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direct-io: Implement generic deferred AIO completions

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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>
This commit is contained in:
Christoph Hellwig
2013-09-04 15:04:39 +02:00
committed by Al Viro
parent 4b6ccca701
commit 7b7a8665ed
11 changed files with 105 additions and 131 deletions
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28
fs/xfs/xfs_aops.c
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@@ -86,14 +86,6 @@ xfs_destroy_ioend(
bh->b_end_io(bh, !ioend->io_error);
}
if (ioend->io_iocb) {
inode_dio_done(ioend->io_inode);
if (ioend->io_isasync) {
aio_complete(ioend->io_iocb, ioend->io_error ?
ioend->io_error : ioend->io_result, 0);
}
}
mempool_free(ioend, xfs_ioend_pool);
}
@@ -281,7 +273,6 @@ xfs_alloc_ioend(
* all the I/O from calling the completion routine too early.
*/
atomic_set(&ioend->io_remaining, 1);
ioend->io_isasync = 0;
ioend->io_isdirect = 0;
ioend->io_error = 0;
ioend->io_list = NULL;
@@ -291,8 +282,6 @@ xfs_alloc_ioend(
ioend->io_buffer_tail = NULL;
ioend->io_offset = 0;
ioend->io_size = 0;
ioend->io_iocb = NULL;
ioend->io_result = 0;
ioend->io_append_trans = NULL;
INIT_WORK(&ioend->io_work, xfs_end_io);
@@ -1292,8 +1281,10 @@ __xfs_get_blocks(
if (create || !ISUNWRITTEN(&imap))
xfs_map_buffer(inode, bh_result, &imap, offset);
if (create && ISUNWRITTEN(&imap)) {
if (direct)
if (direct) {
bh_result->b_private = inode;
set_buffer_defer_completion(bh_result);
}
set_buffer_unwritten(bh_result);
}
}
@@ -1390,9 +1381,7 @@ xfs_end_io_direct_write(
struct kiocb *iocb,
loff_t offset,
ssize_t size,
void *private,
int ret,
bool is_async)
void *private)
{
struct xfs_ioend *ioend = iocb->private;
@@ -1414,17 +1403,10 @@ xfs_end_io_direct_write(
ioend->io_offset = offset;
ioend->io_size = size;
ioend->io_iocb = iocb;
ioend->io_result = ret;
if (private && size > 0)
ioend->io_type = XFS_IO_UNWRITTEN;
if (is_async) {
ioend->io_isasync = 1;
xfs_finish_ioend(ioend);
} else {
xfs_finish_ioend_sync(ioend);
}
xfs_finish_ioend_sync(ioend);
}
STATIC ssize_t