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fuse: enable asynchronous processing direct IO 

In case of synchronous DIO request (i.e. read(2) or write(2) for a file
opened with O_DIRECT), the patch submits fuse requests asynchronously, but
waits for their completions before return from fuse_direct_IO().

In case of asynchronous DIO request (i.e. libaio io_submit() or a file opened
with O_DIRECT), the patch submits fuse requests asynchronously and return
-EIOCBQUEUED immediately.

The only special case is async DIO extending file. Here the patch falls back
to old behaviour because we can't return -EIOCBQUEUED and update i_size later,
without i_mutex hold. And we have no method to wait on real async I/O
requests.

The patch also clean __fuse_direct_write() up: it's better to update i_size
in its callers. Thanks Brian for suggestion.

Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
Maxim Patlasov 2012-12-14 19:21:08 +04:00 committed by Miklos Szeredi
parent 36cf66ed9f
commit bcba24ccdc
1 changed files with 44 additions and 7 deletions
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51
fs/fuse/file.c
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@ -1366,11 +1366,8 @@ static ssize_t __fuse_direct_write(struct fuse_io_priv *io,
ssize_t res;
res = generic_write_checks(file, ppos, &count, 0);
if (!res) {
if (!res)
res = fuse_direct_io(io, iov, nr_segs, count, ppos, 1);
if (!io->async && res > 0)
fuse_write_update_size(inode, *ppos);
}
fuse_invalidate_attr(inode);
@ -1391,6 +1388,8 @@ static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
/* Don't allow parallel writes to the same file */
mutex_lock(&inode->i_mutex);
res = __fuse_direct_write(&io, &iov, 1, ppos);
if (res > 0)
fuse_write_update_size(inode, *ppos);
mutex_unlock(&inode->i_mutex);
return res;
@ -2360,23 +2359,61 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
ssize_t ret = 0;
struct file *file = NULL;
loff_t pos = 0;
struct inode *inode;
loff_t i_size;
size_t count = iov_length(iov, nr_segs);
struct fuse_io_priv *io;
file = iocb->ki_filp;
pos = offset;
inode = file->f_mapping->host;
i_size = i_size_read(inode);
io = kzalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
if (!io)
return -ENOMEM;
spin_lock_init(&io->lock);
io->reqs = 1;
io->bytes = -1;
io->size = 0;
io->offset = offset;
io->write = (rw == WRITE);
io->err = 0;
io->file = file;
/*
* By default, we want to optimize all I/Os with async request
* submission to the client filesystem.
*/
io->async = 1;
io->iocb = iocb;
/*
* We cannot asynchronously extend the size of a file. We have no method
* to wait on real async I/O requests, so we must submit this request
* synchronously.
*/
if (!is_sync_kiocb(iocb) && (offset + count > i_size) && rw == WRITE)
io->async = false;
if (rw == WRITE)
ret = __fuse_direct_write(io, iov, nr_segs, &pos);
else
ret = __fuse_direct_read(io, iov, nr_segs, &pos);
kfree(io);
if (io->async) {
fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
/* we have a non-extending, async request, so return */
if (ret > 0 && !is_sync_kiocb(iocb))
return -EIOCBQUEUED;
ret = wait_on_sync_kiocb(iocb);
} else {
kfree(io);
}
if (rw == WRITE && ret > 0)
fuse_write_update_size(inode, pos);
return ret;
}