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pin iocb through aio. 

aio_poll() is not the only case that needs file pinned; worse, while
aio_read()/aio_write() can live without pinning iocb itself, the
proof is rather brittle and can easily break on later changes.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Linus Torvalds 2019-03-06 20:22:54 -05:00 committed by Al Viro
parent 9e98c678c2
commit b53119f13a
1 changed files with 21 additions and 16 deletions
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37
fs/aio.c
View File

@ -1022,6 +1022,9 @@ static bool get_reqs_available(struct kioctx *ctx)
/* aio_get_req
* Allocate a slot for an aio request.
* Returns NULL if no requests are free.
*
* The refcount is initialized to 2 - one for the async op completion,
* one for the synchronous code that does this.
*/
static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
{
@ -1034,7 +1037,7 @@ static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
percpu_ref_get(&ctx->reqs);
req->ki_ctx = ctx;
INIT_LIST_HEAD(&req->ki_list);
refcount_set(&req->ki_refcnt, 0);
refcount_set(&req->ki_refcnt, 2);
req->ki_eventfd = NULL;
return req;
}
@ -1067,15 +1070,18 @@ out:
return ret;
}
static inline void iocb_destroy(struct aio_kiocb *iocb)
{
if (iocb->ki_filp)
fput(iocb->ki_filp);
percpu_ref_put(&iocb->ki_ctx->reqs);
kmem_cache_free(kiocb_cachep, iocb);
}
static inline void iocb_put(struct aio_kiocb *iocb)
{
if (refcount_read(&iocb->ki_refcnt) == 0 ||
refcount_dec_and_test(&iocb->ki_refcnt)) {
if (iocb->ki_filp)
fput(iocb->ki_filp);
percpu_ref_put(&iocb->ki_ctx->reqs);
kmem_cache_free(kiocb_cachep, iocb);
}
if (refcount_dec_and_test(&iocb->ki_refcnt))
iocb_destroy(iocb);
}
static void aio_fill_event(struct io_event *ev, struct aio_kiocb *iocb,
@ -1749,9 +1755,6 @@ static ssize_t aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
INIT_LIST_HEAD(&req->wait.entry);
init_waitqueue_func_entry(&req->wait, aio_poll_wake);
/* one for removal from waitqueue, one for this function */
refcount_set(&aiocb->ki_refcnt, 2);
mask = vfs_poll(req->file, &apt.pt) & req->events;
if (unlikely(!req->head)) {
/* we did not manage to set up a waitqueue, done */
@ -1782,7 +1785,6 @@ out:
if (mask)
aio_poll_complete(aiocb, mask);
iocb_put(aiocb);
return 0;
}
@ -1873,18 +1875,21 @@ static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
break;
}
/* Done with the synchronous reference */
iocb_put(req);
/*
* If ret is 0, we'd either done aio_complete() ourselves or have
* arranged for that to be done asynchronously. Anything non-zero
* means that we need to destroy req ourselves.
*/
if (ret)
goto out_put_req;
return 0;
if (!ret)
return 0;
out_put_req:
if (req->ki_eventfd)
eventfd_ctx_put(req->ki_eventfd);
iocb_put(req);
iocb_destroy(req);
out_put_reqs_available:
put_reqs_available(ctx, 1);
return ret;