io_submit() could return -EAGAIN on memory allocation failure when it should
really have been returning -ENOMEM. This could confuse applications (i.e. fio)
since -EAGAIN means "too many requests outstanding, wait until completions have
been reaped" and if the application actually was tracking outstanding
completions this wouldn't make a lot of sense.
NOTE:
the man page seems to imply that the current behaviour (-EAGAIN on allocation
failure) has always been the case. I don't think it makes a lot of sense, but
this should probably be discussed more widely in case applications have somehow
come to rely on the current behaviour...
Signed-off-by: Kent Overstreet <k...@daterainc.com>
Cc: Benjamin LaHaise <b...@kvack.org>
Cc: Zach Brown <z...@zabbo.net>
Cc: Jeff Moyer <jmo...@redhat.com>
Cc: Jens Axboe <ax...@kernel.dk>
Cc: Slava Pestov <s...@daterainc.com>
---
fs/aio.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 733750096b..556547044b 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -933,23 +933,14 @@ static inline struct kiocb *aio_get_req(struct kioctx
*ctx)
{
struct kiocb *req;
- if (!get_reqs_available(ctx)) {
- user_refill_reqs_available(ctx);
- if (!get_reqs_available(ctx))
- return NULL;
- }
-
req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
if (unlikely(!req))
- goto out_put;
+ return NULL;
percpu_ref_get(&ctx->reqs);
req->ki_ctx = ctx;
return req;
-out_put:
- put_reqs_available(ctx, 1);
- return NULL;
}
static void kiocb_free(struct kiocb *req)
@@ -1489,9 +1480,17 @@ static int io_submit_one(struct kioctx *ctx, struct iocb
__user *user_iocb,
return -EINVAL;
}
+ if (!get_reqs_available(ctx)) {
+ user_refill_reqs_available(ctx);
+ if (!get_reqs_available(ctx))
+ return -EAGAIN;
+ }
+
req = aio_get_req(ctx);
- if (unlikely(!req))
- return -EAGAIN;
+ if (unlikely(!req)) {
+ ret = -ENOMEM;
+ goto out_put;
+ }
req->ki_filp = fget(iocb->aio_fildes);
if (unlikely(!req->ki_filp)) {
@@ -1533,9 +1532,10 @@ static int io_submit_one(struct kioctx *ctx, struct iocb
__user *user_iocb,
return 0;
out_put_req:
- put_reqs_available(ctx, 1);
percpu_ref_put(&ctx->reqs);
kiocb_free(req);
+out_put:
+ put_reqs_available(ctx, 1);
return ret;
}
--
2.1.1
--
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