On 10:52 22/09, Josef Bacik wrote: > On 9/21/20 10:43 AM, Goldwyn Rodrigues wrote: > > From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> > > > > Direct writes within EOF are safe to be performed with inode shared lock > > to improve parallelization with other direct writes or reads because EOF > > is not changed and there is no race with truncate(). > > > > Direct reads are already performed under shared inode lock. > > > > This patch is precursor to removing btrfs_inode->dio_sem. > > > > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> > > --- > > fs/btrfs/file.c | 33 +++++++++++++++++++++------------ > > 1 file changed, 21 insertions(+), 12 deletions(-) > > > > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c > > index d9c3be19d7b3..50092d24eee2 100644 > > --- a/fs/btrfs/file.c > > +++ b/fs/btrfs/file.c > > @@ -1977,7 +1977,6 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from) > > struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > > loff_t pos; > > ssize_t written = 0; > > - bool relock = false; > > ssize_t written_buffered; > > loff_t endbyte; > > int err; > > @@ -1986,6 +1985,15 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from) > > if (iocb->ki_flags & IOCB_NOWAIT) > > ilock_flags |= BTRFS_ILOCK_TRY; > > + /* > > + * If the write DIO within EOF, use a shared lock > > + */ > > + if (iocb->ki_pos + iov_iter_count(from) <= i_size_read(inode)) > > + ilock_flags |= BTRFS_ILOCK_SHARED; > > + else if (iocb->ki_flags & IOCB_NOWAIT) > > + return -EAGAIN; > > + > > +relock: > > Huh? Why are you making it so EOF extending NOWAIT writes now fail? We are > still using ILOCK_TRY here, so we may still not block, am I missing > something? Thanks, > Yes, this is incorrect. I had thought of this would block on disk space allocations. But did not consider the prealloc case. I am removing this check to match the previous behavior. -- Goldwyn
