* [PATCH] ext4: fix off-by-one error when writing back pages before dio read
@ 2017-05-23 1:34 Eric Biggers
2017-05-23 7:53 ` Jan Kara
0 siblings, 1 reply; 3+ messages in thread
From: Eric Biggers @ 2017-05-23 1:34 UTC (permalink / raw)
To: linux-ext4; +Cc: Theodore Ts'o, Jan Kara, Eric Biggers
From: Eric Biggers <ebiggers@google.com>
The 'lend' argument of filemap_write_and_wait_range() is inclusive, so
we need to subtract 1 from pos + count.
Note that 'count' is guaranteed to be nonzero since
ext4_file_read_iter() returns early when given a 0 count.
Fixes: 16c54688592c ("ext4: Allow parallel DIO reads")
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/ext4/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7c6e715b4d2e..3080ea82dd6d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3710,7 +3710,7 @@ static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter)
*/
inode_lock_shared(inode);
ret = filemap_write_and_wait_range(mapping, iocb->ki_pos,
- iocb->ki_pos + count);
+ iocb->ki_pos + count - 1);
if (ret)
goto out_unlock;
ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
--
2.13.0.219.gdb65acc882-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ext4: fix off-by-one error when writing back pages before dio read
2017-05-23 1:34 [PATCH] ext4: fix off-by-one error when writing back pages before dio read Eric Biggers
@ 2017-05-23 7:53 ` Jan Kara
2017-05-24 22:08 ` Theodore Ts'o
0 siblings, 1 reply; 3+ messages in thread
From: Jan Kara @ 2017-05-23 7:53 UTC (permalink / raw)
To: Eric Biggers; +Cc: linux-ext4, Theodore Ts'o, Jan Kara, Eric Biggers
On Mon 22-05-17 18:34:41, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> The 'lend' argument of filemap_write_and_wait_range() is inclusive, so
> we need to subtract 1 from pos + count.
>
> Note that 'count' is guaranteed to be nonzero since
> ext4_file_read_iter() returns early when given a 0 count.
>
> Fixes: 16c54688592c ("ext4: Allow parallel DIO reads")
> Signed-off-by: Eric Biggers <ebiggers@google.com>
Yeah. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
> ---
> fs/ext4/inode.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 7c6e715b4d2e..3080ea82dd6d 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3710,7 +3710,7 @@ static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter)
> */
> inode_lock_shared(inode);
> ret = filemap_write_and_wait_range(mapping, iocb->ki_pos,
> - iocb->ki_pos + count);
> + iocb->ki_pos + count - 1);
> if (ret)
> goto out_unlock;
> ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
> --
> 2.13.0.219.gdb65acc882-goog
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ext4: fix off-by-one error when writing back pages before dio read
2017-05-23 7:53 ` Jan Kara
@ 2017-05-24 22:08 ` Theodore Ts'o
0 siblings, 0 replies; 3+ messages in thread
From: Theodore Ts'o @ 2017-05-24 22:08 UTC (permalink / raw)
To: Jan Kara; +Cc: Eric Biggers, linux-ext4, Jan Kara, Eric Biggers
On Tue, May 23, 2017 at 09:53:05AM +0200, Jan Kara wrote:
> On Mon 22-05-17 18:34:41, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> >
> > The 'lend' argument of filemap_write_and_wait_range() is inclusive, so
> > we need to subtract 1 from pos + count.
> >
> > Note that 'count' is guaranteed to be nonzero since
> > ext4_file_read_iter() returns early when given a 0 count.
> >
> > Fixes: 16c54688592c ("ext4: Allow parallel DIO reads")
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
>
> Yeah. You can add:
>
> Reviewed-by: Jan Kara <jack@suse.cz>
Thanks, applied.
- Ted
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-05-24 22:08 UTC | newest]
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2017-05-23 1:34 [PATCH] ext4: fix off-by-one error when writing back pages before dio read Eric Biggers
2017-05-23 7:53 ` Jan Kara
2017-05-24 22:08 ` Theodore Ts'o
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