On Wed 20-11-19 10:30:21, Ritesh Harjani wrote:
> Apparently our current rwsem code doesn't like doing the trylock, then
> lock for real scheme. So change our dax read/write methods to just do the
> trylock for the RWF_NOWAIT case.
> This seems to fix AIM7 regression in some scalable filesystems upto ~25%
> in some cases. Claimed in commit 942491c9e6d6 ("xfs: fix AIM7 regression")
>
> Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/ext4/file.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 6a7293a5cda2..977ac58dc718 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -88,9 +88,10 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
> struct inode *inode = file_inode(iocb->ki_filp);
> ssize_t ret;
>
> - if (!inode_trylock_shared(inode)) {
> - if (iocb->ki_flags & IOCB_NOWAIT)
> + if (iocb->ki_flags & IOCB_NOWAIT) {
> + if (!inode_trylock_shared(inode))
> return -EAGAIN;
> + } else {
> inode_lock_shared(inode);
> }
> /*
> @@ -487,9 +488,10 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
> bool extend = false;
> struct inode *inode = file_inode(iocb->ki_filp);
>
> - if (!inode_trylock(inode)) {
> - if (iocb->ki_flags & IOCB_NOWAIT)
> + if (iocb->ki_flags & IOCB_NOWAIT) {
> + if (!inode_trylock(inode))
> return -EAGAIN;
> + } else {
> inode_lock(inode);
> }
>
> --
> 2.21.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
