| Message ID | 20100622123113.011371666@bombadil.infradead.org |
|---|---|
| State | New, archived |
| Headers | show |
On Tue 22-06-10 08:21:45, Christoph Hellwig wrote: > Filesystems with unwritten extent support must not complete an AIO request > until the transaction to convert the extent has been commited. That means > the aio_complete calls needs to be moved into the ->end_io callback so > that the filesystem can control when to call it exactly. > > This makes a bit of a mess out of dio_complete and the ->end_io callback > prototype even more complicated. In addition ->end_io is now called with > i_alloc_sem held for DIO_LOCKING filesystems. The only filesystem that > has both and ->end_io callback and sets DIO_LOCKING is ext4, which doesn't > appear to do anything that could deadlock with i_alloc_sem in ->end_io. Umm, I don't get this. Looking at the ->end_io callback it has been always called with i_alloc_sem held. It's only aio_complete() which will be called with i_alloc_sem held after your changes. Or am I missing something? Moreover the async testing you do does not seem to be completely right. dio->is_async is a flag that controls whether dio code waits for IO to be completed or not. In particular it is not set for AIO that spans beyond current i_size so it does not seem to be exactly what you need (at least for ext4 it isn't). I think that is_sync_kiocb() is a test that should be used to recognize AIO - and that has an advantage that you don't have to pass the is_async flag around. Honza > > Signed-off-by: Christoph Hellwig <hch@lst.de> > > Index: linux-2.6/fs/direct-io.c > =================================================================== > --- linux-2.6.orig/fs/direct-io.c 2010-06-22 09:48:37.239004298 +0200 > +++ linux-2.6/fs/direct-io.c 2010-06-22 11:54:42.281003878 +0200 > @@ -218,7 +218,7 @@ static struct page *dio_get_page(struct > * filesystems can use it to hold additional state between get_block calls and > * dio_complete. > */ > -static int dio_complete(struct dio *dio, loff_t offset, int ret) > +static int dio_complete(struct dio *dio, loff_t offset, int ret, bool is_async) > { > ssize_t transferred = 0; > > @@ -239,14 +239,6 @@ static int dio_complete(struct dio *dio, > transferred = dio->i_size - offset; > } > > - if (dio->end_io && dio->result) > - dio->end_io(dio->iocb, offset, transferred, > - dio->map_bh.b_private); > - > - if (dio->flags & DIO_LOCKING) > - /* lockdep: non-owner release */ > - up_read_non_owner(&dio->inode->i_alloc_sem); > - > if (ret == 0) > ret = dio->page_errors; > if (ret == 0) > @@ -254,6 +246,17 @@ static int dio_complete(struct dio *dio, > if (ret == 0) > ret = transferred; > > + if (dio->end_io && dio->result) { > + dio->end_io(dio->iocb, offset, transferred, > + dio->map_bh.b_private, ret, is_async); > + } else if (is_async) { > + aio_complete(dio->iocb, ret, 0); > + } > + > + if (dio->flags & DIO_LOCKING) > + /* lockdep: non-owner release */ > + up_read_non_owner(&dio->inode->i_alloc_sem); > + > return ret; > } > > @@ -277,8 +280,7 @@ static void dio_bio_end_aio(struct bio * > spin_unlock_irqrestore(&dio->bio_lock, flags); > > if (remaining == 0) { > - int ret = dio_complete(dio, dio->iocb->ki_pos, 0); > - aio_complete(dio->iocb, ret, 0); > + dio_complete(dio, dio->iocb->ki_pos, 0, true); > kfree(dio); > } > } > @@ -1126,7 +1128,7 @@ direct_io_worker(int rw, struct kiocb *i > spin_unlock_irqrestore(&dio->bio_lock, flags); > > if (ret2 == 0) { > - ret = dio_complete(dio, offset, ret); > + ret = dio_complete(dio, offset, ret, false); > kfree(dio); > } else > BUG_ON(ret != -EIOCBQUEUED); > Index: linux-2.6/fs/ext4/inode.c > =================================================================== > --- linux-2.6.orig/fs/ext4/inode.c 2010-06-22 09:48:37.249004508 +0200 > +++ linux-2.6/fs/ext4/inode.c 2010-06-22 12:18:45.883255381 +0200 > @@ -3775,7 +3775,8 @@ static ext4_io_end_t *ext4_init_io_end ( > } > > static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, > - ssize_t size, void *private) > + ssize_t size, void *private, int ret, > + bool is_async) > { > ext4_io_end_t *io_end = iocb->private; > struct workqueue_struct *wq; > @@ -3784,7 +3785,7 @@ static void ext4_end_io_dio(struct kiocb > > /* if not async direct IO or dio with 0 bytes write, just return */ > if (!io_end || !size) > - return; > + goto out; > > ext_debug("ext4_end_io_dio(): io_end 0x%p" > "for inode %lu, iocb 0x%p, offset %llu, size %llu\n", > @@ -3795,7 +3796,7 @@ static void ext4_end_io_dio(struct kiocb > if (io_end->flag != EXT4_IO_UNWRITTEN){ > ext4_free_io_end(io_end); > iocb->private = NULL; > - return; > + goto out; > } > > io_end->offset = offset; > @@ -3812,6 +3813,9 @@ static void ext4_end_io_dio(struct kiocb > list_add_tail(&io_end->list, &ei->i_completed_io_list); > spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); > iocb->private = NULL; > +out: > + if (is_async) > + aio_complete(iocb, ret, 0); > } > > static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate) > Index: linux-2.6/fs/ocfs2/aops.c > =================================================================== > --- linux-2.6.orig/fs/ocfs2/aops.c 2010-06-22 09:48:37.259012749 +0200 > +++ linux-2.6/fs/ocfs2/aops.c 2010-06-22 12:19:03.931005757 +0200 > @@ -609,7 +609,9 @@ bail: > static void ocfs2_dio_end_io(struct kiocb *iocb, > loff_t offset, > ssize_t bytes, > - void *private) > + void *private, > + int ret, > + bool is_async) > { > struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode; > int level; > @@ -623,6 +625,9 @@ static void ocfs2_dio_end_io(struct kioc > if (!level) > up_read(&inode->i_alloc_sem); > ocfs2_rw_unlock(inode, level); > + > + if (is_async) > + aio_complete(iocb, ret, 0); > } > > /* > Index: linux-2.6/fs/xfs/linux-2.6/xfs_aops.c > =================================================================== > --- linux-2.6.orig/fs/xfs/linux-2.6/xfs_aops.c 2010-06-22 09:48:37.268012190 +0200 > +++ linux-2.6/fs/xfs/linux-2.6/xfs_aops.c 2010-06-22 14:05:02.522005722 +0200 > @@ -1599,7 +1599,9 @@ xfs_end_io_direct( > struct kiocb *iocb, > loff_t offset, > ssize_t size, > - void *private) > + void *private, > + int ret, > + bool is_async) > { > xfs_ioend_t *ioend = iocb->private; > > @@ -1645,6 +1647,9 @@ xfs_end_io_direct( > * against double-freeing. > */ > iocb->private = NULL; > + > + if (is_async) > + aio_complete(iocb, ret, 0); > } > > STATIC ssize_t > Index: linux-2.6/fs/xfs/linux-2.6/xfs_aops.h > =================================================================== > --- linux-2.6.orig/fs/xfs/linux-2.6/xfs_aops.h 2010-06-22 09:48:37.278274238 +0200 > +++ linux-2.6/fs/xfs/linux-2.6/xfs_aops.h 2010-06-22 09:49:12.388034051 +0200 > @@ -37,6 +37,8 @@ typedef struct xfs_ioend { > size_t io_size; /* size of the extent */ > xfs_off_t io_offset; /* offset in the file */ > struct work_struct io_work; /* xfsdatad work queue */ > + struct kiocb *io_iocb; > + int io_result; > } xfs_ioend_t; > > extern const struct address_space_operations xfs_address_space_operations; > Index: linux-2.6/include/linux/fs.h > =================================================================== > --- linux-2.6.orig/include/linux/fs.h 2010-06-22 09:49:07.188253984 +0200 > +++ linux-2.6/include/linux/fs.h 2010-06-22 10:34:10.128005975 +0200 > @@ -415,7 +415,8 @@ struct buffer_head; > typedef int (get_block_t)(struct inode *inode, sector_t iblock, > struct buffer_head *bh_result, int create); > typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset, > - ssize_t bytes, void *private); > + ssize_t bytes, void *private, int ret, > + bool is_async); > > /* > * Attribute flags. These should be or-ed together to figure out what > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Jun 24, 2010 at 11:59:22PM +0200, Jan Kara wrote: > Umm, I don't get this. Looking at the ->end_io callback it has been > always called with i_alloc_sem held. It's only aio_complete() which will > be called with i_alloc_sem held after your changes. Or am I missing > something? No, that part of the commit message is flat out wrong. Not sure what I was thinking when I wrote it. > Moreover the async testing you do does not seem to be completely right. > dio->is_async is a flag that controls whether dio code waits for IO to