2020-07-08 15:37:17

by Jan Kara

Subject: [PATCH] ext4: Do not block RWF_NOWAIT dio write on unallocated space

Since commit 378f32bab371 ("ext4: introduce direct I/O write using iomap
infrastructure") we don't properly bail out of RWF_NOWAIT direct IO
write if underlying blocks are not allocated. Also
ext4_dio_write_checks() does not honor RWF_NOWAIT when re-acquiring
i_rwsem. Fix both issues.

Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap infrastructure")
Reported-by: Filipe Manana <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
---
fs/ext4/file.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 2a01e31a032c..8f742b53f1d4 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -428,6 +428,10 @@ static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
*/
if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
!ext4_overwrite_io(inode, offset, count))) {
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ ret = -EAGAIN;
+ goto out;
+ }
inode_unlock_shared(inode);
*ilock_shared = false;
inode_lock(inode);
--
2.16.4

2020-07-08 17:56:25

by Ritesh Harjani

Subject: Re: [PATCH] ext4: Do not block RWF_NOWAIT dio write on unallocated space

On 7/8/20 9:05 PM, Jan Kara wrote:
> Since commit 378f32bab371 ("ext4: introduce direct I/O write using iomap
> infrastructure") we don't properly bail out of RWF_NOWAIT direct IO
> write if underlying blocks are not allocated. Also
> ext4_dio_write_checks() does not honor RWF_NOWAIT when re-acquiring
> i_rwsem. Fix both issues.
>
> Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap infrastructure")
> Reported-by: Filipe Manana <[email protected]>
> Signed-off-by: Jan Kara <[email protected]>

LGTM, feel free to add
Reviewed-by: Ritesh Harjani <[email protected]>

> ---
> fs/ext4/file.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 2a01e31a032c..8f742b53f1d4 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -428,6 +428,10 @@ static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
> */
> if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
> !ext4_overwrite_io(inode, offset, count))) {
> + if (iocb->ki_flags & IOCB_NOWAIT) {
> + ret = -EAGAIN;
> + goto out;
> + }
> inode_unlock_shared(inode);
> *ilock_shared = false;
> inode_lock(inode);
>

2020-08-05 19:28:50

by Jan Kara

Subject: Re: [PATCH] ext4: Do not block RWF_NOWAIT dio write on unallocated space

On Wed 08-07-20 17:35:16, Jan Kara wrote:
> Since commit 378f32bab371 ("ext4: introduce direct I/O write using iomap
> infrastructure") we don't properly bail out of RWF_NOWAIT direct IO
> write if underlying blocks are not allocated. Also
> ext4_dio_write_checks() does not honor RWF_NOWAIT when re-acquiring
> i_rwsem. Fix both issues.
>
> Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap infrastructure")
> Reported-by: Filipe Manana <[email protected]>
> Signed-off-by: Jan Kara <[email protected]>

Ted, can you please merge this patch? Thanks!

Honza

> ---
> fs/ext4/file.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 2a01e31a032c..8f742b53f1d4 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -428,6 +428,10 @@ static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
> */
> if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
> !ext4_overwrite_io(inode, offset, count))) {
> + if (iocb->ki_flags & IOCB_NOWAIT) {
> + ret = -EAGAIN;
> + goto out;
> + }
> inode_unlock_shared(inode);
> *ilock_shared = false;
> inode_lock(inode);
> --
> 2.16.4
>
--
Jan Kara <[email protected]>
SUSE Labs, CR

2020-08-06 05:07:30

by Theodore Ts'o

Subject: Re: [PATCH] ext4: Do not block RWF_NOWAIT dio write on unallocated space

On Wed, Jul 08, 2020 at 05:35:16PM +0200, Jan Kara wrote:
> Since commit 378f32bab371 ("ext4: introduce direct I/O write using iomap
> infrastructure") we don't properly bail out of RWF_NOWAIT direct IO
> write if underlying blocks are not allocated. Also
> ext4_dio_write_checks() does not honor RWF_NOWAIT when re-acquiring
> i_rwsem. Fix both issues.
>
> Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap infrastructure")
> Reported-by: Filipe Manana <[email protected]>
> Signed-off-by: Jan Kara <[email protected]>

Applied, thanks.

- Ted