[patch -next] ext4: locking issue on error path

[patch -next] ext4: locking issue on error path

[Dan Carpenter]

We recently changed how the locking worked here, but this error path was
missed.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8c84070..2728fb7 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3031,8 +3031,10 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 		if (!is_sync_kiocb(iocb)) {
 			ext4_io_end_t *io_end =
 				ext4_init_io_end(inode, GFP_NOFS);
-			if (!io_end)
-				return -ENOMEM;
+			if (!io_end) {
+				ret = -ENOMEM;
+				goto retake_lock;
+			}
 			io_end->flag |= EXT4_IO_END_DIRECT;
 			iocb->private = io_end;
 			/*
@@ -3094,6 +3096,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 			ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
 		}
 
+retake_lock:
 		/* take i_mutex locking again if we do a ovewrite dio */
 		if (overwrite) {
 			up_read(&EXT4_I(inode)->i_data_sem);

Re: [patch -next] ext4: locking issue on error path

[Zheng Liu]

On Tue, Jul 17, 2012 at 09:31:06AM +0300, Dan Carpenter wrote:
> We recently changed how the locking worked here, but this error path was
> missed.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Sorry, it is my fault.  Thanks for pointing out this bug.

Regards,
Zheng

> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 8c84070..2728fb7 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3031,8 +3031,10 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
>  		if (!is_sync_kiocb(iocb)) {
>  			ext4_io_end_t *io_end =
>  				ext4_init_io_end(inode, GFP_NOFS);
> -			if (!io_end)
> -				return -ENOMEM;
> +			if (!io_end) {
> +				ret = -ENOMEM;
> +				goto retake_lock;
> +			}
>  			io_end->flag |= EXT4_IO_END_DIRECT;
>  			iocb->private = io_end;
>  			/*
> @@ -3094,6 +3096,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
>  			ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
>  		}
>  
> +retake_lock:
>  		/* take i_mutex locking again if we do a ovewrite dio */
>  		if (overwrite) {
>  			up_read(&EXT4_I(inode)->i_data_sem);
> --
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Re: [patch -next] ext4: locking issue on error path

[Theodore Ts'o]

On Tue, Jul 17, 2012 at 04:13:51PM +0800, Zheng Liu wrote:
> On Tue, Jul 17, 2012 at 09:31:06AM +0300, Dan Carpenter wrote:
> > We recently changed how the locking worked here, but this error path was
> > missed.
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> Sorry, it is my fault.  Thanks for pointing out this bug.

Since this patch hadn't been promoted past the master branch pointer
(it was only in the dev branch, which can be rebased), I've merged
this fix up with Zheng's original patch.

Dan, may thanks for finding and pointing it out!!

					- Ted