be > completed or not. In particular it is not set for AIO that spans beyond > current i_size so it does not seem to be exactly what you need (at least > for ext4 it isn't). I think that is_sync_kiocb() is a test that should be > used to recognize AIO - and that has an advantage that you don't have to > pass the is_async flag around. No. is_sync_kiocb() means the ioctb was not intended as sync I/O from the start. But we can only call aio_complete when we returned -EIOCBQUEUED from ->aio_read/write. Take a look at the comment near the end of direct_io_worker(). AIO beyond i_size is not supported using blockdev_direct_IO yet. I think I can add it fairly easily for XFS, but that will require passing a new DIO_* flag to __blockdev_direct_IO which will make is_async true for writes beyond i_size. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri 25-06-10 02:36:10, Christoph Hellwig wrote: > On Thu, Jun 24, 2010 at 11:59:22PM +0200, Jan Kara wrote: > > Moreover the async testing you do does not seem to be completely right. > > dio->is_async is a flag that controls whether dio code waits for IO to be > > completed or not. In particular it is not set for AIO that spans beyond > > current i_size so it does not seem to be exactly what you need (at least > > for ext4 it isn't). I think that is_sync_kiocb() is a test that should be > > used to recognize AIO - and that has an advantage that you don't have to > > pass the is_async flag around. > > No. is_sync_kiocb() means the ioctb was not intended as sync I/O from > the start. But we can only call aio_complete when we returned > -EIOCBQUEUED from ->aio_read/write. Take a look at the comment near the > end of direct_io_worker(). Ah, I see. Thanks for explanation. It's ugly but I also don't see a nicer way how to handle this. Honza
Index: linux-2.6/fs/direct-io.c =================================================================== --- linux-2.6.orig/fs/direct-io.c 2010-06-22 09:48:37.239004298 +0200 +++ linux-2.6/fs/direct-io.c 2010-06-22 11:54:42.281003878 +0200 @@ -218,7 +218,7 @@ static struct page *dio_get_page(struct * filesystems can use it to hold additional state between get_block calls and * dio_complete. */ -static int dio_complete(struct dio *dio, loff_t offset, int ret) +static int dio_complete(struct dio *dio, loff_t offset, int ret, bool is_async) { ssize_t transferred = 0; @@ -239,14 +239,6 @@ static int dio_complete(struct dio *dio, transferred = dio->i_size - offset; } - if (dio->end_io && dio->result) - dio->end_io(dio->iocb, offset, transferred, - dio->map_bh.b_private); - - if (dio->flags & DIO_LOCKING) - /* lockdep: non-owner release */ - up_read_non_owner(&dio->inode->i_alloc_sem); - if (ret == 0) ret = dio->page_errors; if (ret == 0) @@ -254,6 +246,17 @@ static int dio_complete(struct dio *dio, if (ret == 0) ret = transferred; + if (dio->end_io && dio->result) { + dio->end_io(dio->iocb, offset, transferred, + dio->map_bh.b_private, ret, is_async); + } else if (is_async) { + aio_complete(dio->iocb, ret, 0); + } + + if (dio->flags & DIO_LOCKING) + /* lockdep: non-owner release */ + up_read_non_owner(&dio->inode->i_alloc_sem); + return ret; } @@ -277,8 +280,7 @@ static void dio_bio_end_aio(struct bio * spin_unlock_irqrestore(&dio->bio_lock, flags); if (remaining == 0) { - int ret = dio_complete(dio, dio->iocb->ki_pos, 0); - aio_complete(dio->iocb, ret, 0); + dio_complete(dio, dio->iocb->ki_pos, 0, true); kfree(dio); } } @@ -1126,7 +1128,7 @@ direct_io_worker(int rw, struct kiocb *i spin_unlock_irqrestore(&dio->bio_lock, flags); if (ret2 == 0) { - ret = dio_complete(dio, offset, ret); + ret = dio_complete(dio, offset, ret, false); kfree(dio); } else BUG_ON(ret != -EIOCBQUEUED); Index: linux-2.6/fs/ext4/inode.c =================================================================== --- linux-2.6.orig/fs/ext4/inode.c 2010-06-22 09:48:37.249004508 +0200 +++ linux-2.6/fs/ext4/inode.c 2010-06-22 12:18:45.883255381 +0200 @@ -3775,7 +3775,8 @@ static ext4_io_end_t *ext4_init_io_end ( } static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, - ssize_t size, void *private) + ssize_t size, void *private, int ret, + bool is_async) { ext4_io_end_t *io_end = iocb->private; struct workqueue_struct *wq; @@ -3784,7 +3785,7 @@ static void ext4_end_io_dio(struct kiocb /* if not async direct IO or dio with 0 bytes write, just return */ if (!io_end || !size) - return; + goto out; ext_debug("ext4_end_io_dio(): io_end 0x%p" "for inode %lu, iocb 0x%p, offset %llu, size %llu\n", @@ -3795,7 +3796,7 @@ static void ext4_end_io_dio(struct kiocb if (io_end->flag != EXT4_IO_UNWRITTEN){ ext4_free_io_end(io_end); iocb->private = NULL; - return; + goto out; } io_end->offset = offset; @@ -3812,6 +3813,9 @@ static void ext4_end_io_dio(struct kiocb list_add_tail(&io_end->list, &ei->i_completed_io_list); spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); iocb->private = NULL; +out: + if (is_async) + aio_complete(iocb, ret, 0); } static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate) Index: linux-2.6/fs/ocfs2/aops.c =================================================================== --- linux-2.6.orig/fs/ocfs2/aops.c 2010-06-22 09:48:37.259012749 +0200 +++ linux-2.6/fs/ocfs2/aops.c 2010-06-22 12:19:03.931005757 +0200 @@ -609,7 +609,9 @@ bail: static void ocfs2_dio_end_io(struct kiocb *iocb, loff_t offset, ssize_t bytes, - void *private) + void *private, + int ret, + bool is_async) { struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode; int level; @@ -623,6 +625,9 @@ static void ocfs2_dio_end_io(struct kioc if (!level) up_read(&inode->i_alloc_sem); ocfs2_rw_unlock(inode, level); + + if (is_async) + aio_complete(iocb, ret, 0); } /* Index: linux-2.6/fs/xfs/linux-2.6/xfs_aops.c =================================================================== --- linux-2.6.orig/fs/xfs/linux-2.6/xfs_aops.c 2010-06-22 09:48:37.268012190 +0200 +++ linux-2.6/fs/xfs/linux-2.6/xfs_aops.c 2010-06-22 14:05:02.522005722 +0200 @@ -1599,7 +1599,9 @@ xfs_end_io_direct( struct kiocb *iocb, loff_t offset, ssize_t size, - void *private) + void *private, + int ret, + bool is_async) { xfs_ioend_t *ioend = iocb->private; @@ -1645,6 +1647,9 @@ xfs_end_io_direct( * against double-freeing. */ iocb->private = NULL; + + if (is_async) + aio_complete(iocb, ret, 0); } STATIC ssize_t Index: linux-2.6/fs/xfs/linux-2.6/xfs_aops.h =================================================================== --- linux-2.6.orig/fs/xfs/linux-2.6/xfs_aops.h 2010-06-22 09:48:37.278274238 +0200 +++ linux-2.6/fs/xfs/linux-2.6/xfs_aops.h 2010-06-22 09:49:12.388034051 +0200 @@ -37,6 +37,8 @@ typedef struct xfs_ioend { size_t io_size; /* size of the extent */ xfs_off_t io_offset; /* offset in the file */ struct work_struct io_work; /* xfsdatad work queue */ + struct kiocb *io_iocb; + int io_result; } xfs_ioend_t; extern const struct address_space_operations xfs_address_space_operations; Index: linux-2.6/include/linux/fs.h =================================================================== --- linux-2.6.orig/include/linux/fs.h 2010-06-22 09:49:07.188253984 +0200 +++ linux-2.6/include/linux/fs.h 2010-06-22 10:34:10.128005975 +0200 @@ -415,7 +415,8 @@ struct buffer_head; typedef int (get_block_t)(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create); typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset, - ssize_t bytes, void *private); + ssize_t bytes, void *private, int ret, + bool is_async); /* * Attribute flags. These should be or-ed together to figure out what
Filesystems with unwritten extent support must not complete an AIO request until the transaction to convert the extent has been commited. That means the aio_complete calls needs to be moved into the ->end_io callback so that the filesystem can control when to call it exactly. This makes a bit of a mess out of dio_complete and the ->end_io callback prototype even more complicated. In addition ->end_io is now called with i_alloc_sem held for DIO_LOCKING filesystems. The only filesystem that has both and ->end_io callback and sets DIO_LOCKING is ext4, which doesn't appear to do anything that could deadlock with i_alloc_sem in ->end_io. Signed-off-by: Christoph Hellwig <hch@lst.de> -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html