direct-io: Implement generic deferred AIO completions
Add support to the core direct-io code to defer AIO completions to user
context using a workqueue. This replaces opencoded and less efficient
code in XFS and ext4 (we save a memory allocation for each direct IO)
and will be needed to properly support O_(D)SYNC for AIO.
The communication between the filesystem and the direct I/O code requires
a new buffer head flag, which is a bit ugly but not avoidable until the
direct I/O code stops abusing the buffer_head structure for communicating
with the filesystems.
Currently this creates a per-superblock unbound workqueue for these
completions, which is taken from an earlier patch by Jan Kara. I'm
not really convinced about this use and would prefer a "normal" global
workqueue with a high concurrency limit, but this needs further discussion.
JK: Fixed ext4 part, dynamic allocation of the workqueue.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c2ca04e..123bd81 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -727,8 +727,12 @@
ret = ext4_map_blocks(handle, inode, &map, flags);
if (ret > 0) {
+ ext4_io_end_t *io_end = ext4_inode_aio(inode);
+
map_bh(bh, inode->i_sb, map.m_pblk);
bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
+ if (io_end && io_end->flag & EXT4_IO_END_UNWRITTEN)
+ set_buffer_defer_completion(bh);
bh->b_size = inode->i_sb->s_blocksize * map.m_len;
ret = 0;
}
@@ -2991,19 +2995,13 @@
}
static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
- ssize_t size, void *private, int ret,
- bool is_async)
+ ssize_t size, void *private)
{
- struct inode *inode = file_inode(iocb->ki_filp);
ext4_io_end_t *io_end = iocb->private;
/* if not async direct IO just return */
- if (!io_end) {
- inode_dio_done(inode);
- if (is_async)
- aio_complete(iocb, ret, 0);
+ if (!io_end)
return;
- }
ext_debug("ext4_end_io_dio(): io_end 0x%p "
"for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
@@ -3013,11 +3011,7 @@
iocb->private = NULL;
io_end->offset = offset;
io_end->size = size;
- if (is_async) {
- io_end->iocb = iocb;
- io_end->result = ret;
- }
- ext4_put_io_end_defer(io_end);
+ ext4_put_io_end(io_end);
}
/*
@@ -3102,7 +3096,6 @@
ret = -ENOMEM;
goto retake_lock;
}
- io_end->flag |= EXT4_IO_END_DIRECT;
/*
* Grab reference for DIO. Will be dropped in ext4_end_io_dio()
*/
@@ -3147,13 +3140,6 @@
if (ret <= 0 && ret != -EIOCBQUEUED && iocb->private) {
WARN_ON(iocb->private != io_end);
WARN_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
- WARN_ON(io_end->iocb);
- /*
- * Generic code already did inode_dio_done() so we
- * have to clear EXT4_IO_END_DIRECT to not do it for
- * the second time.
- */
- io_end->flag = 0;
ext4_put_io_end(io_end);
iocb->private = NULL;
}