref item is superfluous, it only makes us reserve more > metadata than necessary and often adding more reclaim pressure if we are > low on available metadata space. > > Signed-off-by: Filipe Manana <fdmanana@suse.com> That's a neat little optimisation. Reviewed-by: Nikolay Borisov <nborisov@suse.com> > --- > fs/btrfs/inode.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index b42d6e7e4049..adc8b684fe31 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -6138,12 +6138,15 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args, > (*trans_num_items)++; > } else { > /* > - * 1 to add inode ref > * 1 to add dir item > * 1 to add dir index > * 1 to update parent inode item > + * > + * No need for 1 unit for the inode ref item because it is > + * inserted in a batch together with the inode item at > + * btrfs_create_new_inode(). > */ > - *trans_num_items += 4; > + *trans_num_items += 3; > } > return 0; > }
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b42d6e7e4049..adc8b684fe31 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6138,12 +6138,15 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args, (*trans_num_items)++; } else { /* - * 1 to add inode ref * 1 to add dir item * 1 to add dir index * 1 to update parent inode item + * + * No need for 1 unit for the inode ref item because it is + * inserted in a batch together with the inode item at + * btrfs_create_new_inode(). */ - *trans_num_items += 4; + *trans_num_items += 3; } return 0; }