Initialize unaligned I/O bit to clear

PATCH New Goldwyn Rodrigues 2 participants 3 messages Dec 26, 2012 – Dec 27, 2012

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OCFS2 Aio

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Goldwyn Rodrigues

author

2012-12-26 22:52 UTC #0 lore raw

PATCH 1/1 Initialize unaligned I/O bit to clear

The fields of kiocb received in ocfs2_file_aio_write can be uninitialized/non-zero. This could result in UNALIGED_AIO bit in iocb->private set. This causes the oi->ip_unaligned_aio to decrement, well below zero blocking future AIO.

Clear unaligned bit to fix this.

Signed-off-by Goldwyn Rodrigues <[email protected]>

---

fs/ocfs2/file.c +1 -0

index 37d313e..d3bc462 100644
@@ -2254,6 +2254,7 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
 
 	mutex_lock(&inode->i_mutex);
 
+	ocfs2_iocb_clear_unaligned_aio(iocb);
 	ocfs2_iocb_clear_sem_locked(iocb);
 
 relock:

Junxiao Bi

2012-12-27 02:25 UTC #1 lore raw

PATCH 1/1 Initialize unaligned I/O bit to clear

Hi Goldwyn,

Not the correct way to fix this issue. The root cause of your issue is kiocb->private is not init well. And it had been fixed in commit 2dfd06036ba7ae8e7be2daf5a2fff1dac42390bf.

commit 2dfd06036ba7ae8e7be2daf5a2fff1dac42390bf

Author: Junxiao Bi <[email protected]>
Date:   Wed Jun 27 17:09:54 2012 +0800

aio: make kiocb->private NUll in init_sync_kiocb()

Ocfs2 uses kiocb.*private as a flag of unsigned long size. In commit a11f7e6 ocfs2: serialize unaligned aio, the unaligned io flag is involved in it to serialize the unaligned aio. As *private is not initialized in init_sync_kiocb() of do_sync_write(), this unaligned io flag may be unexpectly set in an aligned dio. And this will cause OCFS2_I(inode)->ip_unaligned_aio decreased to -1 in ocfs2_dio_end_io(), thus the following unaligned dio will hang forever at ocfs2_aiodio_wait() in ocfs2_file_aio_write().

Signed-off-by Junxiao Bi <[email protected]>

Cc stable at vger.kernel.org

Acked-by Jeff Moyer <[email protected]>

Signed-off-by Joel Becker <[email protected]>

include/linux/aio.h +1 -0

index 2314ad8..b1a520e 100644
@@ -140,6 +140,7 @@ struct kiocb {
                (x)->ki_dtor = NULL;                    \
                (x)->ki_obj.tsk = tsk;                  \
                (x)->ki_user_data = 0;                  \
+               (x)->private = NULL;                    \
        } while (0)
 
 #define AIO_RING_MAGIC                 0xa10a10a1

Thanks,
Junxiao.

Quoted 27 lines · Goldwyn Rodrigues

The fields of kiocb received in ocfs2_file_aio_write can be uninitialized/non-zero. This could result in UNALIGED_AIO bit in iocb->private set. This causes the oi->ip_unaligned_aio to decrement, well below zero blocking future AIO.
Clear unaligned bit to fix this.
Signed-off-by Goldwyn Rodrigues <[email protected]>
---
fs/ocfs2/file.c +1 -0
index 37d313e..d3bc462 100644
@@ -2254,6 +2254,7 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
 
 	mutex_lock(&inode->i_mutex);
 
+	ocfs2_iocb_clear_unaligned_aio(iocb);
 	ocfs2_iocb_clear_sem_locked(iocb);
 
 relock:
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Ocfs2-devel at oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel

Goldwyn Rodrigues

author

2012-12-27 18:08 UTC #2 lore raw

PATCH 1/1 Initialize unaligned I/O bit to clear

Hi Junxiao,

Quoted 5 lines · Junxiao Bi

Hi Goldwyn,
Not the correct way to fix this issue. The root cause of your issue is kiocb->private is not init well. And it had been fixed in commit 2dfd06036ba7ae8e7be2daf5a2fff1dac42390bf.

I agree. Thanks, this is a much better fix.

OTOH, you could remove ocfs2_iocb_clear_sem_locked() from ocfs2_file_aio_write/read()
This will save some a couple of cycles / CPU cache operations.

Quoted 67 lines

commit 2dfd06036ba7ae8e7be2daf5a2fff1dac42390bf
Author: Junxiao Bi <[email protected]>
Date:   Wed Jun 27 17:09:54 2012 +0800
aio: make kiocb->private NUll in init_sync_kiocb()
Ocfs2 uses kiocb.*private as a flag of unsigned long size. In commit a11f7e6 ocfs2: serialize unaligned aio, the unaligned io flag is involved in it to serialize the unaligned aio. As *private is not initialized in init_sync_kiocb() of do_sync_write(), this unaligned io flag may be unexpectly set in an aligned dio. And this will cause OCFS2_I(inode)->ip_unaligned_aio decreased to -1 in ocfs2_dio_end_io(), thus the following unaligned dio will hang forever at ocfs2_aiodio_wait() in ocfs2_file_aio_write().
Signed-off-by Junxiao Bi <[email protected]>
Cc stable at vger.kernel.org
Acked-by Jeff Moyer <[email protected]>
Signed-off-by Joel Becker <[email protected]>
include/linux/aio.h +1 -0
index 2314ad8..b1a520e 100644
@@ -140,6 +140,7 @@ struct kiocb {
                (x)->ki_dtor = NULL;                    \
                (x)->ki_obj.tsk = tsk;                  \
                (x)->ki_user_data = 0;                  \
+               (x)->private = NULL;                    \
        } while (0)
 
 #define AIO_RING_MAGIC                 0xa10a10a1
Thanks,
Junxiao.
Quoted 27 lines · Goldwyn Rodrigues
The fields of kiocb received in ocfs2_file_aio_write can be uninitialized/non-zero. This could result in UNALIGED_AIO bit in iocb->private set. This causes the oi->ip_unaligned_aio to decrement, well below zero blocking future AIO.
Clear unaligned bit to fix this.
Signed-off-by Goldwyn Rodrigues <[email protected]>
---
fs/ocfs2/file.c +1 -0
index 37d313e..d3bc462 100644
@@ -2254,6 +2254,7 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
 
      mutex_lock(&inode->i_mutex);
 
+     ocfs2_iocb_clear_unaligned_aio(iocb);
      ocfs2_iocb_clear_sem_locked(iocb);
 
 relock:
_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel at oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel

Signature · 1 line

Goldwyn