On Tue, Sep 16, 2008 at 2:59 PM, Marco Stornelli
<marco.stornelli@xxxxxxxxxx> wrote:
> From: Marco Stornelli <marco.stornelli@xxxxxxxxx>
>
> If a filesystem in the file operations specifies for read and write operations only do_sync_read and do_sync_write without
> init aio_read and aio_write, there will be a kernel oops, because the vfs code check the presence of (to read for example)
> read OR aio_read method, then it calls read if it's pointer is not null. It's not sufficient because if the read function is
> actually a do_sync_read, it calls aio_read but without checking the presence. I think a BUG_ON check can be more useful.
Instead of doing a BUG_ON() why can't we simply fall back to the
generic_aio functions since most of the fs tend to do so as below.
Signed-off-by: Manish Katiyar <mkatiyar@xxxxxxxxx>
---
fs/read_write.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 9ba495d..5439bc4 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -225,7 +225,11 @@ ssize_t do_sync_read(struct file *filp, char
__user *buf, size_t len, loff_t *pp
kiocb.ki_left = len;
for (;;) {
- ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos);
+ if (filp->f_op->aio_read)
+ ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos);
+ else
+ ret = generic_file_aio_read(&kiocb, &iov, 1, kiocb.ki_pos);
if (ret != -EIOCBRETRY)
break;
wait_on_retry_sync_kiocb(&kiocb);
@@ -280,7 +284,10 @@ ssize_t do_sync_write(struct file *filp, const
char __user *buf, size_t len, lof
kiocb.ki_left = len;
for (;;) {
- ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
+ if (filp->f_op->aio_write)
+ ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
+ else
+ ret = generic_file_aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
if (ret != -EIOCBRETRY)
break;
wait_on_retry_sync_kiocb(&kiocb);
--
1.5.4.3
Thanks -
Manish
> Signed-off-by: Marco Stornelli <marco.stornelli@xxxxxxxxx>
> ---
>
> --- linux-2.6.26.5/fs/read_write.c.orig 2008-08-20 20:11:37.000000000 +0200
> +++ linux-2.6.26.5/fs/read_write.c 2008-09-16 11:01:13.000000000 +0200
> @@ -240,6 +240,7 @@ ssize_t do_sync_read(struct file *filp,
> kiocb.ki_pos = *ppos;
> kiocb.ki_left = len;
>
> + BUG_ON(!filp->f_op->aio_read);
> for (;;) {
> ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos);
> if (ret != -EIOCBRETRY)
> @@ -295,6 +296,7 @@ ssize_t do_sync_write(struct file *filp,
> kiocb.ki_pos = *ppos;
> kiocb.ki_left = len;
>
> + BUG_ON(!filp->f_op->aio_write);
> for (;;) {
> ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
> if (ret != -EIOCBRETRY)
>
> --
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