On Mon 21-10-19 20:18:46, Matthew Bobrowski wrote:
> This patch updates the lock pattern in ext4_dio_read_iter() to only
> perform the trylock in IOCB_NOWAIT cases.
The changelog is actually misleading. It should say something like "This
patch updates the lock pattern in ext4_dio_read_iter() to not block on
inode lock in case of IOCB_NOWAIT direct IO reads."
Also to ease backporting of easy fixes, we try to put patches like this
early in the series (fixing code in ext4_direct_IO_read(), and then the
fixed code would just carry over to ext4_dio_read_iter()).
The change itself looks good to me.
Honza
>
> Signed-off-by: Matthew Bobrowski <mbobrowski@xxxxxxxxxxxxxx>
> ---
> fs/ext4/file.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 6ea7e00e0204..8420686b90f5 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -52,7 +52,13 @@ static int ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
> ssize_t ret;
> struct inode *inode = file_inode(iocb->ki_filp);
>
> - inode_lock_shared(inode);
> + if (iocb->ki_flags & IOCB_NOWAIT) {
> + if (!inode_trylock_shared(inode))
> + return -EAGAIN;
> + } else {
> + inode_lock_shared(inode);
> + }
> +
> if (!ext4_dio_supported(inode)) {
> inode_unlock_shared(inode);
> /*
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
